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Replace opendir/closedir calls throughout the backend with AllocateDir

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and FreeDir routines modeled on the existing AllocateFile/FreeFile.
Like the latter, these routines will avoid failing on EMFILE/ENFILE
conditions whenever possible, and will prevent leakage of directory
descriptors if an elog() occurs while one is open.
Also, reduce PANIC to ERROR in MoveOfflineLogs() --- this is not
critical code and there is no reason to force a DB restart on failure.
All per recent trouble report from Olivier Hubaut.
This commit is contained in:
Tom Lane
2004-02-23 23:03:10 +00:00
parent 4f571319d3
commit 7a57a67278
6 changed files with 138 additions and 41 deletions
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126
src/backend/storage/file/fd.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/storage/file/fd.c,v 1.107 2004/02/23 20:45:59 tgl Exp $
* $PostgreSQL: pgsql/src/backend/storage/file/fd.c,v 1.108 2004/02/23 23:03:10 tgl Exp $
*
* NOTES:
*
@ -43,8 +43,6 @@
#include <sys/file.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
@ -87,11 +85,11 @@ int max_files_per_process = 1000;
/*
* Maximum number of file descriptors to open for either VFD entries or
* AllocateFile files. This is initialized to a conservative value, and
* remains that way indefinitely in bootstrap or standalone-backend cases.
* In normal postmaster operation, the postmaster calls set_max_safe_fds()
* late in initialization to update the value, and that value is then
* inherited by forked subprocesses.
* AllocateFile/AllocateDir operations. This is initialized to a conservative
* value, and remains that way indefinitely in bootstrap or standalone-backend
* cases. In normal postmaster operation, the postmaster calls
* set_max_safe_fds() late in initialization to update the value, and that
* value is then inherited by forked subprocesses.
*
* Note: the value of max_files_per_process is taken into account while
* setting this variable, and so need not be tested separately.
@ -159,6 +157,17 @@ static int nfile = 0;
static int numAllocatedFiles = 0;
static FILE *allocatedFiles[MAX_ALLOCATED_FILES];
/*
* List of <dirent.h> DIRs opened with AllocateDir.
*
* Since we don't have heavy use of AllocateDir, it seems OK to put a pretty
* small maximum limit on the number of simultaneously allocated dirs.
*/
#define MAX_ALLOCATED_DIRS 10
static int numAllocatedDirs = 0;
static DIR *allocatedDirs[MAX_ALLOCATED_DIRS];
/*
* Number of temporary files opened during the current session;
* this is used in generation of tempfile names.
@ -489,7 +498,7 @@ LruInsert(File file)
if (FileIsNotOpen(file))
{
while (nfile + numAllocatedFiles >= max_safe_fds)
while (nfile + numAllocatedFiles + numAllocatedDirs >= max_safe_fds)
{
if (!ReleaseLruFile())
break;
@ -748,7 +757,7 @@ fileNameOpenFile(FileName fileName,
file = AllocateVfd();
vfdP = &VfdCache[file];
while (nfile + numAllocatedFiles >= max_safe_fds)
while (nfile + numAllocatedFiles + numAllocatedDirs >= max_safe_fds)
{
if (!ReleaseLruFile())
break;
@ -1099,8 +1108,8 @@ AllocateFile(char *name, char *mode)
* looping.
*/
if (numAllocatedFiles >= MAX_ALLOCATED_FILES ||
numAllocatedFiles >= max_safe_fds - 1)
elog(ERROR, "too many private FDs demanded");
numAllocatedFiles + numAllocatedDirs >= max_safe_fds - 1)
elog(ERROR, "too many private files demanded");
TryAgain:
if ((file = fopen(name, mode)) != NULL)
@ -1155,6 +1164,86 @@ FreeFile(FILE *file)
return fclose(file);
}
/*
* Routines that want to use <dirent.h> (ie, DIR*) should use AllocateDir
* rather than plain opendir(). This lets fd.c deal with freeing FDs if
* necessary to open the directory, and with closing it after an elog.
