pgstat.c

PostgreSQL7.4.6 for Linux

/* ----------
 * pgstat.c
 *
 *	All the statistics collector stuff hacked up in one big, ugly file.
 *
 *	TODO:	- Separate collector, postmaster and backend stuff
 *			  into different files.
 *
 *			- Add some automatic call for pgstat vacuuming.
 *
 *			- Add a pgstat config column to pg_database, so this
 *			  entire thing can be enabled/disabled on a per db base.
 *
 *	Copyright (c) 2001-2003, PostgreSQL Global Development Group
 *
 *	$Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.45.2.2 2003/11/15 17:24:19 tgl Exp $
 * ----------
 */
#include "postgres.h"

#include <unistd.h>
#include <fcntl.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <signal.h>

#include "pgstat.h"

#include "access/xact.h"
#include "access/heapam.h"
#include "catalog/catname.h"
#include "catalog/pg_shadow.h"
#include "catalog/pg_database.h"
#include "libpq/pqsignal.h"
#include "libpq/libpq.h"
#include "mb/pg_wchar.h"
#include "miscadmin.h"
#include "utils/memutils.h"
#include "storage/backendid.h"
#include "storage/ipc.h"
#include "storage/pg_shmem.h"
#include "utils/rel.h"
#include "utils/hsearch.h"
#include "utils/ps_status.h"
#include "utils/syscache.h"


/* ----------
 * GUC parameters
 * ----------
 */
bool		pgstat_collect_startcollector = true;
bool		pgstat_collect_resetonpmstart = true;
bool		pgstat_collect_querystring = false;
bool		pgstat_collect_tuplelevel = false;
bool		pgstat_collect_blocklevel = false;

/* ----------
 * Other global variables
 * ----------
 */
bool		pgstat_is_running = false;

/* ----------
 * Local data
 * ----------
 */
static int	pgStatSock = -1;
static int	pgStatPipe[2];
static struct sockaddr_storage pgStatAddr;
static int	pgStatPmPipe[2] = {-1, -1};

static int	pgStatPid;
static time_t last_pgstat_start_time;

static long pgStatNumMessages = 0;

static bool pgStatRunningInCollector = FALSE;

static int	pgStatTabstatAlloc = 0;
static int	pgStatTabstatUsed = 0;
static PgStat_MsgTabstat **pgStatTabstatMessages = NULL;

#define TABSTAT_QUANTUM		4	/* we alloc this many at a time */

static int	pgStatXactCommit = 0;
static int	pgStatXactRollback = 0;

static TransactionId pgStatDBHashXact = InvalidTransactionId;
static HTAB *pgStatDBHash = NULL;
static HTAB *pgStatBeDead = NULL;
static PgStat_StatBeEntry *pgStatBeTable = NULL;
static int	pgStatNumBackends = 0;

static char pgStat_tmpfname[MAXPGPATH];
static char pgStat_fname[MAXPGPATH];


/* ----------
 * Local function forward declarations
 * ----------
 */
static void pgstat_main(void);
static void pgstat_recvbuffer(void);
static void pgstat_die(SIGNAL_ARGS);

static int	pgstat_add_backend(PgStat_MsgHdr *msg);
static void pgstat_sub_backend(int procpid);
static void pgstat_drop_database(Oid databaseid);
static void pgstat_write_statsfile(void);
static void pgstat_read_statsfile(HTAB **dbhash, Oid onlydb,
					  PgStat_StatBeEntry **betab,
					  int *numbackends);

static void pgstat_setheader(PgStat_MsgHdr *hdr, int mtype);
static void pgstat_send(void *msg, int len);

static void pgstat_recv_bestart(PgStat_MsgBestart *msg, int len);
static void pgstat_recv_beterm(PgStat_MsgBeterm *msg, int len);
static void pgstat_recv_activity(PgStat_MsgActivity *msg, int len);
static void pgstat_recv_tabstat(PgStat_MsgTabstat *msg, int len);
static void pgstat_recv_tabpurge(PgStat_MsgTabpurge *msg, int len);
static void pgstat_recv_dropdb(PgStat_MsgDropdb *msg, int len);
static void pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len);


/* ------------------------------------------------------------
 * Public functions called from postmaster follow
 * ------------------------------------------------------------
 */


/* ----------
 * pgstat_init() -
 *
 *	Called from postmaster at startup. Create the resources required
 *	by the statistics collector process.  If unable to do so, do not
 *	fail --- better to let the postmaster start with stats collection
 *	disabled.
 * ----------
 */
void
pgstat_init(void)
{
	ACCEPT_TYPE_ARG3 alen;
	struct addrinfo *addrs = NULL,
			   *addr,
				hints;
	int			ret;

	/*
	 * Force start of collector daemon if something to collect
	 */
	if (pgstat_collect_querystring ||
		pgstat_collect_tuplelevel ||
		pgstat_collect_blocklevel)
		pgstat_collect_startcollector = true;

