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postgres/src/backend/postmaster/syslogger.c

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/*-------------------------------------------------------------------------
*
* syslogger.c
*
* The system logger (syslogger) is new in Postgres 8.0. It catches all
* stderr output from the postmaster, backends, and other subprocesses
* by redirecting to a pipe, and writes it to a set of logfiles.
* It's possible to have size and age limits for the logfile configured
* in postgresql.conf. If these limits are reached or passed, the
* current logfile is closed and a new one is created (rotated).
* The logfiles are stored in a subdirectory (configurable in
* postgresql.conf), using an internal naming scheme that mangles
* creation time and current postmaster pid.
*
* Author: Andreas Pflug <pgadmin@pse-consulting.de>
*
* Copyright (c) 2004, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/postmaster/syslogger.c,v 1.5 2004/08/09 20:28:48 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <fcntl.h>
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include "libpq/pqsignal.h"
#include "miscadmin.h"
#include "postmaster/postmaster.h"
#include "postmaster/syslogger.h"
#include "pgtime.h"
#include "storage/ipc.h"
#include "storage/pg_shmem.h"
#include "utils/guc.h"
#include "utils/ps_status.h"
/*
* We really want line-buffered mode for logfile output, but Windows does
* not have it, and interprets _IOLBF as _IOFBF (bozos). So use _IONBF
* instead on Windows.
*/
#ifdef WIN32
#define LBF_MODE _IONBF
#else
#define LBF_MODE _IOLBF
#endif
/*
* GUC parameters. Redirect_stderr cannot be changed after postmaster
* start, but the rest can change at SIGHUP.
*/
bool Redirect_stderr = false;
int Log_RotationAge = 24*60;
int Log_RotationSize = 10*1024;
char * Log_directory = "pg_log";
char * Log_filename_prefix = "postgresql-";
/*
* Globally visible state (used by elog.c)
*/
bool am_syslogger = false;
/*
* Private state
*/
static pg_time_t last_rotation_time = 0;
static bool redirection_done = false;
static bool pipe_eof_seen = false;
static FILE *syslogFile = NULL;
/* These must be exported for EXEC_BACKEND case ... annoying */
#ifndef WIN32
int syslogPipe[2] = {-1, -1};
#else
HANDLE syslogPipe[2] = {0, 0};
#endif
#ifdef WIN32
static HANDLE threadHandle=0;
static CRITICAL_SECTION sysfileSection;
#endif
/*
* Flags set by interrupt handlers for later service in the main loop.
*/
static volatile sig_atomic_t got_SIGHUP = false;
/* Local subroutines */
#ifdef EXEC_BACKEND
static pid_t syslogger_forkexec(void);
static void syslogger_parseArgs(int argc, char *argv[]);
#endif
static void write_syslogger_file_binary(const char *buffer, int count);
#ifdef WIN32
static unsigned int __stdcall pipeThread(void *arg);
#endif
static void logfile_rotate(void);
static char* logfile_getname(pg_time_t timestamp);
static void sigHupHandler(SIGNAL_ARGS);
/*
* Main entry point for syslogger process
* argc/argv parameters are valid only in EXEC_BACKEND case.
*/
NON_EXEC_STATIC void
SysLoggerMain(int argc, char *argv[])
{
char currentLogDir[MAXPGPATH];
IsUnderPostmaster = true; /* we are a postmaster subprocess now */
MyProcPid = getpid(); /* reset MyProcPid */
/* Lose the postmaster's on-exit routines */
on_exit_reset();
#ifdef EXEC_BACKEND
syslogger_parseArgs(argc, argv);
#endif /* EXEC_BACKEND */
am_syslogger = true;
init_ps_display("logger process", "", "");
set_ps_display("");
/*
* If we restarted, our stderr is already redirected into our own
* input pipe. This is of course pretty useless, not to mention that
* it interferes with detecting pipe EOF. Point stderr to /dev/null.
* This assumes that all interesting messages generated in the syslogger
* will come through elog.c and will be sent to write_syslogger_file.
*/
if (redirection_done)
{
int fd = open(NULL_DEV, O_WRONLY);
/*
* The closes might look redundant, but they are not: we want to be
* darn sure the pipe gets closed even if the open failed. We can
* survive running with stderr pointing nowhere, but we can't afford
* to have extra pipe input descriptors hanging around.
