pgstat.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

void
pgstat_reset_counters(void)
{
	PgStat_MsgResetcounter msg;

	if (pgStatSock < 0)
		return;

	if (!superuser())
		ereport(ERROR,
				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
				 errmsg("must be superuser to reset statistics counters")));

	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_RESETCOUNTER);
	msg.m_databaseid = MyDatabaseId;
	pgstat_send(&msg, sizeof(msg));
}


/* ----------
 * pgstat_ping() -
 *
 *	Send some junk data to the collector to increase traffic.
 * ----------
 */
void
pgstat_ping(void)
{
	PgStat_MsgDummy msg;

	if (pgStatSock < 0)
		return;

	pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_DUMMY);
	pgstat_send(&msg, sizeof(msg));
}

/*
 * Enlarge a TabStatArray
 */
static void
more_tabstat_space(TabStatArray *tsarr)
{
	PgStat_MsgTabstat *newMessages;
	PgStat_MsgTabstat **msgArray;
	int			newAlloc;
	int			i;

	AssertArg(PointerIsValid(tsarr));

	newAlloc = tsarr->tsa_alloc + TABSTAT_QUANTUM;

	/* Create (another) quantum of message buffers */
	newMessages = (PgStat_MsgTabstat *)
		MemoryContextAllocZero(TopMemoryContext,
							   sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);

	/* Create or enlarge the pointer array */
	if (tsarr->tsa_messages == NULL)
		msgArray = (PgStat_MsgTabstat **)
			MemoryContextAlloc(TopMemoryContext,
							   sizeof(PgStat_MsgTabstat *) * newAlloc);
	else
		msgArray = (PgStat_MsgTabstat **)
			repalloc(tsarr->tsa_messages,
					 sizeof(PgStat_MsgTabstat *) * newAlloc);

	for (i = 0; i < TABSTAT_QUANTUM; i++)
		msgArray[tsarr->tsa_alloc + i] = newMessages++;
	tsarr->tsa_messages = msgArray;
	tsarr->tsa_alloc = newAlloc;

	Assert(tsarr->tsa_used < tsarr->tsa_alloc);
}

/* ----------
 * pgstat_initstats() -
 *
 *	Called from various places usually dealing with initialization
 *	of Relation or Scan structures. The data placed into these
 *	structures from here tell where later to count for buffer reads,
 *	scans and tuples fetched.
 * ----------
 */
void
pgstat_initstats(PgStat_Info *stats, Relation rel)
{
	Oid			rel_id = rel->rd_id;
	PgStat_TableEntry *useent;
	TabStatArray *tsarr;
	PgStat_MsgTabstat *tsmsg;
	int			mb;
	int			i;

	/*
	 * Initialize data not to count at all.
	 */
	stats->tabentry = NULL;

	if (pgStatSock < 0 ||
		!(pgstat_collect_tuplelevel ||
		  pgstat_collect_blocklevel))
		return;

	tsarr = rel->rd_rel->relisshared ? &SharedTabStat : &RegularTabStat;

	/*
	 * Search the already-used message slots for this relation.
	 */
	for (mb = 0; mb < tsarr->tsa_used; mb++)
	{
		tsmsg = tsarr->tsa_messages[mb];

		for (i = tsmsg->m_nentries; --i >= 0;)
		{
			if (tsmsg->m_entry[i].t_id == rel_id)
			{
				stats->tabentry = (void *) &(tsmsg->m_entry[i]);
				return;
			}
		}

		if (tsmsg->m_nentries >= PGSTAT_NUM_TABENTRIES)
			continue;

		/*
		 * Not found, but found a message buffer with an empty slot instead.
		 * Fine, let's use this one.
		 */
		i = tsmsg->m_nentries++;
		useent = &tsmsg->m_entry[i];
		MemSet(useent, 0, sizeof(PgStat_TableEntry));
		useent->t_id = rel_id;
		stats->tabentry = (void *) useent;
		return;
	}

