3613 lines
101 KiB
C
3613 lines
101 KiB
C
/*-------------------------------------------------------------------------
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*
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* walsender.c
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*
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* The WAL sender process (walsender) is new as of Postgres 9.0. It takes
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* care of sending XLOG from the primary server to a single recipient.
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* (Note that there can be more than one walsender process concurrently.)
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* It is started by the postmaster when the walreceiver of a standby server
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* connects to the primary server and requests XLOG streaming replication.
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*
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* A walsender is similar to a regular backend, ie. there is a one-to-one
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* relationship between a connection and a walsender process, but instead
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* of processing SQL queries, it understands a small set of special
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* replication-mode commands. The START_REPLICATION command begins streaming
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* WAL to the client. While streaming, the walsender keeps reading XLOG
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* records from the disk and sends them to the standby server over the
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* COPY protocol, until either side ends the replication by exiting COPY
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* mode (or until the connection is closed).
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*
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* Normal termination is by SIGTERM, which instructs the walsender to
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* close the connection and exit(0) at the next convenient moment. Emergency
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* termination is by SIGQUIT; like any backend, the walsender will simply
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* abort and exit on SIGQUIT. A close of the connection and a FATAL error
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* are treated as not a crash but approximately normal termination;
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* the walsender will exit quickly without sending any more XLOG records.
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*
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* If the server is shut down, checkpointer sends us
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* PROCSIG_WALSND_INIT_STOPPING after all regular backends have exited. If
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* the backend is idle or runs an SQL query this causes the backend to
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* shutdown, if logical replication is in progress all existing WAL records
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* are processed followed by a shutdown. Otherwise this causes the walsender
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* to switch to the "stopping" state. In this state, the walsender will reject
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* any further replication commands. The checkpointer begins the shutdown
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* checkpoint once all walsenders are confirmed as stopping. When the shutdown
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* checkpoint finishes, the postmaster sends us SIGUSR2. This instructs
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* walsender to send any outstanding WAL, including the shutdown checkpoint
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* record, wait for it to be replicated to the standby, and then exit.
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*
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*
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* Portions Copyright (c) 2010-2020, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/backend/replication/walsender.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include <signal.h>
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#include <unistd.h>
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#include "access/printtup.h"
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#include "access/timeline.h"
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#include "access/transam.h"
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#include "access/xact.h"
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#include "access/xlog_internal.h"
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#include "access/xlogutils.h"
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#include "catalog/pg_authid.h"
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#include "catalog/pg_type.h"
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#include "commands/dbcommands.h"
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#include "commands/defrem.h"
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#include "funcapi.h"
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#include "libpq/libpq.h"
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#include "libpq/pqformat.h"
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#include "miscadmin.h"
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#include "nodes/replnodes.h"
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#include "pgstat.h"
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#include "postmaster/interrupt.h"
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#include "replication/basebackup.h"
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#include "replication/decode.h"
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#include "replication/logical.h"
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#include "replication/logicalfuncs.h"
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#include "replication/slot.h"
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#include "replication/snapbuild.h"
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#include "replication/syncrep.h"
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#include "replication/walreceiver.h"
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#include "replication/walsender.h"
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#include "replication/walsender_private.h"
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#include "storage/condition_variable.h"
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#include "storage/fd.h"
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#include "storage/ipc.h"
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#include "storage/pmsignal.h"
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#include "storage/proc.h"
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#include "storage/procarray.h"
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#include "tcop/dest.h"
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#include "tcop/tcopprot.h"
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#include "utils/builtins.h"
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#include "utils/guc.h"
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#include "utils/memutils.h"
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#include "utils/pg_lsn.h"
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#include "utils/portal.h"
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#include "utils/ps_status.h"
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#include "utils/timeout.h"
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#include "utils/timestamp.h"
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/*
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* Maximum data payload in a WAL data message. Must be >= XLOG_BLCKSZ.
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*
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* We don't have a good idea of what a good value would be; there's some
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* overhead per message in both walsender and walreceiver, but on the other
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* hand sending large batches makes walsender less responsive to signals
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* because signals are checked only between messages. 128kB (with
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* default 8k blocks) seems like a reasonable guess for now.
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*/
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#define MAX_SEND_SIZE (XLOG_BLCKSZ * 16)
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/* Array of WalSnds in shared memory */
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WalSndCtlData *WalSndCtl = NULL;
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/* My slot in the shared memory array */
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WalSnd *MyWalSnd = NULL;
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/* Global state */
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bool am_walsender = false; /* Am I a walsender process? */
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bool am_cascading_walsender = false; /* Am I cascading WAL to another
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* standby? */
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bool am_db_walsender = false; /* Connected to a database? */
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/* User-settable parameters for walsender */
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int max_wal_senders = 0; /* the maximum number of concurrent
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* walsenders */
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int wal_sender_timeout = 60 * 1000; /* maximum time to send one WAL
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* data message */
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bool log_replication_commands = false;
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/*
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* State for WalSndWakeupRequest
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*/
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bool wake_wal_senders = false;
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static WALOpenSegment *sendSeg = NULL;
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static WALSegmentContext *sendCxt = NULL;
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/*
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* These variables keep track of the state of the timeline we're currently
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* sending. sendTimeLine identifies the timeline. If sendTimeLineIsHistoric,
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* the timeline is not the latest timeline on this server, and the server's
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* history forked off from that timeline at sendTimeLineValidUpto.
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*/
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static TimeLineID sendTimeLine = 0;
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static TimeLineID sendTimeLineNextTLI = 0;
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static bool sendTimeLineIsHistoric = false;
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static XLogRecPtr sendTimeLineValidUpto = InvalidXLogRecPtr;
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/*
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* How far have we sent WAL already? This is also advertised in
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* MyWalSnd->sentPtr. (Actually, this is the next WAL location to send.)
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*/
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static XLogRecPtr sentPtr = 0;
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/* Buffers for constructing outgoing messages and processing reply messages. */
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static StringInfoData output_message;
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static StringInfoData reply_message;
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static StringInfoData tmpbuf;
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/* Timestamp of last ProcessRepliesIfAny(). */
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static TimestampTz last_processing = 0;
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/*
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* Timestamp of last ProcessRepliesIfAny() that saw a reply from the
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* standby. Set to 0 if wal_sender_timeout doesn't need to be active.
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*/
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static TimestampTz last_reply_timestamp = 0;
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/* Have we sent a heartbeat message asking for reply, since last reply? */
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static bool waiting_for_ping_response = false;
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/*
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* While streaming WAL in Copy mode, streamingDoneSending is set to true
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* after we have sent CopyDone. We should not send any more CopyData messages
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* after that. streamingDoneReceiving is set to true when we receive CopyDone
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* from the other end. When both become true, it's time to exit Copy mode.
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*/
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static bool streamingDoneSending;
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static bool streamingDoneReceiving;
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/* Are we there yet? */
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static bool WalSndCaughtUp = false;
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/* Flags set by signal handlers for later service in main loop */
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static volatile sig_atomic_t got_SIGUSR2 = false;
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static volatile sig_atomic_t got_STOPPING = false;
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/*
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* This is set while we are streaming. When not set
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* PROCSIG_WALSND_INIT_STOPPING signal will be handled like SIGTERM. When set,
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* the main loop is responsible for checking got_STOPPING and terminating when
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* it's set (after streaming any remaining WAL).
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*/
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static volatile sig_atomic_t replication_active = false;
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static LogicalDecodingContext *logical_decoding_ctx = NULL;
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/* A sample associating a WAL location with the time it was written. */
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typedef struct
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{
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XLogRecPtr lsn;
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TimestampTz time;
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} WalTimeSample;
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/* The size of our buffer of time samples. */
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#define LAG_TRACKER_BUFFER_SIZE 8192
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/* A mechanism for tracking replication lag. */
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typedef struct
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{
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XLogRecPtr last_lsn;
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WalTimeSample buffer[LAG_TRACKER_BUFFER_SIZE];
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int write_head;
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int read_heads[NUM_SYNC_REP_WAIT_MODE];
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WalTimeSample last_read[NUM_SYNC_REP_WAIT_MODE];
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} LagTracker;
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static LagTracker *lag_tracker;
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/* Signal handlers */
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static void WalSndLastCycleHandler(SIGNAL_ARGS);
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/* Prototypes for private functions */
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typedef void (*WalSndSendDataCallback) (void);
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static void WalSndLoop(WalSndSendDataCallback send_data);
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static void InitWalSenderSlot(void);
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static void WalSndKill(int code, Datum arg);
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static void WalSndShutdown(void) pg_attribute_noreturn();
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static void XLogSendPhysical(void);
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static void XLogSendLogical(void);
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static void WalSndDone(WalSndSendDataCallback send_data);
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static XLogRecPtr GetStandbyFlushRecPtr(void);
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static void IdentifySystem(void);
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static void CreateReplicationSlot(CreateReplicationSlotCmd *cmd);
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static void DropReplicationSlot(DropReplicationSlotCmd *cmd);
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static void StartReplication(StartReplicationCmd *cmd);
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static void StartLogicalReplication(StartReplicationCmd *cmd);
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static void ProcessStandbyMessage(void);
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static void ProcessStandbyReplyMessage(void);
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static void ProcessStandbyHSFeedbackMessage(void);
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static void ProcessRepliesIfAny(void);
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static void WalSndKeepalive(bool requestReply);
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static void WalSndKeepaliveIfNecessary(void);
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static void WalSndCheckTimeOut(void);
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static long WalSndComputeSleeptime(TimestampTz now);
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static void WalSndPrepareWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write);
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static void WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write);
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static void WalSndUpdateProgress(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid);
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static XLogRecPtr WalSndWaitForWal(XLogRecPtr loc);
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static void LagTrackerWrite(XLogRecPtr lsn, TimestampTz local_flush_time);
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static TimeOffset LagTrackerRead(int head, XLogRecPtr lsn, TimestampTz now);
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static bool TransactionIdInRecentPast(TransactionId xid, uint32 epoch);
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static int WalSndSegmentOpen(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
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TimeLineID *tli_p);
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static void UpdateSpillStats(LogicalDecodingContext *ctx);
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/* Initialize walsender process before entering the main command loop */
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void
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InitWalSender(void)
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{
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am_cascading_walsender = RecoveryInProgress();
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/* Create a per-walsender data structure in shared memory */
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InitWalSenderSlot();
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/*
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* We don't currently need any ResourceOwner in a walsender process, but
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* if we did, we could call CreateAuxProcessResourceOwner here.
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*/
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/*
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* Let postmaster know that we're a WAL sender. Once we've declared us as
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* a WAL sender process, postmaster will let us outlive the bgwriter and
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* kill us last in the shutdown sequence, so we get a chance to stream all
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* remaining WAL at shutdown, including the shutdown checkpoint. Note that
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* there's no going back, and we mustn't write any WAL records after this.
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*/
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MarkPostmasterChildWalSender();
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SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
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/* Initialize empty timestamp buffer for lag tracking. */
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lag_tracker = MemoryContextAllocZero(TopMemoryContext, sizeof(LagTracker));
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/* Make sure we can remember the current read position in XLOG. */
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sendSeg = (WALOpenSegment *)
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MemoryContextAlloc(TopMemoryContext, sizeof(WALOpenSegment));
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sendCxt = (WALSegmentContext *)
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MemoryContextAlloc(TopMemoryContext, sizeof(WALSegmentContext));
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WALOpenSegmentInit(sendSeg, sendCxt, wal_segment_size, NULL);
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}
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/*
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* Clean up after an error.
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*
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* WAL sender processes don't use transactions like regular backends do.
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* This function does any cleanup required after an error in a WAL sender
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* process, similar to what transaction abort does in a regular backend.
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*/
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void
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WalSndErrorCleanup(void)
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{
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LWLockReleaseAll();
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ConditionVariableCancelSleep();
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pgstat_report_wait_end();
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if (sendSeg->ws_file >= 0)
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{
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close(sendSeg->ws_file);
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sendSeg->ws_file = -1;
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}
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if (MyReplicationSlot != NULL)
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ReplicationSlotRelease();
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ReplicationSlotCleanup();
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replication_active = false;
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if (got_STOPPING || got_SIGUSR2)
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proc_exit(0);
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/* Revert back to startup state */
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WalSndSetState(WALSNDSTATE_STARTUP);
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}
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/*
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* Handle a client's connection abort in an orderly manner.
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*/
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static void
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WalSndShutdown(void)
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{
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/*
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* Reset whereToSendOutput to prevent ereport from attempting to send any
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* more messages to the standby.
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*/
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if (whereToSendOutput == DestRemote)
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whereToSendOutput = DestNone;
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proc_exit(0);
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abort(); /* keep the compiler quiet */
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}
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/*
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* Handle the IDENTIFY_SYSTEM command.
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*/
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static void
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IdentifySystem(void)
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{
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char sysid[32];
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char xloc[MAXFNAMELEN];
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XLogRecPtr logptr;
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char *dbname = NULL;
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DestReceiver *dest;
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TupOutputState *tstate;
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TupleDesc tupdesc;
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Datum values[4];
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bool nulls[4];
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/*
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* Reply with a result set with one row, four columns. First col is system
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* ID, second is timeline ID, third is current xlog location and the
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* fourth contains the database name if we are connected to one.
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*/
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snprintf(sysid, sizeof(sysid), UINT64_FORMAT,
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GetSystemIdentifier());
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am_cascading_walsender = RecoveryInProgress();
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if (am_cascading_walsender)
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{
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/* this also updates ThisTimeLineID */
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logptr = GetStandbyFlushRecPtr();
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}
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else
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logptr = GetFlushRecPtr();
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snprintf(xloc, sizeof(xloc), "%X/%X", (uint32) (logptr >> 32), (uint32) logptr);
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if (MyDatabaseId != InvalidOid)
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{
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MemoryContext cur = CurrentMemoryContext;
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/* syscache access needs a transaction env. */
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StartTransactionCommand();
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/* make dbname live outside TX context */
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MemoryContextSwitchTo(cur);
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dbname = get_database_name(MyDatabaseId);
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CommitTransactionCommand();
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/* CommitTransactionCommand switches to TopMemoryContext */
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MemoryContextSwitchTo(cur);
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}
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dest = CreateDestReceiver(DestRemoteSimple);
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MemSet(nulls, false, sizeof(nulls));
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/* need a tuple descriptor representing four columns */
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tupdesc = CreateTemplateTupleDesc(4);
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TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "systemid",
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TEXTOID, -1, 0);
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TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "timeline",
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INT4OID, -1, 0);
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TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "xlogpos",
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TEXTOID, -1, 0);
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TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 4, "dbname",
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TEXTOID, -1, 0);
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/* prepare for projection of tuples */
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tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
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/* column 1: system identifier */
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values[0] = CStringGetTextDatum(sysid);
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/* column 2: timeline */
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values[1] = Int32GetDatum(ThisTimeLineID);
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/* column 3: wal location */
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values[2] = CStringGetTextDatum(xloc);
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/* column 4: database name, or NULL if none */
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if (dbname)
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values[3] = CStringGetTextDatum(dbname);
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else
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nulls[3] = true;
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/* send it to dest */
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do_tup_output(tstate, values, nulls);
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end_tup_output(tstate);
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}
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/*
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* Handle TIMELINE_HISTORY command.
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*/
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static void
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SendTimeLineHistory(TimeLineHistoryCmd *cmd)
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{
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StringInfoData buf;
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char histfname[MAXFNAMELEN];
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char path[MAXPGPATH];
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int fd;
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off_t histfilelen;
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off_t bytesleft;
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Size len;
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/*
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* Reply with a result set with one row, and two columns. The first col is
|
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* the name of the history file, 2nd is the contents.
