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The attached patch modifies libpgtcl per previous discussion: the 

pg_notifies statement is eliminated, and callbacks defined by
pg_listen are instead invoked automatically from the Tcl idle loop
whenever a NOTIFY message is received.

I have done only cursory testing, so there may be problems still
lurking (particularly on non-Unix machines?).  But it seems to
work.

Patch is against today's cvs sources.  Note that this will not work
with the 6.3.2 release since it depends on the new libpq.

The diffs are a bit large so I've gzipped them.  A patch to update
libpgtcl.sgml is included too.

			regards, tom lane
This commit is contained in:
Bruce Momjian 1998-06-16 04:10:17 +00:00
parent 693b156a70
commit 583891833f
6 changed files with 551 additions and 174 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

135
doc/src/sgml/libpgtcl.sgml
View File

@ -3,11 +3,8 @@
<Para>
pgtcl is a tcl package for front-end programs to interface with <ProductName>Postgres</ProductName>
backends. pgtcl does not use the libpq library but communicates to
the backend directly via the frontend-backend protocol. Thus, it is
more efficient than previous postgres->tcl bindings which are layered
on top of libpq. In addition, pgtcl can handle multiple backend
connections from a single frontend application.
backends. It makes most of the functionality of libpq available to
tcl scripts.
</Para>
<Para>
@ -42,17 +39,25 @@ the standard Unix file system interface.
<ENTRY>pg_disconnect</ENTRY>
<ENTRY>closes a connection</ENTRY>
</ROW>
<ROW>
<ENTRY>pg_conndefaults</ENTRY>
<ENTRY>get connection options and their defaults</ENTRY>
</ROW>
<ROW>
<ENTRY>pg_exec</ENTRY>
<ENTRY>send a query to the backend</ENTRY>
</ROW>
<ROW>
<ENTRY>pg_result</ENTRY>
<ENTRY>manipulate the results of a query</ENTRY>
</ROW>
<ROW>
<ENTRY>pg_select</ENTRY>
<ENTRY>loop over the result of a select statement</ENTRY>
</ROW>
<ROW>
<ENTRY>pg_result</ENTRY>
<ENTRY>manipulate the results of a query</ENTRY>
<ENTRY>pg_listen</ENTRY>
<ENTRY>establish a callback for NOTIFY messages</ENTRY>
</ROW>
<ROW>
@ -101,8 +106,7 @@ the standard Unix file system interface.
</Para>
<Para>
Some commands equivalent to libpq commands are provided for connection
and query operations.
These commands are described further on subsequent pages.
</Para>
<Para>
@ -142,7 +146,7 @@ proc getDBs { {host "localhost"} {port "5432"} } {
</Sect1>
<Sect1>
<Title>Reference Information</Title>
<Title>pgtcl Command Reference Information</Title>
<REFENTRY ID="PGTCL-PGCONNECT-1">
<REFMETA>
@ -235,7 +239,7 @@ pg_connect <REPLACEABLE CLASS="PARAMETER">dbName</REPLACEABLE> <OPTIONAL>-host <
<LISTITEM>
<PARA>
The return result is either an error message or a handle for a database
connection. Handles start with the prefix "pgp"
connection. Handles start with the prefix "pgsql"
</PARA>
</LISTITEM>
</VARLISTENTRY>
@ -414,7 +418,114 @@ pg_exec <REPLACEABLE CLASS="PARAMETER">dbHandle</REPLACEABLE> <REPLACEABLE CLASS
</TITLE>
<PARA>
<FUNCTION>pg_exec</FUNCTION> submits a query to the <ProductName>Postgres</ProductName> backend and returns a result.
Handles start with the prefix "pgp".
Query result handles start with the connection handle and add a period
and a result number.
</PARA>
</REFSECT1>
<REFENTRY ID="PGTCL-PGLISTEN-1">
<REFMETA>
<REFENTRYTITLE>pg_listen</REFENTRYTITLE>
<REFMISCINFO>PGTCL - Asynchronous Notify</REFMISCINFO>
</REFMETA>
<REFNAMEDIV>
<REFNAME>pg_listen
</REFNAME>
<REFPURPOSE>sets or changes a callback for asynchronous NOTIFY messages
</REFPURPOSE>
<INDEXTERM ID="IX-PGTCL-PGLISTEN-1"><PRIMARY>pgtcl</PRIMARY><SECONDARY>notify</SECONDARY></INDEXTERM>
<INDEXTERM ID="IX-PGTCL-PGLISTEN-2"><PRIMARY>notify</PRIMARY></INDEXTERM>
</REFNAMEDIV>
<REFSYNOPSISDIV>
<REFSYNOPSISDIVINFO>
<DATE>1998-5-22</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
pg_listen <REPLACEABLE CLASS="PARAMETER">dbHandle</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">notifyName</REPLACEABLE> <REPLACEABLE CLASS="PARAMETER">callbackCommand</REPLACEABLE>
</SYNOPSIS>
<REFSECT2 ID="R2-PGTCL-PGLISTEN-1">
<REFSECT2INFO>
<DATE>1998-5-22</DATE>
</REFSECT2INFO>
<TITLE>Inputs
</TITLE>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">dbHandle</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>Specifies a valid database handle.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">notifyName</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>Specifies the notification name to start or stop listening to.
</PARA>
</LISTITEM>
</VARLISTENTRY>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">callbackCommand</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>If present and not empty, provides the command string to execute
when a matching notification arrives.
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-PGTCL-PGLISTEN-2">
<REFSECT2INFO>
<DATE>1998-5-22</DATE>
</REFSECT2INFO>
<TITLE>Outputs
</TITLE>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
None
</TERM>
<LISTITEM>
<PARA>
</PARA>
</LISTITEM>
</VARLISTENTRY>
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-PGTCL-PGLISTEN-1">
<REFSECT1INFO>
<DATE>1998-5-22</DATE>
</REFSECT1INFO>
<TITLE>Description
</TITLE>
<PARA><FUNCTION>pg_listen</FUNCTION> creates, changes, or cancels a request
to listen for asynchronous NOTIFY messages from the
<ProductName>Postgres</ProductName> backend. With a callbackCommand
parameter, the request is established, or the command string of an already
existing request is replaced. With no callbackCommand parameter, a prior
request is canceled.
</PARA>
After a <PARA><FUNCTION>pg_listen</FUNCTION> request is established,
the specified command string is executed whenever a NOTIFY message bearing
the given name arrives from the backend. This occurs when any
<ProductName>Postgres</ProductName> client application issues a NOTIFY command
referencing that name. (Note that the name can be, but does not have to be,
that of an existing relation in the database.)
The command string is executed from the Tcl idle loop. That is the normal
idle state of an application written with Tk. In non-Tk Tcl shells, you can
execute <FUNCTION>update</FUNCTION> or <FUNCTION>vwait</FUNCTION> to cause
the idle loop to be entered.
</PARA>
</REFSECT1>

