syslogger.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

/*-------------------------------------------------------------------------
 *
 * 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 <[e-mail]>
 *
 * Copyright (c) 2004-2005, PostgreSQL Global Development Group
 *
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/backend/postmaster/syslogger.c,v 1.20.2.1 2005/11/22 18:23:16 momjian 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/fork_process.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"
#include "utils/timestamp.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 = HOURS_PER_DAY * MINS_PER_HOUR;
int			Log_RotationSize = 10 * 1024;
char	   *Log_directory = NULL;
char	   *Log_filename = NULL;
bool		Log_truncate_on_rotation = false;

/*
 * Globally visible state (used by elog.c)
 */
bool		am_syslogger = false;

/*
 * Private state
 */
static pg_time_t next_rotation_time;

static bool redirection_done = false;

static bool pipe_eof_seen = false;

static FILE *syslogFile = NULL;

static char *last_file_name = 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;
static volatile sig_atomic_t rotation_requested = 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(bool time_based_rotation);
static char *logfile_getname(pg_time_t timestamp);
static void set_next_rotation_time(void);
static void sigHupHandler(SIGNAL_ARGS);
static void sigUsr1Handler(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;
	char	   *currentLogFilename;
	int			currentLogRotationAge;

	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, sigUsr1Handler);	/* request log rotation */
	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 active logfile parameters */
	currentLogDir = pstrdup(Log_directory);
	currentLogFilename = pstrdup(Log_filename);
	currentLogRotationAge = Log_RotationAge;
	/* set next planned rotation time */
	set_next_rotation_time();

	/* main worker loop */
	for (;;)
	{
		bool		time_based_rotation = 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 or filename pattern changed in
			 * postgresql.conf. If so, force rotation to make sure we're
			 * writing the logfiles in the right place.
			 */
			if (strcmp(Log_directory, currentLogDir) != 0)
			{
				pfree(currentLogDir);
				currentLogDir = pstrdup(Log_directory);
				rotation_requested = true;
			}
			if (strcmp(Log_filename, currentLogFilename) != 0)
			{
				pfree(currentLogFilename);
				currentLogFilename = pstrdup(Log_filename);
				rotation_requested = true;
			}

			/*
			 * If rotation time parameter changed, reset next rotation time,
			 * but don't immediately force a rotation.
			 */
			if (currentLogRotationAge != Log_RotationAge)
			{
				currentLogRotationAge = Log_RotationAge;
				set_next_rotation_time();
			}
		}

		if (!rotation_requested && Log_RotationAge > 0)
		{
			/* Do a logfile rotation if it's time */
			pg_time_t	now = time(NULL);

			if (now >= next_rotation_time)
				rotation_requested = time_based_rotation = 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(time_based_rotation);

#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;
	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 syslog: %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 syslog: %m"))));
	}
#endif

	/*
	 * Create log directory if not present; ignore errors
	 */
	mkdir(Log_directory, 0700);

	/*
	 * The initial logfile is created right in the postmaster, to verify that
	 * the Log_directory is writable.
	 */
	filename = logfile_getname(time(NULL));

	syslogFile = fopen(filename, "a");

	if (!syslogFile)
		ereport(FATAL,
				(errcode_for_file_access(),
				 (errmsg("could not create log file \"%s\": %m",
						 filename))));

	setvbuf(syslogFile, NULL, LBF_MODE, 0);

	pfree(filename);