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*/
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TLHistoryFileName(histfname, cmd->timeline);
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TLHistoryFilePath(path, cmd->timeline);
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/* Send a RowDescription message */
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pq_beginmessage(&buf, 'T');
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pq_sendint16(&buf, 2); /* 2 fields */
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/* first field */
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pq_sendstring(&buf, "filename"); /* col name */
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pq_sendint32(&buf, 0); /* table oid */
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pq_sendint16(&buf, 0); /* attnum */
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pq_sendint32(&buf, TEXTOID); /* type oid */
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pq_sendint16(&buf, -1); /* typlen */
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pq_sendint32(&buf, 0); /* typmod */
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pq_sendint16(&buf, 0); /* format code */
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/* second field */
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pq_sendstring(&buf, "content"); /* col name */
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pq_sendint32(&buf, 0); /* table oid */
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pq_sendint16(&buf, 0); /* attnum */
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pq_sendint32(&buf, BYTEAOID); /* type oid */
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pq_sendint16(&buf, -1); /* typlen */
|
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pq_sendint32(&buf, 0); /* typmod */
|
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pq_sendint16(&buf, 0); /* format code */
|
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pq_endmessage(&buf);
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|
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/* Send a DataRow message */
|
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pq_beginmessage(&buf, 'D');
|
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pq_sendint16(&buf, 2); /* # of columns */
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len = strlen(histfname);
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pq_sendint32(&buf, len); /* col1 len */
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pq_sendbytes(&buf, histfname, len);
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|
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fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
|
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if (fd < 0)
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ereport(ERROR,
|
|
(errcode_for_file_access(),
|
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errmsg("could not open file \"%s\": %m", path)));
|
|
|
|
/* Determine file length and send it to client */
|
|
histfilelen = lseek(fd, 0, SEEK_END);
|
|
if (histfilelen < 0)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not seek to end of file \"%s\": %m", path)));
|
|
if (lseek(fd, 0, SEEK_SET) != 0)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not seek to beginning of file \"%s\": %m", path)));
|
|
|
|
pq_sendint32(&buf, histfilelen); /* col2 len */
|
|
|
|
bytesleft = histfilelen;
|
|
while (bytesleft > 0)
|
|
{
|
|
PGAlignedBlock rbuf;
|
|
int nread;
|
|
|
|
pgstat_report_wait_start(WAIT_EVENT_WALSENDER_TIMELINE_HISTORY_READ);
|
|
nread = read(fd, rbuf.data, sizeof(rbuf));
|
|
pgstat_report_wait_end();
|
|
if (nread < 0)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not read file \"%s\": %m",
|
|
path)));
|
|
else if (nread == 0)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DATA_CORRUPTED),
|
|
errmsg("could not read file \"%s\": read %d of %zu",
|
|
path, nread, (Size) bytesleft)));
|
|
|
|
pq_sendbytes(&buf, rbuf.data, nread);
|
|
bytesleft -= nread;
|
|
}
|
|
|
|
if (CloseTransientFile(fd) != 0)
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not close file \"%s\": %m", path)));
|
|
|
|
pq_endmessage(&buf);
|
|
}
|
|
|
|
/*
|
|
* Handle START_REPLICATION command.
|
|
*
|
|
* At the moment, this never returns, but an ereport(ERROR) will take us back
|
|
* to the main loop.
|
|
*/
|
|
static void
|
|
StartReplication(StartReplicationCmd *cmd)
|
|
{
|
|
StringInfoData buf;
|
|
XLogRecPtr FlushPtr;
|
|
|
|
if (ThisTimeLineID == 0)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
|
|
errmsg("IDENTIFY_SYSTEM has not been run before START_REPLICATION")));
|
|
|
|
/*
|
|
* We assume here that we're logging enough information in the WAL for
|
|
* log-shipping, since this is checked in PostmasterMain().
|
|
*
|
|
* NOTE: wal_level can only change at shutdown, so in most cases it is
|
|
* difficult for there to be WAL data that we can still see that was
|
|
* written at wal_level='minimal'.
|
|
*/
|
|
|
|
if (cmd->slotname)
|
|
{
|
|
ReplicationSlotAcquire(cmd->slotname, true);
|
|
if (SlotIsLogical(MyReplicationSlot))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
|
|
(errmsg("cannot use a logical replication slot for physical replication"))));
|
|
}
|
|
|
|
/*
|
|
* Select the timeline. If it was given explicitly by the client, use
|
|
* that. Otherwise use the timeline of the last replayed record, which is
|
|
* kept in ThisTimeLineID.
|
|
*/
|
|
if (am_cascading_walsender)
|
|
{
|
|
/* this also updates ThisTimeLineID */
|
|
FlushPtr = GetStandbyFlushRecPtr();
|
|
}
|
|
else
|
|
FlushPtr = GetFlushRecPtr();
|
|
|
|
if (cmd->timeline != 0)
|
|
{
|
|
XLogRecPtr switchpoint;
|
|
|
|
sendTimeLine = cmd->timeline;
|
|
if (sendTimeLine == ThisTimeLineID)
|
|
{
|
|
sendTimeLineIsHistoric = false;
|
|
sendTimeLineValidUpto = InvalidXLogRecPtr;
|
|
}
|
|
else
|
|
{
|
|
List *timeLineHistory;
|
|
|
|
sendTimeLineIsHistoric = true;
|
|
|
|
/*
|
|
* Check that the timeline the client requested exists, and the
|
|
* requested start location is on that timeline.
|
|
*/
|
|
timeLineHistory = readTimeLineHistory(ThisTimeLineID);
|
|
switchpoint = tliSwitchPoint(cmd->timeline, timeLineHistory,
|
|
&sendTimeLineNextTLI);
|
|
list_free_deep(timeLineHistory);
|
|
|
|
/*
|
|
* Found the requested timeline in the history. Check that
|
|
* requested startpoint is on that timeline in our history.
|
|
*
|
|
* This is quite loose on purpose. We only check that we didn't
|
|
* fork off the requested timeline before the switchpoint. We
|
|
* don't check that we switched *to* it before the requested
|
|
* starting point. This is because the client can legitimately
|
|
* request to start replication from the beginning of the WAL
|
|
* segment that contains switchpoint, but on the new timeline, so
|
|
* that it doesn't end up with a partial segment. If you ask for
|
|
* too old a starting point, you'll get an error later when we
|
|
* fail to find the requested WAL segment in pg_wal.
|
|
*
|
|
* XXX: we could be more strict here and only allow a startpoint
|
|
* that's older than the switchpoint, if it's still in the same
|
|
* WAL segment.
|
|
*/
|
|
if (!XLogRecPtrIsInvalid(switchpoint) &&
|
|
switchpoint < cmd->startpoint)
|
|
{
|
|
ereport(ERROR,
|
|
(errmsg("requested starting point %X/%X on timeline %u is not in this server's history",
|
|
(uint32) (cmd->startpoint >> 32),
|
|
(uint32) (cmd->startpoint),
|
|
cmd->timeline),
|
|
errdetail("This server's history forked from timeline %u at %X/%X.",
|
|
cmd->timeline,
|
|
(uint32) (switchpoint >> 32),
|
|
(uint32) (switchpoint))));
|
|
}
|
|
sendTimeLineValidUpto = switchpoint;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
sendTimeLine = ThisTimeLineID;
|
|
sendTimeLineValidUpto = InvalidXLogRecPtr;
|
|
sendTimeLineIsHistoric = false;
|
|
}
|
|
|
|
streamingDoneSending = streamingDoneReceiving = false;
|
|
|
|
/* If there is nothing to stream, don't even enter COPY mode */
|
|
if (!sendTimeLineIsHistoric || cmd->startpoint < sendTimeLineValidUpto)
|
|
{
|
|
/*
|
|
* When we first start replication the standby will be behind the
|
|
* primary. For some applications, for example synchronous
|
|
* replication, it is important to have a clear state for this initial
|
|
* catchup mode, so we can trigger actions when we change streaming
|
|
* state later. We may stay in this state for a long time, which is
|
|
* exactly why we want to be able to monitor whether or not we are
|
|
* still here.
|
|
*/
|
|
WalSndSetState(WALSNDSTATE_CATCHUP);
|
|
|
|
/* Send a CopyBothResponse message, and start streaming */
|
|
pq_beginmessage(&buf, 'W');
|
|
pq_sendbyte(&buf, 0);
|
|
pq_sendint16(&buf, 0);
|
|
pq_endmessage(&buf);
|
|
pq_flush();
|
|
|
|
/*
|
|
* Don't allow a request to stream from a future point in WAL that
|
|
* hasn't been flushed to disk in this server yet.
|
|
*/
|
|
if (FlushPtr < cmd->startpoint)
|
|
{
|
|
ereport(ERROR,
|
|
(errmsg("requested starting point %X/%X is ahead of the WAL flush position of this server %X/%X",
|
|
(uint32) (cmd->startpoint >> 32),
|
|
(uint32) (cmd->startpoint),
|
|
(uint32) (FlushPtr >> 32),
|
|
(uint32) (FlushPtr))));
|
|
}
|
|
|
|
/* Start streaming from the requested point */
|
|
sentPtr = cmd->startpoint;
|
|
|
|
/* Initialize shared memory status, too */
|
|
SpinLockAcquire(&MyWalSnd->mutex);
|
|
MyWalSnd->sentPtr = sentPtr;
|
|
SpinLockRelease(&MyWalSnd->mutex);
|
|
|
|
SyncRepInitConfig();
|
|
|
|
/* Main loop of walsender */
|
|
replication_active = true;
|
|
|
|
WalSndLoop(XLogSendPhysical);
|
|
|
|
replication_active = false;
|
|
if (got_STOPPING)
|
|
proc_exit(0);
|
|
WalSndSetState(WALSNDSTATE_STARTUP);
|
|
|
|
Assert(streamingDoneSending && streamingDoneReceiving);
|
|
}
|
|
|
|
if (cmd->slotname)
|
|
ReplicationSlotRelease();
|
|
|
|
/*
|
|
* Copy is finished now. Send a single-row result set indicating the next
|
|
* timeline.
|
|
*/
|
|
if (sendTimeLineIsHistoric)
|
|
{
|
|
char startpos_str[8 + 1 + 8 + 1];
|
|
DestReceiver *dest;
|
|
TupOutputState *tstate;
|
|
TupleDesc tupdesc;
|
|
Datum values[2];
|
|
bool nulls[2];
|
|
|
|
snprintf(startpos_str, sizeof(startpos_str), "%X/%X",
|
|
(uint32) (sendTimeLineValidUpto >> 32),
|
|
(uint32) sendTimeLineValidUpto);
|
|
|
|
dest = CreateDestReceiver(DestRemoteSimple);
|
|
MemSet(nulls, false, sizeof(nulls));
|
|
|
|
/*
|
|
* Need a tuple descriptor representing two columns. int8 may seem
|
|
* like a surprising data type for this, but in theory int4 would not
|
|
* be wide enough for this, as TimeLineID is unsigned.
|
|
*/
|
|
tupdesc = CreateTemplateTupleDesc(2);
|
|
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "next_tli",
|
|
INT8OID, -1, 0);
|
|
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "next_tli_startpos",
|
|
TEXTOID, -1, 0);
|
|
|
|
/* prepare for projection of tuple */
|
|
tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
|
|
|
|
values[0] = Int64GetDatum((int64) sendTimeLineNextTLI);
|
|
values[1] = CStringGetTextDatum(startpos_str);
|
|
|
|
/* send it to dest */
|
|
do_tup_output(tstate, values, nulls);
|
|
|
|
end_tup_output(tstate);
|
|
}
|
|
|
|
/* Send CommandComplete message */
|
|
pq_puttextmessage('C', "START_STREAMING");
|
|
}
|
|
|
|
/*
|
|
* read_page callback for logical decoding contexts, as a walsender process.
|
|
*
|
|
* Inside the walsender we can do better than logical_read_local_xlog_page,
|
|
* which has to do a plain sleep/busy loop, because the walsender's latch gets
|
|
* set every time WAL is flushed.
|
|
*/
|
|
static int
|
|
logical_read_xlog_page(XLogReaderState *state, XLogRecPtr targetPagePtr, int reqLen,
|
|
XLogRecPtr targetRecPtr, char *cur_page)
|
|
{
|
|
XLogRecPtr flushptr;
|
|
int count;
|
|
WALReadError errinfo;
|
|
XLogSegNo segno;
|
|
|
|
XLogReadDetermineTimeline(state, targetPagePtr, reqLen);
|
|
sendTimeLineIsHistoric = (state->currTLI != ThisTimeLineID);
|
|
sendTimeLine = state->currTLI;
|
|
sendTimeLineValidUpto = state->currTLIValidUntil;
|
|
sendTimeLineNextTLI = state->nextTLI;
|
|
|
|
/* make sure we have enough WAL available */
|
|
flushptr = WalSndWaitForWal(targetPagePtr + reqLen);
|
|
|
|
/* fail if not (implies we are going to shut down) */
|
|
if (flushptr < targetPagePtr + reqLen)
|
|
return -1;
|
|
|
|
if (targetPagePtr + XLOG_BLCKSZ <= flushptr)
|
|
count = XLOG_BLCKSZ; /* more than one block available */
|
|
else
|
|
count = flushptr - targetPagePtr; /* part of the page available */
|
|
|
|
/* now actually read the data, we know it's there */
|
|
if (!WALRead(cur_page,
|
|
targetPagePtr,
|
|
XLOG_BLCKSZ,
|
|
sendSeg->ws_tli, /* Pass the current TLI because only
|
|
* WalSndSegmentOpen controls whether new
|
|
* TLI is needed. */
|
|
sendSeg,
|
|
sendCxt,
|
|
WalSndSegmentOpen,
|
|
&errinfo))
|
|
WALReadRaiseError(&errinfo);
|
|
|
|
/*
|
|
* After reading into the buffer, check that what we read was valid. We do
|
|
* this after reading, because even though the segment was present when we
|
|
* opened it, it might get recycled or removed while we read it. The
|
|
* read() succeeds in that case, but the data we tried to read might
|
|
* already have been overwritten with new WAL records.
|
|
*/
|
|
XLByteToSeg(targetPagePtr, segno, sendCxt->ws_segsize);
|
|
CheckXLogRemoved(segno, sendSeg->ws_tli);
|
|
|
|
return count;
|
|
}
|
|
|
|
/*
|
|
* Process extra options given to CREATE_REPLICATION_SLOT.
|
|
*/
|
|
static void
|
|
parseCreateReplSlotOptions(CreateReplicationSlotCmd *cmd,
|
|
bool *reserve_wal,
|
|
CRSSnapshotAction *snapshot_action)
|
|
{
|
|
ListCell *lc;
|
|
bool snapshot_action_given = false;
|
|
bool reserve_wal_given = false;
|
|
|
|
/* Parse options */
|
|
foreach(lc, cmd->options)
|
|
{
|
|
DefElem *defel = (DefElem *) lfirst(lc);
|
|
|
|
if (strcmp(defel->defname, "export_snapshot") == 0)
|
|
{
|
|
if (snapshot_action_given || cmd->kind != REPLICATION_KIND_LOGICAL)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_SYNTAX_ERROR),
|
|
errmsg("conflicting or redundant options")));
|
|
|
|
snapshot_action_given = true;
|
|
*snapshot_action = defGetBoolean(defel) ? CRS_EXPORT_SNAPSHOT :
|
|
CRS_NOEXPORT_SNAPSHOT;
|
|
}
|
|
else if (strcmp(defel->defname, "use_snapshot") == 0)
|
|
{
|
|
if (snapshot_action_given || cmd->kind != REPLICATION_KIND_LOGICAL)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_SYNTAX_ERROR),
|
|
errmsg("conflicting or redundant options")));
|
|
|
|
snapshot_action_given = true;
|
|
*snapshot_action = CRS_USE_SNAPSHOT;
|
|
}
|
|
else if (strcmp(defel->defname, "reserve_wal") == 0)
|
|
{
|
|
if (reserve_wal_given || cmd->kind != REPLICATION_KIND_PHYSICAL)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_SYNTAX_ERROR),
|
|
errmsg("conflicting or redundant options")));
|
|
|
|
reserve_wal_given = true;
|
|
*reserve_wal = true;
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized option: %s", defel->defname);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Create a new replication slot.
|
|
*/
|
|
static void
|
|
CreateReplicationSlot(CreateReplicationSlotCmd *cmd)
|
|
{
|
|
const char *snapshot_name = NULL;
|
|
char xloc[MAXFNAMELEN];
|
|
char *slot_name;
|
|
bool reserve_wal = false;
|
|
CRSSnapshotAction snapshot_action = CRS_EXPORT_SNAPSHOT;
|
|
DestReceiver *dest;
|
|
TupOutputState *tstate;
|
|
TupleDesc tupdesc;
|
|
Datum values[4];
|
|
bool nulls[4];
|
|
|
|
Assert(!MyReplicationSlot);
|
|
|
|
parseCreateReplSlotOptions(cmd, &reserve_wal, &snapshot_action);
|
|
|
|
/* setup state for XLogRead */
|
|
sendTimeLineIsHistoric = false;
|
|
sendTimeLine = ThisTimeLineID;
|
|
|
|
if (cmd->kind == REPLICATION_KIND_PHYSICAL)
|
|
{
|
|
ReplicationSlotCreate(cmd->slotname, false,
|
|
cmd->temporary ? RS_TEMPORARY : RS_PERSISTENT);
|
|
}
|
|
else
|
|
{
|
|
CheckLogicalDecodingRequirements();
|
|
|
|
/*
|
|
* Initially create persistent slot as ephemeral - that allows us to
|
|
* nicely handle errors during initialization because it'll get
|
|
* dropped if this transaction fails. We'll make it persistent at the
|
|
* end. Temporary slots can be created as temporary from beginning as
|
|
* they get dropped on error as well.
