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Expand the use of get_dirent_type(), shaving a few calls to stat()/lstat() 

Several backend-side loops scanning one or more directories with
ReadDir() (WAL segment recycle/removal in xlog.c, backend-side directory
copy, temporary file removal, configuration file parsing, some logical
decoding logic and some pgtz stuff) already know the type of the entry
being scanned thanks to the dirent structure associated to the entry, on
platforms where we know about DT_REG, DT_DIR and DT_LNK to make the
difference between a regular file, a directory and a symbolic link.

Relying on the direct structure of an entry saves a few system calls to
stat() and lstat() in the loops updated here, shaving some code while on
it.  The logic of the code remains the same, calling stat() or lstat()
depending on if it is necessary to look through symlinks.

Authors: Nathan Bossart, Bharath Rupireddy
Reviewed-by: Andres Freund, Thomas Munro, Michael Paquier
Discussion: https://postgr.es/m/CALj2ACV8n-J-f=yiLUOx2=HrQGPSOZM3nWzyQQvLPcccPXxEdg@mail.gmail.com
This commit is contained in:
Michael Paquier 2022-09-02 16:58:06 +09:00
parent 11e5f99d39
commit bfb9dfd937
8 changed files with 53 additions and 75 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
src/backend/access/heap/rewriteheap.c
View File

@ -113,6 +113,7 @@
#include "access/xact.h"
#include "access/xloginsert.h"
#include "catalog/catalog.h"
#include "common/file_utils.h"
#include "lib/ilist.h"
#include "miscadmin.h"
#include "pgstat.h"
@ -1213,7 +1214,6 @@ CheckPointLogicalRewriteHeap(void)
mappings_dir = AllocateDir("pg_logical/mappings");
while ((mapping_de = ReadDir(mappings_dir, "pg_logical/mappings")) != NULL)
{
struct stat statbuf;
Oid dboid;
Oid relid;
XLogRecPtr lsn;
@ -1221,13 +1221,16 @@ CheckPointLogicalRewriteHeap(void)
TransactionId create_xid;
uint32 hi,
lo;
PGFileType de_type;
if (strcmp(mapping_de->d_name, ".") == 0 ||
strcmp(mapping_de->d_name, "..") == 0)
continue;
snprintf(path, sizeof(path), "pg_logical/mappings/%s", mapping_de->d_name);
if (lstat(path, &statbuf) == 0 && !S_ISREG(statbuf.st_mode))
de_type = get_dirent_type(path, mapping_de, false, DEBUG1);
if (de_type != PGFILETYPE_ERROR && de_type != PGFILETYPE_REG)
continue;
/* Skip over files that cannot be ours. */

26
src/backend/access/transam/xlog.c
View File

@ -657,8 +657,9 @@ static void PreallocXlogFiles(XLogRecPtr endptr, TimeLineID tli);
static void RemoveTempXlogFiles(void);
static void RemoveOldXlogFiles(XLogSegNo segno, XLogRecPtr lastredoptr,
XLogRecPtr endptr, TimeLineID insertTLI);
static void RemoveXlogFile(const char *segname, XLogSegNo recycleSegNo,
XLogSegNo *endlogSegNo, TimeLineID insertTLI);
static void RemoveXlogFile(const struct dirent *segment_de,
XLogSegNo recycleSegNo, XLogSegNo *endlogSegNo,
TimeLineID insertTLI);
static void UpdateLastRemovedPtr(char *filename);
static void ValidateXLOGDirectoryStructure(void);
static void CleanupBackupHistory(void);
@ -3596,8 +3597,7 @@ RemoveOldXlogFiles(XLogSegNo segno, XLogRecPtr lastredoptr, XLogRecPtr endptr,
/* Update the last removed location in shared memory first */
UpdateLastRemovedPtr(xlde->d_name);
RemoveXlogFile(xlde->d_name, recycleSegNo, &endlogSegNo,
insertTLI);
RemoveXlogFile(xlde, recycleSegNo, &endlogSegNo, insertTLI);
}
}
}
@ -3669,8 +3669,7 @@ RemoveNonParentXlogFiles(XLogRecPtr switchpoint, TimeLineID newTLI)
* - but seems safer to let them be archived and removed later.
*/
if (!XLogArchiveIsReady(xlde->d_name))
RemoveXlogFile(xlde->d_name, recycleSegNo, &endLogSegNo,
newTLI);
RemoveXlogFile(xlde, recycleSegNo, &endLogSegNo, newTLI);
}
}
@ -3680,9 +3679,9 @@ RemoveNonParentXlogFiles(XLogRecPtr switchpoint, TimeLineID newTLI)
/*
* Recycle or remove a log file that's no longer needed.
*
* segname is the name of the segment to recycle or remove. recycleSegNo
* is the segment number to recycle up to. endlogSegNo is the segment
* number of the current (or recent) end of WAL.
* segment_de is the dirent structure of the segment to recycle or remove.
* recycleSegNo is the segment number to recycle up to. endlogSegNo is
* the segment number of the current (or recent) end of WAL.
*
* endlogSegNo gets incremented if the segment is recycled so as it is not
* checked again with future callers of this function.
@ -3691,14 +3690,15 @@ RemoveNonParentXlogFiles(XLogRecPtr switchpoint, TimeLineID newTLI)
* should be used for this timeline.
*/
static void
RemoveXlogFile(const char *segname, XLogSegNo recycleSegNo,
XLogSegNo *endlogSegNo, TimeLineID insertTLI)
RemoveXlogFile(const struct dirent *segment_de,
XLogSegNo recycleSegNo, XLogSegNo *endlogSegNo,
TimeLineID insertTLI)
{
char path[MAXPGPATH];
#ifdef WIN32
char newpath[MAXPGPATH];
#endif
struct stat statbuf;
const char *segname = segment_de->d_name;
snprintf(path, MAXPGPATH, XLOGDIR "/%s", segname);
@ -3710,7 +3710,7 @@ RemoveXlogFile(const char *segname, XLogSegNo recycleSegNo,
if (wal_recycle &&
*endlogSegNo <= recycleSegNo &&
XLogCtl->InstallXLogFileSegmentActive && /* callee rechecks this */
lstat(path, &statbuf) == 0 && S_ISREG(statbuf.st_mode) &&
get_dirent_type(path, segment_de, false, DEBUG2) == PGFILETYPE_REG &&
InstallXLogFileSegment(endlogSegNo, path,
true, recycleSegNo, insertTLI))
{