	/*
	 * Initialize the filenames for the status reports.
	 */
	snprintf(pgStat_tmpfname, MAXPGPATH,
			 PGSTAT_STAT_TMPFILE, DataDir, getpid());
	snprintf(pgStat_fname, MAXPGPATH,
			 PGSTAT_STAT_FILENAME, DataDir);

	/*
	 * If we don't have to start a collector or should reset the collected
	 * statistics on postmaster start, simply remove the file.
	 */
	if (!pgstat_collect_startcollector || pgstat_collect_resetonpmstart)
		unlink(pgStat_fname);

	/*
	 * Nothing else required if collector will not get started
	 */
	if (!pgstat_collect_startcollector)
		return;

	/*
	 * Create the UDP socket for sending and receiving statistic messages
	 */
	hints.ai_flags = AI_PASSIVE;
	hints.ai_family = PF_UNSPEC;
	hints.ai_socktype = SOCK_DGRAM;
	hints.ai_protocol = 0;
	hints.ai_addrlen = 0;
	hints.ai_addr = NULL;
	hints.ai_canonname = NULL;
	hints.ai_next = NULL;
	ret = getaddrinfo_all("localhost", NULL, &hints, &addrs);
	if (ret || !addrs)
	{
		ereport(LOG,
				(errmsg("could not resolve \"localhost\": %s",
						gai_strerror(ret))));
		goto startup_failed;
	}

	/*
	 * On some platforms, getaddrinfo_all() may return multiple addresses
	 * only one of which will actually work (eg, both IPv6 and IPv4 addresses
	 * when kernel will reject IPv6).  Worse, the failure may occur at the
	 * bind() or perhaps even connect() stage.  So we must loop through the
	 * results till we find a working combination.  We will generate LOG
	 * messages, but no error, for bogus combinations.
	 */
	for (addr = addrs; addr; addr = addr->ai_next)
	{
#ifdef HAVE_UNIX_SOCKETS
		/* Ignore AF_UNIX sockets, if any are returned. */
		if (addr->ai_family == AF_UNIX)
			continue;
#endif
		/*
		 * Create the socket.
		 */
		if ((pgStatSock = socket(addr->ai_family, SOCK_DGRAM, 0)) < 0)
		{
			ereport(LOG,
					(errcode_for_socket_access(),
					 errmsg("could not create socket for statistics collector: %m")));
			continue;
		}

		/*
		 * Bind it to a kernel assigned port on localhost and get the assigned
		 * port via getsockname().
		 */
		if (bind(pgStatSock, addr->ai_addr, addr->ai_addrlen) < 0)
		{
			ereport(LOG,
					(errcode_for_socket_access(),
					 errmsg("could not bind socket for statistics collector: %m")));
			closesocket(pgStatSock);
			pgStatSock = -1;
			continue;
		}

		alen = sizeof(pgStatAddr);
		if (getsockname(pgStatSock, (struct sockaddr *) &pgStatAddr, &alen) < 0)
		{
			ereport(LOG,
					(errcode_for_socket_access(),
					 errmsg("could not get address of socket for statistics collector: %m")));
			closesocket(pgStatSock);
			pgStatSock = -1;
			continue;
		}

		/*
		 * Connect the socket to its own address.  This saves a few cycles by
		 * not having to respecify the target address on every send. This also
		 * provides a kernel-level check that only packets from this same
		 * address will be received.
		 */
		if (connect(pgStatSock, (struct sockaddr *) &pgStatAddr, alen) < 0)
		{
			ereport(LOG,
					(errcode_for_socket_access(),
					 errmsg("could not connect socket for statistics collector: %m")));
			closesocket(pgStatSock);
			pgStatSock = -1;
			continue;
		}

		/* If we get here, we have a working socket */
		break;
	}

	/* Did we find a working address? */
	if (!addr || pgStatSock < 0)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
				 errmsg("disabling statistics collector for lack of working socket")));
		goto startup_failed;
	}

	/*
	 * Set the socket to non-blocking IO.  This ensures that if the
	 * collector falls behind (despite the buffering process), statistics
	 * messages will be discarded; backends won't block waiting to send
	 * messages to the collector.
	 */
	if (FCNTL_NONBLOCK(pgStatSock) < 0)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
		errmsg("could not set statistics collector socket to nonblocking mode: %m")));
		goto startup_failed;
	}

	/*
	 * Create the pipe that controls the statistics collector shutdown
	 */
	if (pipe(pgStatPmPipe) < 0)
	{
		ereport(LOG,
				(errcode_for_socket_access(),
		  errmsg("could not create pipe for statistics collector: %m")));
		goto startup_failed;
	}

	freeaddrinfo_all(hints.ai_family, addrs);

	return;

startup_failed:
	if (addrs)
		freeaddrinfo_all(hints.ai_family, addrs);

	if (pgStatSock >= 0)
		closesocket(pgStatSock);
	pgStatSock = -1;

	/* Adjust GUC variables to suppress useless activity */
	pgstat_collect_startcollector = false;
	pgstat_collect_querystring = false;
	pgstat_collect_tuplelevel = false;
	pgstat_collect_blocklevel = false;
}