|
|
*/
|
|
ReplicationSlotCreate(cmd->slotname, true,
|
|
cmd->temporary ? RS_TEMPORARY : RS_EPHEMERAL);
|
|
}
|
|
|
|
if (cmd->kind == REPLICATION_KIND_LOGICAL)
|
|
{
|
|
LogicalDecodingContext *ctx;
|
|
bool need_full_snapshot = false;
|
|
|
|
/*
|
|
* Do options check early so that we can bail before calling the
|
|
* DecodingContextFindStartpoint which can take long time.
|
|
*/
|
|
if (snapshot_action == CRS_EXPORT_SNAPSHOT)
|
|
{
|
|
if (IsTransactionBlock())
|
|
ereport(ERROR,
|
|
/*- translator: %s is a CREATE_REPLICATION_SLOT statement */
|
|
(errmsg("%s must not be called inside a transaction",
|
|
"CREATE_REPLICATION_SLOT ... EXPORT_SNAPSHOT")));
|
|
|
|
need_full_snapshot = true;
|
|
}
|
|
else if (snapshot_action == CRS_USE_SNAPSHOT)
|
|
{
|
|
if (!IsTransactionBlock())
|
|
ereport(ERROR,
|
|
/*- translator: %s is a CREATE_REPLICATION_SLOT statement */
|
|
(errmsg("%s must be called inside a transaction",
|
|
"CREATE_REPLICATION_SLOT ... USE_SNAPSHOT")));
|
|
|
|
if (XactIsoLevel != XACT_REPEATABLE_READ)
|
|
ereport(ERROR,
|
|
/*- translator: %s is a CREATE_REPLICATION_SLOT statement */
|
|
(errmsg("%s must be called in REPEATABLE READ isolation mode transaction",
|
|
"CREATE_REPLICATION_SLOT ... USE_SNAPSHOT")));
|
|
|
|
if (FirstSnapshotSet)
|
|
ereport(ERROR,
|
|
/*- translator: %s is a CREATE_REPLICATION_SLOT statement */
|
|
(errmsg("%s must be called before any query",
|
|
"CREATE_REPLICATION_SLOT ... USE_SNAPSHOT")));
|
|
|
|
if (IsSubTransaction())
|
|
ereport(ERROR,
|
|
/*- translator: %s is a CREATE_REPLICATION_SLOT statement */
|
|
(errmsg("%s must not be called in a subtransaction",
|
|
"CREATE_REPLICATION_SLOT ... USE_SNAPSHOT")));
|
|
|
|
need_full_snapshot = true;
|
|
}
|
|
|
|
ctx = CreateInitDecodingContext(cmd->plugin, NIL, need_full_snapshot,
|
|
InvalidXLogRecPtr,
|
|
logical_read_xlog_page,
|
|
WalSndPrepareWrite, WalSndWriteData,
|
|
WalSndUpdateProgress);
|
|
|
|
/*
|
|
* Signal that we don't need the timeout mechanism. We're just
|
|
* creating the replication slot and don't yet accept feedback
|
|
* messages or send keepalives. As we possibly need to wait for
|
|
* further WAL the walsender would otherwise possibly be killed too
|
|
* soon.
|
|
*/
|
|
last_reply_timestamp = 0;
|
|
|
|
/* build initial snapshot, might take a while */
|
|
DecodingContextFindStartpoint(ctx);
|
|
|
|
/*
|
|
* Export or use the snapshot if we've been asked to do so.
|
|
*
|
|
* NB. We will convert the snapbuild.c kind of snapshot to normal
|
|
* snapshot when doing this.
|
|
*/
|
|
if (snapshot_action == CRS_EXPORT_SNAPSHOT)
|
|
{
|
|
snapshot_name = SnapBuildExportSnapshot(ctx->snapshot_builder);
|
|
}
|
|
else if (snapshot_action == CRS_USE_SNAPSHOT)
|
|
{
|
|
Snapshot snap;
|
|
|
|
snap = SnapBuildInitialSnapshot(ctx->snapshot_builder);
|
|
RestoreTransactionSnapshot(snap, MyProc);
|
|
}
|
|
|
|
/* don't need the decoding context anymore */
|
|
FreeDecodingContext(ctx);
|
|
|
|
if (!cmd->temporary)
|
|
ReplicationSlotPersist();
|
|
}
|
|
else if (cmd->kind == REPLICATION_KIND_PHYSICAL && reserve_wal)
|
|
{
|
|
ReplicationSlotReserveWal();
|
|
|
|
ReplicationSlotMarkDirty();
|
|
|
|
/* Write this slot to disk if it's a permanent one. */
|
|
if (!cmd->temporary)
|
|
ReplicationSlotSave();
|
|
}
|
|
|
|
snprintf(xloc, sizeof(xloc), "%X/%X",
|
|
(uint32) (MyReplicationSlot->data.confirmed_flush >> 32),
|
|
(uint32) MyReplicationSlot->data.confirmed_flush);
|
|
|
|
dest = CreateDestReceiver(DestRemoteSimple);
|
|
MemSet(nulls, false, sizeof(nulls));
|
|
|
|
/*----------
|
|
* Need a tuple descriptor representing four columns:
|
|
* - first field: the slot name
|
|
* - second field: LSN at which we became consistent
|
|
* - third field: exported snapshot's name
|
|
* - fourth field: output plugin
|
|
*----------
|
|
*/
|
|
tupdesc = CreateTemplateTupleDesc(4);
|
|
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 1, "slot_name",
|
|
TEXTOID, -1, 0);
|
|
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 2, "consistent_point",
|
|
TEXTOID, -1, 0);
|
|
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 3, "snapshot_name",
|
|
TEXTOID, -1, 0);
|
|
TupleDescInitBuiltinEntry(tupdesc, (AttrNumber) 4, "output_plugin",
|
|
TEXTOID, -1, 0);
|
|
|
|
/* prepare for projection of tuples */
|
|
tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsVirtual);
|
|
|
|
/* slot_name */
|
|
slot_name = NameStr(MyReplicationSlot->data.name);
|
|
values[0] = CStringGetTextDatum(slot_name);
|
|
|
|
/* consistent wal location */
|
|
values[1] = CStringGetTextDatum(xloc);
|
|
|
|
/* snapshot name, or NULL if none */
|
|
if (snapshot_name != NULL)
|
|
values[2] = CStringGetTextDatum(snapshot_name);
|
|
else
|
|
nulls[2] = true;
|
|
|
|
/* plugin, or NULL if none */
|
|
if (cmd->plugin != NULL)
|
|
values[3] = CStringGetTextDatum(cmd->plugin);
|
|
else
|
|
nulls[3] = true;
|
|
|
|
/* send it to dest */
|
|
do_tup_output(tstate, values, nulls);
|
|
end_tup_output(tstate);
|
|
|
|
ReplicationSlotRelease();
|
|
}
|
|
|
|
/*
|
|
* Get rid of a replication slot that is no longer wanted.
|
|
*/
|
|
static void
|
|
DropReplicationSlot(DropReplicationSlotCmd *cmd)
|
|
{
|
|
ReplicationSlotDrop(cmd->slotname, !cmd->wait);
|
|
EndCommand("DROP_REPLICATION_SLOT", DestRemote);
|
|
}
|
|
|
|
/*
|
|
* Load previously initiated logical slot and prepare for sending data (via
|
|
* WalSndLoop).
|
|
*/
|
|
static void
|
|
StartLogicalReplication(StartReplicationCmd *cmd)
|
|
{
|
|
StringInfoData buf;
|
|
|
|
/* make sure that our requirements are still fulfilled */
|
|
CheckLogicalDecodingRequirements();
|
|
|
|
Assert(!MyReplicationSlot);
|
|
|
|
ReplicationSlotAcquire(cmd->slotname, true);
|
|
|
|
/*
|
|
* Force a disconnect, so that the decoding code doesn't need to care
|
|
* about an eventual switch from running in recovery, to running in a
|
|
* normal environment. Client code is expected to handle reconnects.
|
|
*/
|
|
if (am_cascading_walsender && !RecoveryInProgress())
|
|
{
|
|
ereport(LOG,
|
|
(errmsg("terminating walsender process after promotion")));
|
|
got_STOPPING = true;
|
|
}
|
|
|
|
/*
|
|
* Create our decoding context, making it start at the previously ack'ed
|
|
* position.
|
|
*
|
|
* Do this before sending a CopyBothResponse message, so that any errors
|
|
* are reported early.
|
|
*/
|
|
logical_decoding_ctx =
|
|
CreateDecodingContext(cmd->startpoint, cmd->options, false,
|
|
logical_read_xlog_page,
|
|
WalSndPrepareWrite, WalSndWriteData,
|
|
WalSndUpdateProgress);
|
|
|
|
|
|
WalSndSetState(WALSNDSTATE_CATCHUP);
|
|
|
|
/* Send a CopyBothResponse message, and start streaming */
|
|
pq_beginmessage(&buf, 'W');
|
|
pq_sendbyte(&buf, 0);
|
|
pq_sendint16(&buf, 0);
|
|
pq_endmessage(&buf);
|
|
pq_flush();
|
|
|
|
/* Start reading WAL from the oldest required WAL. */
|
|
XLogBeginRead(logical_decoding_ctx->reader,
|
|
MyReplicationSlot->data.restart_lsn);
|
|
|
|
/*
|
|
* Report the location after which we'll send out further commits as the
|
|
* current sentPtr.
|
|
*/
|
|
sentPtr = MyReplicationSlot->data.confirmed_flush;
|
|
|
|
/* Also update the sent position status in shared memory */
|
|
SpinLockAcquire(&MyWalSnd->mutex);
|
|
MyWalSnd->sentPtr = MyReplicationSlot->data.restart_lsn;
|
|
SpinLockRelease(&MyWalSnd->mutex);
|
|
|
|
replication_active = true;
|
|
|
|
SyncRepInitConfig();
|
|
|
|
/* Main loop of walsender */
|
|
WalSndLoop(XLogSendLogical);
|
|
|
|
FreeDecodingContext(logical_decoding_ctx);
|
|
ReplicationSlotRelease();
|
|
|
|
replication_active = false;
|
|
if (got_STOPPING)
|
|
proc_exit(0);
|
|
WalSndSetState(WALSNDSTATE_STARTUP);
|
|
|
|
/* Get out of COPY mode (CommandComplete). */
|
|
EndCommand("COPY 0", DestRemote);
|
|
}
|
|
|
|
/*
|
|
* LogicalDecodingContext 'prepare_write' callback.
|
|
*
|
|
* Prepare a write into a StringInfo.
|
|
*
|
|
* Don't do anything lasting in here, it's quite possible that nothing will be done
|
|
* with the data.
|
|
*/
|
|
static void
|
|
WalSndPrepareWrite(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid, bool last_write)
|
|
{
|
|
/* can't have sync rep confused by sending the same LSN several times */
|
|
if (!last_write)
|
|
lsn = InvalidXLogRecPtr;
|
|
|
|
resetStringInfo(ctx->out);
|
|
|
|
pq_sendbyte(ctx->out, 'w');
|
|
pq_sendint64(ctx->out, lsn); /* dataStart */
|
|
pq_sendint64(ctx->out, lsn); /* walEnd */
|
|
|
|
/*
|
|
* Fill out the sendtime later, just as it's done in XLogSendPhysical, but
|
|
* reserve space here.
|
|
*/
|
|
pq_sendint64(ctx->out, 0); /* sendtime */
|
|
}
|
|
|
|
/*
|
|
* LogicalDecodingContext 'write' callback.
|
|
*
|
|
* Actually write out data previously prepared by WalSndPrepareWrite out to
|
|
* the network. Take as long as needed, but process replies from the other
|
|
* side and check timeouts during that.
|
|
*/
|
|
static void
|
|
WalSndWriteData(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid,
|
|
bool last_write)
|
|
{
|
|
TimestampTz now;
|
|
|
|
/*
|
|
* Fill the send timestamp last, so that it is taken as late as possible.
|
|
* This is somewhat ugly, but the protocol is set as it's already used for
|
|
* several releases by streaming physical replication.
|
|
*/
|
|
resetStringInfo(&tmpbuf);
|
|
now = GetCurrentTimestamp();
|
|
pq_sendint64(&tmpbuf, now);
|
|
memcpy(&ctx->out->data[1 + sizeof(int64) + sizeof(int64)],
|
|
tmpbuf.data, sizeof(int64));
|
|
|
|
/* output previously gathered data in a CopyData packet */
|
|
pq_putmessage_noblock('d', ctx->out->data, ctx->out->len);
|
|
|
|
CHECK_FOR_INTERRUPTS();
|
|
|
|
/* Try to flush pending output to the client */
|
|
if (pq_flush_if_writable() != 0)
|
|
WalSndShutdown();
|
|
|
|
/* Try taking fast path unless we get too close to walsender timeout. */
|
|
if (now < TimestampTzPlusMilliseconds(last_reply_timestamp,
|
|
wal_sender_timeout / 2) &&
|
|
!pq_is_send_pending())
|
|
{
|
|
return;
|
|
}
|
|
|
|
/* If we have pending write here, go to slow path */
|
|
for (;;)
|
|
{
|
|
int wakeEvents;
|
|
long sleeptime;
|
|
|
|
/* Check for input from the client */
|
|
ProcessRepliesIfAny();
|
|
|
|
/* die if timeout was reached */
|
|
WalSndCheckTimeOut();
|
|
|
|
/* Send keepalive if the time has come */
|
|
WalSndKeepaliveIfNecessary();
|
|
|
|
if (!pq_is_send_pending())
|
|
break;
|
|
|
|
sleeptime = WalSndComputeSleeptime(GetCurrentTimestamp());
|
|
|
|
wakeEvents = WL_LATCH_SET | WL_EXIT_ON_PM_DEATH |
|
|
WL_SOCKET_WRITEABLE | WL_SOCKET_READABLE | WL_TIMEOUT;
|
|
|
|
/* Sleep until something happens or we time out */
|
|
(void) WaitLatchOrSocket(MyLatch, wakeEvents,
|
|
MyProcPort->sock, sleeptime,
|
|
WAIT_EVENT_WAL_SENDER_WRITE_DATA);
|
|
|
|
/* Clear any already-pending wakeups */
|
|
ResetLatch(MyLatch);
|
|
|
|
CHECK_FOR_INTERRUPTS();
|
|
|
|
/* Process any requests or signals received recently */
|
|
if (ConfigReloadPending)
|
|
{
|
|
ConfigReloadPending = false;
|
|
ProcessConfigFile(PGC_SIGHUP);
|
|
SyncRepInitConfig();
|
|
}
|
|
|
|
/* Try to flush pending output to the client */
|
|
if (pq_flush_if_writable() != 0)
|
|
WalSndShutdown();
|
|
}
|
|
|
|
/* reactivate latch so WalSndLoop knows to continue */
|
|
SetLatch(MyLatch);
|
|
}
|
|
|
|
/*
|
|
* LogicalDecodingContext 'update_progress' callback.
|
|
*
|
|
* Write the current position to the lag tracker (see XLogSendPhysical),
|
|
* and update the spill statistics.
|
|
*/
|
|
static void
|
|
WalSndUpdateProgress(LogicalDecodingContext *ctx, XLogRecPtr lsn, TransactionId xid)
|
|
{
|
|
static TimestampTz sendTime = 0;
|
|
TimestampTz now = GetCurrentTimestamp();
|
|
|
|
/*
|
|
* Track lag no more than once per WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS to
|
|
* avoid flooding the lag tracker when we commit frequently.
|
|
*/
|
|
#define WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS 1000
|
|
if (!TimestampDifferenceExceeds(sendTime, now,
|
|
WALSND_LOGICAL_LAG_TRACK_INTERVAL_MS))
|
|
return;
|
|
|
|
LagTrackerWrite(lsn, now);
|
|
sendTime = now;
|
|
|
|
/*
|
|
* Update statistics about transactions that spilled to disk.
|
|
*/
|
|
UpdateSpillStats(ctx);
|
|
}
|
|
|
|
/*
|
|
* Wait till WAL < loc is flushed to disk so it can be safely sent to client.
|
|
*
|
|
* Returns end LSN of flushed WAL. Normally this will be >= loc, but
|
|
* if we detect a shutdown request (either from postmaster or client)
|
|
* we will return early, so caller must always check.
|
|
*/
|
|
static XLogRecPtr
|
|
WalSndWaitForWal(XLogRecPtr loc)
|
|
{
|
|
int wakeEvents;
|
|
static XLogRecPtr RecentFlushPtr = InvalidXLogRecPtr;
|
|
|
|
/*
|
|
* Fast path to avoid acquiring the spinlock in case we already know we
|
|
* have enough WAL available. This is particularly interesting if we're
|
|
* far behind.
