Remove STATUS_WAITING

Add a separate enum for use in the locking APIs, which were the only
user.

Discussion: https://www.postgresql.org/message-id/flat/a6f91ead-0ce4-2a34-062b-7ab9813ea308%402ndquadrant.com

src/backend/access/transam/twophase.c

@@ -460,7 +460,7 @@ MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
 	MemSet(proc, 0, sizeof(PGPROC));
 	proc->pgprocno = gxact->pgprocno;
 	SHMQueueElemInit(&(proc->links));
-	proc->waitStatus = STATUS_OK;
+	proc->waitStatus = PROC_WAIT_STATUS_OK;
 	/* We set up the gxact's VXID as InvalidBackendId/XID */
 	proc->lxid = (LocalTransactionId) xid;
 	pgxact->xid = xid;

src/backend/storage/lmgr/lock.c

@@ -1856,7 +1856,7 @@ WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
 	 */
 	PG_TRY();
 	{
-		if (ProcSleep(locallock, lockMethodTable) != STATUS_OK)
+		if (ProcSleep(locallock, lockMethodTable) != PROC_WAIT_STATUS_OK)
 		{
 			/*
 			 * We failed as a result of a deadlock, see CheckDeadLock(). Quit
@@ -1907,7 +1907,7 @@ WaitOnLock(LOCALLOCK *locallock, ResourceOwner owner)
 /*
  * Remove a proc from the wait-queue it is on (caller must know it is on one).
  * This is only used when the proc has failed to get the lock, so we set its
- * waitStatus to STATUS_ERROR.
+ * waitStatus to PROC_WAIT_STATUS_ERROR.
  *
  * Appropriate partition lock must be held by caller.  Also, caller is
  * responsible for signaling the proc if needed.
@@ -1923,7 +1923,7 @@ RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode)
 	LOCKMETHODID lockmethodid = LOCK_LOCKMETHOD(*waitLock);
 
 	/* Make sure proc is waiting */
-	Assert(proc->waitStatus == STATUS_WAITING);
+	Assert(proc->waitStatus == PROC_WAIT_STATUS_WAITING);
 	Assert(proc->links.next != NULL);
 	Assert(waitLock);
 	Assert(waitLock->waitProcs.size > 0);
@@ -1946,7 +1946,7 @@ RemoveFromWaitQueue(PGPROC *proc, uint32 hashcode)
 	/* Clean up the proc's own state, and pass it the ok/fail signal */
 	proc->waitLock = NULL;
 	proc->waitProcLock = NULL;
-	proc->waitStatus = STATUS_ERROR;
+	proc->waitStatus = PROC_WAIT_STATUS_ERROR;
 
 	/*
 	 * Delete the proclock immediately if it represents no already-held locks.

src/backend/storage/lmgr/proc.c

@@ -383,7 +383,7 @@ InitProcess(void)
 	 * initialized by InitProcGlobal.
 	 */
 	SHMQueueElemInit(&(MyProc->links));
-	MyProc->waitStatus = STATUS_OK;
+	MyProc->waitStatus = PROC_WAIT_STATUS_OK;
 	MyProc->lxid = InvalidLocalTransactionId;
 	MyProc->fpVXIDLock = false;
 	MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
@@ -567,7 +567,7 @@ InitAuxiliaryProcess(void)
 	 * initialized by InitProcGlobal.
 	 */
 	SHMQueueElemInit(&(MyProc->links));
-	MyProc->waitStatus = STATUS_OK;
+	MyProc->waitStatus = PROC_WAIT_STATUS_OK;
 	MyProc->lxid = InvalidLocalTransactionId;
 	MyProc->fpVXIDLock = false;
 	MyProc->fpLocalTransactionId = InvalidLocalTransactionId;
@@ -755,7 +755,7 @@ LockErrorCleanup(void)
 		 * did grant us the lock, we'd better remember it in our local lock
 		 * table.
 		 */
-		if (MyProc->waitStatus == STATUS_OK)
+		if (MyProc->waitStatus == PROC_WAIT_STATUS_OK)
 			GrantAwaitedLock();
 	}
 
