diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index ac971abb184d1923273aa5c0bec392cff6a95a36..01273e193405a19b4e229810c8635c2f6e791ef9 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -28,12 +28,6 @@
#include <arpa/inet.h>
#include <signal.h>
#include <time.h>
-#ifdef HAVE_POLL_H
-#include <poll.h>
-#endif
-#ifdef HAVE_SYS_POLL_H
-#include <sys/poll.h>
-#endif
#include "pgstat.h"
@@ -55,8 +49,8 @@
#include "storage/backendid.h"
#include "storage/fd.h"
#include "storage/ipc.h"
+#include "storage/latch.h"
#include "storage/pg_shmem.h"
-#include "storage/pmsignal.h"
#include "storage/procsignal.h"
#include "utils/ascii.h"
#include "utils/guc.h"
@@ -94,9 +88,6 @@
* failed statistics collector; in
* seconds. */
-#define PGSTAT_SELECT_TIMEOUT 2 /* How often to check for postmaster
- * death; in seconds. */
-
#define PGSTAT_POLL_LOOP_COUNT (PGSTAT_MAX_WAIT_TIME / PGSTAT_RETRY_DELAY)
#define PGSTAT_INQ_LOOP_COUNT (PGSTAT_INQ_INTERVAL / PGSTAT_RETRY_DELAY)
@@ -139,6 +130,8 @@ PgStat_MsgBgWriter BgWriterStats;
*/
NON_EXEC_STATIC pgsocket pgStatSock = PGINVALID_SOCKET;
+static Latch pgStatLatch;
+
static struct sockaddr_storage pgStatAddr;
static time_t last_pgstat_start_time;
@@ -3009,15 +3002,7 @@ PgstatCollectorMain(int argc, char *argv[])
{
int len;
PgStat_Msg msg;
-
-#ifndef WIN32
-#ifdef HAVE_POLL
- struct pollfd input_fd;
-#else
- struct timeval sel_timeout;
- fd_set rfds;
-#endif
-#endif
+ int wr;
IsUnderPostmaster = true; /* we are a postmaster subprocess now */
@@ -3036,9 +3021,13 @@ PgstatCollectorMain(int argc, char *argv[])
elog(FATAL, "setsid() failed: %m");
#endif
+ /* Initialize private latch for use by signal handlers */
+ InitLatch(&pgStatLatch);
+
/*
* Ignore all signals usually bound to some action in the postmaster,
- * except SIGQUIT.
+ * except SIGHUP and SIGQUIT. Note we don't need a SIGUSR1 handler to
+ * support latch operations, because pgStatLatch is local not shared.
*/
pqsignal(SIGHUP, pgstat_sighup_handler);
pqsignal(SIGINT, SIG_IGN);
@@ -3073,26 +3062,24 @@ PgstatCollectorMain(int argc, char *argv[])
pgStatRunningInCollector = true;
pgStatDBHash = pgstat_read_statsfile(InvalidOid, true);
- /*
- * Setup the descriptor set for select(2). Since only one bit in the set
- * ever changes, we need not repeat FD_ZERO each time.
- */
-#if !defined(HAVE_POLL) && !defined(WIN32)
- FD_ZERO(&rfds);
-#endif
-
/*
* Loop to process messages until we get SIGQUIT or detect ungraceful
* death of our parent postmaster.
*
- * For performance reasons, we don't want to do a PostmasterIsAlive() test
- * after every message; instead, do it only when select()/poll() is
- * interrupted by timeout. In essence, we'll stay alive as long as
- * backends keep sending us stuff often, even if the postmaster is gone.
+ * For performance reasons, we don't want to do ResetLatch/WaitLatch after
+ * every message; instead, do that only after a recv() fails to obtain a
+ * message. (This effectively means that if backends are sending us stuff
+ * like mad, we won't notice postmaster death until things slack off a
+ * bit; which seems fine.) To do that, we have an inner loop that
+ * iterates as long as recv() succeeds. We do recognize got_SIGHUP inside
+ * the inner loop, which means that such interrupts will get serviced but
+ * the latch won't get cleared until next time there is a break in the
+ * action.
*/
for (;;)
{
- int got_data;
+ /* Clear any already-pending wakeups */
+ ResetLatch(&pgStatLatch);
/*
* Quit if we get SIGQUIT from the postmaster.
@@ -3101,87 +3088,37 @@ PgstatCollectorMain(int argc, char *argv[])
break;
/*
- * Reload configuration if we got SIGHUP from the postmaster.
- */
- if (got_SIGHUP)
- {
- ProcessConfigFile(PGC_SIGHUP);
- got_SIGHUP = false;
- }
-
- /*
- * Write the stats file if a new request has arrived that is not
- * satisfied by existing file.