11
src/interfaces/libpgtcl/pgtcl.c
View File

@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtcl.c,v 1.10 1998/03/15 08:02:57 scrappy Exp $
* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtcl.c,v 1.11 1998/06/16 04:10:15 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -36,7 +36,7 @@ Pgtcl_Init (Tcl_Interp *interp)
* to guess where it might be by position in the struct. This is needed
* for Tcl7.6 and beyond, which have the getfileproc.
*/
#if (TCL_MAJOR_VERSION == 7 && TCL_MINOR_VERSION == 6)
#if HAVE_TCL_GETFILEPROC
Pg_ConnType.getFileProc = PgGetFileProc;
#endif
@ -126,12 +126,7 @@ Pgtcl_Init (Tcl_Interp *interp)
Pg_listen,
(ClientData)NULL, (Tcl_CmdDeleteProc*)NULL);
Tcl_CreateCommand(interp,
"pg_notifies",
Pg_notifies,
(ClientData)NULL, (Tcl_CmdDeleteProc*)NULL);
Tcl_PkgProvide(interp, "Pgtcl", "1.1");
Tcl_PkgProvide(interp, "Pgtcl", "1.2");
return TCL_OK;
}

244
src/interfaces/libpgtcl/pgtclCmds.c
View File

@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclCmds.c,v 1.24 1998/06/15 19:30:17 momjian Exp $
* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclCmds.c,v 1.25 1998/06/16 04:10:16 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -15,6 +15,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <tcl.h>
#include "postgres.h"
@ -415,7 +416,6 @@ Pg_exec(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], &connid);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -426,6 +426,10 @@ Pg_exec(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
connStatus = conn->status;
result = PQexec(conn, argv[2]);
/* Transfer any notify events from libpq to Tcl event queue. */
PgNotifyTransferEvents(connid);
if (result) {
int rId = PgSetResultId(interp, argv[1], result);
if (result->resultStatus == PGRES_COPY_IN ||
@ -439,9 +443,11 @@ Pg_exec(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
/* error occurred during the query */
Tcl_SetResult(interp, conn->errorMessage, TCL_STATIC);
if (connStatus == CONNECTION_OK) {
/* Is this REALLY a good idea? I don't think so! */
PQreset(conn);
if (conn->status == CONNECTION_OK) {
result = PQexec(conn, argv[2]);
PgNotifyTransferEvents(connid);
if (result) {
int rId = PgSetResultId(interp, argv[1], result);
if (result->resultStatus == PGRES_COPY_IN ||
@ -699,7 +705,6 @@ Pg_lo_open(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -766,7 +771,6 @@ Pg_lo_close(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -804,7 +808,6 @@ Pg_lo_read(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -854,7 +857,6 @@ Pg_lo_write(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -900,7 +902,6 @@ Pg_lo_lseek(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -952,7 +953,6 @@ Pg_lo_creat(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -1008,7 +1008,6 @@ Pg_lo_tell(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -1043,7 +1042,6 @@ Pg_lo_unlink(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -1085,7 +1083,6 @@ Pg_lo_import(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -1125,7 +1122,6 @@ Pg_lo_export(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
@ -1164,6 +1160,7 @@ Pg_lo_export(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
int
Pg_select(ClientData cData, Tcl_Interp *interp, int argc, char **argv)
{
Pg_ConnectionId *connid;
PGconn *conn;
PGresult *result;
int r;
@ -1182,7 +1179,7 @@ Pg_select(ClientData cData, Tcl_Interp *interp, int argc, char **argv)
return TCL_ERROR;
}
conn = PgGetConnectionId(interp, argv[1], (Pg_ConnectionId**)NULL);
conn = PgGetConnectionId(interp, argv[1], &connid);
if (conn == (PGconn *)NULL) {
return TCL_ERROR;
}
@ -1194,6 +1191,9 @@ Pg_select(ClientData cData, Tcl_Interp *interp, int argc, char **argv)
return TCL_ERROR;
}
/* Transfer any notify events from libpq to Tcl event queue. */
PgNotifyTransferEvents(connid);
if ((info = (struct info_s *)ckalloc(sizeof(*info) * (ncols = PQnfields(result)))) == NULL)
{
Tcl_AppendResult(interp, "Not enough memory", 0);
@ -1248,145 +1248,139 @@ Pg_select(ClientData cData, Tcl_Interp *interp, int argc, char **argv)
return TCL_OK;
}
/***********************************
Pg_listen
create or remove a callback request for notifies on a given name
syntax:
pg_listen conn notifyname ?callbackcommand?
With a fourth arg, creates or changes the callback command for
notifies on the given name; without, cancels the callback request.
Callbacks can occur whenever Tcl is executing its event loop.
This is the normal idle loop in Tk; in plain tclsh applications,
vwait or update can be used to enter the Tcl event loop.
***********************************/
int
Pg_listen(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
{
int new;
char *relname;
char *callback = NULL;
char *origrelname;
char *caserelname;
char *callback = NULL;
Pg_TclNotifies *notifies;
Tcl_HashEntry *entry;
Pg_ConnectionId *connid;
PGconn *conn;
PGresult *result;
int new;
if ((argc < 3) || (argc > 4)) {
Tcl_AppendResult(interp, "wrong # args, should be \"",
argv[0], " connection relname ?callback?\"", 0);
return TCL_ERROR;
if (argc < 3 || argc > 4) {
Tcl_AppendResult(interp, "wrong # args, should be \"",
argv[0], " connection relname ?callback?\"", 0);
return TCL_ERROR;
}
/*
* Get the command arguments. Note that relname will copied by
* Tcl_CreateHashEntry while callback must be allocated.
* Get the command arguments. Note that the relation name will be copied
* by Tcl_CreateHashEntry while the callback string must be allocated.
*/