*/
close(fileno(stdout));
close(fileno(stderr));
dup2(fd, fileno(stdout));
dup2(fd, fileno(stderr));
close(fd);
}
/*
* Also close our copy of the write end of the pipe. This is needed
* to ensure we can detect pipe EOF correctly. (But note that in the
* restart case, the postmaster already did this.)
*/
#ifndef WIN32
if (syslogPipe[1] >= 0)
close(syslogPipe[1]);
syslogPipe[1] = -1;
#else
if (syslogPipe[1])
CloseHandle(syslogPipe[1]);
syslogPipe[1] = 0;
#endif
/*
* Properly accept or ignore signals the postmaster might send us
*
* Note: we ignore all termination signals, and instead exit only when
* all upstream processes are gone, to ensure we don't miss any dying
* gasps of broken backends...
*/
pqsignal(SIGHUP, sigHupHandler); /* set flag to read config file */
pqsignal(SIGINT, SIG_IGN);
pqsignal(SIGTERM, SIG_IGN);
pqsignal(SIGQUIT, SIG_IGN);
pqsignal(SIGALRM, SIG_IGN);
pqsignal(SIGPIPE, SIG_IGN);
pqsignal(SIGUSR1, SIG_IGN);
pqsignal(SIGUSR2, SIG_IGN);
/*
* Reset some signals that are accepted by postmaster but not here
*/
pqsignal(SIGCHLD, SIG_DFL);
pqsignal(SIGTTIN, SIG_DFL);
pqsignal(SIGTTOU, SIG_DFL);
pqsignal(SIGCONT, SIG_DFL);
pqsignal(SIGWINCH, SIG_DFL);
PG_SETMASK(&UnBlockSig);
#ifdef WIN32
/* Fire up separate data transfer thread */
InitializeCriticalSection(&sysfileSection);
{
unsigned int tid;
threadHandle = (HANDLE)_beginthreadex(0, 0, pipeThread, 0, 0, &tid);
}
#endif /* WIN32 */
/* remember age of initial logfile */
last_rotation_time = time(NULL);
/* remember active logfile directory */
strncpy(currentLogDir, Log_directory, MAXPGPATH);
/* main worker loop */
for (;;)
{
bool rotation_requested = false;
#ifndef WIN32
char logbuffer[1024];
int bytesRead;
int rc;
fd_set rfds;
struct timeval timeout;
#endif
if (got_SIGHUP)
{
got_SIGHUP = false;
ProcessConfigFile(PGC_SIGHUP);
/*
* Check if the log directory changed in postgresql.conf. If so,
* force rotation to make sure we're writing the logfiles in the
* right place.
*
* XXX is it worth responding similarly to a change of
* Log_filename_prefix?
*/
if (strncmp(Log_directory, currentLogDir, MAXPGPATH) != 0)
{
strncpy(currentLogDir, Log_directory, MAXPGPATH);
rotation_requested = true;
}
}
if (!rotation_requested &&
last_rotation_time != 0 &&
Log_RotationAge > 0)
{
/*
* Do a logfile rotation if too much time has elapsed
* since the last one.
*/
pg_time_t now = time(NULL);
int elapsed_secs = now - last_rotation_time;
if (elapsed_secs >= Log_RotationAge * 60)
rotation_requested = true;
}
if (!rotation_requested && Log_RotationSize > 0)
{
/*
* Do a rotation if file is too big
*/
if (ftell(syslogFile) >= Log_RotationSize * 1024L)
rotation_requested = true;
}
if (rotation_requested)
logfile_rotate();
#ifndef WIN32
/*
* Wait for some data, timing out after 1 second
*/
FD_ZERO(&rfds);
FD_SET(syslogPipe[0], &rfds);
timeout.tv_sec=1;
timeout.tv_usec=0;
rc = select(syslogPipe[0]+1, &rfds, NULL, NULL, &timeout);
if (rc < 0)
{
if (errno != EINTR)
ereport(LOG,
(errcode_for_socket_access(),
errmsg("select() failed in logger process: %m")));
}
else if (rc > 0 && FD_ISSET(syslogPipe[0], &rfds))
{
bytesRead = piperead(syslogPipe[0],
logbuffer, sizeof(logbuffer));
if (bytesRead < 0)
{
if (errno != EINTR)
ereport(LOG,
(errcode_for_socket_access(),
errmsg("could not read from logger pipe: %m")));
}
else if (bytesRead > 0)
{
write_syslogger_file_binary(logbuffer, bytesRead);
continue;
}
else
{
/*
* Zero bytes read when select() is saying read-ready
* means EOF on the pipe: that is, there are no longer
* any processes with the pipe write end open. Therefore,
* the postmaster and all backends are shut down, and we
* are done.
