Rename delayChkpt to delayChkptFlags.

Before commit 412ad7a556, delayChkpt
was a Boolean. Now it's an integer. Extensions using it need to be
appropriately updated, so let's rename the field to make sure that
a hard compilation failure occurs.

Replacing delayChkpt with delayChkptFlags made a few comments extend
past 80 characters, so I reflowed them and changed some wording very
slightly.

The back-branches will need a different change to restore compatibility
with existing minor releases; this is just for master.

Per suggestion from Tom Lane.

Discussion: http://postgr.es/m/a7880f4d-1d74-582a-ada7-dad168d046d1@enterprisedb.com

src/backend/storage/buffer/bufmgr.c

@@ -4021,7 +4021,7 @@ MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
 	{
 		XLogRecPtr	lsn = InvalidXLogRecPtr;
 		bool		dirtied = false;
-		bool		delayChkpt = false;
+		bool		delayChkptFlags = false;
 		uint32		buf_state;
 
 		/*
@@ -4071,9 +4071,9 @@ MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
 			 * essential that CreateCheckPoint waits for virtual transactions
 			 * rather than full transactionids.
 			 */
-			Assert((MyProc->delayChkpt & DELAY_CHKPT_START) == 0);
-			MyProc->delayChkpt |= DELAY_CHKPT_START;
-			delayChkpt = true;
+			Assert((MyProc->delayChkptFlags & DELAY_CHKPT_START) == 0);
+			MyProc->delayChkptFlags |= DELAY_CHKPT_START;
+			delayChkptFlags = true;
 			lsn = XLogSaveBufferForHint(buffer, buffer_std);
 		}
 
@@ -4105,8 +4105,8 @@ MarkBufferDirtyHint(Buffer buffer, bool buffer_std)
 		buf_state |= BM_DIRTY | BM_JUST_DIRTIED;
 		UnlockBufHdr(bufHdr, buf_state);
 
-		if (delayChkpt)
-			MyProc->delayChkpt &= ~DELAY_CHKPT_START;
+		if (delayChkptFlags)
+			MyProc->delayChkptFlags &= ~DELAY_CHKPT_START;
 
 		if (dirtied)
 		{

src/backend/storage/ipc/procarray.c

@@ -700,7 +700,7 @@ ProcArrayEndTransaction(PGPROC *proc, TransactionId latestXid)
 		proc->xmin = InvalidTransactionId;
 
 		/* be sure this is cleared in abort */
-		proc->delayChkpt = 0;
+		proc->delayChkptFlags = 0;
 
 		proc->recoveryConflictPending = false;
 
@@ -742,7 +742,7 @@ ProcArrayEndTransactionInternal(PGPROC *proc, TransactionId latestXid)
 	proc->xmin = InvalidTransactionId;
 
 	/* be sure this is cleared in abort */
-	proc->delayChkpt = 0;
+	proc->delayChkptFlags = 0;
 
 	proc->recoveryConflictPending = false;
 
@@ -929,7 +929,7 @@ ProcArrayClearTransaction(PGPROC *proc)
 	proc->recoveryConflictPending = false;
 
 	Assert(!(proc->statusFlags & PROC_VACUUM_STATE_MASK));
-	Assert(!proc->delayChkpt);
+	Assert(!proc->delayChkptFlags);
 
 	/*
 	 * Need to increment completion count even though transaction hasn't
@@ -3059,19 +3059,20 @@ GetOldestSafeDecodingTransactionId(bool catalogOnly)
  * delaying checkpoint because they have critical actions in progress.
  *
  * Constructs an array of VXIDs of transactions that are currently in commit
- * critical sections, as shown by having specified delayChkpt bits set in their
- * PGPROC.
+ * critical sections, as shown by having specified delayChkptFlags bits set
+ * in their PGPROC.
  *
  * Returns a palloc'd array that should be freed by the caller.
  * *nvxids is the number of valid entries.
  *
- * Note that because backends set or clear delayChkpt without holding any lock,
- * the result is somewhat indeterminate, but we don't really care.  Even in
- * a multiprocessor with delayed writes to shared memory, it should be certain
- * that setting of delayChkpt will propagate to shared memory when the backend
- * takes a lock, so we cannot fail to see a virtual xact as delayChkpt if
- * it's already inserted its commit record.  Whether it takes a little while
- * for clearing of delayChkpt to propagate is unimportant for correctness.
+ * Note that because backends set or clear delayChkptFlags without holding any
+ * lock, the result is somewhat indeterminate, but we don't really care.  Even
+ * in a multiprocessor with delayed writes to shared memory, it should be
+ * certain that setting of delayChkptFlags will propagate to shared memory
+ * when the backend takes a lock, so we cannot fail to see a virtual xact as
+ * delayChkptFlags if it's already inserted its commit record.  Whether it
+ * takes a little while for clearing of delayChkptFlags to propagate is
+ * unimportant for correctness.
  */
 VirtualTransactionId *
 GetVirtualXIDsDelayingChkpt(int *nvxids, int type)
@@ -3094,7 +3095,7 @@ GetVirtualXIDsDelayingChkpt(int *nvxids, int type)
 		int			pgprocno = arrayP->pgprocnos[index];
 		PGPROC	   *proc = &allProcs[pgprocno];
 
-		if ((proc->delayChkpt & type) != 0)
+		if ((proc->delayChkptFlags & type) != 0)
 		{
 			VirtualTransactionId vxid;
 
@@ -3138,7 +3139,7 @@ HaveVirtualXIDsDelayingChkpt(VirtualTransactionId *vxids, int nvxids, int type)
 
 		GET_VXID_FROM_PGPROC(vxid, *proc);
 
-		if ((proc->delayChkpt & type) != 0 &&
+		if ((proc->delayChkptFlags & type) != 0 &&
 			VirtualTransactionIdIsValid(vxid))
 		{
 			int			i;

src/backend/storage/lmgr/proc.c

@@ -393,7 +393,7 @@ InitProcess(void)
 	MyProc->roleId = InvalidOid;
 	MyProc->tempNamespaceId = InvalidOid;
 	MyProc->isBackgroundWorker = IsBackgroundWorker;
-	MyProc->delayChkpt = 0;
+	MyProc->delayChkptFlags = 0;
 	MyProc->statusFlags = 0;
 	/* NB -- autovac launcher intentionally does not set IS_AUTOVACUUM */
 	if (IsAutoVacuumWorkerProcess())
@@ -578,7 +578,7 @@ InitAuxiliaryProcess(void)
 	MyProc->roleId = InvalidOid;
 	MyProc->tempNamespaceId = InvalidOid;
 	MyProc->isBackgroundWorker = IsBackgroundWorker;
-	MyProc->delayChkpt = 0;
+	MyProc->delayChkptFlags = 0;
 	MyProc->statusFlags = 0;
 	MyProc->lwWaiting = false;
 	MyProc->lwWaitMode = 0;