6
src/backend/replication/logical/snapbuild.c
View File

@ -123,6 +123,7 @@
#include "access/heapam_xlog.h"
#include "access/transam.h"
#include "access/xact.h"
#include "common/file_utils.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "replication/logical.h"
@ -2061,15 +2062,16 @@ CheckPointSnapBuild(void)
uint32 hi;
uint32 lo;
XLogRecPtr lsn;
struct stat statbuf;
PGFileType de_type;
if (strcmp(snap_de->d_name, ".") == 0 ||
strcmp(snap_de->d_name, "..") == 0)
continue;
snprintf(path, sizeof(path), "pg_logical/snapshots/%s", snap_de->d_name);
de_type = get_dirent_type(path, snap_de, false, DEBUG1);
if (lstat(path, &statbuf) == 0 && !S_ISREG(statbuf.st_mode))
if (de_type != PGFILETYPE_ERROR && de_type != PGFILETYPE_REG)
{
elog(DEBUG1, "only regular files expected: %s", path);
continue;

6
src/backend/replication/slot.c
View File

@ -41,6 +41,7 @@
#include "access/transam.h"
#include "access/xlog_internal.h"
#include "common/file_utils.h"
#include "common/string.h"
#include "miscadmin.h"
#include "pgstat.h"
@ -1442,17 +1443,18 @@ StartupReplicationSlots(void)
replication_dir = AllocateDir("pg_replslot");
while ((replication_de = ReadDir(replication_dir, "pg_replslot")) != NULL)
{
struct stat statbuf;
char path[MAXPGPATH + 12];
PGFileType de_type;
if (strcmp(replication_de->d_name, ".") == 0 ||
strcmp(replication_de->d_name, "..") == 0)
continue;
snprintf(path, sizeof(path), "pg_replslot/%s", replication_de->d_name);
de_type = get_dirent_type(path, replication_de, false, DEBUG1);
/* we're only creating directories here, skip if it's not our's */
if (lstat(path, &statbuf) == 0 && !S_ISDIR(statbuf.st_mode))
if (de_type != PGFILETYPE_ERROR && de_type != PGFILETYPE_DIR)
continue;
/* we crashed while a slot was being setup or deleted, clean up */

21
src/backend/storage/file/copydir.c
View File

@ -22,6 +22,7 @@
#include <unistd.h>
#include <sys/stat.h>
#include "common/file_utils.h"
#include "miscadmin.h"
#include "pgstat.h"
#include "storage/copydir.h"
@ -50,7 +51,7 @@ copydir(char *fromdir, char *todir, bool recurse)
while ((xlde = ReadDir(xldir, fromdir)) != NULL)
{
struct stat fst;
PGFileType xlde_type;
/* If we got a cancel signal during the copy of the directory, quit */
CHECK_FOR_INTERRUPTS();
@ -62,18 +63,15 @@ copydir(char *fromdir, char *todir, bool recurse)
snprintf(fromfile, sizeof(fromfile), "%s/%s", fromdir, xlde->d_name);
snprintf(tofile, sizeof(tofile), "%s/%s", todir, xlde->d_name);
if (lstat(fromfile, &fst) < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m", fromfile)));
xlde_type = get_dirent_type(fromfile, xlde, false, ERROR);
if (S_ISDIR(fst.st_mode))
if (xlde_type == PGFILETYPE_DIR)
{
/* recurse to handle subdirectories */
if (recurse)
copydir(fromfile, tofile, true);
}
else if (S_ISREG(fst.st_mode))
else if (xlde_type == PGFILETYPE_REG)
copy_file(fromfile, tofile);
}
FreeDir(xldir);
@ -89,8 +87,6 @@ copydir(char *fromdir, char *todir, bool recurse)
while ((xlde = ReadDir(xldir, todir)) != NULL)
{
struct stat fst;
if (strcmp(xlde->d_name, ".") == 0 ||
strcmp(xlde->d_name, "..") == 0)
continue;
@ -101,12 +97,7 @@ copydir(char *fromdir, char *todir, bool recurse)
* We don't need to sync subdirectories here since the recursive
* copydir will do it before it returns
*/
if (lstat(tofile, &fst) < 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m", tofile)));
if (S_ISREG(fst.st_mode))
if (get_dirent_type(tofile, xlde, false, ERROR) == PGFILETYPE_REG)
fsync_fname(tofile, false);
}
FreeDir(xldir);

