Fix poll() implementation of WaitLatchOrSocket to notice postmaster death.

hlinnaka · hlinnaka · commit b2b4af535eb7 · 2012-01-15T22:08:03.000+02:00
When the remote end of the pipe is closed, select() reports the fd as
readable, but poll() has a separate POLLHUP return code for that.

Spotted by Peter Geoghegan.
diff --git a/src/backend/port/unix_latch.c b/src/backend/port/unix_latch.c
@@ -310,8 +310,13 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
 		{
 			result |= WL_SOCKET_WRITEABLE;
 		}
+		/*
+		 * We expect a POLLHUP when the remote end is closed, but because we
+		 * don't expect the pipe to become readable or to have any errors
+		 * either, treat those as postmaster death, too.
+		 */
 		if ((wakeEvents & WL_POSTMASTER_DEATH) &&
-			(pfds[nfds - 1].revents & POLLIN))
+			(pfds[nfds - 1].revents & (POLLHUP | POLLIN | POLLERR | POLLNVAL)))
 		{
 			result |= WL_POSTMASTER_DEATH;
 		}

Original file line number	Diff line number	Diff line change
`@@ -310,8 +310,13 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,`
`310`	`310`	`{`
`311`	`311`	`result \|= WL_SOCKET_WRITEABLE;`
`312`	`312`	`}`
	`313`	`+ /*`
	`314`	`+ * We expect a POLLHUP when the remote end is closed, but because we`
	`315`	`+ * don't expect the pipe to become readable or to have any errors`
	`316`	`+ * either, treat those as postmaster death, too.`
	`317`	`+ */`
`313`	`318`	`if ((wakeEvents & WL_POSTMASTER_DEATH) &&`
`314`		`- (pfds[nfds - 1].revents & POLLIN))`
	`319`	`+ (pfds[nfds - 1].revents & (POLLHUP \| POLLIN \| POLLERR \| POLLNVAL)))`
`315`	`320`	`{`
`316`	`321`	`result \|= WL_POSTMASTER_DEATH;`
`317`	`322`	`}`