pgstat.c

PostgreSQL7.4.6 for Linux

 *
 *	Called from tcop/postgres.c to send the so far collected
 *	per table access statistics to the collector.
 * ----------
 */
void
pgstat_report_tabstat(void)
{
	int			i;

	if (pgStatSock < 0 ||
		!(pgstat_collect_querystring ||
		  pgstat_collect_tuplelevel ||
		  pgstat_collect_blocklevel))
	{
		/* Not reporting stats, so just flush whatever we have */
		pgStatTabstatUsed = 0;
		return;
	}

	/*
	 * For each message buffer used during the last query set the header
	 * fields and send it out.
	 */
	for (i = 0; i < pgStatTabstatUsed; i++)
	{
		PgStat_MsgTabstat *tsmsg = pgStatTabstatMessages[i];
		int			n;
		int			len;

		n = tsmsg->m_nentries;
		len = offsetof(PgStat_MsgTabstat, m_entry[0]) +
			n * sizeof(PgStat_TableEntry);

		tsmsg->m_xact_commit = pgStatXactCommit;
		tsmsg->m_xact_rollback = pgStatXactRollback;
		pgStatXactCommit = 0;
		pgStatXactRollback = 0;

		pgstat_setheader(&tsmsg->m_hdr, PGSTAT_MTYPE_TABSTAT);
		pgstat_send(tsmsg, len);
	}

	pgStatTabstatUsed = 0;
}


/* ----------
 * pgstat_vacuum_tabstat() -
 *
 *	Will tell the collector about objects he can get rid of.
 * ----------
 */
int
pgstat_vacuum_tabstat(void)
{
	Relation	dbrel;
	HeapScanDesc dbscan;
	HeapTuple	dbtup;
	Oid		   *dbidlist;
	int			dbidalloc;
	int			dbidused;
	HASH_SEQ_STATUS hstat;
	PgStat_StatDBEntry *dbentry;
	PgStat_StatTabEntry *tabentry;
	HeapTuple	reltup;
	int			nobjects = 0;
	PgStat_MsgTabpurge msg;
	int			len;
	int			i;

	if (pgStatSock < 0)
		return 0;

	/*
	 * If not done for this transaction, read the statistics collector
	 * stats file into some hash tables.
	 */
	if (!TransactionIdEquals(pgStatDBHashXact, GetCurrentTransactionId()))
	{
		pgstat_read_statsfile(&pgStatDBHash, MyDatabaseId,
							  &pgStatBeTable, &pgStatNumBackends);
		pgStatDBHashXact = GetCurrentTransactionId();
	}

	/*
	 * Lookup our own database entry
	 */
	dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
												 (void *) &MyDatabaseId,
												 HASH_FIND, NULL);
	if (dbentry == NULL)
		return -1;

	if (dbentry->tables == NULL)
		return 0;

	/*
	 * Initialize our messages table counter to zero
	 */
	msg.m_nentries = 0;

	/*
	 * Check for all tables if they still exist.
	 */
	hash_seq_init(&hstat, dbentry->tables);
	while ((tabentry = (PgStat_StatTabEntry *) hash_seq_search(&hstat)) != NULL)
	{
		/*
		 * Check if this relation is still alive by looking up it's
		 * pg_class tuple in the system catalog cache.
		 */
		reltup = SearchSysCache(RELOID,
								ObjectIdGetDatum(tabentry->tableid),
								0, 0, 0);
		if (HeapTupleIsValid(reltup))
		{
			ReleaseSysCache(reltup);
			continue;
		}

		/*
		 * Add this tables Oid to the message
		 */
		msg.m_tableid[msg.m_nentries++] = tabentry->tableid;
		nobjects++;

		/*
		 * If the message is full, send it out and reinitialize ot zero
		 */
		if (msg.m_nentries >= PGSTAT_NUM_TABPURGE)
		{
			len = offsetof(PgStat_MsgTabpurge, m_tableid[0])
				+msg.m_nentries * sizeof(Oid);

			pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_TABPURGE);
			pgstat_send(&msg, len);

			msg.m_nentries = 0;
		}
	}

	/*
	 * Send the rest
	 */
	if (msg.m_nentries > 0)
	{
		len = offsetof(PgStat_MsgTabpurge, m_tableid[0])
			+msg.m_nentries * sizeof(Oid);

		pgstat_setheader(&msg.m_hdr, PGSTAT_MTYPE_TABPURGE);
		pgstat_send(&msg, len);
	}

	/*
	 * Read pg_database and remember the Oid's of all existing databases
	 */
	dbidalloc = 256;
	dbidused = 0;
	dbidlist = (Oid *) palloc(sizeof(Oid) * dbidalloc);

	dbrel = heap_openr(DatabaseRelationName, AccessShareLock);
	dbscan = heap_beginscan(dbrel, SnapshotNow, 0, NULL);
	while ((dbtup = heap_getnext(dbscan, ForwardScanDirection)) != NULL)
	{
		if (dbidused >= dbidalloc)
		{
			dbidalloc *= 2;
			dbidlist = (Oid *) repalloc((char *) dbidlist,
										sizeof(Oid) * dbidalloc);
		}
		dbidlist[dbidused++] = HeapTupleGetOid(dbtup);
	}
	heap_endscan(dbscan);
	heap_close(dbrel, AccessShareLock);