/* ----------
 * pgstat_start() -
 *
 *	Called from postmaster at startup or after an existing collector
 *	died.  Attempt to fire up a fresh statistics collector.
 *
 *	Note: if fail, we will be called again from the postmaster main loop.
 * ----------
 */
void
pgstat_start(void)
{
	time_t		curtime;

	/*
	 * Do nothing if no collector needed
	 */
	if (pgstat_is_running || !pgstat_collect_startcollector)
		return;

	/*
	 * Do nothing if too soon since last collector start.  This is a
	 * safety valve to protect against continuous respawn attempts if the
	 * collector is dying immediately at launch.  Note that since we will
	 * be re-called from the postmaster main loop, we will get another
	 * chance later.
	 */
	curtime = time(NULL);
	if ((unsigned int) (curtime - last_pgstat_start_time) <
		(unsigned int) PGSTAT_RESTART_INTERVAL)
		return;
	last_pgstat_start_time = curtime;

	/*
	 * Check that the socket is there, else pgstat_init failed.
	 */
	if (pgStatSock < 0)
	{
		ereport(LOG,
				(errmsg("statistics collector startup skipped")));

		/*
		 * We can only get here if someone tries to manually turn
		 * pgstat_collect_startcollector on after it had been off.
		 */
		pgstat_collect_startcollector = false;
		return;
	}

	/*
	 * Okay, fork off the collector.  Remember its PID for
	 * pgstat_ispgstat.
	 */

	fflush(stdout);
	fflush(stderr);

#ifdef __BEOS__
	/* Specific beos actions before backend startup */
	beos_before_backend_startup();
#endif

	switch ((pgStatPid = (int) fork()))
	{
		case -1:
#ifdef __BEOS__
			/* Specific beos actions */
			beos_backend_startup_failed();
#endif
			ereport(LOG,
					(errmsg("could not fork statistics buffer: %m")));
			return;

		case 0:
			break;

		default:
			pgstat_is_running = true;
			return;
	}

	/* in postmaster child ... */

#ifdef __BEOS__
	/* Specific beos actions after backend startup */
	beos_backend_startup();
#endif

	IsUnderPostmaster = true;	/* we are a postmaster subprocess now */

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

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

	/* Close the postmaster's sockets, except for pgstat link */
	ClosePostmasterPorts(false);

	/* Drop our connection to postmaster's shared memory, as well */
	PGSharedMemoryDetach();

	pgstat_main();

	exit(0);
}


/* ----------
 * pgstat_ispgstat() -
 *
 *	Called from postmaster to check if a terminated child process
 *	was the statistics collector.
 * ----------
 */
bool
pgstat_ispgstat(int pid)
{
	if (!pgstat_is_running)
		return false;

	if (pgStatPid != pid)
		return false;

	/* Oh dear ... */
	pgstat_is_running = false;

	return true;
}


/* ----------
 * pgstat_close_sockets() -
 *
 *	Called when postmaster forks a non-pgstat child process, to close off
 *	file descriptors that should not be held open in child processes.
 * ----------
 */
void
pgstat_close_sockets(void)
{
	if (pgStatPmPipe[0] >= 0)
		closesocket(pgStatPmPipe[0]);
	pgStatPmPipe[0] = -1;
	if (pgStatPmPipe[1] >= 0)
		closesocket(pgStatPmPipe[1]);
	pgStatPmPipe[1] = -1;
}


/* ----------
 * pgstat_beterm() -
 *
 *	Called from postmaster to tell collector a backend terminated.
 * ----------
 */
void
pgstat_beterm(int pid)
{
	PgStat_MsgBeterm msg;

	if (pgStatSock < 0)
		return;

	MemSet(&(msg.m_hdr), 0, sizeof(msg.m_hdr));
	msg.m_hdr.m_type = PGSTAT_MTYPE_BETERM;
	msg.m_hdr.m_procpid = pid;

	pgstat_send(&msg, sizeof(msg));
}


/* ------------------------------------------------------------
 * Public functions used by backends follow
 *------------------------------------------------------------
 */


/* ----------
 * pgstat_bestart() -
 *
 *	Tell the collector that this new backend is soon ready to process
 *	queries. Called from tcop/postgres.c before entering the mainloop.
 * ----------
 */
void
pgstat_bestart(void)
{
	PgStat_MsgBestart msg;

	if (pgStatSock < 0)
		return;

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


/* ----------
 * pgstat_report_activity() -
 *
 *	Called in tcop/postgres.c to tell the collector what the backend
 *	is actually doing (usually "<IDLE>" or the start of the query to
 *	be executed).
 * ----------
 */
void
pgstat_report_activity(const char *what)
{
	PgStat_MsgActivity msg;
	int			len;

	if (!pgstat_collect_querystring || pgStatSock < 0)
		return;

	len = strlen(what);
	len = pg_mbcliplen((const unsigned char *) what, len,
					   PGSTAT_ACTIVITY_SIZE - 1);

	memcpy(msg.m_what, what, len);
	msg.m_what[len] = '\0';
	len += offsetof(PgStat_MsgActivity, m_what) +1;

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


/* ----------
 * pgstat_report_tabstat() -