*/
pipe_eof_seen = true;
}
}
#else /* WIN32 */
/*
* On Windows we leave it to a separate thread to transfer data and
* detect pipe EOF. The main thread just wakes up once a second to
* check for SIGHUP and rotation conditions.
*/
pgwin32_backend_usleep(1000000);
#endif /* WIN32 */
if (pipe_eof_seen)
{
ereport(LOG,
(errmsg("logger shutting down")));
/*
* Normal exit from the syslogger is here. Note that we
* deliberately do not close syslogFile before exiting;
* this is to allow for the possibility of elog messages
* being generated inside proc_exit. Regular exit() will
* take care of flushing and closing stdio channels.
*/
proc_exit(0);
}
}
}
/*
* Postmaster subroutine to start a syslogger subprocess.
*/
int
SysLogger_Start(void)
{
pid_t sysloggerPid;
pg_time_t now;
char *filename;
if (!Redirect_stderr)
return 0;
/*
* If first time through, create the pipe which will receive stderr output.
*
* If the syslogger crashes and needs to be restarted, we continue to use
* the same pipe (indeed must do so, since extant backends will be writing
* into that pipe).
*
* This means the postmaster must continue to hold the read end of the
* pipe open, so we can pass it down to the reincarnated syslogger.
* This is a bit klugy but we have little choice.
*/
#ifndef WIN32
if (syslogPipe[0] < 0)
{
if (pgpipe(syslogPipe) < 0)
ereport(FATAL,
(errcode_for_socket_access(),
(errmsg("could not create pipe for syslogging: %m"))));
}
#else
if (!syslogPipe[0])
{
SECURITY_ATTRIBUTES sa;
memset(&sa, 0, sizeof(SECURITY_ATTRIBUTES));
sa.nLength = sizeof(SECURITY_ATTRIBUTES);
sa.bInheritHandle = TRUE;
if (!CreatePipe(&syslogPipe[0], &syslogPipe[1], &sa, 32768))
ereport(FATAL,
(errcode_for_file_access(),
(errmsg("could not create pipe for syslogging: %m"))));
}
#endif
/*
* create log directory if not present; ignore errors
*/
if (is_absolute_path(Log_directory))
mkdir(Log_directory, 0700);
else
{
filename = palloc(MAXPGPATH);
snprintf(filename, MAXPGPATH, "%s/%s", DataDir, Log_directory);
mkdir(filename, 0700);
pfree(filename);
}
/*
* The initial logfile is created right in the postmaster,
* to verify that the Log_directory is writable.
*/
now = time(NULL);
filename = logfile_getname(now);
syslogFile = fopen(filename, "a");
if (!syslogFile)
ereport(FATAL,
(errcode_for_file_access(),
(errmsg("could not create logfile \"%s\": %m",
filename))));
setvbuf(syslogFile, NULL, LBF_MODE, 0);
pfree(filename);
/*
* Now we can fork off the syslogger subprocess.