conn = PgGetConnectionId(interp, argv[1], &connid);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
relname = argv[2];
if ((argc > 3) && *argv[3]) {
callback = (char *) ckalloc((unsigned) (strlen(argv[3])+1));
strcpy(callback, argv[3]);
return TCL_ERROR;
}
/*
* LISTEN/NOTIFY do not preserve case unless the relation name is
* quoted. We have to do the same thing to ensure that we will find
* the desired pg_listen item.
*/
origrelname = argv[2];
caserelname = (char *) ckalloc((unsigned) (strlen(origrelname) + 1));
if (*origrelname == '"') {
/* Copy a quoted string without downcasing */
strcpy(caserelname, origrelname + 1);
caserelname[strlen(caserelname) - 1] = '\0';
} else {
/* Downcase it */
char *rels = origrelname;
char *reld = caserelname;
while (*rels) {
*reld++ = tolower(*rels++);
}
*reld = '\0';
}
if ((argc > 3) && *argv[3]) {
callback = (char *) ckalloc((unsigned) (strlen(argv[3]) + 1));
strcpy(callback, argv[3]);
}
/* Find or make a Pg_TclNotifies struct for this interp and connection */
for (notifies = connid->notify_list; notifies; notifies = notifies->next) {
if (notifies->interp == interp)
break;
}
if (notifies == NULL) {
notifies = (Pg_TclNotifies *) ckalloc(sizeof(Pg_TclNotifies));
notifies->interp = interp;
Tcl_InitHashTable(&notifies->notify_hash, TCL_STRING_KEYS);
notifies->next = connid->notify_list;
connid->notify_list = notifies;
Tcl_CallWhenDeleted(interp, PgNotifyInterpDelete,
(ClientData) notifies);
}
/*
* Set or update a callback for a relation;
* Set or update a callback for a relation
*/
if (callback) {
entry = Tcl_CreateHashEntry(&(connid->notify_hash), relname, &new);
if (new) {
/* New callback, execute a listen command on the relation */
char *cmd = (char *) ckalloc((unsigned) (strlen(argv[2])+8));
sprintf(cmd, "LISTEN %s", relname);
result = PQexec(conn, cmd);
ckfree(cmd);
if (!result || (result->resultStatus != PGRES_COMMAND_OK)) {
/* Error occurred during the execution of command */
if (result) PQclear(result);
ckfree(callback);
Tcl_DeleteHashEntry(entry);
Tcl_SetResult(interp, conn->errorMessage, TCL_STATIC);
return TCL_ERROR;
}
PQclear(result);
} else {
/* Free the old callback string */
ckfree((char *) Tcl_GetHashValue(entry));
}
/* Store the new callback command */
Tcl_SetHashValue(entry, callback);
entry = Tcl_CreateHashEntry(&notifies->notify_hash, caserelname, &new);
if (new) {
/* New callback, execute a listen command on the relation */
char *cmd = (char *) ckalloc((unsigned) (strlen(origrelname)+8));
sprintf(cmd, "LISTEN %s", origrelname);
result = PQexec(conn, cmd);
ckfree(cmd);
/* Transfer any notify events from libpq to Tcl event queue. */
PgNotifyTransferEvents(connid);
if (!result || (result->resultStatus != PGRES_COMMAND_OK)) {
/* Error occurred during the execution of command */
if (result) PQclear(result);
ckfree(callback);
ckfree(caserelname);
Tcl_DeleteHashEntry(entry);
Tcl_SetResult(interp, PQerrorMessage(conn), TCL_VOLATILE);
return TCL_ERROR;
}
PQclear(result);
} else {
/* Update, free the old callback string */
ckfree((char *) Tcl_GetHashValue(entry));
}
/* Store the new callback string */
Tcl_SetHashValue(entry, callback);
/* Start the notify event source if it isn't already running */
PgStartNotifyEventSource(connid);
}
/*
* Remove a callback for a relation. There is no way to
* un-listen a relation, simply remove the callback from
* un-listen a relation, so we simply remove the callback from
* the notify hash table.
*/
if (callback == NULL) {
entry = Tcl_FindHashEntry(&(connid->notify_hash), relname);
if (entry == NULL) {
Tcl_AppendResult(interp, "not listening on ", relname, 0);
return TCL_ERROR;
}
ckfree((char *) Tcl_GetHashValue(entry));
Tcl_DeleteHashEntry(entry);
entry = Tcl_FindHashEntry(&notifies->notify_hash, caserelname);
if (entry == NULL) {
Tcl_AppendResult(interp, "not listening on ", origrelname, 0);
ckfree(caserelname);
return TCL_ERROR;
}
ckfree((char *) Tcl_GetHashValue(entry));
Tcl_DeleteHashEntry(entry);
}
return TCL_OK;
}
int
Pg_notifies(ClientData cData, Tcl_Interp *interp, int argc, char* argv[])
{
int count;
char buff[12];
char *callback;
Tcl_HashEntry *entry;
Pg_ConnectionId *connid;
PGconn *conn;
PGresult *result;
PGnotify *notify;
if (argc != 2) {
Tcl_AppendResult(interp, "wrong # args, should be \"",
argv[0], " connection\"", 0);
return TCL_ERROR;
}
/*
* Get the connection argument.
*/
conn = (PGconn*)PgGetConnectionId(interp, argv[1], &connid);
if (conn == (PGconn *)NULL) {
Tcl_AppendResult(interp, "First argument is not a valid connection\n", 0);
return TCL_ERROR;
}
/* Execute an empty command to retrieve asynchronous notifications */
result = PQexec(conn, " ");
if (result == NULL) {
/* Error occurred during the execution of command */
Tcl_SetResult(interp, conn->errorMessage, TCL_STATIC);
return TCL_ERROR;
}
PQclear(result);
/*
* Loop while there are pending notifies.
*/
for (count=0; count < 999; count++) {
/* See if there is a pending notification */
notify = PQnotifies(conn);
if (notify == NULL) {
break;
}
entry = Tcl_FindHashEntry(&(connid->notify_hash), notify->relname);
if (entry != NULL) {
callback = (char*)Tcl_GetHashValue(entry);
if (callback) {
/* This should be a global eval, shouldn't it? */
Tcl_Eval(interp, callback);
/* And what if there's an error. Bgerror should be called? */
}
}
free(notify);
}
/*
* Return the number of notifications processed.
*/
sprintf(buff, "%d", count);
Tcl_SetResult(interp, buff, TCL_VOLATILE);
ckfree(caserelname);
return TCL_OK;
}