|
|
*/
|
|
if (RecentFlushPtr != InvalidXLogRecPtr &&
|
|
loc <= RecentFlushPtr)
|
|
return RecentFlushPtr;
|
|
|
|
/* Get a more recent flush pointer. */
|
|
if (!RecoveryInProgress())
|
|
RecentFlushPtr = GetFlushRecPtr();
|
|
else
|
|
RecentFlushPtr = GetXLogReplayRecPtr(NULL);
|
|
|
|
for (;;)
|
|
{
|
|
long sleeptime;
|
|
|
|
/* Clear any already-pending wakeups */
|
|
ResetLatch(MyLatch);
|
|
|
|
CHECK_FOR_INTERRUPTS();
|
|
|
|
/* Process any requests or signals received recently */
|
|
if (ConfigReloadPending)
|
|
{
|
|
ConfigReloadPending = false;
|
|
ProcessConfigFile(PGC_SIGHUP);
|
|
SyncRepInitConfig();
|
|
}
|
|
|
|
/* Check for input from the client */
|
|
ProcessRepliesIfAny();
|
|
|
|
/*
|
|
* If we're shutting down, trigger pending WAL to be written out,
|
|
* otherwise we'd possibly end up waiting for WAL that never gets
|
|
* written, because walwriter has shut down already.
|
|
*/
|
|
if (got_STOPPING)
|
|
XLogBackgroundFlush();
|
|
|
|
/* Update our idea of the currently flushed position. */
|
|
if (!RecoveryInProgress())
|
|
RecentFlushPtr = GetFlushRecPtr();
|
|
else
|
|
RecentFlushPtr = GetXLogReplayRecPtr(NULL);
|
|
|
|
/*
|
|
* If postmaster asked us to stop, don't wait anymore.
|
|
*
|
|
* It's important to do this check after the recomputation of
|
|
* RecentFlushPtr, so we can send all remaining data before shutting
|
|
* down.
|
|
*/
|
|
if (got_STOPPING)
|
|
break;
|
|
|
|
/*
|
|
* We only send regular messages to the client for full decoded
|
|
* transactions, but a synchronous replication and walsender shutdown
|
|
* possibly are waiting for a later location. So we send pings
|
|
* containing the flush location every now and then.
|
|
*/
|
|
if (MyWalSnd->flush < sentPtr &&
|
|
MyWalSnd->write < sentPtr &&
|
|
!waiting_for_ping_response)
|
|
{
|
|
WalSndKeepalive(false);
|
|
waiting_for_ping_response = true;
|
|
}
|
|
|
|
/* check whether we're done */
|
|
if (loc <= RecentFlushPtr)
|
|
break;
|
|
|
|
/* Waiting for new WAL. Since we need to wait, we're now caught up. */
|
|
WalSndCaughtUp = true;
|
|
|
|
/*
|
|
* Try to flush any pending output to the client.
|
|
*/
|
|
if (pq_flush_if_writable() != 0)
|
|
WalSndShutdown();
|
|
|
|
/*
|
|
* If we have received CopyDone from the client, sent CopyDone
|
|
* ourselves, and the output buffer is empty, it's time to exit
|
|
* streaming, so fail the current WAL fetch request.
|
|
*/
|
|
if (streamingDoneReceiving && streamingDoneSending &&
|
|
!pq_is_send_pending())
|
|
break;
|
|
|
|
/* die if timeout was reached */
|
|
WalSndCheckTimeOut();
|
|
|
|
/* Send keepalive if the time has come */
|
|
WalSndKeepaliveIfNecessary();
|
|
|
|
/*
|
|
* Sleep until something happens or we time out. Also wait for the
|
|
* socket becoming writable, if there's still pending output.
|
|
* Otherwise we might sit on sendable output data while waiting for
|
|
* new WAL to be generated. (But if we have nothing to send, we don't
|
|
* want to wake on socket-writable.)
|
|
*/
|
|
sleeptime = WalSndComputeSleeptime(GetCurrentTimestamp());
|
|
|
|
wakeEvents = WL_LATCH_SET | WL_EXIT_ON_PM_DEATH |
|
|
WL_SOCKET_READABLE | WL_TIMEOUT;
|
|
|
|
if (pq_is_send_pending())
|
|
wakeEvents |= WL_SOCKET_WRITEABLE;
|
|
|
|
(void) WaitLatchOrSocket(MyLatch, wakeEvents,
|
|
MyProcPort->sock, sleeptime,
|
|
WAIT_EVENT_WAL_SENDER_WAIT_WAL);
|
|
}
|
|
|
|
/* reactivate latch so WalSndLoop knows to continue */
|
|
SetLatch(MyLatch);
|
|
return RecentFlushPtr;
|
|
}
|
|
|
|
/*
|
|
* Execute an incoming replication command.
|
|
*
|
|
* Returns true if the cmd_string was recognized as WalSender command, false
|
|
* if not.
|
|
*/
|
|
bool
|
|
exec_replication_command(const char *cmd_string)
|
|
{
|
|
int parse_rc;
|
|
Node *cmd_node;
|
|
MemoryContext cmd_context;
|
|
MemoryContext old_context;
|
|
|
|
/*
|
|
* If WAL sender has been told that shutdown is getting close, switch its
|
|
* status accordingly to handle the next replication commands correctly.
|
|
*/
|
|
if (got_STOPPING)
|
|
WalSndSetState(WALSNDSTATE_STOPPING);
|
|
|
|
/*
|
|
* Throw error if in stopping mode. We need prevent commands that could
|
|
* generate WAL while the shutdown checkpoint is being written. To be
|
|
* safe, we just prohibit all new commands.
|
|
*/
|
|
if (MyWalSnd->state == WALSNDSTATE_STOPPING)
|
|
ereport(ERROR,
|
|
(errmsg("cannot execute new commands while WAL sender is in stopping mode")));
|
|
|
|
/*
|
|
* CREATE_REPLICATION_SLOT ... LOGICAL exports a snapshot until the next
|
|
* command arrives. Clean up the old stuff if there's anything.
|
|
*/
|
|
SnapBuildClearExportedSnapshot();
|
|
|
|
CHECK_FOR_INTERRUPTS();
|
|
|
|
cmd_context = AllocSetContextCreate(CurrentMemoryContext,
|
|
"Replication command context",
|
|
ALLOCSET_DEFAULT_SIZES);
|
|
old_context = MemoryContextSwitchTo(cmd_context);
|
|
|
|
replication_scanner_init(cmd_string);
|
|
parse_rc = replication_yyparse();
|
|
if (parse_rc != 0)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_SYNTAX_ERROR),
|
|
(errmsg_internal("replication command parser returned %d",
|
|
parse_rc))));
|
|
|
|
cmd_node = replication_parse_result;
|
|
|
|
/*
|
|
* Log replication command if log_replication_commands is enabled. Even
|
|
* when it's disabled, log the command with DEBUG1 level for backward
|
|
* compatibility. Note that SQL commands are not logged here, and will be
|
|
* logged later if log_statement is enabled.
|
|
*/
|
|
if (cmd_node->type != T_SQLCmd)
|
|
ereport(log_replication_commands ? LOG : DEBUG1,
|
|
(errmsg("received replication command: %s", cmd_string)));
|
|
|
|
/*
|
|
* CREATE_REPLICATION_SLOT ... LOGICAL exports a snapshot. If it was
|
|
* called outside of transaction the snapshot should be cleared here.
|
|
*/
|
|
if (!IsTransactionBlock())
|
|
SnapBuildClearExportedSnapshot();
|
|
|
|
/*
|
|
* For aborted transactions, don't allow anything except pure SQL, the
|
|
* exec_simple_query() will handle it correctly.
|
|
*/
|
|
if (IsAbortedTransactionBlockState() && !IsA(cmd_node, SQLCmd))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
|
|
errmsg("current transaction is aborted, "
|
|
"commands ignored until end of transaction block")));
|
|
|
|
CHECK_FOR_INTERRUPTS();
|
|
|
|
/*
|
|
* Allocate buffers that will be used for each outgoing and incoming
|
|
* message. We do this just once per command to reduce palloc overhead.
|
|
*/
|
|
initStringInfo(&output_message);
|
|
initStringInfo(&reply_message);
|
|
initStringInfo(&tmpbuf);
|
|
|
|
/* Report to pgstat that this process is running */
|
|
pgstat_report_activity(STATE_RUNNING, NULL);
|
|
|
|
switch (cmd_node->type)
|
|
{
|
|
case T_IdentifySystemCmd:
|
|
IdentifySystem();
|
|
break;
|
|
|
|
case T_BaseBackupCmd:
|
|
PreventInTransactionBlock(true, "BASE_BACKUP");
|
|
SendBaseBackup((BaseBackupCmd *) cmd_node);
|
|
break;
|
|
|
|
case T_CreateReplicationSlotCmd:
|
|
CreateReplicationSlot((CreateReplicationSlotCmd *) cmd_node);
|
|
break;
|
|
|
|
case T_DropReplicationSlotCmd:
|
|
DropReplicationSlot((DropReplicationSlotCmd *) cmd_node);
|
|
break;
|
|
|
|
case T_StartReplicationCmd:
|
|
{
|
|
StartReplicationCmd *cmd = (StartReplicationCmd *) cmd_node;
|
|
|
|
PreventInTransactionBlock(true, "START_REPLICATION");
|
|
|
|
if (cmd->kind == REPLICATION_KIND_PHYSICAL)
|
|
StartReplication(cmd);
|
|
else
|
|
StartLogicalReplication(cmd);
|
|
break;
|
|
}
|
|
|
|
case T_TimeLineHistoryCmd:
|
|
PreventInTransactionBlock(true, "TIMELINE_HISTORY");
|
|
SendTimeLineHistory((TimeLineHistoryCmd *) cmd_node);
|
|
break;
|
|
|
|
case T_VariableShowStmt:
|
|
{
|
|
DestReceiver *dest = CreateDestReceiver(DestRemoteSimple);
|
|
VariableShowStmt *n = (VariableShowStmt *) cmd_node;
|
|
|
|
/* syscache access needs a transaction environment */
|
|
StartTransactionCommand();
|
|
GetPGVariable(n->name, dest);
|
|
CommitTransactionCommand();
|
|
}
|
|
break;
|
|
|
|
case T_SQLCmd:
|
|
if (MyDatabaseId == InvalidOid)
|
|
ereport(ERROR,
|
|
(errmsg("cannot execute SQL commands in WAL sender for physical replication")));
|
|
|
|
/* Report to pgstat that this process is now idle */
|
|
pgstat_report_activity(STATE_IDLE, NULL);
|
|
|
|
/* Tell the caller that this wasn't a WalSender command. */
|
|
return false;
|
|
|
|
default:
|
|
elog(ERROR, "unrecognized replication command node tag: %u",
|
|
cmd_node->type);
|
|
}
|
|
|
|
/* done */
|
|
MemoryContextSwitchTo(old_context);
|
|
MemoryContextDelete(cmd_context);
|
|
|
|
/* Send CommandComplete message */
|
|
EndCommand("SELECT", DestRemote);
|
|
|
|
/* Report to pgstat that this process is now idle */
|
|
pgstat_report_activity(STATE_IDLE, NULL);
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Process any incoming messages while streaming. Also checks if the remote
|
|
* end has closed the connection.
|
|
*/
|
|
static void
|
|
ProcessRepliesIfAny(void)
|
|
{
|
|
unsigned char firstchar;
|
|
int r;
|
|
bool received = false;
|
|
|
|
last_processing = GetCurrentTimestamp();
|
|
|
|
for (;;)
|
|
{
|
|
pq_startmsgread();
|
|
r = pq_getbyte_if_available(&firstchar);
|
|
if (r < 0)
|
|
{
|
|
/* unexpected error or EOF */
|
|
ereport(COMMERROR,
|
|
(errcode(ERRCODE_PROTOCOL_VIOLATION),
|
|
errmsg("unexpected EOF on standby connection")));
|
|
proc_exit(0);
|
|
}
|
|
if (r == 0)
|
|
{
|
|
/* no data available without blocking */
|
|
pq_endmsgread();
|
|
break;
|
|
}
|
|
|
|
/* Read the message contents */
|
|
resetStringInfo(&reply_message);
|
|
if (pq_getmessage(&reply_message, 0))
|
|
{
|
|
ereport(COMMERROR,
|
|
(errcode(ERRCODE_PROTOCOL_VIOLATION),
|
|
errmsg("unexpected EOF on standby connection")));
|
|
proc_exit(0);
|
|
}
|
|
|
|
/*
|
|
* If we already received a CopyDone from the frontend, the frontend
|
|
* should not send us anything until we've closed our end of the COPY.
|
|
* XXX: In theory, the frontend could already send the next command
|
|
* before receiving the CopyDone, but libpq doesn't currently allow
|
|
* that.
|
|
*/
|
|
if (streamingDoneReceiving && firstchar != 'X')
|
|
ereport(FATAL,
|
|
(errcode(ERRCODE_PROTOCOL_VIOLATION),
|
|
errmsg("unexpected standby message type \"%c\", after receiving CopyDone",
|
|
firstchar)));
|
|
|
|
/* Handle the very limited subset of commands expected in this phase */
|
|
switch (firstchar)
|
|
{
|
|
/*
|
|
* 'd' means a standby reply wrapped in a CopyData packet.
|
|
*/
|
|
case 'd':
|
|
ProcessStandbyMessage();
|
|
received = true;
|
|
break;
|
|
|
|
/*
|
|
* CopyDone means the standby requested to finish streaming.
|
|
* Reply with CopyDone, if we had not sent that already.
|
|
*/
|
|
case 'c':
|
|
if (!streamingDoneSending)
|
|
{
|
|
pq_putmessage_noblock('c', NULL, 0);
|
|
streamingDoneSending = true;
|
|
}
|
|
|
|
streamingDoneReceiving = true;
|
|
received = true;
|
|
break;
|
|
|
|
/*
|
|
* 'X' means that the standby is closing down the socket.
|
|
*/
|
|
case 'X':
|
|
proc_exit(0);
|
|
|
|
default:
|
|
ereport(FATAL,
|
|
(errcode(ERRCODE_PROTOCOL_VIOLATION),
|
|
errmsg("invalid standby message type \"%c\"",
|
|
firstchar)));
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Save the last reply timestamp if we've received at least one reply.
|
|
*/
|
|
if (received)
|
|
{
|
|
last_reply_timestamp = last_processing;
|
|
waiting_for_ping_response = false;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Process a status update message received from standby.
|
|
*/
|
|
static void
|
|
ProcessStandbyMessage(void)
|
|
{
|
|
char msgtype;
|
|
|
|
/*
|
|
* Check message type from the first byte.
|
|
*/
|
|
msgtype = pq_getmsgbyte(&reply_message);
|
|
|
|
switch (msgtype)
|
|
{
|
|
case 'r':
|
|
ProcessStandbyReplyMessage();
|
|
break;
|
|
|
|
case 'h':
|
|
ProcessStandbyHSFeedbackMessage();
|
|
break;
|
|
|
|
default:
|
|
ereport(COMMERROR,
|
|
(errcode(ERRCODE_PROTOCOL_VIOLATION),
|
|
errmsg("unexpected message type \"%c\"", msgtype)));
|
|
proc_exit(0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Remember that a walreceiver just confirmed receipt of lsn `lsn`.
|
|
*/
|
|
static void
|
|
PhysicalConfirmReceivedLocation(XLogRecPtr lsn)
|
|
{
|
|
bool changed = false;
|
|
ReplicationSlot *slot = MyReplicationSlot;
|
|
|
|
Assert(lsn != InvalidXLogRecPtr);
|
|
SpinLockAcquire(&slot->mutex);
|
|
if (slot->data.restart_lsn != lsn)
|
|
{
|
|
changed = true;
|
|
slot->data.restart_lsn = lsn;
|
|
}
|
|
SpinLockRelease(&slot->mutex);
|
|
|
|
if (changed)
|
|
{
|
|
ReplicationSlotMarkDirty();
|
|
ReplicationSlotsComputeRequiredLSN();
|
|
}
|
|
|
|
/*
|
|
* One could argue that the slot should be saved to disk now, but that'd
|
|
* be energy wasted - the worst lost information can do here is give us
|
|
* wrong information in a statistics view - we'll just potentially be more
|
|
* conservative in removing files.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* Regular reply from standby advising of WAL locations on standby server.