	/*
	 * If we ran out of message buffers, we just allocate more.
	 */
	if (tsarr->tsa_used >= tsarr->tsa_alloc)
		more_tabstat_space(tsarr);

	/*
	 * Use the first entry of the next message buffer.
	 */
	mb = tsarr->tsa_used++;
	tsmsg = tsarr->tsa_messages[mb];
	tsmsg->m_nentries = 1;
	useent = &tsmsg->m_entry[0];
	MemSet(useent, 0, sizeof(PgStat_TableEntry));
	useent->t_id = rel_id;
	stats->tabentry = (void *) useent;
}


/* ----------
 * pgstat_count_xact_commit() -
 *
 *	Called from access/transam/xact.c to count transaction commits.
 * ----------
 */
void
pgstat_count_xact_commit(void)
{
	if (!(pgstat_collect_querystring ||
		  pgstat_collect_tuplelevel ||
		  pgstat_collect_blocklevel))
		return;

	pgStatXactCommit++;

	/*
	 * If there was no relation activity yet, just make one existing message
	 * buffer used without slots, causing the next report to tell new
	 * xact-counters.
	 */
	if (RegularTabStat.tsa_alloc == 0)
		more_tabstat_space(&RegularTabStat);

	if (RegularTabStat.tsa_used == 0)
	{
		RegularTabStat.tsa_used++;
		RegularTabStat.tsa_messages[0]->m_nentries = 0;
	}
}


/* ----------
 * pgstat_count_xact_rollback() -
 *
 *	Called from access/transam/xact.c to count transaction rollbacks.
 * ----------
 */
void
pgstat_count_xact_rollback(void)
{
	if (!(pgstat_collect_querystring ||
		  pgstat_collect_tuplelevel ||
		  pgstat_collect_blocklevel))
		return;

	pgStatXactRollback++;

	/*
	 * If there was no relation activity yet, just make one existing message
	 * buffer used without slots, causing the next report to tell new
	 * xact-counters.
	 */
	if (RegularTabStat.tsa_alloc == 0)
		more_tabstat_space(&RegularTabStat);

	if (RegularTabStat.tsa_used == 0)
	{
		RegularTabStat.tsa_used++;
		RegularTabStat.tsa_messages[0]->m_nentries = 0;
	}
}


/* ----------
 * pgstat_fetch_stat_dbentry() -
 *
 *	Support function for the SQL-callable pgstat* functions. Returns
 *	the collected statistics for one database or NULL. NULL doesn't mean
 *	that the database doesn't exist, it is just not yet known by the
 *	collector, so the caller is better off to report ZERO instead.
 * ----------
 */
PgStat_StatDBEntry *
pgstat_fetch_stat_dbentry(Oid dbid)
{
	/*
	 * If not done for this transaction, read the statistics collector stats
	 * file into some hash tables.
	 */
	backend_read_statsfile();

	/*
	 * Lookup the requested database; return NULL if not found
	 */
	return (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
											  (void *) &dbid,
											  HASH_FIND, NULL);
}


/* ----------
 * pgstat_fetch_stat_tabentry() -
 *
 *	Support function for the SQL-callable pgstat* functions. Returns
 *	the collected statistics for one table or NULL. NULL doesn't mean
 *	that the table doesn't exist, it is just not yet known by the
 *	collector, so the caller is better off to report ZERO instead.
 * ----------
 */
PgStat_StatTabEntry *
pgstat_fetch_stat_tabentry(Oid relid)
{
	Oid			dbid;
	PgStat_StatDBEntry *dbentry;
	PgStat_StatTabEntry *tabentry;

	/*
	 * If not done for this transaction, read the statistics collector stats
	 * file into some hash tables.
	 */
	backend_read_statsfile();