33
src/interfaces/libpgtcl/pgtclCmds.h
View File

@ -5,7 +5,7 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: pgtclCmds.h,v 1.9 1998/03/15 08:02:59 scrappy Exp $
* $Id: pgtclCmds.h,v 1.10 1998/06/16 04:10:17 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -14,13 +14,29 @@
#define PGTCLCMDS_H
#include "tcl.h"
#include "libpq/pqcomm.h"
#include "libpq-fe.h"
#include "libpq/libpq-fs.h"
#define RES_HARD_MAX 128
#define RES_START 16
/*
* Each Pg_ConnectionId has a list of Pg_TclNotifies structs, one for each
* Tcl interpreter that has executed any pg_listens on the connection.
* We need this arrangement to be able to clean up if an interpreter is
* deleted while the connection remains open. A free side benefit is that
* multiple interpreters can be registered to listen for the same notify
* name. (All their callbacks will be called, but in an unspecified order.)
*/
typedef struct Pg_TclNotifies_s {
struct Pg_TclNotifies_s *next; /* list link */
Tcl_Interp *interp; /* This Tcl interpreter */
/* NB: if interp == NULL, the interpreter is gone but we haven't
* yet got round to deleting the Pg_TclNotifies structure.
*/
Tcl_HashTable notify_hash; /* Active pg_listen requests */
} Pg_TclNotifies;
typedef struct Pg_ConnectionId_s {
char id[32];
PGconn *conn;
@ -31,10 +47,11 @@ typedef struct Pg_ConnectionId_s {
int res_copy; /* Query result with active copy */
int res_copyStatus; /* Copying status */
PGresult **results; /* The results */
Tcl_HashTable notify_hash;
} Pg_ConnectionId;
Pg_TclNotifies *notify_list; /* head of list of notify info */
int notifier_running; /* notify event source is live */
} Pg_ConnectionId;
#define RES_COPY_NONE 0
#define RES_COPY_INPROGRESS 1
@ -78,9 +95,5 @@ extern int Pg_lo_export(
ClientData cData, Tcl_Interp *interp, int argc, char* argv[]);
extern int Pg_listen(
ClientData cData, Tcl_Interp *interp, int argc, char* argv[]);
extern int Pg_notifies(
ClientData cData, Tcl_Interp *interp, int argc, char* argv[]);
#endif /*PGTCLCMDS_H*/

