avlauncher_latch.v1.patch

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 2f3fcbf..cf5eb59 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -84,6 +84,7 @@
 #include "postmaster/postmaster.h"
 #include "storage/bufmgr.h"
 #include "storage/ipc.h"
+#include "storage/latch.h"
 #include "storage/pmsignal.h"
 #include "storage/proc.h"
 #include "storage/procsignal.h"
@@ -267,6 +268,10 @@ int			AutovacuumLauncherPid = 0;
 static pid_t avlauncher_forkexec(void);
 static pid_t avworker_forkexec(void);
 #endif
+/*
+ * Latch used by signal handlers to wake up the sleep in the main loop.
+ */
+static Latch mainloop_latch;
 NON_EXEC_STATIC void AutoVacWorkerMain(int argc, char *argv[]);
 NON_EXEC_STATIC void AutoVacLauncherMain(int argc, char *argv[]);
 
@@ -545,6 +550,8 @@ AutoVacLauncherMain(int argc, char *argv[])
 	 */
 	rebuild_database_list(InvalidOid);
 
+	InitLatch(&mainloop_latch);
+
 	for (;;)
 	{
 		struct timeval nap;
@@ -567,38 +574,20 @@ AutoVacLauncherMain(int argc, char *argv[])
 
 		/*
 		 * Sleep for a while according to schedule.
+		 * Wait on Latch.
 		 *
-		 * On some platforms, signals won't interrupt the sleep.  To ensure we
-		 * respond reasonably promptly when someone signals us, break down the
-		 * sleep into 1-second increments, and check for interrupts after each
-		 * nap.
+		 * We handle wait time invalidation by calling
+		 * SetLatch() in signal handlers.
 		 */
-		while (nap.tv_sec > 0 || nap.tv_usec > 0)
-		{
-			uint32		sleeptime;
-
-			if (nap.tv_sec > 0)
-			{
-				sleeptime = 1000000;
-				nap.tv_sec--;
-			}
-			else
-			{
-				sleeptime = nap.tv_usec;
-				nap.tv_usec = 0;
-			}
-			pg_usleep(sleeptime);
-
-			/*
-			 * Emergency bailout if postmaster has died.  This is to avoid the
-			 * necessity for manual cleanup of all postmaster children.
-			 */
-			if (!PostmasterIsAlive())
-				proc_exit(1);
-
-			if (got_SIGTERM || got_SIGHUP || got_SIGUSR2)
-				break;
-		}
+		WaitLatch(&mainloop_latch, WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH, (nap.tv_sec * 1000000L) + nap.tv_usec);
+		/*
+		 * Emergency bailout if postmaster has died.  This is to avoid the
+		 * necessity for manual cleanup of all postmaster children.
+		 *
+		 * This happens again here because we may have slept for quite a while.
+		 */
+		if (!PostmasterIsAlive())
+			proc_exit(1);
 
 		DisableCatchupInterrupt();
 
@@ -1322,6 +1311,8 @@ static void
 avl_sighup_handler(SIGNAL_ARGS)
 {
 	got_SIGHUP = true;
+	/* let the waiting loop iterate */
+	SetLatch(&mainloop_latch);
 }
 
 /* SIGUSR2: a worker is up and running, or just finished, or failed to fork */
@@ -1329,6 +1320,8 @@ static void
 avl_sigusr2_handler(SIGNAL_ARGS)
 {
 	got_SIGUSR2 = true;
+	/* let the waiting loop iterate */
+	SetLatch(&mainloop_latch);
 }
 
 /* SIGTERM: time to die */
@@ -1336,6 +1329,8 @@ static void
 avl_sigterm_handler(SIGNAL_ARGS)
 {
 	got_SIGTERM = true;
+	/* let the waiting loop iterate */
+	SetLatch(&mainloop_latch);
 }