* When done, call FreeDir rather than closedir.
*
* Ideally this should be the *only* direct call of opendir() in the backend.
*/
DIR *
AllocateDir(const char *dirname)
{
DIR *dir;
DO_DB(elog(LOG, "AllocateDir: Allocated %d", numAllocatedDirs));
/*
* The test against MAX_ALLOCATED_DIRS prevents us from overflowing
* allocatedDirs[]; the test against max_safe_fds prevents AllocateDir
* from hogging every one of the available FDs, which'd lead to infinite
* looping.
*/
if (numAllocatedDirs >= MAX_ALLOCATED_DIRS ||
numAllocatedDirs + numAllocatedFiles >= max_safe_fds - 1)
elog(ERROR, "too many private dirs demanded");
TryAgain:
if ((dir = opendir(dirname)) != NULL)
{
allocatedDirs[numAllocatedDirs] = dir;
numAllocatedDirs++;
return dir;
}
if (errno == EMFILE || errno == ENFILE)
{
int save_errno = errno;
ereport(LOG,
(errcode(ERRCODE_INSUFFICIENT_RESOURCES),
errmsg("out of file descriptors: %m; release and retry")));
errno = 0;
if (ReleaseLruFile())
goto TryAgain;
errno = save_errno;
}
return NULL;
}
/*
* Close a directory opened with AllocateDir.
*
* Note we do not check closedir's return value --- it is up to the caller
* to handle close errors.
*/
int
FreeDir(DIR *dir)
{
int i;
DO_DB(elog(LOG, "FreeDir: Allocated %d", numAllocatedDirs));
/* Remove dir from list of allocated dirs, if it's present */
for (i = numAllocatedDirs; --i >= 0;)
{
if (allocatedDirs[i] == dir)
{
numAllocatedDirs--;
allocatedDirs[i] = allocatedDirs[numAllocatedDirs];
break;
}
}
if (i < 0)
elog(WARNING, "dir passed to FreeDir was not obtained from AllocateDir");
return closedir(dir);
}
/*
* closeAllVfds
*
@ -1211,7 +1300,7 @@ AtProcExit_Files(int code, Datum arg)
* exiting. If that's the case, we should remove all temporary files; if
* that's not the case, we are being called for transaction commit/abort
* and should only remove transaction-local temp files. In either case,
* also clean up "allocated" stdio files.
* also clean up "allocated" stdio files and dirs.
*/
static void
CleanupTempFiles(bool isProcExit)
@ -1240,6 +1329,9 @@ CleanupTempFiles(bool isProcExit)
while (numAllocatedFiles > 0)
FreeFile(allocatedFiles[0]);
while (numAllocatedDirs > 0)
FreeDir(allocatedDirs[0]);
}
@ -1271,7 +1363,7 @@ RemovePgTempFiles(void)
* files.
*/
snprintf(db_path, sizeof(db_path), "%s/base", DataDir);
if ((db_dir = opendir(db_path)) != NULL)
if ((db_dir = AllocateDir(db_path)) != NULL)
{
while ((db_de = readdir(db_dir)) != NULL)
{
@ -1287,7 +1379,7 @@ RemovePgTempFiles(void)
"%s/%s/%s",
db_path, db_de->d_name,
PG_TEMP_FILES_DIR);
if ((temp_dir = opendir(temp_path)) != NULL)
if ((temp_dir = AllocateDir(temp_path)) != NULL)
{
while ((temp_de = readdir(temp_dir)) != NULL)
{
@ -1310,9 +1402,9 @@ RemovePgTempFiles(void)
"unexpected file found in temporary-files directory: \"%s\"",
rm_path);
}
closedir(temp_dir);
FreeDir(temp_dir);
}
}
closedir(db_dir);
FreeDir(db_dir);
}
}