Set MyProc->heldLocks in ProcSleep

Previously, ProcSleep()'s caller was responsible for setting
MyProc->heldLocks, and we had comments to remind about that.  But it
seems simpler to make ProcSleep() itself responsible for it.
ProcSleep() already set the other info about the lock its waiting for
(waitLock, waitProcLock and waitLockMode), so it is natural for it to
set heldLocks too.

Reviewed-by: Maxim Orlov
Discussion: https://www.postgresql.org/message-id/7c2090cd-a72a-4e34-afaa-6dd2ef31440e@iki.fi

src/backend/storage/lmgr/lock.c

@@ -1095,11 +1095,6 @@ LockAcquireExtended(const LOCKTAG *locktag,
 	}
 	else
 	{
-		/*
-		 * Set bitmask of locks this process already holds on this object.
-		 */
-		MyProc->heldLocks = proclock->holdMask;
-
 		/*
 		 * Sleep till someone wakes me up. We do this even in the dontWait
 		 * case, because while trying to go to sleep, we may discover that we
@@ -1856,9 +1851,6 @@ MarkLockClear(LOCALLOCK *locallock)
 /*
  * WaitOnLock -- wait to acquire a lock
  *
- * Caller must have set MyProc->heldLocks to reflect locks already held
- * on the lockable object by this process.
- *
  * The appropriate partition lock must be held at entry, and will still be
  * held at exit.
  */

src/backend/storage/lmgr/proc.c

@@ -1080,9 +1080,6 @@ AuxiliaryPidGetProc(int pid)
 /*
  * ProcSleep -- put a process to sleep on the specified lock
  *
- * Caller must have set MyProc->heldLocks to reflect locks already held
- * on the lockable object by this process (under all XIDs).
- *
  * It's not actually guaranteed that we need to wait when this function is
  * called, because it could be that when we try to find a position at which
  * to insert ourself into the wait queue, we discover that we must be inserted
@@ -1112,7 +1109,8 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable, bool dontWait)
 	LWLock	   *partitionLock = LockHashPartitionLock(hashcode);
 	dclist_head *waitQueue = &lock->waitProcs;
 	PGPROC	   *insert_before = NULL;
-	LOCKMASK	myHeldLocks = MyProc->heldLocks;
+	LOCKMASK	myProcHeldLocks;
+	LOCKMASK	myHeldLocks;
 	TimestampTz standbyWaitStart = 0;
 	bool		early_deadlock = false;
 	bool		allow_autovacuum_cancel = true;
@@ -1121,6 +1119,8 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable, bool dontWait)
 	PGPROC	   *leader = MyProc->lockGroupLeader;
 
 	/*
+	 * Determine which locks we're already holding.
+	 *
 	 * If group locking is in use, locks held by members of my locking group
 	 * need to be included in myHeldLocks.  This is not required for relation
 	 * extension lock which conflict among group members. However, including
@@ -1130,6 +1130,8 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable, bool dontWait)
 	 * that kind of locks, but there doesn't appear to be a clear advantage of
 	 * the same.
 	 */
+	myProcHeldLocks = proclock->holdMask;
+	myHeldLocks = myProcHeldLocks;
 	if (leader != NULL)
 	{
 		dlist_iter	iter;
@@ -1234,6 +1236,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable, bool dontWait)
 	lock->waitMask |= LOCKBIT_ON(lockmode);
 
 	/* Set up wait information in PGPROC object, too */
+	MyProc->heldLocks = myProcHeldLocks;
 	MyProc->waitLock = lock;
 	MyProc->waitProcLock = proclock;
 	MyProc->waitLockMode = lockmode;