|
|
*/
|
|
static void
|
|
ProcessStandbyReplyMessage(void)
|
|
{
|
|
XLogRecPtr writePtr,
|
|
flushPtr,
|
|
applyPtr;
|
|
bool replyRequested;
|
|
TimeOffset writeLag,
|
|
flushLag,
|
|
applyLag;
|
|
bool clearLagTimes;
|
|
TimestampTz now;
|
|
TimestampTz replyTime;
|
|
|
|
static bool fullyAppliedLastTime = false;
|
|
|
|
/* the caller already consumed the msgtype byte */
|
|
writePtr = pq_getmsgint64(&reply_message);
|
|
flushPtr = pq_getmsgint64(&reply_message);
|
|
applyPtr = pq_getmsgint64(&reply_message);
|
|
replyTime = pq_getmsgint64(&reply_message);
|
|
replyRequested = pq_getmsgbyte(&reply_message);
|
|
|
|
if (log_min_messages <= DEBUG2)
|
|
{
|
|
char *replyTimeStr;
|
|
|
|
/* Copy because timestamptz_to_str returns a static buffer */
|
|
replyTimeStr = pstrdup(timestamptz_to_str(replyTime));
|
|
|
|
elog(DEBUG2, "write %X/%X flush %X/%X apply %X/%X%s reply_time %s",
|
|
(uint32) (writePtr >> 32), (uint32) writePtr,
|
|
(uint32) (flushPtr >> 32), (uint32) flushPtr,
|
|
(uint32) (applyPtr >> 32), (uint32) applyPtr,
|
|
replyRequested ? " (reply requested)" : "",
|
|
replyTimeStr);
|
|
|
|
pfree(replyTimeStr);
|
|
}
|
|
|
|
/* See if we can compute the round-trip lag for these positions. */
|
|
now = GetCurrentTimestamp();
|
|
writeLag = LagTrackerRead(SYNC_REP_WAIT_WRITE, writePtr, now);
|
|
flushLag = LagTrackerRead(SYNC_REP_WAIT_FLUSH, flushPtr, now);
|
|
applyLag = LagTrackerRead(SYNC_REP_WAIT_APPLY, applyPtr, now);
|
|
|
|
/*
|
|
* If the standby reports that it has fully replayed the WAL in two
|
|
* consecutive reply messages, then the second such message must result
|
|
* from wal_receiver_status_interval expiring on the standby. This is a
|
|
* convenient time to forget the lag times measured when it last
|
|
* wrote/flushed/applied a WAL record, to avoid displaying stale lag data
|
|
* until more WAL traffic arrives.
|
|
*/
|
|
clearLagTimes = false;
|
|
if (applyPtr == sentPtr)
|
|
{
|
|
if (fullyAppliedLastTime)
|
|
clearLagTimes = true;
|
|
fullyAppliedLastTime = true;
|
|
}
|
|
else
|
|
fullyAppliedLastTime = false;
|
|
|
|
/* Send a reply if the standby requested one. */
|
|
if (replyRequested)
|
|
WalSndKeepalive(false);
|
|
|
|
/*
|
|
* Update shared state for this WalSender process based on reply data from
|
|
* standby.
|
|
*/
|
|
{
|
|
WalSnd *walsnd = MyWalSnd;
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
walsnd->write = writePtr;
|
|
walsnd->flush = flushPtr;
|
|
walsnd->apply = applyPtr;
|
|
if (writeLag != -1 || clearLagTimes)
|
|
walsnd->writeLag = writeLag;
|
|
if (flushLag != -1 || clearLagTimes)
|
|
walsnd->flushLag = flushLag;
|
|
if (applyLag != -1 || clearLagTimes)
|
|
walsnd->applyLag = applyLag;
|
|
walsnd->replyTime = replyTime;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
}
|
|
|
|
if (!am_cascading_walsender)
|
|
SyncRepReleaseWaiters();
|
|
|
|
/*
|
|
* Advance our local xmin horizon when the client confirmed a flush.
|
|
*/
|
|
if (MyReplicationSlot && flushPtr != InvalidXLogRecPtr)
|
|
{
|
|
if (SlotIsLogical(MyReplicationSlot))
|
|
LogicalConfirmReceivedLocation(flushPtr);
|
|
else
|
|
PhysicalConfirmReceivedLocation(flushPtr);
|
|
}
|
|
}
|
|
|
|
/* compute new replication slot xmin horizon if needed */
|
|
static void
|
|
PhysicalReplicationSlotNewXmin(TransactionId feedbackXmin, TransactionId feedbackCatalogXmin)
|
|
{
|
|
bool changed = false;
|
|
ReplicationSlot *slot = MyReplicationSlot;
|
|
|
|
SpinLockAcquire(&slot->mutex);
|
|
MyPgXact->xmin = InvalidTransactionId;
|
|
|
|
/*
|
|
* For physical replication we don't need the interlock provided by xmin
|
|
* and effective_xmin since the consequences of a missed increase are
|
|
* limited to query cancellations, so set both at once.
|
|
*/
|
|
if (!TransactionIdIsNormal(slot->data.xmin) ||
|
|
!TransactionIdIsNormal(feedbackXmin) ||
|
|
TransactionIdPrecedes(slot->data.xmin, feedbackXmin))
|
|
{
|
|
changed = true;
|
|
slot->data.xmin = feedbackXmin;
|
|
slot->effective_xmin = feedbackXmin;
|
|
}
|
|
if (!TransactionIdIsNormal(slot->data.catalog_xmin) ||
|
|
!TransactionIdIsNormal(feedbackCatalogXmin) ||
|
|
TransactionIdPrecedes(slot->data.catalog_xmin, feedbackCatalogXmin))
|
|
{
|
|
changed = true;
|
|
slot->data.catalog_xmin = feedbackCatalogXmin;
|
|
slot->effective_catalog_xmin = feedbackCatalogXmin;
|
|
}
|
|
SpinLockRelease(&slot->mutex);
|
|
|
|
if (changed)
|
|
{
|
|
ReplicationSlotMarkDirty();
|
|
ReplicationSlotsComputeRequiredXmin(false);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Check that the provided xmin/epoch are sane, that is, not in the future
|
|
* and not so far back as to be already wrapped around.
|
|
*
|
|
* Epoch of nextXid should be same as standby, or if the counter has
|
|
* wrapped, then one greater than standby.
|
|
*
|
|
* This check doesn't care about whether clog exists for these xids
|
|
* at all.
|
|
*/
|
|
static bool
|
|
TransactionIdInRecentPast(TransactionId xid, uint32 epoch)
|
|
{
|
|
FullTransactionId nextFullXid;
|
|
TransactionId nextXid;
|
|
uint32 nextEpoch;
|
|
|
|
nextFullXid = ReadNextFullTransactionId();
|
|
nextXid = XidFromFullTransactionId(nextFullXid);
|
|
nextEpoch = EpochFromFullTransactionId(nextFullXid);
|
|
|
|
if (xid <= nextXid)
|
|
{
|
|
if (epoch != nextEpoch)
|
|
return false;
|
|
}
|
|
else
|
|
{
|
|
if (epoch + 1 != nextEpoch)
|
|
return false;
|
|
}
|
|
|
|
if (!TransactionIdPrecedesOrEquals(xid, nextXid))
|
|
return false; /* epoch OK, but it's wrapped around */
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* Hot Standby feedback
|
|
*/
|
|
static void
|
|
ProcessStandbyHSFeedbackMessage(void)
|
|
{
|
|
TransactionId feedbackXmin;
|
|
uint32 feedbackEpoch;
|
|
TransactionId feedbackCatalogXmin;
|
|
uint32 feedbackCatalogEpoch;
|
|
TimestampTz replyTime;
|
|
|
|
/*
|
|
* Decipher the reply message. The caller already consumed the msgtype
|
|
* byte. See XLogWalRcvSendHSFeedback() in walreceiver.c for the creation
|
|
* of this message.
|
|
*/
|
|
replyTime = pq_getmsgint64(&reply_message);
|
|
feedbackXmin = pq_getmsgint(&reply_message, 4);
|
|
feedbackEpoch = pq_getmsgint(&reply_message, 4);
|
|
feedbackCatalogXmin = pq_getmsgint(&reply_message, 4);
|
|
feedbackCatalogEpoch = pq_getmsgint(&reply_message, 4);
|
|
|
|
if (log_min_messages <= DEBUG2)
|
|
{
|
|
char *replyTimeStr;
|
|
|
|
/* Copy because timestamptz_to_str returns a static buffer */
|
|
replyTimeStr = pstrdup(timestamptz_to_str(replyTime));
|
|
|
|
elog(DEBUG2, "hot standby feedback xmin %u epoch %u, catalog_xmin %u epoch %u reply_time %s",
|
|
feedbackXmin,
|
|
feedbackEpoch,
|
|
feedbackCatalogXmin,
|
|
feedbackCatalogEpoch,
|
|
replyTimeStr);
|
|
|
|
pfree(replyTimeStr);
|
|
}
|
|
|
|
/*
|
|
* Update shared state for this WalSender process based on reply data from
|
|
* standby.
|
|
*/
|
|
{
|
|
WalSnd *walsnd = MyWalSnd;
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
walsnd->replyTime = replyTime;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
}
|
|
|
|
/*
|
|
* Unset WalSender's xmins if the feedback message values are invalid.
|
|
* This happens when the downstream turned hot_standby_feedback off.
|
|
*/
|
|
if (!TransactionIdIsNormal(feedbackXmin)
|
|
&& !TransactionIdIsNormal(feedbackCatalogXmin))
|
|
{
|
|
MyPgXact->xmin = InvalidTransactionId;
|
|
if (MyReplicationSlot != NULL)
|
|
PhysicalReplicationSlotNewXmin(feedbackXmin, feedbackCatalogXmin);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Check that the provided xmin/epoch are sane, that is, not in the future
|
|
* and not so far back as to be already wrapped around. Ignore if not.
|
|
*/
|
|
if (TransactionIdIsNormal(feedbackXmin) &&
|
|
!TransactionIdInRecentPast(feedbackXmin, feedbackEpoch))
|
|
return;
|
|
|
|
if (TransactionIdIsNormal(feedbackCatalogXmin) &&
|
|
!TransactionIdInRecentPast(feedbackCatalogXmin, feedbackCatalogEpoch))
|
|
return;
|
|
|
|
/*
|
|
* Set the WalSender's xmin equal to the standby's requested xmin, so that
|
|
* the xmin will be taken into account by GetOldestXmin. This will hold
|
|
* back the removal of dead rows and thereby prevent the generation of
|
|
* cleanup conflicts on the standby server.
|
|
*
|
|
* There is a small window for a race condition here: although we just
|
|
* checked that feedbackXmin precedes nextXid, the nextXid could have
|
|
* gotten advanced between our fetching it and applying the xmin below,
|
|
* perhaps far enough to make feedbackXmin wrap around. In that case the
|
|
* xmin we set here would be "in the future" and have no effect. No point
|
|
* in worrying about this since it's too late to save the desired data
|
|
* anyway. Assuming that the standby sends us an increasing sequence of
|
|
* xmins, this could only happen during the first reply cycle, else our
|
|
* own xmin would prevent nextXid from advancing so far.
|
|
*
|
|
* We don't bother taking the ProcArrayLock here. Setting the xmin field
|
|
* is assumed atomic, and there's no real need to prevent a concurrent
|
|
* GetOldestXmin. (If we're moving our xmin forward, this is obviously
|
|
* safe, and if we're moving it backwards, well, the data is at risk
|
|
* already since a VACUUM could have just finished calling GetOldestXmin.)
|
|
*
|
|
* If we're using a replication slot we reserve the xmin via that,
|
|
* otherwise via the walsender's PGXACT entry. We can only track the
|
|
* catalog xmin separately when using a slot, so we store the least of the
|
|
* two provided when not using a slot.
|
|
*
|
|
* XXX: It might make sense to generalize the ephemeral slot concept and
|
|
* always use the slot mechanism to handle the feedback xmin.
|
|
*/
|
|
if (MyReplicationSlot != NULL) /* XXX: persistency configurable? */
|
|
PhysicalReplicationSlotNewXmin(feedbackXmin, feedbackCatalogXmin);
|
|
else
|
|
{
|
|
if (TransactionIdIsNormal(feedbackCatalogXmin)
|
|
&& TransactionIdPrecedes(feedbackCatalogXmin, feedbackXmin))
|
|
MyPgXact->xmin = feedbackCatalogXmin;
|
|
else
|
|
MyPgXact->xmin = feedbackXmin;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Compute how long send/receive loops should sleep.
|
|
*
|
|
* If wal_sender_timeout is enabled we want to wake up in time to send
|
|
* keepalives and to abort the connection if wal_sender_timeout has been
|
|
* reached.
|
|
*/
|
|
static long
|
|
WalSndComputeSleeptime(TimestampTz now)
|
|
{
|
|
long sleeptime = 10000; /* 10 s */
|
|
|
|
if (wal_sender_timeout > 0 && last_reply_timestamp > 0)
|
|
{
|
|
TimestampTz wakeup_time;
|
|
long sec_to_timeout;
|
|
int microsec_to_timeout;
|
|
|
|
/*
|
|
* At the latest stop sleeping once wal_sender_timeout has been
|
|
* reached.
|
|
*/
|
|
wakeup_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
|
|
wal_sender_timeout);
|
|
|
|
/*
|
|
* If no ping has been sent yet, wakeup when it's time to do so.
|
|
* WalSndKeepaliveIfNecessary() wants to send a keepalive once half of
|
|
* the timeout passed without a response.
|
|
*/
|
|
if (!waiting_for_ping_response)
|
|
wakeup_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
|
|
wal_sender_timeout / 2);
|
|
|
|
/* Compute relative time until wakeup. */
|
|
TimestampDifference(now, wakeup_time,
|
|
&sec_to_timeout, µsec_to_timeout);
|
|
|
|
sleeptime = sec_to_timeout * 1000 +
|
|
microsec_to_timeout / 1000;
|
|
}
|
|
|
|
return sleeptime;
|
|
}
|
|
|
|
/*
|
|
* Check whether there have been responses by the client within
|
|
* wal_sender_timeout and shutdown if not. Using last_processing as the
|
|
* reference point avoids counting server-side stalls against the client.
|
|
* However, a long server-side stall can make WalSndKeepaliveIfNecessary()
|
|
* postdate last_processing by more than wal_sender_timeout. If that happens,
|
|
* the client must reply almost immediately to avoid a timeout. This rarely
|
|
* affects the default configuration, under which clients spontaneously send a
|
|
* message every standby_message_timeout = wal_sender_timeout/6 = 10s. We
|
|
* could eliminate that problem by recognizing timeout expiration at
|
|
* wal_sender_timeout/2 after the keepalive.
|
|
*/
|
|
static void
|
|
WalSndCheckTimeOut(void)
|
|
{
|
|
TimestampTz timeout;
|
|
|
|
/* don't bail out if we're doing something that doesn't require timeouts */
|
|
if (last_reply_timestamp <= 0)
|
|
return;
|
|
|
|
timeout = TimestampTzPlusMilliseconds(last_reply_timestamp,
|
|
wal_sender_timeout);
|
|
|
|
if (wal_sender_timeout > 0 && last_processing >= timeout)
|
|
{
|
|
/*
|
|
* Since typically expiration of replication timeout means
|
|
* communication problem, we don't send the error message to the
|
|
* standby.
|
|
*/
|
|
ereport(COMMERROR,
|
|
(errmsg("terminating walsender process due to replication timeout")));
|
|
|
|
WalSndShutdown();
|
|
}
|
|
}
|
|
|
|
/* Main loop of walsender process that streams the WAL over Copy messages. */
|
|
static void
|
|
WalSndLoop(WalSndSendDataCallback send_data)
|
|
{
|
|
/*
|
|
* Initialize the last reply timestamp. That enables timeout processing
|
|
* from hereon.
|
|
*/
|
|
last_reply_timestamp = GetCurrentTimestamp();
|
|
waiting_for_ping_response = false;
|
|
|
|
/*
|
|
* Loop until we reach the end of this timeline or the client requests to
|
|
* stop streaming.
|
|
*/
|
|
for (;;)
|
|
{
|
|
/* Clear any already-pending wakeups */
|
|
ResetLatch(MyLatch);
|
|
|
|
CHECK_FOR_INTERRUPTS();
|
|
|
|
/* Process any requests or signals received recently */
|
|
if (ConfigReloadPending)
|
|
{
|
|
ConfigReloadPending = false;
|
|
ProcessConfigFile(PGC_SIGHUP);
|
|
SyncRepInitConfig();
|
|
}
|
|
|
|
/* Check for input from the client */
|
|
ProcessRepliesIfAny();
|
|
|
|
/*
|
|
* If we have received CopyDone from the client, sent CopyDone
|
|
* ourselves, and the output buffer is empty, it's time to exit
|
|
* streaming.
|
|
*/
|
|
if (streamingDoneReceiving && streamingDoneSending &&
|
|
!pq_is_send_pending())
|
|
break;
|
|
|
|
/*
|
|
* If we don't have any pending data in the output buffer, try to send
|
|
* some more. If there is some, we don't bother to call send_data
|
|
* again until we've flushed it ... but we'd better assume we are not
|
|
* caught up.