283
src/interfaces/libpgtcl/pgtclId.c
View File

@ -12,7 +12,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclId.c,v 1.10 1998/05/06 23:53:30 momjian Exp $
* $Header: /cvsroot/pgsql/src/interfaces/libpgtcl/Attic/pgtclId.c,v 1.11 1998/06/16 04:10:17 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -26,7 +26,8 @@
#include "pgtclCmds.h"
#include "pgtclId.h"
int PgEndCopy(Pg_ConnectionId *connid, int *errorCodePtr)
static int PgEndCopy(Pg_ConnectionId *connid, int *errorCodePtr)
{
connid->res_copyStatus = RES_COPY_NONE;
if (PQendcopy(connid->conn)) {
@ -147,12 +148,14 @@ int PgOutputProc(DRIVER_OUTPUT_PROTO)
return bufSize;
}
#if (TCL_MAJOR_VERSION == 7 && TCL_MINOR_VERSION == 6)
#if HAVE_TCL_GETFILEPROC
Tcl_File
PgGetFileProc(ClientData cData, int direction)
{
return (Tcl_File)NULL;
}
#endif
Tcl_ChannelType Pg_ConnType = {
@ -184,14 +187,18 @@ PgSetConnectionId(Tcl_Interp *interp, PGconn *conn)
connid->res_copy = -1;
connid->res_copyStatus = RES_COPY_NONE;
connid->results = (PGresult**)ckalloc(sizeof(PGresult*) * RES_START);
for (i = 0; i < RES_START; i++) connid->results[i] = NULL;
Tcl_InitHashTable(&connid->notify_hash, TCL_STRING_KEYS);
for (i = 0; i < RES_START; i++)
connid->results[i] = NULL;
connid->notify_list = NULL;
connid->notifier_running = 0;
sprintf(connid->id, "pgsql%d", PQsocket(conn));
#if TCL_MAJOR_VERSION == 7 && TCL_MINOR_VERSION == 5
/* Original signature (only seen in Tcl 7.5) */
conn_chan = Tcl_CreateChannel(&Pg_ConnType, connid->id, NULL, NULL, (ClientData)connid);
#else
/* Tcl 7.6 and later use this */
conn_chan = Tcl_CreateChannel(&Pg_ConnType, connid->id, (ClientData)connid,
TCL_READABLE | TCL_WRITABLE);
#endif
@ -214,7 +221,7 @@ PgGetConnectionId(Tcl_Interp *interp, char *id, Pg_ConnectionId **connid_p)
conn_chan = Tcl_GetChannel(interp, id, 0);
if(conn_chan == NULL || Tcl_GetChannelType(conn_chan) != &Pg_ConnType) {
Tcl_ResetResult(interp);
Tcl_AppendResult(interp, id, " is not a valid postgresql connection\n", 0);
Tcl_AppendResult(interp, id, " is not a valid postgresql connection", 0);
return (PGconn *)NULL;
}
@ -232,9 +239,9 @@ PgGetConnectionId(Tcl_Interp *interp, char *id, Pg_ConnectionId **connid_p)
int PgDelConnectionId(DRIVER_DEL_PROTO)
{
Tcl_HashEntry *entry;
char *hval;
Tcl_HashSearch hsearch;
Pg_ConnectionId *connid;
Pg_TclNotifies *notifies;
int i;
connid = (Pg_ConnectionId *)cData;
@ -245,17 +252,38 @@ int PgDelConnectionId(DRIVER_DEL_PROTO)
}
ckfree((void*)connid->results);
for (entry = Tcl_FirstHashEntry(&(connid->notify_hash), &hsearch);
entry != NULL;
entry = Tcl_NextHashEntry(&hsearch))
{
hval = (char*)Tcl_GetHashValue(entry);
ckfree(hval);
/* Release associated notify info */
while ((notifies = connid->notify_list) != NULL) {
connid->notify_list = notifies->next;
for (entry = Tcl_FirstHashEntry(&notifies->notify_hash, &hsearch);
entry != NULL;
entry = Tcl_NextHashEntry(&hsearch)) {
ckfree((char*) Tcl_GetHashValue(entry));
}
Tcl_DeleteHashTable(&notifies->notify_hash);
Tcl_DontCallWhenDeleted(notifies->interp, PgNotifyInterpDelete,
(ClientData) notifies);
ckfree((void*) notifies);
}
Tcl_DeleteHashTable(&connid->notify_hash);
/* Turn off the Tcl event source for this connection,
* and delete any pending notify events.
*/
PgStopNotifyEventSource(connid);
/* Close the libpq connection too */
PQfinish(connid->conn);
ckfree((void*)connid);
connid->conn = NULL;
/*
* We must use Tcl_EventuallyFree because we don't want the connid struct
* to vanish instantly if Pg_Notify_EventProc is active for it.