	/*
	 * Search the database hash table for dead databases and tell the
	 * collector to drop them as well.
	 */
	hash_seq_init(&hstat, pgStatDBHash);
	while ((dbentry = (PgStat_StatDBEntry *) hash_seq_search(&hstat)) != NULL)
	{
		Oid			dbid = dbentry->databaseid;

		for (i = 0; i < dbidused; i++)
		{
			if (dbidlist[i] == dbid)
			{
				dbid = InvalidOid;
				break;
			}
		}

		if (dbid != InvalidOid)
		{
			nobjects++;
			pgstat_drop_database(dbid);
		}
	}

	/*
	 * Free the dbid list.
	 */
	pfree((char *) dbidlist);

	/*
	 * Tell the caller how many removeable objects we found
	 */
	return nobjects;
}


/* ----------
 * pgstat_drop_database() -
 *
 *	Tell the collector that we just dropped a database.
 *	This is the only message that shouldn't get lost in space. Otherwise
 *	the collector will keep the statistics for the dead DB until his
 *	stats file got removed while the postmaster is down.
 * ----------
 */
static void
pgstat_drop_database(Oid databaseid)
{
	PgStat_MsgDropdb msg;

	if (pgStatSock < 0)
		return;

	msg.m_databaseid = databaseid;

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


/* ----------
 * pgstat_reset_counters() -
 *
 *	Tell the statistics collector to reset counters for our database.
 * ----------
 */
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);
	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));
}

/*
 * Create or enlarge the pgStatTabstatMessages array
 */
static bool
more_tabstat_space(void)
{
	PgStat_MsgTabstat *newMessages;
	PgStat_MsgTabstat **msgArray;
	int			newAlloc = pgStatTabstatAlloc + TABSTAT_QUANTUM;
	int			i;

	/* Create (another) quantum of message buffers */
	newMessages = (PgStat_MsgTabstat *)
		malloc(sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);
	if (newMessages == NULL)
	{
		ereport(LOG,
				(errcode(ERRCODE_OUT_OF_MEMORY),
				 errmsg("out of memory")));
		return false;
	}

	/* Create or enlarge the pointer array */
	if (pgStatTabstatMessages == NULL)
		msgArray = (PgStat_MsgTabstat **)
			malloc(sizeof(PgStat_MsgTabstat *) * newAlloc);
	else
		msgArray = (PgStat_MsgTabstat **)
			realloc(pgStatTabstatMessages,
					sizeof(PgStat_MsgTabstat *) * newAlloc);
	if (msgArray == NULL)
	{
		free(newMessages);
		ereport(LOG,
				(errcode(ERRCODE_OUT_OF_MEMORY),
				 errmsg("out of memory")));
		return false;
	}

	MemSet(newMessages, 0, sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);
	for (i = 0; i < TABSTAT_QUANTUM; i++)
		msgArray[pgStatTabstatAlloc + i] = newMessages++;
	pgStatTabstatMessages = msgArray;
	pgStatTabstatAlloc = newAlloc;

	return true;
}

/* ----------
 * 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;
	PgStat_MsgTabstat *tsmsg;
	int			mb;
	int			i;

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

	if (pgStatSock < 0 ||
		!(pgstat_collect_tuplelevel ||
		  pgstat_collect_blocklevel))
	{
		stats->no_stats = TRUE;
		return;
	}

	/*
	 * Search the already-used message slots for this relation.
	 */
	for (mb = 0; mb < pgStatTabstatUsed; mb++)
	{
		tsmsg = pgStatTabstatMessages[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 (pgStatTabstatUsed >= pgStatTabstatAlloc)
	{
		if (!more_tabstat_space())
		{
			stats->no_stats = TRUE;
			return;
		}
		Assert(pgStatTabstatUsed < pgStatTabstatAlloc);
	}

	/*
	 * Use the first entry of the next message buffer.
	 */
	mb = pgStatTabstatUsed++;
	tsmsg = pgStatTabstatMessages[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 (pgStatTabstatAlloc == 0)
	{
		if (!more_tabstat_space())
			return;
	}
	if (pgStatTabstatUsed == 0)
	{
		pgStatTabstatUsed++;
		pgStatTabstatMessages[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 (pgStatTabstatAlloc == 0)
	{
		if (!more_tabstat_space())
			return;
	}
	if (pgStatTabstatUsed == 0)
	{
		pgStatTabstatUsed++;
		pgStatTabstatMessages[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)
{
	PgStat_StatDBEntry *dbentry;

	/*
	 * If not done for this transaction, read the statistics collector
	 * stats file into some hash tables. Be careful with the
	 * read_statsfile() call below!
	 */
	if (!TransactionIdEquals(pgStatDBHashXact, GetCurrentTransactionId()))
	{
		pgstat_read_statsfile(&pgStatDBHash, MyDatabaseId,
							  &pgStatBeTable, &pgStatNumBackends);
		pgStatDBHashXact = GetCurrentTransactionId();
	}

	/*
	 * Lookup the requested database
	 */
	dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
												 (void *) &dbid,
												 HASH_FIND, NULL);
	if (dbentry == NULL)
		return NULL;

	return dbentry;
}


/* ----------
 * 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)
{
	PgStat_StatDBEntry *dbentry;
	PgStat_StatTabEntry *tabentry;

	/*
	 * If not done for this transaction, read the statistics collector
	 * stats file into some hash tables. Be careful with the
	 * read_statsfile() call below!
	 */
	if (!TransactionIdEquals(pgStatDBHashXact, GetCurrentTransactionId()))
	{
		pgstat_read_statsfile(&pgStatDBHash, MyDatabaseId,
							  &pgStatBeTable, &pgStatNumBackends);
		pgStatDBHashXact = GetCurrentTransactionId();
	}

	/*
	 * Lookup our database.
	 */
	dbentry = (PgStat_StatDBEntry *) hash_search(pgStatDBHash,
												 (void *) &MyDatabaseId,
												 HASH_FIND, NULL);
	if (dbentry == NULL)