|
|
*/
|
|
if (!pq_is_send_pending())
|
|
send_data();
|
|
else
|
|
WalSndCaughtUp = false;
|
|
|
|
/* Try to flush pending output to the client */
|
|
if (pq_flush_if_writable() != 0)
|
|
WalSndShutdown();
|
|
|
|
/* If nothing remains to be sent right now ... */
|
|
if (WalSndCaughtUp && !pq_is_send_pending())
|
|
{
|
|
/*
|
|
* If we're in catchup state, move to streaming. This is an
|
|
* important state change for users to know about, since before
|
|
* this point data loss might occur if the primary dies and we
|
|
* need to failover to the standby. The state change is also
|
|
* important for synchronous replication, since commits that
|
|
* started to wait at that point might wait for some time.
|
|
*/
|
|
if (MyWalSnd->state == WALSNDSTATE_CATCHUP)
|
|
{
|
|
ereport(DEBUG1,
|
|
(errmsg("\"%s\" has now caught up with upstream server",
|
|
application_name)));
|
|
WalSndSetState(WALSNDSTATE_STREAMING);
|
|
}
|
|
|
|
/*
|
|
* When SIGUSR2 arrives, we send any outstanding logs up to the
|
|
* shutdown checkpoint record (i.e., the latest record), wait for
|
|
* them to be replicated to the standby, and exit. This may be a
|
|
* normal termination at shutdown, or a promotion, the walsender
|
|
* is not sure which.
|
|
*/
|
|
if (got_SIGUSR2)
|
|
WalSndDone(send_data);
|
|
}
|
|
|
|
/* Check for replication timeout. */
|
|
WalSndCheckTimeOut();
|
|
|
|
/* Send keepalive if the time has come */
|
|
WalSndKeepaliveIfNecessary();
|
|
|
|
/*
|
|
* We don't block if not caught up, unless there is unsent data
|
|
* pending in which case we'd better block until the socket is
|
|
* write-ready. This test is only needed for the case where the
|
|
* send_data callback handled a subset of the available data but then
|
|
* pq_flush_if_writable flushed it all --- we should immediately try
|
|
* to send more.
|
|
*/
|
|
if ((WalSndCaughtUp && !streamingDoneSending) || pq_is_send_pending())
|
|
{
|
|
long sleeptime;
|
|
int wakeEvents;
|
|
|
|
wakeEvents = WL_LATCH_SET | WL_EXIT_ON_PM_DEATH | WL_TIMEOUT |
|
|
WL_SOCKET_READABLE;
|
|
|
|
/*
|
|
* Use fresh timestamp, not last_processing, to reduce the chance
|
|
* of reaching wal_sender_timeout before sending a keepalive.
|
|
*/
|
|
sleeptime = WalSndComputeSleeptime(GetCurrentTimestamp());
|
|
|
|
if (pq_is_send_pending())
|
|
wakeEvents |= WL_SOCKET_WRITEABLE;
|
|
|
|
/* Sleep until something happens or we time out */
|
|
(void) WaitLatchOrSocket(MyLatch, wakeEvents,
|
|
MyProcPort->sock, sleeptime,
|
|
WAIT_EVENT_WAL_SENDER_MAIN);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Initialize a per-walsender data structure for this walsender process */
|
|
static void
|
|
InitWalSenderSlot(void)
|
|
{
|
|
int i;
|
|
|
|
/*
|
|
* WalSndCtl should be set up already (we inherit this by fork() or
|
|
* EXEC_BACKEND mechanism from the postmaster).
|
|
*/
|
|
Assert(WalSndCtl != NULL);
|
|
Assert(MyWalSnd == NULL);
|
|
|
|
/*
|
|
* Find a free walsender slot and reserve it. This must not fail due to
|
|
* the prior check for free WAL senders in InitProcess().
|
|
*/
|
|
for (i = 0; i < max_wal_senders; i++)
|
|
{
|
|
WalSnd *walsnd = &WalSndCtl->walsnds[i];
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
|
|
if (walsnd->pid != 0)
|
|
{
|
|
SpinLockRelease(&walsnd->mutex);
|
|
continue;
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Found a free slot. Reserve it for us.
|
|
*/
|
|
walsnd->pid = MyProcPid;
|
|
walsnd->sentPtr = InvalidXLogRecPtr;
|
|
walsnd->write = InvalidXLogRecPtr;
|
|
walsnd->flush = InvalidXLogRecPtr;
|
|
walsnd->apply = InvalidXLogRecPtr;
|
|
walsnd->writeLag = -1;
|
|
walsnd->flushLag = -1;
|
|
walsnd->applyLag = -1;
|
|
walsnd->state = WALSNDSTATE_STARTUP;
|
|
walsnd->latch = &MyProc->procLatch;
|
|
walsnd->replyTime = 0;
|
|
walsnd->spillTxns = 0;
|
|
walsnd->spillCount = 0;
|
|
walsnd->spillBytes = 0;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
/* don't need the lock anymore */
|
|
MyWalSnd = (WalSnd *) walsnd;
|
|
|
|
break;
|
|
}
|
|
}
|
|
|
|
Assert(MyWalSnd != NULL);
|
|
|
|
/* Arrange to clean up at walsender exit */
|
|
on_shmem_exit(WalSndKill, 0);
|
|
}
|
|
|
|
/* Destroy the per-walsender data structure for this walsender process */
|
|
static void
|
|
WalSndKill(int code, Datum arg)
|
|
{
|
|
WalSnd *walsnd = MyWalSnd;
|
|
|
|
Assert(walsnd != NULL);
|
|
|
|
MyWalSnd = NULL;
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
/* clear latch while holding the spinlock, so it can safely be read */
|
|
walsnd->latch = NULL;
|
|
/* Mark WalSnd struct as no longer being in use. */
|
|
walsnd->pid = 0;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
}
|
|
|
|
/* walsender's openSegment callback for WALRead */
|
|
static int
|
|
WalSndSegmentOpen(XLogSegNo nextSegNo, WALSegmentContext *segcxt,
|
|
TimeLineID *tli_p)
|
|
{
|
|
char path[MAXPGPATH];
|
|
int fd;
|
|
|
|
/*-------
|
|
* When reading from a historic timeline, and there is a timeline switch
|
|
* within this segment, read from the WAL segment belonging to the new
|
|
* timeline.
|
|
*
|
|
* For example, imagine that this server is currently on timeline 5, and
|
|
* we're streaming timeline 4. The switch from timeline 4 to 5 happened at
|
|
* 0/13002088. In pg_wal, we have these files:
|
|
*
|
|
* ...
|
|
* 000000040000000000000012
|
|
* 000000040000000000000013
|
|
* 000000050000000000000013
|
|
* 000000050000000000000014
|
|
* ...
|
|
*
|
|
* In this situation, when requested to send the WAL from segment 0x13, on
|
|
* timeline 4, we read the WAL from file 000000050000000000000013. Archive
|
|
* recovery prefers files from newer timelines, so if the segment was
|
|
* restored from the archive on this server, the file belonging to the old
|
|
* timeline, 000000040000000000000013, might not exist. Their contents are
|
|
* equal up to the switchpoint, because at a timeline switch, the used
|
|
* portion of the old segment is copied to the new file. -------
|
|
*/
|
|
*tli_p = sendTimeLine;
|
|
if (sendTimeLineIsHistoric)
|
|
{
|
|
XLogSegNo endSegNo;
|
|
|
|
XLByteToSeg(sendTimeLineValidUpto, endSegNo, segcxt->ws_segsize);
|
|
if (sendSeg->ws_segno == endSegNo)
|
|
*tli_p = sendTimeLineNextTLI;
|
|
}
|
|
|
|
XLogFilePath(path, *tli_p, nextSegNo, segcxt->ws_segsize);
|
|
fd = BasicOpenFile(path, O_RDONLY | PG_BINARY);
|
|
if (fd >= 0)
|
|
return fd;
|
|
|
|
/*
|
|
* If the file is not found, assume it's because the standby asked for a
|
|
* too old WAL segment that has already been removed or recycled.
|
|
*/
|
|
if (errno == ENOENT)
|
|
{
|
|
char xlogfname[MAXFNAMELEN];
|
|
int save_errno = errno;
|
|
|
|
XLogFileName(xlogfname, *tli_p, nextSegNo, wal_segment_size);
|
|
errno = save_errno;
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("requested WAL segment %s has already been removed",
|
|
xlogfname)));
|
|
}
|
|
else
|
|
ereport(ERROR,
|
|
(errcode_for_file_access(),
|
|
errmsg("could not open file \"%s\": %m",
|
|
path)));
|
|
return -1; /* keep compiler quiet */
|
|
}
|
|
|
|
/*
|
|
* Send out the WAL in its normal physical/stored form.
|
|
*
|
|
* Read up to MAX_SEND_SIZE bytes of WAL that's been flushed to disk,
|
|
* but not yet sent to the client, and buffer it in the libpq output
|
|
* buffer.
|
|
*
|
|
* If there is no unsent WAL remaining, WalSndCaughtUp is set to true,
|
|
* otherwise WalSndCaughtUp is set to false.
|
|
*/
|
|
static void
|
|
XLogSendPhysical(void)
|
|
{
|
|
XLogRecPtr SendRqstPtr;
|
|
XLogRecPtr startptr;
|
|
XLogRecPtr endptr;
|
|
Size nbytes;
|
|
XLogSegNo segno;
|
|
WALReadError errinfo;
|
|
|
|
/* If requested switch the WAL sender to the stopping state. */
|
|
if (got_STOPPING)
|
|
WalSndSetState(WALSNDSTATE_STOPPING);
|
|
|
|
if (streamingDoneSending)
|
|
{
|
|
WalSndCaughtUp = true;
|
|
return;
|
|
}
|
|
|
|
/* Figure out how far we can safely send the WAL. */
|
|
if (sendTimeLineIsHistoric)
|
|
{
|
|
/*
|
|
* Streaming an old timeline that's in this server's history, but is
|
|
* not the one we're currently inserting or replaying. It can be
|
|
* streamed up to the point where we switched off that timeline.
|
|
*/
|
|
SendRqstPtr = sendTimeLineValidUpto;
|
|
}
|
|
else if (am_cascading_walsender)
|
|
{
|
|
/*
|
|
* Streaming the latest timeline on a standby.
|
|
*
|
|
* Attempt to send all WAL that has already been replayed, so that we
|
|
* know it's valid. If we're receiving WAL through streaming
|
|
* replication, it's also OK to send any WAL that has been received
|
|
* but not replayed.
|
|
*
|
|
* The timeline we're recovering from can change, or we can be
|
|
* promoted. In either case, the current timeline becomes historic. We
|
|
* need to detect that so that we don't try to stream past the point
|
|
* where we switched to another timeline. We check for promotion or
|
|
* timeline switch after calculating FlushPtr, to avoid a race
|
|
* condition: if the timeline becomes historic just after we checked
|
|
* that it was still current, it's still be OK to stream it up to the
|
|
* FlushPtr that was calculated before it became historic.
|
|
*/
|
|
bool becameHistoric = false;
|
|
|
|
SendRqstPtr = GetStandbyFlushRecPtr();
|
|
|
|
if (!RecoveryInProgress())
|
|
{
|
|
/*
|
|
* We have been promoted. RecoveryInProgress() updated
|
|
* ThisTimeLineID to the new current timeline.
|
|
*/
|
|
am_cascading_walsender = false;
|
|
becameHistoric = true;
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Still a cascading standby. But is the timeline we're sending
|
|
* still the one recovery is recovering from? ThisTimeLineID was
|
|
* updated by the GetStandbyFlushRecPtr() call above.
|
|
*/
|
|
if (sendTimeLine != ThisTimeLineID)
|
|
becameHistoric = true;
|
|
}
|
|
|
|
if (becameHistoric)
|
|
{
|
|
/*
|
|
* The timeline we were sending has become historic. Read the
|
|
* timeline history file of the new timeline to see where exactly
|
|
* we forked off from the timeline we were sending.
|
|
*/
|
|
List *history;
|
|
|
|
history = readTimeLineHistory(ThisTimeLineID);
|
|
sendTimeLineValidUpto = tliSwitchPoint(sendTimeLine, history, &sendTimeLineNextTLI);
|
|
|
|
Assert(sendTimeLine < sendTimeLineNextTLI);
|
|
list_free_deep(history);
|
|
|
|
sendTimeLineIsHistoric = true;
|
|
|
|
SendRqstPtr = sendTimeLineValidUpto;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Streaming the current timeline on a master.
|
|
*
|
|
* Attempt to send all data that's already been written out and
|
|
* fsync'd to disk. We cannot go further than what's been written out
|
|
* given the current implementation of XLogRead(). And in any case
|
|
* it's unsafe to send WAL that is not securely down to disk on the
|
|
* master: if the master subsequently crashes and restarts, standbys
|
|
* must not have applied any WAL that got lost on the master.
|
|
*/
|
|
SendRqstPtr = GetFlushRecPtr();
|
|
}
|
|
|
|
/*
|
|
* Record the current system time as an approximation of the time at which
|
|
* this WAL location was written for the purposes of lag tracking.
|
|
*
|
|
* In theory we could make XLogFlush() record a time in shmem whenever WAL
|
|
* is flushed and we could get that time as well as the LSN when we call
|
|
* GetFlushRecPtr() above (and likewise for the cascading standby
|
|
* equivalent), but rather than putting any new code into the hot WAL path
|
|
* it seems good enough to capture the time here. We should reach this
|
|
* after XLogFlush() runs WalSndWakeupProcessRequests(), and although that
|
|
* may take some time, we read the WAL flush pointer and take the time
|
|
* very close to together here so that we'll get a later position if it is
|
|
* still moving.
|
|
*
|
|
* Because LagTrackerWrite ignores samples when the LSN hasn't advanced,
|
|
* this gives us a cheap approximation for the WAL flush time for this
|
|
* LSN.
|
|
*
|
|
* Note that the LSN is not necessarily the LSN for the data contained in
|
|
* the present message; it's the end of the WAL, which might be further
|
|
* ahead. All the lag tracking machinery cares about is finding out when
|
|
* that arbitrary LSN is eventually reported as written, flushed and
|
|
* applied, so that it can measure the elapsed time.
|
|
*/
|
|
LagTrackerWrite(SendRqstPtr, GetCurrentTimestamp());
|
|
|
|
/*
|
|
* If this is a historic timeline and we've reached the point where we
|
|
* forked to the next timeline, stop streaming.
|
|
*
|
|
* Note: We might already have sent WAL > sendTimeLineValidUpto. The
|
|
* startup process will normally replay all WAL that has been received
|
|
* from the master, before promoting, but if the WAL streaming is
|
|
* terminated at a WAL page boundary, the valid portion of the timeline
|
|
* might end in the middle of a WAL record. We might've already sent the
|
|
* first half of that partial WAL record to the cascading standby, so that
|
|
* sentPtr > sendTimeLineValidUpto. That's OK; the cascading standby can't
|
|
* replay the partial WAL record either, so it can still follow our
|
|
* timeline switch.
|
|
*/
|
|
if (sendTimeLineIsHistoric && sendTimeLineValidUpto <= sentPtr)
|
|
{
|
|
/* close the current file. */
|
|
if (sendSeg->ws_file >= 0)
|
|
close(sendSeg->ws_file);
|
|
sendSeg->ws_file = -1;
|
|
|
|
/* Send CopyDone */
|
|
pq_putmessage_noblock('c', NULL, 0);
|
|
streamingDoneSending = true;
|
|
|
|
WalSndCaughtUp = true;
|
|
|
|
elog(DEBUG1, "walsender reached end of timeline at %X/%X (sent up to %X/%X)",
|
|
(uint32) (sendTimeLineValidUpto >> 32), (uint32) sendTimeLineValidUpto,
|
|
(uint32) (sentPtr >> 32), (uint32) sentPtr);
|
|
return;
|
|
}
|
|
|
|
/* Do we have any work to do? */
|
|
Assert(sentPtr <= SendRqstPtr);
|
|
if (SendRqstPtr <= sentPtr)
|
|
{
|
|
WalSndCaughtUp = true;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Figure out how much to send in one message. If there's no more than
|
|
* MAX_SEND_SIZE bytes to send, send everything. Otherwise send
|
|
* MAX_SEND_SIZE bytes, but round back to logfile or page boundary.
|
|
*
|
|
* The rounding is not only for performance reasons. Walreceiver relies on
|
|
* the fact that we never split a WAL record across two messages. Since a
|
|
* long WAL record is split at page boundary into continuation records,
|
|
* page boundary is always a safe cut-off point. We also assume that
|
|
* SendRqstPtr never points to the middle of a WAL record.
|
|
*/
|
|
startptr = sentPtr;
|
|
endptr = startptr;
|
|
endptr += MAX_SEND_SIZE;
|
|
|
|
/* if we went beyond SendRqstPtr, back off */
|
|
if (SendRqstPtr <= endptr)
|
|
{
|
|
endptr = SendRqstPtr;
|
|
if (sendTimeLineIsHistoric)
|
|
WalSndCaughtUp = false;
|
|
else
|
|
WalSndCaughtUp = true;
|
|
}
|
|
else
|
|
{
|
|
/* round down to page boundary. */
|
|
endptr -= (endptr % XLOG_BLCKSZ);
|
|
WalSndCaughtUp = false;
|
|
}
|
|
|
|
nbytes = endptr - startptr;
|
|
Assert(nbytes <= MAX_SEND_SIZE);
|
|
|
|
/*
|
|
* OK to read and send the slice.