* (Otherwise, closing the connection from inside a pg_listen callback
* could lead to coredump.) Pg_Notify_EventProc can detect that the
* connection has been deleted from under it by checking connid->conn.
*/
Tcl_EventuallyFree((ClientData) connid, TCL_DYNAMIC);
return 0;
}
@ -407,3 +435,226 @@ PgGetConnByResultId(Tcl_Interp *interp, char *resid_c)
}
/********************************************
Notify event source
These functions allow asynchronous notify messages arriving from
the SQL server to be dispatched as Tcl events. See the Tcl
Notifier(3) man page for more info.
The main trick in this code is that we have to cope with status changes
between the queueing and the execution of a Tcl event. For example,
if the user changes or cancels the pg_listen callback command, we should
use the new setting; we do that by not resolving the notify relation
name until the last possible moment.
We also have to handle closure of the channel or deletion of the interpreter
to be used for the callback (note that with multiple interpreters,
the channel can outlive the interpreter it was created by!)
Upon closure of the channel, we immediately delete any pending events
that reference it. But for interpreter deletion, we just set any
matching interp pointers in the Pg_TclNotifies list to NULL. The
list item stays around until the connection is deleted. (This avoids
trouble with walking through a list whose members may get deleted under us.)
*******************************************/
typedef struct {
Tcl_Event header; /* Standard Tcl event info */
PGnotify info; /* Notify name from SQL server */
Pg_ConnectionId *connid; /* Connection for server */
} NotifyEvent;
/* Setup before waiting in event loop */
static void Pg_Notify_SetupProc (ClientData clientData, int flags)
{
Pg_ConnectionId *connid = (Pg_ConnectionId *) clientData;
Tcl_File handle;
/* We classify SQL notifies as Tcl file events. */
if (!(flags & TCL_FILE_EVENTS)) {
return;
}
/* Set up to watch for asynchronous data arrival on backend channel */
handle = Tcl_GetFile((ClientData) PQsocket(connid->conn), TCL_UNIX_FD);
Tcl_WatchFile(handle, TCL_READABLE);
}
/* Check to see if events have arrived in event loop */
static void Pg_Notify_CheckProc (ClientData clientData, int flags)
{
Pg_ConnectionId *connid = (Pg_ConnectionId *) clientData;
Tcl_File handle;
/* We classify SQL notifies as Tcl file events. */
if (!(flags & TCL_FILE_EVENTS)) {
return;
}
/* Consume any data available from the SQL server
* (this just buffers it internally to libpq).
* We use Tcl_FileReady to avoid a useless kernel call
* when no data is available.
*/
handle = Tcl_GetFile((ClientData) PQsocket(connid->conn), TCL_UNIX_FD);
if (Tcl_FileReady(handle, TCL_READABLE) != 0) {
PQconsumeInput(connid->conn);
}
/* Transfer notify events from libpq to Tcl event queue. */
PgNotifyTransferEvents(connid);
}
/* Dispatch an event that has reached the front of the event queue */
static int Pg_Notify_EventProc (Tcl_Event *evPtr, int flags)
{
NotifyEvent *event = (NotifyEvent *) evPtr;
Pg_TclNotifies *notifies;
Tcl_HashEntry *entry;
char *callback;
char *svcallback;
/* We classify SQL notifies as Tcl file events. */
if (!(flags & TCL_FILE_EVENTS)) {
return 0;
}
/* Preserve/Release to ensure the connection struct doesn't disappear
* underneath us.
*/
Tcl_Preserve((ClientData) event->connid);
/*
* Loop for each interpreter that has ever registered on the connection.
* Each one can get a callback.
*/
for (notifies = event->connid->notify_list;
notifies != NULL;