	/*
	 * Lookup our database, then look in its table hash table.
	 */
	dbid = MyDatabaseId;
	dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
												 (void *) &dbid,
												 HASH_FIND, NULL);
	if (dbentry != NULL && dbentry->tables != NULL)
	{
		tabentry = (PgStat_StatTabEntry *) hash_search(dbentry->tables,
													   (void *) &relid,
													   HASH_FIND, NULL);
		if (tabentry)
			return tabentry;
	}

	/*
	 * If we didn't find it, maybe it's a shared table.
	 */
	dbid = InvalidOid;
	dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
												 (void *) &dbid,
												 HASH_FIND, NULL);
	if (dbentry != NULL && dbentry->tables != NULL)
	{
		tabentry = (PgStat_StatTabEntry *) hash_search(dbentry->tables,
													   (void *) &relid,
													   HASH_FIND, NULL);
		if (tabentry)
			return tabentry;
	}

	return NULL;
}


/* ----------
 * pgstat_fetch_stat_beentry() -
 *
 *	Support function for the SQL-callable pgstat* functions. Returns
 *	the actual activity slot of one active backend. The caller is
 *	responsible for a check if the actual user is permitted to see
 *	that info (especially the querystring).
 * ----------
 */
PgStat_StatBeEntry *
pgstat_fetch_stat_beentry(int beid)
{
	backend_read_statsfile();

	if (beid < 1 || beid > pgStatNumBackends)
		return NULL;

	return &pgStatBeTable[beid - 1];
}


/* ----------
 * pgstat_fetch_stat_numbackends() -
 *
 *	Support function for the SQL-callable pgstat* functions. Returns
 *	the maximum current backend id.
 * ----------
 */
int
pgstat_fetch_stat_numbackends(void)
{
	backend_read_statsfile();

	return pgStatNumBackends;
}



/* ------------------------------------------------------------
 * Local support functions follow
 * ------------------------------------------------------------
 */


/* ----------
 * pgstat_setheader() -
 *
 *		Set common header fields in a statistics message
 * ----------
 */
static void
pgstat_setheader(PgStat_MsgHdr *hdr, StatMsgType mtype)
{
	hdr->m_type = mtype;
	hdr->m_backendid = MyBackendId;
	hdr->m_procpid = MyProcPid;
}


/* ----------
 * pgstat_send() -
 *
 *		Send out one statistics message to the collector
 * ----------
 */
static void
pgstat_send(void *msg, int len)
{
	if (pgStatSock < 0)
		return;

	((PgStat_MsgHdr *) msg)->m_size = len;

#ifdef USE_ASSERT_CHECKING
	if (send(pgStatSock, msg, len, 0) < 0)
		elog(LOG, "could not send to statistics collector: %m");
#else
	send(pgStatSock, msg, len, 0);
	/* We deliberately ignore any error from send() */
#endif
}


/* ----------
 * PgstatBufferMain() -
 *
 *	Start up the statistics buffer process.  This is the body of the
 *	postmaster child process.
 *
 *	The argc/argv parameters are valid only in EXEC_BACKEND case.
 * ----------
 */
NON_EXEC_STATIC void
PgstatBufferMain(int argc, char *argv[])
{
	IsUnderPostmaster = true;	/* we are a postmaster subprocess now */

	MyProcPid = getpid();		/* reset MyProcPid */

	/* Lose the postmaster's on-exit routines */
	on_exit_reset();

	/*
	 * Ignore all signals usually bound to some action in the postmaster,
	 * except for SIGCHLD and SIGQUIT --- see pgstat_recvbuffer.
	 */
	pqsignal(SIGHUP, SIG_IGN);
	pqsignal(SIGINT, SIG_IGN);
	pqsignal(SIGTERM, SIG_IGN);
	pqsignal(SIGQUIT, pgstat_exit);
	pqsignal(SIGALRM, SIG_IGN);
	pqsignal(SIGPIPE, SIG_IGN);
	pqsignal(SIGUSR1, SIG_IGN);
	pqsignal(SIGUSR2, SIG_IGN);
	pqsignal(SIGCHLD, pgstat_die);
	pqsignal(SIGTTIN, SIG_DFL);
	pqsignal(SIGTTOU, SIG_DFL);
	pqsignal(SIGCONT, SIG_DFL);
	pqsignal(SIGWINCH, SIG_DFL);
	/* unblock will happen in pgstat_recvbuffer */

