From: Bruce Momjian <bruce@momjian.us>
Date: Tue, 29 Dec 1998 19:32:08 +0000 (+0000)
Subject: Update for deadlock detection.
X-Git-Tag: REL6_5~855
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6059c5a14131cdb71750838ddd7b2034fe540193;p=postgresql

Update for deadlock detection.
---

diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 0a36c61847..704448b16f 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.46 1998/12/29 18:36:29 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.47 1998/12/29 19:32:08 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -46,7 +46,7 @@
  *		This is so that we can support more backends. (system-wide semaphore
  *		sets run out pretty fast.)				  -ay 4/95
  *
- * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.46 1998/12/29 18:36:29 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.47 1998/12/29 19:32:08 momjian Exp $
  */
 #include <sys/time.h>
 #include <unistd.h>
@@ -77,7 +77,7 @@
 #include "storage/proc.h"
 #include "utils/trace.h"
 
-static void HandleDeadLock(void);
+static void HandleDeadLock(int sig);
 static PROC *ProcWakeup(PROC *proc, int errType);
 
 #define DeadlockCheckTimer pg_options[OPT_DEADLOCKTIMEOUT]
@@ -154,6 +154,8 @@ InitProcess(IPCKey key)
 	 * Routine called if deadlock timer goes off. See ProcSleep()
 	 * ------------------
 	 */
+	pqsignal(SIGALRM, HandleDeadLock);
+
 	SpinAcquire(ProcStructLock);
 
 	/* attach to the free list */
@@ -447,8 +449,10 @@ ProcSleep(PROC_QUEUE *waitQueue,/* lock->waitProcs */
 		  TransactionId xid)	/* needed by user locks, see below */
 {
 	int			i;
-	bool		deadlock_checked = false;
 	PROC	   *proc;
+	bool		deadlock_checked = false;
+	struct itimerval timeval,
+				dummy;
 
 	/*
 	 * If the first entries in the waitQueue have a greater priority than
@@ -512,28 +516,27 @@ ProcSleep(PROC_QUEUE *waitQueue,/* lock->waitProcs */
 	SpinRelease(spinlock);
 
 	/* --------------
-	 * We set this so we can wake up after one second to check for a deadlock.
+	 * We set this so we can wake up periodically and check for a deadlock.
 	 * If a deadlock is detected, the handler releases the processes
 	 * semaphore and aborts the current transaction.
+	 *
+	 * Need to zero out struct to set the interval and the micro seconds fields
+	 * to 0.
 	 * --------------
 	 */
+	MemSet(&timeval, 0, sizeof(struct itimerval));
+	timeval.it_value.tv_sec = \
+		(DeadlockCheckTimer ? DeadlockCheckTimer : DEADLOCK_CHECK_TIMER);
 
 	do
 	{
 		MyProc->errType = NO_ERROR;		/* reset flag after deadlock check */
 
-		if (deadlock_checked == false)
-		{
-			if (sleep(DeadlockCheckTimer ? DeadlockCheckTimer : DEADLOCK_CHECK_TIMER)
-				== 0 /* no signal interruption */ )
-			{
-				HandleDeadLock();
-				deadlock_checked = true;
-			}
-		}
-		else
-			pause();
-		
+		if (!deadlock_checked)
+			if (setitimer(ITIMER_REAL, &timeval, &dummy))
+				elog(FATAL, "ProcSleep: Unable to set timer for process wakeup");
+		deadlock_checked = true;
+
 		/* --------------
 		 * if someone wakes us between SpinRelease and IpcSemaphoreLock,
 		 * IpcSemaphoreLock will not block.  The wakeup is "saved" by
@@ -545,6 +548,14 @@ ProcSleep(PROC_QUEUE *waitQueue,/* lock->waitProcs */
 	} while (MyProc->errType == STATUS_NOT_FOUND);		/* sleep after deadlock
 														 * check */
 
+	/* ---------------
+	 * We were awoken before a timeout - now disable the timer
+	 * ---------------
+	 */
+	timeval.it_value.tv_sec = 0;
+	if (setitimer(ITIMER_REAL, &timeval, &dummy))
+		elog(FATAL, "ProcSleep: Unable to diable timer for process wakeup");
+
 	/* ----------------
 	 * We were assumed to be in a critical section when we went
 	 * to sleep.
@@ -687,7 +698,7 @@ ProcAddLock(SHM_QUEUE *elem)
  * --------------------
  */
 static void
-HandleDeadLock()
+HandleDeadLock(int sig)
 {
 	LOCK	   *mywaitlock;