notifies = notifies->next) {
Tcl_Interp *interp = notifies->interp;
if (interp == NULL)
continue; /* ignore deleted interpreter */
/*
* Find the callback to be executed for this interpreter, if any.
*/
entry = Tcl_FindHashEntry(&notifies->notify_hash,
event->info.relname);
if (entry == NULL)
continue; /* no pg_listen in this interpreter */
callback = (char *) Tcl_GetHashValue(entry);
if (callback == NULL)
continue; /* safety check -- shouldn't happen */
/*
* We have to copy the callback string in case the user executes
* a new pg_listen during the callback.
*/
svcallback = (char *) ckalloc((unsigned) (strlen(callback) + 1));
strcpy(svcallback, callback);
/*
* Execute the callback.
*/
Tcl_Preserve((ClientData) interp);
if (Tcl_GlobalEval(interp, svcallback) != TCL_OK) {
Tcl_AddErrorInfo(interp, "\n (\"pg_listen\" script)");
Tcl_BackgroundError(interp);
}
Tcl_Release((ClientData) interp);
ckfree(svcallback);
/*
* Check for the possibility that the callback closed the connection.
*/
if (event->connid->conn == NULL)
break;
}
Tcl_Release((ClientData) event->connid);
return 1;
}
/*
* Transfer any notify events available from libpq into the Tcl event queue.
* Note that this must be called after each PQexec (to capture notifies
* that arrive during command execution) as well as in Pg_Notify_CheckProc
* (to capture notifies that arrive when we're idle).
*/
void PgNotifyTransferEvents (Pg_ConnectionId *connid)
{
PGnotify *notify;
while ((notify = PQnotifies(connid->conn)) != NULL) {
NotifyEvent *event = (NotifyEvent *) ckalloc(sizeof(NotifyEvent));
event->header.proc = Pg_Notify_EventProc;
event->info = *notify;
event->connid = connid;
Tcl_QueueEvent((Tcl_Event *) event, TCL_QUEUE_TAIL);
free(notify);
}
}
/*
* Cleanup code for coping when an interpreter or a channel is deleted.
*
* PgNotifyInterpDelete is registered as an interpreter deletion callback
* for each extant Pg_TclNotifies structure.
* NotifyEventDeleteProc is used by PgStopNotifyEventSource to get
* rid of pending Tcl events that reference a dying connection.
*/
void PgNotifyInterpDelete(ClientData clientData, Tcl_Interp *interp)
{
/* Mark the interpreter dead, but don't do anything else yet */
Pg_TclNotifies *notifies = (Pg_TclNotifies *) clientData;
notifies->interp = NULL;
}
/* Comparison routine for detecting events to be removed by DeleteEvent */
static int NotifyEventDeleteProc(Tcl_Event *evPtr, ClientData clientData)
{
NotifyEvent *event;
Pg_ConnectionId *connid = (Pg_ConnectionId *) clientData;
if (evPtr->proc != Pg_Notify_EventProc) {
return 0;
}
event = (NotifyEvent *) evPtr;
if (event->connid != connid) {
return 0;
}
return 1;
}
/* Start and stop the notify event source for a connection.
* We do not bother to run the notifier unless at least one
* pg_listen has been executed on the connection. Currently,
* once started the notifier is run until the connection is
* closed.
*/
void PgStartNotifyEventSource(Pg_ConnectionId *connid)
{
/* Start the notify event source if it isn't already running */
if (! connid->notifier_running) {
Tcl_CreateEventSource(Pg_Notify_SetupProc, Pg_Notify_CheckProc,
(ClientData) connid);
connid->notifier_running = 1;
}
}
void PgStopNotifyEventSource(Pg_ConnectionId *connid)
{
/* Remove the event source */
if (connid->notifier_running) {
Tcl_DeleteEventSource(Pg_Notify_SetupProc, Pg_Notify_CheckProc,
(ClientData) connid);
connid->notifier_running = 0;
}
/* Kill any queued Tcl events that reference this channel */
Tcl_DeleteEvents(NotifyEventDeleteProc, (ClientData) connid);
}