*/
fflush(stdout);
fflush(stderr);
#ifdef __BEOS__
/* Specific beos actions before backend startup */
beos_before_backend_startup();
#endif
#ifdef EXEC_BACKEND
switch ((sysloggerPid = syslogger_forkexec()))
#else
switch ((sysloggerPid = fork()))
#endif
{
case -1:
#ifdef __BEOS__
/* Specific beos actions */
beos_backend_startup_failed();
#endif
ereport(LOG,
(errmsg("could not fork system logger: %m")));
return 0;
#ifndef EXEC_BACKEND
case 0:
/* in postmaster child ... */
#ifdef __BEOS__
/* Specific beos actions after backend startup */
beos_backend_startup();
#endif
/* Close the postmaster's sockets */
ClosePostmasterPorts(true);
/* Drop our connection to postmaster's shared memory, as well */
PGSharedMemoryDetach();
/* do the work */
SysLoggerMain(0, NULL);
break;
#endif
default:
/* success, in postmaster */
/* now we redirect stderr, if not done already */
if (!redirection_done)
{
#ifndef WIN32
fflush(stdout);
if (dup2(syslogPipe[1], fileno(stdout)) < 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not redirect stdout: %m")));
fflush(stderr);
if (dup2(syslogPipe[1], fileno(stderr)) < 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not redirect stderr: %m")));
/* Now we are done with the write end of the pipe. */
close(syslogPipe[1]);
syslogPipe[1] = -1;
#else
int fd;
fflush(stderr);
fd = _open_osfhandle((long) syslogPipe[1],
_O_APPEND | _O_TEXT);
if (dup2(fd, _fileno(stderr)) < 0)
ereport(FATAL,
(errcode_for_file_access(),
errmsg("could not redirect stderr: %m")));
close(fd);
/* Now we are done with the write end of the pipe. */
CloseHandle(syslogPipe[1]);
syslogPipe[1] = 0;
#endif
redirection_done = true;
}
/* postmaster will never write the file; close it */
fclose(syslogFile);
syslogFile = NULL;
return (int) sysloggerPid;
}
/* we should never reach here */
return 0;
}
#ifdef EXEC_BACKEND
/*
* syslogger_forkexec() -
*
* Format up the arglist for, then fork and exec, a syslogger process
*/
static pid_t
syslogger_forkexec(void)
{
char *av[10];
int ac = 0, bufc = 0, i;
char numbuf[2][32];
av[ac++] = "postgres";
av[ac++] = "-forklog";
av[ac++] = NULL; /* filled in by postmaster_forkexec */
/* static variables (those not passed by write_backend_variables) */
#ifndef WIN32
if (syslogFile != NULL)
snprintf(numbuf[bufc++], 32, "%d", fileno(syslogFile));
else
strcpy(numbuf[bufc++], "-1");
snprintf(numbuf[bufc++], 32, "%d", (int) redirection_done);
#else /* WIN32 */
if (syslogFile != NULL)
snprintf(numbuf[bufc++], 32, "%ld",
_get_osfhandle(_fileno(syslogFile)));
else
strcpy(numbuf[bufc++], "0");
snprintf(numbuf[bufc++], 32, "%d", (int) redirection_done);
#endif /* WIN32 */
/* Add to the arg list */
Assert(bufc <= lengthof(numbuf));
for (i = 0; i < bufc; i++)
av[ac++] = numbuf[i];
av[ac] = NULL;
Assert(ac < lengthof(av));
return postmaster_forkexec(ac, av);
}
/*
* syslogger_parseArgs() -
*
* Extract data from the arglist for exec'ed syslogger process
*/
static void
syslogger_parseArgs(int argc, char *argv[])
{
int fd;
Assert(argc == 5);
argv += 3;
#ifndef WIN32
fd = atoi(*argv++);
if (fd != -1)
{
syslogFile = fdopen(fd, "a");
setvbuf(syslogFile, NULL, LBF_MODE, 0);
}
redirection_done = (bool) atoi(*argv++);
#else /* WIN32 */
fd = atoi(*argv++);
if (fd != 0)
{
fd = _open_osfhandle(fd, _O_APPEND);
if (fd > 0)
{
syslogFile = fdopen(fd, "a");
setvbuf(syslogFile, NULL, LBF_MODE, 0);
}
}
redirection_done = (bool) atoi(*argv++);
#endif /* WIN32 */
}
#endif /* EXEC_BACKEND */
/* --------------------------------
* logfile routines
* --------------------------------
*/
/*
* Write text to the currently open logfile
*
* This is exported so that elog.c can call it when am_syslogger is true.
* This allows the syslogger process to record elog messages of its own,
* even though its stderr does not point at the syslog pipe.
*/
void
write_syslogger_file(const char *buffer, int count)
{
#ifdef WIN32
/*
* On Windows we need to do our own newline-to-CRLF translation.