#ifdef EXEC_BACKEND
	pgstat_parseArgs(argc, argv);
#endif

	/*
	 * Start a buffering process to read from the socket, so we have a little
	 * more time to process incoming messages.
	 *
	 * NOTE: the process structure is: postmaster is parent of buffer process
	 * is parent of collector process.	This way, the buffer can detect
	 * collector failure via SIGCHLD, whereas otherwise it wouldn't notice
	 * collector failure until it tried to write on the pipe.  That would mean
	 * that after the postmaster started a new collector, we'd have two buffer
	 * processes competing to read from the UDP socket --- not good.
	 */
	if (pgpipe(pgStatPipe) < 0)
		ereport(ERROR,
				(errcode_for_socket_access(),
				 errmsg("could not create pipe for statistics buffer: %m")));

	/* child becomes collector process */
#ifdef EXEC_BACKEND
	pgStatCollectorPid = pgstat_forkexec(STAT_PROC_COLLECTOR);
#else
	pgStatCollectorPid = fork();
#endif
	switch (pgStatCollectorPid)
	{
		case -1:
			ereport(ERROR,
					(errmsg("could not fork statistics collector: %m")));

#ifndef EXEC_BACKEND
		case 0:
			/* child becomes collector process */
			PgstatCollectorMain(0, NULL);
			break;
#endif

		default:
			/* parent becomes buffer process */
			closesocket(pgStatPipe[0]);
			pgstat_recvbuffer();
	}
	exit(0);
}


/* ----------
 * PgstatCollectorMain() -
 *
 *	Start up the statistics collector itself.  This is the body of the
 *	postmaster grandchild process.
 *
 *	The argc/argv parameters are valid only in EXEC_BACKEND case.
 * ----------
 */
NON_EXEC_STATIC void
PgstatCollectorMain(int argc, char *argv[])
{
	PgStat_Msg	msg;
	fd_set		rfds;
	int			readPipe;
	int			nready;
	int			len = 0;
	struct timeval timeout;
	struct timeval next_statwrite;
	bool		need_statwrite;
	HASHCTL		hash_ctl;

	MyProcPid = getpid();		/* reset MyProcPid */

	/*
	 * Reset signal handling.  With the exception of restoring default SIGCHLD
	 * and SIGQUIT handling, this is a no-op in the non-EXEC_BACKEND case
	 * because we'll have inherited these settings from the buffer process;
	 * but it's not a no-op for EXEC_BACKEND.
	 */
	pqsignal(SIGHUP, SIG_IGN);
	pqsignal(SIGINT, SIG_IGN);
	pqsignal(SIGTERM, SIG_IGN);
#ifndef WIN32
	pqsignal(SIGQUIT, SIG_IGN);
#else
	/* kluge to allow buffer process to kill collector; FIXME */
	pqsignal(SIGQUIT, pgstat_exit);
#endif
	pqsignal(SIGALRM, SIG_IGN);
	pqsignal(SIGPIPE, SIG_IGN);
	pqsignal(SIGUSR1, SIG_IGN);
	pqsignal(SIGUSR2, SIG_IGN);
	pqsignal(SIGCHLD, SIG_DFL);
	pqsignal(SIGTTIN, SIG_DFL);
	pqsignal(SIGTTOU, SIG_DFL);
	pqsignal(SIGCONT, SIG_DFL);
	pqsignal(SIGWINCH, SIG_DFL);
	PG_SETMASK(&UnBlockSig);

#ifdef EXEC_BACKEND
	pgstat_parseArgs(argc, argv);
#endif

	/* Close unwanted files */
	closesocket(pgStatPipe[1]);