19
src/interfaces/libpgtcl/pgtclId.h
View File

@ -8,14 +8,15 @@
*
* Copyright (c) 1994, Regents of the University of California
*
* $Id: pgtclId.h,v 1.6 1998/03/15 08:03:00 scrappy Exp $
* $Id: pgtclId.h,v 1.7 1998/06/16 04:10:17 momjian Exp $
*
*-------------------------------------------------------------------------
*/
extern void PgSetConnectionId(Tcl_Interp *interp, PGconn *conn);
#if (TCL_MAJOR_VERSION == 7 && TCL_MINOR_VERSION == 5)
#if TCL_MAJOR_VERSION == 7 && TCL_MINOR_VERSION == 5
/* Only Tcl 7.5 had drivers with this signature */
# define DRIVER_DEL_PROTO ClientData cData, Tcl_Interp *interp, \
Tcl_File inFile, Tcl_File outFile
# define DRIVER_OUTPUT_PROTO ClientData cData, Tcl_File outFile, char *buf, \
@ -23,6 +24,7 @@ extern void PgSetConnectionId(Tcl_Interp *interp, PGconn *conn);
# define DRIVER_INPUT_PROTO ClientData cData, Tcl_File inFile, char *buf, \
int bufSize, int *errorCodePtr
#else
/* Tcl 7.6 and beyond use this signature */
# define DRIVER_OUTPUT_PROTO ClientData cData, char *buf, int bufSize, \
int *errorCodePtr
# define DRIVER_INPUT_PROTO ClientData cData, char *buf, int bufSize, \
@ -39,8 +41,19 @@ extern int PgSetResultId(Tcl_Interp *interp, char *connid, PGresult *res);
extern PGresult *PgGetResultId(Tcl_Interp *interp, char *id);
extern void PgDelResultId(Tcl_Interp *interp, char *id);
extern int PgGetConnByResultId(Tcl_Interp *interp, char *resid);
extern void PgStartNotifyEventSource(Pg_ConnectionId *connid);
extern void PgStopNotifyEventSource(Pg_ConnectionId *connid);
extern void PgNotifyTransferEvents(Pg_ConnectionId *connid);
extern void PgNotifyInterpDelete(ClientData clientData, Tcl_Interp *interp);
#if (TCL_MAJOR_VERSION < 8)
/* GetFileProc is needed in Tcl 7.6 and later */
#if (TCL_MAJOR_VERSION * 100 + TCL_MINOR_VERSION) >= 706
#define HAVE_TCL_GETFILEPROC 1
#else
#define HAVE_TCL_GETFILEPROC 0
#endif
#if HAVE_TCL_GETFILEPROC
extern Tcl_File PgGetFileProc(ClientData cData, int direction);
#endif