+ * Inner loop iterates as long as we keep getting messages, or until
+ * need_exit becomes set.
*/
- if (last_statwrite < last_statrequest)
- pgstat_write_statsfile(false);
-
- /*
- * Wait for a message to arrive; but not for more than
- * PGSTAT_SELECT_TIMEOUT seconds. (This determines how quickly we will
- * shut down after an ungraceful postmaster termination; so it needn't
- * be very fast. However, on some systems SIGQUIT won't interrupt the
- * poll/select call, so this also limits speed of response to SIGQUIT,
- * which is more important.)
- *
- * We use poll(2) if available, otherwise select(2). Win32 has its own
- * implementation.
- */
-#ifndef WIN32
-#ifdef HAVE_POLL
- input_fd.fd = pgStatSock;
- input_fd.events = POLLIN | POLLERR;
- input_fd.revents = 0;
-
- if (poll(&input_fd, 1, PGSTAT_SELECT_TIMEOUT * 1000) < 0)
- {
- if (errno == EINTR)
- continue;
- ereport(ERROR,
- (errcode_for_socket_access(),
- errmsg("poll() failed in statistics collector: %m")));
- }
-
- got_data = (input_fd.revents != 0);
-#else /* !HAVE_POLL */
-
- FD_SET(pgStatSock, &rfds);
-
- /*
- * timeout struct is modified by select() on some operating systems,
- * so re-fill it each time.
- */
- sel_timeout.tv_sec = PGSTAT_SELECT_TIMEOUT;
- sel_timeout.tv_usec = 0;
-
- if (select(pgStatSock + 1, &rfds, NULL, NULL, &sel_timeout) < 0)
+ while (!need_exit)
{
- if (errno == EINTR)
- continue;
- ereport(ERROR,
- (errcode_for_socket_access(),
- errmsg("select() failed in statistics collector: %m")));
- }
+ /*
+ * Reload configuration if we got SIGHUP from the postmaster.
+ */
+ if (got_SIGHUP)
+ {
+ got_SIGHUP = false;
+ ProcessConfigFile(PGC_SIGHUP);
+ }
- got_data = FD_ISSET(pgStatSock, &rfds);
-#endif /* HAVE_POLL */
-#else /* WIN32 */
- got_data = pgwin32_waitforsinglesocket(pgStatSock, FD_READ,
- PGSTAT_SELECT_TIMEOUT * 1000);
-#endif
+ /*
+ * Write the stats file if a new request has arrived that is not
+ * satisfied by existing file.
+ */
+ if (last_statwrite < last_statrequest)
+ pgstat_write_statsfile(false);
- /*
- * If there is a message on the socket, read it and check for
- * validity.
- */
- if (got_data)
- {
+ /*
+ * Try to receive and process a message. This will not block,
+ * since the socket is set to non-blocking mode.
+ */
len = recv(pgStatSock, (char *) &msg,
sizeof(PgStat_Msg), 0);
if (len < 0)
{
- if (errno == EINTR)
- continue;
+ if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
+ break; /* out of inner loop */
ereport(ERROR,
(errcode_for_socket_access(),
errmsg("could not read statistics message: %m")));
@@ -3279,17 +3216,21 @@ PgstatCollectorMain(int argc, char *argv[])
default:
break;
}
- }
- else
- {
- /*
- * We can only get here if the select/poll timeout elapsed. Check
- * for postmaster death.
- */
- if (!PostmasterIsAlive())
- break;
- }
- } /* end of message-processing loop */
+ } /* end of inner message-processing loop */
+
+ /* Sleep until there's something to do */
+ wr = WaitLatchOrSocket(&pgStatLatch,
+ WL_LATCH_SET | WL_POSTMASTER_DEATH | WL_SOCKET_READABLE,
+ pgStatSock,
+ -1L);
+
+ /*
+ * Emergency bailout if postmaster has died. This is to avoid the
+ * necessity for manual cleanup of all postmaster children.
+ */
+ if (wr & WL_POSTMASTER_DEATH)
+ break;
+ } /* end of outer loop */
/*
* Save the final stats to reuse at next startup.
@@ -3304,14 +3245,24 @@ PgstatCollectorMain(int argc, char *argv[])
static void
pgstat_exit(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
need_exit = true;
+ SetLatch(&pgStatLatch);
+
+ errno = save_errno;
}
/* SIGHUP handler for collector process */
static void
pgstat_sighup_handler(SIGNAL_ARGS)
{
+ int save_errno = errno;
+
got_SIGHUP = true;
+ SetLatch(&pgStatLatch);
+
+ errno = save_errno;
}