|
|
*/
|
|
resetStringInfo(&output_message);
|
|
pq_sendbyte(&output_message, 'w');
|
|
|
|
pq_sendint64(&output_message, startptr); /* dataStart */
|
|
pq_sendint64(&output_message, SendRqstPtr); /* walEnd */
|
|
pq_sendint64(&output_message, 0); /* sendtime, filled in last */
|
|
|
|
/*
|
|
* Read the log directly into the output buffer to avoid extra memcpy
|
|
* calls.
|
|
*/
|
|
enlargeStringInfo(&output_message, nbytes);
|
|
|
|
retry:
|
|
if (!WALRead(&output_message.data[output_message.len],
|
|
startptr,
|
|
nbytes,
|
|
sendSeg->ws_tli, /* Pass the current TLI because only
|
|
* WalSndSegmentOpen controls whether new
|
|
* TLI is needed. */
|
|
sendSeg,
|
|
sendCxt,
|
|
WalSndSegmentOpen,
|
|
&errinfo))
|
|
WALReadRaiseError(&errinfo);
|
|
|
|
/* See logical_read_xlog_page(). */
|
|
XLByteToSeg(startptr, segno, sendCxt->ws_segsize);
|
|
CheckXLogRemoved(segno, sendSeg->ws_tli);
|
|
|
|
/*
|
|
* During recovery, the currently-open WAL file might be replaced with the
|
|
* file of the same name retrieved from archive. So we always need to
|
|
* check what we read was valid after reading into the buffer. If it's
|
|
* invalid, we try to open and read the file again.
|
|
*/
|
|
if (am_cascading_walsender)
|
|
{
|
|
WalSnd *walsnd = MyWalSnd;
|
|
bool reload;
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
reload = walsnd->needreload;
|
|
walsnd->needreload = false;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
|
|
if (reload && sendSeg->ws_file >= 0)
|
|
{
|
|
close(sendSeg->ws_file);
|
|
sendSeg->ws_file = -1;
|
|
|
|
goto retry;
|
|
}
|
|
}
|
|
|
|
output_message.len += nbytes;
|
|
output_message.data[output_message.len] = '\0';
|
|
|
|
/*
|
|
* Fill the send timestamp last, so that it is taken as late as possible.
|
|
*/
|
|
resetStringInfo(&tmpbuf);
|
|
pq_sendint64(&tmpbuf, GetCurrentTimestamp());
|
|
memcpy(&output_message.data[1 + sizeof(int64) + sizeof(int64)],
|
|
tmpbuf.data, sizeof(int64));
|
|
|
|
pq_putmessage_noblock('d', output_message.data, output_message.len);
|
|
|
|
sentPtr = endptr;
|
|
|
|
/* Update shared memory status */
|
|
{
|
|
WalSnd *walsnd = MyWalSnd;
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
walsnd->sentPtr = sentPtr;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
}
|
|
|
|
/* Report progress of XLOG streaming in PS display */
|
|
if (update_process_title)
|
|
{
|
|
char activitymsg[50];
|
|
|
|
snprintf(activitymsg, sizeof(activitymsg), "streaming %X/%X",
|
|
(uint32) (sentPtr >> 32), (uint32) sentPtr);
|
|
set_ps_display(activitymsg, false);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Stream out logically decoded data.
|
|
*/
|
|
static void
|
|
XLogSendLogical(void)
|
|
{
|
|
XLogRecord *record;
|
|
char *errm;
|
|
|
|
/*
|
|
* We'll use the current flush point to determine whether we've caught up.
|
|
* This variable is static in order to cache it across calls. Caching is
|
|
* helpful because GetFlushRecPtr() needs to acquire a heavily-contended
|
|
* spinlock.
|
|
*/
|
|
static XLogRecPtr flushPtr = InvalidXLogRecPtr;
|
|
|
|
/*
|
|
* Don't know whether we've caught up yet. We'll set WalSndCaughtUp to
|
|
* true in WalSndWaitForWal, if we're actually waiting. We also set to
|
|
* true if XLogReadRecord() had to stop reading but WalSndWaitForWal
|
|
* didn't wait - i.e. when we're shutting down.
|
|
*/
|
|
WalSndCaughtUp = false;
|
|
|
|
record = XLogReadRecord(logical_decoding_ctx->reader, &errm);
|
|
|
|
/* xlog record was invalid */
|
|
if (errm != NULL)
|
|
elog(ERROR, "%s", errm);
|
|
|
|
if (record != NULL)
|
|
{
|
|
/*
|
|
* Note the lack of any call to LagTrackerWrite() which is handled by
|
|
* WalSndUpdateProgress which is called by output plugin through
|
|
* logical decoding write api.
|
|
*/
|
|
LogicalDecodingProcessRecord(logical_decoding_ctx, logical_decoding_ctx->reader);
|
|
|
|
sentPtr = logical_decoding_ctx->reader->EndRecPtr;
|
|
}
|
|
|
|
/*
|
|
* If first time through in this session, initialize flushPtr. Otherwise,
|
|
* we only need to update flushPtr if EndRecPtr is past it.
|
|
*/
|
|
if (flushPtr == InvalidXLogRecPtr)
|
|
flushPtr = GetFlushRecPtr();
|
|
else if (logical_decoding_ctx->reader->EndRecPtr >= flushPtr)
|
|
flushPtr = GetFlushRecPtr();
|
|
|
|
/* If EndRecPtr is still past our flushPtr, it means we caught up. */
|
|
if (logical_decoding_ctx->reader->EndRecPtr >= flushPtr)
|
|
WalSndCaughtUp = true;
|
|
|
|
/*
|
|
* If we're caught up and have been requested to stop, have WalSndLoop()
|
|
* terminate the connection in an orderly manner, after writing out all
|
|
* the pending data.
|
|
*/
|
|
if (WalSndCaughtUp && got_STOPPING)
|
|
got_SIGUSR2 = true;
|
|
|
|
/* Update shared memory status */
|
|
{
|
|
WalSnd *walsnd = MyWalSnd;
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
walsnd->sentPtr = sentPtr;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Shutdown if the sender is caught up.
|
|
*
|
|
* NB: This should only be called when the shutdown signal has been received
|
|
* from postmaster.
|
|
*
|
|
* Note that if we determine that there's still more data to send, this
|
|
* function will return control to the caller.
|
|
*/
|
|
static void
|
|
WalSndDone(WalSndSendDataCallback send_data)
|
|
{
|
|
XLogRecPtr replicatedPtr;
|
|
|
|
/* ... let's just be real sure we're caught up ... */
|
|
send_data();
|
|
|
|
/*
|
|
* To figure out whether all WAL has successfully been replicated, check
|
|
* flush location if valid, write otherwise. Tools like pg_receivewal will
|
|
* usually (unless in synchronous mode) return an invalid flush location.
|
|
*/
|
|
replicatedPtr = XLogRecPtrIsInvalid(MyWalSnd->flush) ?
|
|
MyWalSnd->write : MyWalSnd->flush;
|
|
|
|
if (WalSndCaughtUp && sentPtr == replicatedPtr &&
|
|
!pq_is_send_pending())
|
|
{
|
|
/* Inform the standby that XLOG streaming is done */
|
|
EndCommand("COPY 0", DestRemote);
|
|
pq_flush();
|
|
|
|
proc_exit(0);
|
|
}
|
|
if (!waiting_for_ping_response)
|
|
{
|
|
WalSndKeepalive(true);
|
|
waiting_for_ping_response = true;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Returns the latest point in WAL that has been safely flushed to disk, and
|
|
* can be sent to the standby. This should only be called when in recovery,
|
|
* ie. we're streaming to a cascaded standby.
|
|
*
|
|
* As a side-effect, ThisTimeLineID is updated to the TLI of the last
|
|
* replayed WAL record.
|
|
*/
|
|
static XLogRecPtr
|
|
GetStandbyFlushRecPtr(void)
|
|
{
|
|
XLogRecPtr replayPtr;
|
|
TimeLineID replayTLI;
|
|
XLogRecPtr receivePtr;
|
|
TimeLineID receiveTLI;
|
|
XLogRecPtr result;
|
|
|
|
/*
|
|
* We can safely send what's already been replayed. Also, if walreceiver
|
|
* is streaming WAL from the same timeline, we can send anything that it
|
|
* has streamed, but hasn't been replayed yet.
|
|
*/
|
|
|
|
receivePtr = GetWalRcvWriteRecPtr(NULL, &receiveTLI);
|
|
replayPtr = GetXLogReplayRecPtr(&replayTLI);
|
|
|
|
ThisTimeLineID = replayTLI;
|
|
|
|
result = replayPtr;
|
|
if (receiveTLI == ThisTimeLineID && receivePtr > replayPtr)
|
|
result = receivePtr;
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* Request walsenders to reload the currently-open WAL file
|
|
*/
|
|
void
|
|
WalSndRqstFileReload(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < max_wal_senders; i++)
|
|
{
|
|
WalSnd *walsnd = &WalSndCtl->walsnds[i];
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
if (walsnd->pid == 0)
|
|
{
|
|
SpinLockRelease(&walsnd->mutex);
|
|
continue;
|
|
}
|
|
walsnd->needreload = true;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Handle PROCSIG_WALSND_INIT_STOPPING signal.
|
|
*/
|
|
void
|
|
HandleWalSndInitStopping(void)
|
|
{
|
|
Assert(am_walsender);
|
|
|
|
/*
|
|
* If replication has not yet started, die like with SIGTERM. If
|
|
* replication is active, only set a flag and wake up the main loop. It
|
|
* will send any outstanding WAL, wait for it to be replicated to the
|
|
* standby, and then exit gracefully.
|
|
*/
|
|
if (!replication_active)
|
|
kill(MyProcPid, SIGTERM);
|
|
else
|
|
got_STOPPING = true;
|
|
}
|
|
|
|
/*
|
|
* SIGUSR2: set flag to do a last cycle and shut down afterwards. The WAL
|
|
* sender should already have been switched to WALSNDSTATE_STOPPING at
|
|
* this point.
|
|
*/
|
|
static void
|
|
WalSndLastCycleHandler(SIGNAL_ARGS)
|
|
{
|
|
int save_errno = errno;
|
|
|
|
got_SIGUSR2 = true;
|
|
SetLatch(MyLatch);
|
|
|
|
errno = save_errno;
|
|
}
|
|
|
|
/* Set up signal handlers */
|
|
void
|
|
WalSndSignals(void)
|
|
{
|
|
/* Set up signal handlers */
|
|
pqsignal(SIGHUP, SignalHandlerForConfigReload);
|
|
pqsignal(SIGINT, StatementCancelHandler); /* query cancel */
|
|
pqsignal(SIGTERM, die); /* request shutdown */
|
|
pqsignal(SIGQUIT, quickdie); /* hard crash time */
|
|
InitializeTimeouts(); /* establishes SIGALRM handler */
|
|
pqsignal(SIGPIPE, SIG_IGN);
|
|
pqsignal(SIGUSR1, procsignal_sigusr1_handler);
|
|
pqsignal(SIGUSR2, WalSndLastCycleHandler); /* request a last cycle and
|
|
* shutdown */
|
|
|
|
/* Reset some signals that are accepted by postmaster but not here */
|
|
pqsignal(SIGCHLD, SIG_DFL);
|
|
}
|
|
|
|
/* Report shared-memory space needed by WalSndShmemInit */
|
|
Size
|
|
WalSndShmemSize(void)
|
|
{
|
|
Size size = 0;
|
|
|
|
size = offsetof(WalSndCtlData, walsnds);
|
|
size = add_size(size, mul_size(max_wal_senders, sizeof(WalSnd)));
|
|
|
|
return size;
|
|
}
|
|
|
|
/* Allocate and initialize walsender-related shared memory */
|
|
void
|
|
WalSndShmemInit(void)
|
|
{
|
|
bool found;
|
|
int i;
|
|
|
|
WalSndCtl = (WalSndCtlData *)
|
|
ShmemInitStruct("Wal Sender Ctl", WalSndShmemSize(), &found);
|
|
|
|
if (!found)
|
|
{
|
|
/* First time through, so initialize */
|
|
MemSet(WalSndCtl, 0, WalSndShmemSize());
|
|
|
|
for (i = 0; i < NUM_SYNC_REP_WAIT_MODE; i++)
|
|
SHMQueueInit(&(WalSndCtl->SyncRepQueue[i]));
|
|
|
|
for (i = 0; i < max_wal_senders; i++)
|
|
{
|
|
WalSnd *walsnd = &WalSndCtl->walsnds[i];
|
|
|
|
SpinLockInit(&walsnd->mutex);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Wake up all walsenders
|
|
*
|
|
* This will be called inside critical sections, so throwing an error is not
|
|
* advisable.
|
|
*/
|
|
void
|
|
WalSndWakeup(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < max_wal_senders; i++)
|
|
{
|
|
Latch *latch;
|
|
WalSnd *walsnd = &WalSndCtl->walsnds[i];
|
|
|
|
/*
|
|
* Get latch pointer with spinlock held, for the unlikely case that
|
|
* pointer reads aren't atomic (as they're 8 bytes).
|
|
*/
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
latch = walsnd->latch;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
|
|
if (latch != NULL)
|
|
SetLatch(latch);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Signal all walsenders to move to stopping state.
|
|
*
|
|
* This will trigger walsenders to move to a state where no further WAL can be
|
|
* generated. See this file's header for details.
|
|
*/
|
|
void
|
|
WalSndInitStopping(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < max_wal_senders; i++)
|
|
{
|
|
WalSnd *walsnd = &WalSndCtl->walsnds[i];
|
|
pid_t pid;
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
pid = walsnd->pid;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
|
|
if (pid == 0)
|
|
continue;
|
|
|
|
SendProcSignal(pid, PROCSIG_WALSND_INIT_STOPPING, InvalidBackendId);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Wait that all the WAL senders have quit or reached the stopping state. This
|
|
* is used by the checkpointer to control when the shutdown checkpoint can
|
|
* safely be performed.
|
|
*/
|
|
void
|
|
WalSndWaitStopping(void)
|
|
{
|
|
for (;;)
|
|
{
|
|
int i;
|
|
bool all_stopped = true;
|
|
|
|
for (i = 0; i < max_wal_senders; i++)
|
|
{
|
|
WalSnd *walsnd = &WalSndCtl->walsnds[i];
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
|
|
if (walsnd->pid == 0)
|
|
{
|
|
SpinLockRelease(&walsnd->mutex);
|
|
continue;
|
|
}
|
|
|
|
if (walsnd->state != WALSNDSTATE_STOPPING)
|
|
{
|
|
all_stopped = false;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
break;
|
|
}
|
|
SpinLockRelease(&walsnd->mutex);
|
|
}
|
|
|
|
/* safe to leave if confirmation is done for all WAL senders */
|
|
if (all_stopped)
|
|
return;
|
|
|
|
pg_usleep(10000L); /* wait for 10 msec */
|
|
}
|
|
}
|
|
|
|
/* Set state for current walsender (only called in walsender) */
|
|
void
|
|
WalSndSetState(WalSndState state)
|
|
{
|
|
WalSnd *walsnd = MyWalSnd;
|
|
|
|
Assert(am_walsender);
|
|
|
|
if (walsnd->state == state)
|
|
return;
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
walsnd->state = state;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
}
|
|
|
|
/*
|
|
* Return a string constant representing the state. This is used
|
|
* in system views, and should *not* be translated.
|
|
*/
|
|
static const char *
|
|
WalSndGetStateString(WalSndState state)
|
|
{
|
|
switch (state)
|
|
{
|
|
case WALSNDSTATE_STARTUP:
|
|
return "startup";
|
|
case WALSNDSTATE_BACKUP:
|
|
return "backup";
|
|
case WALSNDSTATE_CATCHUP:
|
|
return "catchup";
|
|
case WALSNDSTATE_STREAMING:
|
|
return "streaming";
|
|
case WALSNDSTATE_STOPPING:
|
|
return "stopping";
|
|
}
|
|
return "UNKNOWN";
|
|
}
|
|
|
|
static Interval *
|
|
offset_to_interval(TimeOffset offset)
|
|
{
|
|
Interval *result = palloc(sizeof(Interval));
|
|
|
|
result->month = 0;
|
|
result->day = 0;
|
|
result->time = offset;
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* Returns activity of walsenders, including pids and xlog locations sent to
|
|
* standby servers.