@@ -1051,14 +1051,14 @@ ProcQueueInit(PROC_QUEUE *queue)
  * The lock table's partition lock must be held at entry, and will be held
  * at exit.
  *
- * Result: STATUS_OK if we acquired the lock, STATUS_ERROR if not (deadlock).
+ * Result: PROC_WAIT_STATUS_OK if we acquired the lock, PROC_WAIT_STATUS_ERROR if not (deadlock).
  *
  * ASSUME: that no one will fiddle with the queue until after
  *		we release the partition lock.
  *
  * NOTES: The process queue is now a priority queue for locking.
  */
-int
+ProcWaitStatus
 ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 {
 	LOCKMODE	lockmode = locallock->tag.mode;
@@ -1070,7 +1070,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	LOCKMASK	myHeldLocks = MyProc->heldLocks;
 	bool		early_deadlock = false;
 	bool		allow_autovacuum_cancel = true;
-	int			myWaitStatus;
+	ProcWaitStatus myWaitStatus;
 	PGPROC	   *proc;
 	PGPROC	   *leader = MyProc->lockGroupLeader;
 	int			i;
@@ -1161,7 +1161,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 					/* Skip the wait and just grant myself the lock. */
 					GrantLock(lock, proclock, lockmode);
 					GrantAwaitedLock();
-					return STATUS_OK;
+					return PROC_WAIT_STATUS_OK;
 				}
 				/* Break out of loop to put myself before him */
 				break;
@@ -1195,7 +1195,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	MyProc->waitProcLock = proclock;
 	MyProc->waitLockMode = lockmode;
 
-	MyProc->waitStatus = STATUS_WAITING;
+	MyProc->waitStatus = PROC_WAIT_STATUS_WAITING;
 
 	/*
 	 * If we detected deadlock, give up without waiting.  This must agree with
@@ -1204,7 +1204,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	if (early_deadlock)
 	{
 		RemoveFromWaitQueue(MyProc, hashcode);
-		return STATUS_ERROR;
+		return PROC_WAIT_STATUS_ERROR;
 	}
 
 	/* mark that we are waiting for a lock */
@@ -1236,7 +1236,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	/*
 	 * Set timer so we can wake up after awhile and check for a deadlock. If a
 	 * deadlock is detected, the handler sets MyProc->waitStatus =
-	 * STATUS_ERROR, allowing us to know that we must report failure rather
+	 * PROC_WAIT_STATUS_ERROR, allowing us to know that we must report failure rather
 	 * than success.
 	 *
 	 * By delaying the check until we've waited for a bit, we can avoid
@@ -1302,11 +1302,11 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 		}
 
 		/*
-		 * waitStatus could change from STATUS_WAITING to something else
+		 * waitStatus could change from PROC_WAIT_STATUS_WAITING to something else
 		 * asynchronously.  Read it just once per loop to prevent surprising
 		 * behavior (such as missing log messages).
 		 */
-		myWaitStatus = *((volatile int *) &MyProc->waitStatus);
+		myWaitStatus = *((volatile ProcWaitStatus *) &MyProc->waitStatus);
 
 		/*
 		 * If we are not deadlocked, but are waiting on an autovacuum-induced
@@ -1487,24 +1487,24 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 											   lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
 			}
 
-			if (myWaitStatus == STATUS_WAITING)
+			if (myWaitStatus == PROC_WAIT_STATUS_WAITING)
 				ereport(LOG,
 						(errmsg("process %d still waiting for %s on %s after %ld.%03d ms",
 								MyProcPid, modename, buf.data, msecs, usecs),
 						 (errdetail_log_plural("Process holding the lock: %s. Wait queue: %s.",
 											   "Processes holding the lock: %s. Wait queue: %s.",
 											   lockHoldersNum, lock_holders_sbuf.data, lock_waiters_sbuf.data))));
-			else if (myWaitStatus == STATUS_OK)
+			else if (myWaitStatus == PROC_WAIT_STATUS_OK)
 				ereport(LOG,
 						(errmsg("process %d acquired %s on %s after %ld.%03d ms",
 								MyProcPid, modename, buf.data, msecs, usecs)));
 			else
 			{
-				Assert(myWaitStatus == STATUS_ERROR);
+				Assert(myWaitStatus == PROC_WAIT_STATUS_ERROR);
 
 				/*
 				 * Currently, the deadlock checker always kicks its own
-				 * process, which means that we'll only see STATUS_ERROR when
+				 * process, which means that we'll only see PROC_WAIT_STATUS_ERROR when
 				 * deadlock_state == DS_HARD_DEADLOCK, and there's no need to
 				 * print redundant messages.  But for completeness and
 				 * future-proofing, print a message if it looks like someone
@@ -1529,7 +1529,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 			pfree(lock_holders_sbuf.data);
 			pfree(lock_waiters_sbuf.data);
 		}
-	} while (myWaitStatus == STATUS_WAITING);
+	} while (myWaitStatus == PROC_WAIT_STATUS_WAITING);
 