12
src/backend/storage/file/fd.c
View File

@ -3156,17 +3156,11 @@ RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok, bool unlink_all)
PG_TEMP_FILE_PREFIX,
strlen(PG_TEMP_FILE_PREFIX)) == 0)
{
struct stat statbuf;
PGFileType type = get_dirent_type(rm_path, temp_de, false, LOG);
if (lstat(rm_path, &statbuf) < 0)
{
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m", rm_path)));
if (type == PGFILETYPE_ERROR)
continue;
}
if (S_ISDIR(statbuf.st_mode))
else if (type == PGFILETYPE_DIR)
{
/* recursively remove contents, then directory itself */
RemovePgTempFilesInDir(rm_path, false, true);

42
src/backend/utils/misc/guc-file.l
View File

@ -14,6 +14,7 @@
#include <ctype.h>
#include <unistd.h>
#include "common/file_utils.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "storage/fd.h"
@ -1017,7 +1018,7 @@ ParseConfigDirectory(const char *includedir,
while ((de = ReadDir(d, directory)) != NULL)
{
struct stat st;
PGFileType de_type;
char filename[MAXPGPATH];
/*
@ -1034,32 +1035,9 @@ ParseConfigDirectory(const char *includedir,
join_path_components(filename, directory, de->d_name);
canonicalize_path(filename);
if (stat(filename, &st) == 0)
de_type = get_dirent_type(filename, de, true, elevel);
if (de_type == PGFILETYPE_ERROR)
{
if (!S_ISDIR(st.st_mode))
{
/* Add file to array, increasing its size in blocks of 32 */
if (num_filenames >= size_filenames)
{
size_filenames += 32;
filenames = (char **) repalloc(filenames,
size_filenames * sizeof(char *));
}
filenames[num_filenames] = pstrdup(filename);
num_filenames++;
}
}
else
{
/*
* stat does not care about permissions, so the most likely reason
* a file can't be accessed now is if it was removed between the
* directory listing and now.
*/
ereport(elevel,
(errcode_for_file_access(),
errmsg("could not stat file \"%s\": %m",
filename)));
record_config_file_error(psprintf("could not stat file \"%s\"",
filename),
calling_file, calling_lineno,
@ -1067,6 +1045,18 @@ ParseConfigDirectory(const char *includedir,
status = false;
goto cleanup;
}
else if (de_type != PGFILETYPE_DIR)
{
/* Add file to array, increasing its size in blocks of 32 */
if (num_filenames >= size_filenames)
{
size_filenames += 32;
filenames = (char **) repalloc(filenames,
size_filenames * sizeof(char *));
}
filenames[num_filenames] = pstrdup(filename);
num_filenames++;
}
}
if (num_filenames > 0)

8
src/timezone/pgtz.c
View File

@ -17,6 +17,7 @@
#include <sys/stat.h>
#include <time.h>
#include "common/file_utils.h"
#include "datatype/timestamp.h"
#include "miscadmin.h"
#include "pgtz.h"
@ -429,7 +430,6 @@ pg_tzenumerate_next(pg_tzenum *dir)
{
struct dirent *direntry;
char fullname[MAXPGPATH * 2];
struct stat statbuf;
direntry = ReadDir(dir->dirdesc[dir->depth], dir->dirname[dir->depth]);
@ -447,12 +447,8 @@ pg_tzenumerate_next(pg_tzenum *dir)
snprintf(fullname, sizeof(fullname), "%s/%s",
dir->dirname[dir->depth], direntry->d_name);
if (stat(fullname, &statbuf) != 0)
ereport(ERROR,
(errcode_for_file_access(),
errmsg("could not stat \"%s\": %m", fullname)));
if (S_ISDIR(statbuf.st_mode))
if (get_dirent_type(fullname, direntry, true, ERROR) == PGFILETYPE_DIR)
{
/* Step into the subdirectory */
if (dir->depth >= MAX_TZDIR_DEPTH - 1)