|
|
*/
|
|
Datum
|
|
pg_stat_get_wal_senders(PG_FUNCTION_ARGS)
|
|
{
|
|
#define PG_STAT_GET_WAL_SENDERS_COLS 15
|
|
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
|
|
TupleDesc tupdesc;
|
|
Tuplestorestate *tupstore;
|
|
MemoryContext per_query_ctx;
|
|
MemoryContext oldcontext;
|
|
List *sync_standbys;
|
|
int i;
|
|
|
|
/* check to see if caller supports us returning a tuplestore */
|
|
if (rsinfo == NULL || !IsA(rsinfo, ReturnSetInfo))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("set-valued function called in context that cannot accept a set")));
|
|
if (!(rsinfo->allowedModes & SFRM_Materialize))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("materialize mode required, but it is not allowed in this context")));
|
|
|
|
/* Build a tuple descriptor for our result type */
|
|
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
|
|
elog(ERROR, "return type must be a row type");
|
|
|
|
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
|
|
oldcontext = MemoryContextSwitchTo(per_query_ctx);
|
|
|
|
tupstore = tuplestore_begin_heap(true, false, work_mem);
|
|
rsinfo->returnMode = SFRM_Materialize;
|
|
rsinfo->setResult = tupstore;
|
|
rsinfo->setDesc = tupdesc;
|
|
|
|
MemoryContextSwitchTo(oldcontext);
|
|
|
|
/*
|
|
* Get the currently active synchronous standbys.
|
|
*/
|
|
LWLockAcquire(SyncRepLock, LW_SHARED);
|
|
sync_standbys = SyncRepGetSyncStandbys(NULL);
|
|
LWLockRelease(SyncRepLock);
|
|
|
|
for (i = 0; i < max_wal_senders; i++)
|
|
{
|
|
WalSnd *walsnd = &WalSndCtl->walsnds[i];
|
|
XLogRecPtr sentPtr;
|
|
XLogRecPtr write;
|
|
XLogRecPtr flush;
|
|
XLogRecPtr apply;
|
|
TimeOffset writeLag;
|
|
TimeOffset flushLag;
|
|
TimeOffset applyLag;
|
|
int priority;
|
|
int pid;
|
|
WalSndState state;
|
|
TimestampTz replyTime;
|
|
int64 spillTxns;
|
|
int64 spillCount;
|
|
int64 spillBytes;
|
|
Datum values[PG_STAT_GET_WAL_SENDERS_COLS];
|
|
bool nulls[PG_STAT_GET_WAL_SENDERS_COLS];
|
|
|
|
SpinLockAcquire(&walsnd->mutex);
|
|
if (walsnd->pid == 0)
|
|
{
|
|
SpinLockRelease(&walsnd->mutex);
|
|
continue;
|
|
}
|
|
pid = walsnd->pid;
|
|
sentPtr = walsnd->sentPtr;
|
|
state = walsnd->state;
|
|
write = walsnd->write;
|
|
flush = walsnd->flush;
|
|
apply = walsnd->apply;
|
|
writeLag = walsnd->writeLag;
|
|
flushLag = walsnd->flushLag;
|
|
applyLag = walsnd->applyLag;
|
|
priority = walsnd->sync_standby_priority;
|
|
replyTime = walsnd->replyTime;
|
|
spillTxns = walsnd->spillTxns;
|
|
spillCount = walsnd->spillCount;
|
|
spillBytes = walsnd->spillBytes;
|
|
SpinLockRelease(&walsnd->mutex);
|
|
|
|
memset(nulls, 0, sizeof(nulls));
|
|
values[0] = Int32GetDatum(pid);
|
|
|
|
if (!is_member_of_role(GetUserId(), DEFAULT_ROLE_READ_ALL_STATS))
|
|
{
|
|
/*
|
|
* Only superusers and members of pg_read_all_stats can see
|
|
* details. Other users only get the pid value to know it's a
|
|
* walsender, but no details.
|
|
*/
|
|
MemSet(&nulls[1], true, PG_STAT_GET_WAL_SENDERS_COLS - 1);
|
|
}
|
|
else
|
|
{
|
|
values[1] = CStringGetTextDatum(WalSndGetStateString(state));
|
|
|
|
if (XLogRecPtrIsInvalid(sentPtr))
|
|
nulls[2] = true;
|
|
values[2] = LSNGetDatum(sentPtr);
|
|
|
|
if (XLogRecPtrIsInvalid(write))
|
|
nulls[3] = true;
|
|
values[3] = LSNGetDatum(write);
|
|
|
|
if (XLogRecPtrIsInvalid(flush))
|
|
nulls[4] = true;
|
|
values[4] = LSNGetDatum(flush);
|
|
|
|
if (XLogRecPtrIsInvalid(apply))
|
|
nulls[5] = true;
|
|
values[5] = LSNGetDatum(apply);
|
|
|
|
/*
|
|
* Treat a standby such as a pg_basebackup background process
|
|
* which always returns an invalid flush location, as an
|
|
* asynchronous standby.
|
|
*/
|
|
priority = XLogRecPtrIsInvalid(flush) ? 0 : priority;
|
|
|
|
if (writeLag < 0)
|
|
nulls[6] = true;
|
|
else
|
|
values[6] = IntervalPGetDatum(offset_to_interval(writeLag));
|
|
|
|
if (flushLag < 0)
|
|
nulls[7] = true;
|
|
else
|
|
values[7] = IntervalPGetDatum(offset_to_interval(flushLag));
|
|
|
|
if (applyLag < 0)
|
|
nulls[8] = true;
|
|
else
|
|
values[8] = IntervalPGetDatum(offset_to_interval(applyLag));
|
|
|
|
values[9] = Int32GetDatum(priority);
|
|
|
|
/*
|
|
* More easily understood version of standby state. This is purely
|
|
* informational.
|
|
*
|
|
* In quorum-based sync replication, the role of each standby
|
|
* listed in synchronous_standby_names can be changing very
|
|
* frequently. Any standbys considered as "sync" at one moment can
|
|
* be switched to "potential" ones at the next moment. So, it's
|
|
* basically useless to report "sync" or "potential" as their sync
|
|
* states. We report just "quorum" for them.
|
|
*/
|
|
if (priority == 0)
|
|
values[10] = CStringGetTextDatum("async");
|
|
else if (list_member_int(sync_standbys, i))
|
|
values[10] = SyncRepConfig->syncrep_method == SYNC_REP_PRIORITY ?
|
|
CStringGetTextDatum("sync") : CStringGetTextDatum("quorum");
|
|
else
|
|
values[10] = CStringGetTextDatum("potential");
|
|
|
|
if (replyTime == 0)
|
|
nulls[11] = true;
|
|
else
|
|
values[11] = TimestampTzGetDatum(replyTime);
|
|
|
|
/* spill to disk */
|
|
values[12] = Int64GetDatum(spillTxns);
|
|
values[13] = Int64GetDatum(spillCount);
|
|
values[14] = Int64GetDatum(spillBytes);
|
|
}
|
|
|
|
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
|
|
}
|
|
|
|
/* clean up and return the tuplestore */
|
|
tuplestore_donestoring(tupstore);
|
|
|
|
return (Datum) 0;
|
|
}
|
|
|
|
/*
|
|
* This function is used to send a keepalive message to standby.
|
|
* If requestReply is set, sets a flag in the message requesting the standby
|
|
* to send a message back to us, for heartbeat purposes.
|
|
*/
|
|
static void
|
|
WalSndKeepalive(bool requestReply)
|
|
{
|
|
elog(DEBUG2, "sending replication keepalive");
|
|
|
|
/* construct the message... */
|
|
resetStringInfo(&output_message);
|
|
pq_sendbyte(&output_message, 'k');
|
|
pq_sendint64(&output_message, sentPtr);
|
|
pq_sendint64(&output_message, GetCurrentTimestamp());
|
|
pq_sendbyte(&output_message, requestReply ? 1 : 0);
|
|
|
|
/* ... and send it wrapped in CopyData */
|
|
pq_putmessage_noblock('d', output_message.data, output_message.len);
|
|
}
|
|
|
|
/*
|
|
* Send keepalive message if too much time has elapsed.
|
|
*/
|
|
static void
|
|
WalSndKeepaliveIfNecessary(void)
|
|
{
|
|
TimestampTz ping_time;
|
|
|
|
/*
|
|
* Don't send keepalive messages if timeouts are globally disabled or
|
|
* we're doing something not partaking in timeouts.
|
|
*/
|
|
if (wal_sender_timeout <= 0 || last_reply_timestamp <= 0)
|
|
return;
|
|
|
|
if (waiting_for_ping_response)
|
|
return;
|
|
|
|
/*
|
|
* If half of wal_sender_timeout has lapsed without receiving any reply
|
|
* from the standby, send a keep-alive message to the standby requesting
|
|
* an immediate reply.
|
|
*/
|
|
ping_time = TimestampTzPlusMilliseconds(last_reply_timestamp,
|
|
wal_sender_timeout / 2);
|
|
if (last_processing >= ping_time)
|
|
{
|
|
WalSndKeepalive(true);
|
|
waiting_for_ping_response = true;
|
|
|
|
/* Try to flush pending output to the client */
|
|
if (pq_flush_if_writable() != 0)
|
|
WalSndShutdown();
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Record the end of the WAL and the time it was flushed locally, so that
|
|
* LagTrackerRead can compute the elapsed time (lag) when this WAL location is
|
|
* eventually reported to have been written, flushed and applied by the
|
|
* standby in a reply message.
|
|
*/
|
|
static void
|
|
LagTrackerWrite(XLogRecPtr lsn, TimestampTz local_flush_time)
|
|
{
|
|
bool buffer_full;
|
|
int new_write_head;
|
|
int i;
|
|
|
|
if (!am_walsender)
|
|
return;
|
|
|
|
/*
|
|
* If the lsn hasn't advanced since last time, then do nothing. This way
|
|
* we only record a new sample when new WAL has been written.
|
|
*/
|
|
if (lag_tracker->last_lsn == lsn)
|
|
return;
|
|
lag_tracker->last_lsn = lsn;
|
|
|
|
/*
|
|
* If advancing the write head of the circular buffer would crash into any
|
|
* of the read heads, then the buffer is full. In other words, the
|
|
* slowest reader (presumably apply) is the one that controls the release
|
|
* of space.
|
|
*/
|
|
new_write_head = (lag_tracker->write_head + 1) % LAG_TRACKER_BUFFER_SIZE;
|
|
buffer_full = false;
|
|
for (i = 0; i < NUM_SYNC_REP_WAIT_MODE; ++i)
|
|
{
|
|
if (new_write_head == lag_tracker->read_heads[i])
|
|
buffer_full = true;
|
|
}
|
|
|
|
/*
|
|
* If the buffer is full, for now we just rewind by one slot and overwrite
|
|
* the last sample, as a simple (if somewhat uneven) way to lower the
|
|
* sampling rate. There may be better adaptive compaction algorithms.
|
|
*/
|
|
if (buffer_full)
|
|
{
|
|
new_write_head = lag_tracker->write_head;
|
|
if (lag_tracker->write_head > 0)
|
|
lag_tracker->write_head--;
|
|
else
|
|
lag_tracker->write_head = LAG_TRACKER_BUFFER_SIZE - 1;
|
|
}
|
|
|
|
/* Store a sample at the current write head position. */
|
|
lag_tracker->buffer[lag_tracker->write_head].lsn = lsn;
|
|
lag_tracker->buffer[lag_tracker->write_head].time = local_flush_time;
|
|
lag_tracker->write_head = new_write_head;
|
|
}
|
|
|
|
/*
|
|
* Find out how much time has elapsed between the moment WAL location 'lsn'
|
|
* (or the highest known earlier LSN) was flushed locally and the time 'now'.
|
|
* We have a separate read head for each of the reported LSN locations we
|
|
* receive in replies from standby; 'head' controls which read head is
|
|
* used. Whenever a read head crosses an LSN which was written into the
|
|
* lag buffer with LagTrackerWrite, we can use the associated timestamp to
|
|
* find out the time this LSN (or an earlier one) was flushed locally, and
|
|
* therefore compute the lag.
|
|
*
|
|
* Return -1 if no new sample data is available, and otherwise the elapsed
|
|
* time in microseconds.
|
|
*/
|
|
static TimeOffset
|
|
LagTrackerRead(int head, XLogRecPtr lsn, TimestampTz now)
|
|
{
|
|
TimestampTz time = 0;
|
|
|
|
/* Read all unread samples up to this LSN or end of buffer. */
|
|
while (lag_tracker->read_heads[head] != lag_tracker->write_head &&
|
|
lag_tracker->buffer[lag_tracker->read_heads[head]].lsn <= lsn)
|
|
{
|
|
time = lag_tracker->buffer[lag_tracker->read_heads[head]].time;
|
|
lag_tracker->last_read[head] =
|
|
lag_tracker->buffer[lag_tracker->read_heads[head]];
|
|
lag_tracker->read_heads[head] =
|
|
(lag_tracker->read_heads[head] + 1) % LAG_TRACKER_BUFFER_SIZE;
|
|
}
|
|
|
|
/*
|
|
* If the lag tracker is empty, that means the standby has processed
|
|
* everything we've ever sent so we should now clear 'last_read'. If we
|
|
* didn't do that, we'd risk using a stale and irrelevant sample for
|
|
* interpolation at the beginning of the next burst of WAL after a period
|
|
* of idleness.
|
|
*/
|
|
if (lag_tracker->read_heads[head] == lag_tracker->write_head)
|
|
lag_tracker->last_read[head].time = 0;
|
|
|
|
if (time > now)
|
|
{
|
|
/* If the clock somehow went backwards, treat as not found. */
|
|
return -1;
|
|
}
|
|
else if (time == 0)
|
|
{
|
|
/*
|
|
* We didn't cross a time. If there is a future sample that we
|
|
* haven't reached yet, and we've already reached at least one sample,
|
|
* let's interpolate the local flushed time. This is mainly useful
|
|
* for reporting a completely stuck apply position as having
|
|
* increasing lag, since otherwise we'd have to wait for it to
|
|
* eventually start moving again and cross one of our samples before
|
|
* we can show the lag increasing.
|
|
*/
|
|
if (lag_tracker->read_heads[head] == lag_tracker->write_head)
|
|
{
|
|
/* There are no future samples, so we can't interpolate. */
|
|
return -1;
|
|
}
|
|
else if (lag_tracker->last_read[head].time != 0)
|
|
{
|
|
/* We can interpolate between last_read and the next sample. */
|
|
double fraction;
|
|
WalTimeSample prev = lag_tracker->last_read[head];
|
|
WalTimeSample next = lag_tracker->buffer[lag_tracker->read_heads[head]];
|
|
|
|
if (lsn < prev.lsn)
|
|
{
|
|
/*
|
|
* Reported LSNs shouldn't normally go backwards, but it's
|
|
* possible when there is a timeline change. Treat as not
|
|
* found.
|
|
*/
|
|
return -1;
|
|
}
|
|
|
|
Assert(prev.lsn < next.lsn);
|
|
|
|
if (prev.time > next.time)
|
|
{
|
|
/* If the clock somehow went backwards, treat as not found. */
|
|
return -1;
|
|
}
|
|
|
|
/* See how far we are between the previous and next samples. */
|
|
fraction =
|
|
(double) (lsn - prev.lsn) / (double) (next.lsn - prev.lsn);
|
|
|
|
/* Scale the local flush time proportionally. */
|
|
time = (TimestampTz)
|
|
((double) prev.time + (next.time - prev.time) * fraction);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* We have only a future sample, implying that we were entirely
|
|
* caught up but and now there is a new burst of WAL and the
|
|
* standby hasn't processed the first sample yet. Until the
|
|
* standby reaches the future sample the best we can do is report
|
|
* the hypothetical lag if that sample were to be replayed now.
|
|
*/
|
|
time = lag_tracker->buffer[lag_tracker->read_heads[head]].time;
|
|
}
|
|
}
|
|
|
|
/* Return the elapsed time since local flush time in microseconds. */
|
|
Assert(time != 0);
|
|
return now - time;
|
|
}
|
|
|
|
static void
|
|
UpdateSpillStats(LogicalDecodingContext *ctx)
|
|
{
|
|
ReorderBuffer *rb = ctx->reorder;
|
|
|
|
SpinLockAcquire(&MyWalSnd->mutex);
|
|
|
|
MyWalSnd->spillTxns = rb->spillTxns;
|
|
MyWalSnd->spillCount = rb->spillCount;
|
|
MyWalSnd->spillBytes = rb->spillBytes;
|
|
|
|
elog(DEBUG2, "UpdateSpillStats: updating stats %p %lld %lld %lld",
|
|
rb,
|
|
(long long) rb->spillTxns,
|
|
(long long) rb->spillCount,
|
|
(long long) rb->spillBytes);
|
|
|
|
SpinLockRelease(&MyWalSnd->mutex);
|
|
}
|