 	/*
 	 * Disable the timers, if they are still running.  As in LockErrorCleanup,
@@ -1568,7 +1568,7 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
 	/*
 	 * If we got the lock, be sure to remember it in the locallock table.
 	 */
-	if (MyProc->waitStatus == STATUS_OK)
+	if (MyProc->waitStatus == PROC_WAIT_STATUS_OK)
 		GrantAwaitedLock();
 
 	/*
@@ -1590,10 +1590,10 @@ ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable)
  * XXX: presently, this code is only used for the "success" case, and only
  * works correctly for that case.  To clean up in failure case, would need
  * to twiddle the lock's request counts too --- see RemoveFromWaitQueue.
- * Hence, in practice the waitStatus parameter must be STATUS_OK.
+ * Hence, in practice the waitStatus parameter must be PROC_WAIT_STATUS_OK.
  */
 PGPROC *
-ProcWakeup(PGPROC *proc, int waitStatus)
+ProcWakeup(PGPROC *proc, ProcWaitStatus waitStatus)
 {
 	PGPROC	   *retProc;
 
@@ -1601,7 +1601,7 @@ ProcWakeup(PGPROC *proc, int waitStatus)
 	if (proc->links.prev == NULL ||
 		proc->links.next == NULL)
 		return NULL;
-	Assert(proc->waitStatus == STATUS_WAITING);
+	Assert(proc->waitStatus == PROC_WAIT_STATUS_WAITING);
 
 	/* Save next process before we zap the list link */
 	retProc = (PGPROC *) proc->links.next;
@@ -1657,7 +1657,7 @@ ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock)
 		{
 			/* OK to waken */
 			GrantLock(lock, proc->waitProcLock, lockmode);
-			proc = ProcWakeup(proc, STATUS_OK);
+			proc = ProcWakeup(proc, PROC_WAIT_STATUS_OK);
 
 			/*
 			 * ProcWakeup removes proc from the lock's waiting process queue
@@ -1737,7 +1737,7 @@ CheckDeadLock(void)
 		 * preserve the flexibility to kill some other transaction than the
 		 * one detecting the deadlock.)
 		 *
-		 * RemoveFromWaitQueue sets MyProc->waitStatus to STATUS_ERROR, so
+		 * RemoveFromWaitQueue sets MyProc->waitStatus to PROC_WAIT_STATUS_ERROR, so
 		 * ProcSleep will report an error after we return from the signal
 		 * handler.
 		 */

src/include/c.h

@@ -1133,7 +1133,6 @@ typedef union PGAlignedXLogBlock
 #define STATUS_OK				(0)
 #define STATUS_ERROR			(-1)
 #define STATUS_EOF				(-2)
-#define STATUS_WAITING			(2)
 
 /*
  * gettext support

src/include/storage/proc.h

@@ -76,6 +76,13 @@ struct XidCache
  */
 #define INVALID_PGPROCNO		PG_INT32_MAX
 
+typedef enum
+{
+	PROC_WAIT_STATUS_OK,
+	PROC_WAIT_STATUS_WAITING,
+	PROC_WAIT_STATUS_ERROR,
+} ProcWaitStatus;
+
 /*
  * Each backend has a PGPROC struct in shared memory.  There is also a list of
  * currently-unused PGPROC structs that will be reallocated to new backends.
@@ -99,7 +106,7 @@ struct PGPROC
 	PGPROC	  **procgloballist; /* procglobal list that owns this PGPROC */
 
 	PGSemaphore sem;			/* ONE semaphore to sleep on */
-	int			waitStatus;		/* STATUS_WAITING, STATUS_OK or STATUS_ERROR */
+	ProcWaitStatus waitStatus;
 
 	Latch		procLatch;		/* generic latch for process */
 
@@ -315,8 +322,8 @@ extern bool HaveNFreeProcs(int n);
 extern void ProcReleaseLocks(bool isCommit);
 
 extern void ProcQueueInit(PROC_QUEUE *queue);
-extern int	ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable);
-extern PGPROC *ProcWakeup(PGPROC *proc, int waitStatus);
+extern ProcWaitStatus ProcSleep(LOCALLOCK *locallock, LockMethod lockMethodTable);
+extern PGPROC *ProcWakeup(PGPROC *proc, ProcWaitStatus waitStatus);
 extern void ProcLockWakeup(LockMethod lockMethodTable, LOCK *lock);
 extern void CheckDeadLockAlert(void);
 extern bool IsWaitingForLock(void);