*/
char convbuf[256];
char *p;
int n;
p = convbuf;
n = 0;
while (count-- > 0)
{
if (*buffer == '\n')
{
*p++ = '\r';
n++;
}
*p++ = *buffer++;
n++;
if (n >= sizeof(convbuf) - 1)
{
write_syslogger_file_binary(convbuf, n);
p = convbuf;
n = 0;
}
}
if (n > 0)
write_syslogger_file_binary(convbuf, n);
#else /* !WIN32 */
write_syslogger_file_binary(buffer, count);
#endif
}
/*
* Write binary data to the currently open logfile
*
* On Windows the data arriving in the pipe already has CR/LF newlines,
* so we must send it to the file without further translation.
*/
static void
write_syslogger_file_binary(const char *buffer, int count)
{
int rc;
#ifndef WIN32
rc = fwrite(buffer, 1, count, syslogFile);
#else
EnterCriticalSection(&sysfileSection);
rc = fwrite(buffer, 1, count, syslogFile);
LeaveCriticalSection(&sysfileSection);
#endif
if (rc != count)
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not write to logfile: %m")));
}
#ifdef WIN32
/*
* Worker thread to transfer data from the pipe to the current logfile.
*
* We need this because on Windows, WaitForSingleObject does not work on
* unnamed pipes: it always reports "signaled", so the blocking ReadFile won't
* allow for SIGHUP; and select is for sockets only.
*/
static unsigned int __stdcall
pipeThread(void *arg)
{
DWORD bytesRead;
char logbuffer[1024];
for (;;)
{
if (!ReadFile(syslogPipe[0], logbuffer, sizeof(logbuffer),
&bytesRead, 0))
{
DWORD error = GetLastError();
if (error == ERROR_HANDLE_EOF ||
error == ERROR_BROKEN_PIPE)
break;
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not read from logger pipe: %m")));
}
else if (bytesRead > 0)
write_syslogger_file_binary(logbuffer, bytesRead);
}
/* We exit the above loop only upon detecting pipe EOF */
pipe_eof_seen = true;
_endthread();
return 0;
}
#endif /* WIN32 */
/*
* perform logfile rotation
*/
static void
logfile_rotate(void)
{
char *filename;
pg_time_t now;
FILE *fh;
now = time(NULL);
filename = logfile_getname(now);
fh = fopen(filename, "a");
if (!fh)
{
int saveerrno = errno;
ereport(LOG,
(errcode_for_file_access(),
errmsg("could not open new logfile \"%s\": %m",
filename)));
/*
* ENFILE/EMFILE are not too surprising on a busy system; just keep
* using the old file till we manage to get a new one. Otherwise,
* assume something's wrong with Log_directory and stop trying to
* create files.
*/
if (saveerrno != ENFILE && saveerrno != EMFILE)
{
ereport(LOG,
(errmsg("disabling auto rotation (use SIGHUP to reenable)")));
Log_RotationAge = 0;
Log_RotationSize = 0;
}
pfree(filename);
return;
}
setvbuf(fh, NULL, LBF_MODE, 0);
/* On Windows, need to interlock against data-transfer thread */
#ifdef WIN32
EnterCriticalSection(&sysfileSection);
#endif
fclose(syslogFile);
syslogFile = fh;
#ifdef WIN32
LeaveCriticalSection(&sysfileSection);
#endif
last_rotation_time = now;
pfree(filename);
}
/*
* construct logfile name using timestamp information
*
* Result is palloc'd.
*/
static char*
logfile_getname(pg_time_t timestamp)
{
char *filename;
char stamptext[128];
pg_strftime(stamptext, sizeof(stamptext), "%Y-%m-%d_%H%M%S",
pg_localtime(&timestamp));
filename = palloc(MAXPGPATH);
if (is_absolute_path(Log_directory))
snprintf(filename, MAXPGPATH, "%s/%s%05u_%s.log",
Log_directory, Log_filename_prefix,
(unsigned int) PostmasterPid, stamptext);
else
snprintf(filename, MAXPGPATH, "%s/%s/%s%05u_%s.log",
DataDir, Log_directory, Log_filename_prefix,
(unsigned int) PostmasterPid, stamptext);
return filename;
}
/* --------------------------------
* signal handler routines
* --------------------------------
*/
/* SIGHUP: set flag to reload config file */
static void
sigHupHandler(SIGNAL_ARGS)
{
got_SIGHUP = true;
}
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