Assert that WaitLatch's timeout is not more than INT_MAX milliseconds.

tglsfdc · tglsfdc · commit 14ddff44c22c · 2012-11-18T15:39:51.000-05:00
The behavior with larger values is unspecified by the Single Unix Spec.
It appears that BSD-derived kernels report EINVAL, although Linux does not.
If waiting for longer intervals is desired, the calling code has to do
something to limit the delay; we can't portably fix it here since "long"
may not be any wider than "int" in the first place.

Part of response to bug #7670, though this change doesn't fix that
(in fact, it converts the problem from an ERROR into an Assert failure).
No back-patch since it's just an assertion addition.
diff --git a/src/backend/port/unix_latch.c b/src/backend/port/unix_latch.c
@@ -33,6 +33,7 @@
 #include "postgres.h"
 
 #include <fcntl.h>
+#include <limits.h>
 #include <signal.h>
 #include <unistd.h>
 #include <sys/time.h>
@@ -176,9 +177,10 @@ DisownLatch(volatile Latch *latch)
  * to wait for. If the latch is already set (and WL_LATCH_SET is given), the
  * function returns immediately.
  *
- * The 'timeout' is given in milliseconds. It must be >= 0 if WL_TIMEOUT flag
- * is given.  Note that some extra overhead is incurred when WL_TIMEOUT is
- * given, so avoid using a timeout if possible.
+ * The "timeout" is given in milliseconds. It must be >= 0 if WL_TIMEOUT flag
+ * is given.  Although it is declared as "long", we don't actually support
+ * timeouts longer than INT_MAX milliseconds.  Note that some extra overhead
+ * is incurred when WL_TIMEOUT is given, so avoid using a timeout if possible.
  *
  * The latch must be owned by the current process, ie. it must be a
  * backend-local latch initialized with InitLatch, or a shared latch
@@ -243,7 +245,7 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
 	if (wakeEvents & WL_TIMEOUT)
 	{
 		INSTR_TIME_SET_CURRENT(start_time);
-		Assert(timeout >= 0);
+		Assert(timeout >= 0 && timeout <= INT_MAX);
 		cur_timeout = timeout;
 
 #ifndef HAVE_POLL
diff --git a/src/backend/port/win32_latch.c b/src/backend/port/win32_latch.c
@@ -20,6 +20,7 @@
 #include "postgres.h"
 
 #include <fcntl.h>
+#include <limits.h>
 #include <signal.h>
 #include <unistd.h>
 
@@ -130,7 +131,7 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,
 	if (wakeEvents & WL_TIMEOUT)
 	{
 		INSTR_TIME_SET_CURRENT(start_time);
-		Assert(timeout >= 0);
+		Assert(timeout >= 0 && timeout <= INT_MAX);
 		cur_timeout = timeout;
 	}
 	else

Original file line number	Diff line number	Diff line change
`@@ -20,6 +20,7 @@`
`20`	`20`	`#include "postgres.h"`
`21`	`21`
`22`	`22`	`#include <fcntl.h>`
	`23`	`+#include <limits.h>`
`23`	`24`	`#include <signal.h>`
`24`	`25`	`#include <unistd.h>`
`25`	`26`
`@@ -130,7 +131,7 @@ WaitLatchOrSocket(volatile Latch *latch, int wakeEvents, pgsocket sock,`
`130`	`131`	`if (wakeEvents & WL_TIMEOUT)`
`131`	`132`	`{`
`132`	`133`	`INSTR_TIME_SET_CURRENT(start_time);`
`133`		`- Assert(timeout >= 0);`
	`134`	`+ Assert(timeout >= 0 && timeout <= INT_MAX);`
`134`	`135`	`cur_timeout = timeout;`
`135`	`136`	`}`
`136`	`137`	`else`