Replace PGPROC.isBackgroundWorker with isRegularBackend.

Commit 34486b6 effectively redefined isBackgroundWorker as meaning
"not a regular backend", whereas before it had the narrower
meaning of AmBackgroundWorkerProcess().  For clarity, rename the
field to isRegularBackend and invert its sense.

Discussion: https://postgr.es/m/1808397.1735156190@sss.pgh.pa.us

Author: tglsfdc

src/backend/access/transam/twophase.c

@@ -466,7 +466,7 @@ MarkAsPreparingGuts(GlobalTransaction gxact, TransactionId xid, const char *gid,
 	proc->databaseId = databaseid;
 	proc->roleId = owner;
 	proc->tempNamespaceId = InvalidOid;
-	proc->isBackgroundWorker = true;
+	proc->isRegularBackend = false;
 	proc->lwWaiting = LW_WS_NOT_WAITING;
 	proc->lwWaitMode = 0;
 	proc->waitLock = NULL;

src/backend/storage/ipc/procarray.c

@@ -3640,8 +3640,8 @@ CountDBConnections(Oid databaseid)
 
 		if (proc->pid == 0)
 			continue;			/* do not count prepared xacts */
-		if (proc->isBackgroundWorker)
-			continue;			/* do not count background workers */
+		if (!proc->isRegularBackend)
+			continue;			/* count only regular backend processes */
 		if (!OidIsValid(databaseid) ||
 			proc->databaseId == databaseid)
 			count++;
@@ -3712,8 +3712,8 @@ CountUserBackends(Oid roleid)
 
 		if (proc->pid == 0)
 			continue;			/* do not count prepared xacts */
-		if (proc->isBackgroundWorker)
-			continue;			/* do not count background workers */
+		if (!proc->isRegularBackend)
+			continue;			/* count only regular backend processes */
 		if (proc->roleId == roleid)
 			count++;
 	}

src/backend/storage/lmgr/proc.c

@@ -432,7 +432,7 @@ InitProcess(void)
 	MyProc->databaseId = InvalidOid;
 	MyProc->roleId = InvalidOid;
 	MyProc->tempNamespaceId = InvalidOid;
-	MyProc->isBackgroundWorker = !AmRegularBackendProcess();
+	MyProc->isRegularBackend = AmRegularBackendProcess();
 	MyProc->delayChkptFlags = 0;
 	MyProc->statusFlags = 0;
 	/* NB -- autovac launcher intentionally does not set IS_AUTOVACUUM */
@@ -631,7 +631,7 @@ InitAuxiliaryProcess(void)
 	MyProc->databaseId = InvalidOid;
 	MyProc->roleId = InvalidOid;
 	MyProc->tempNamespaceId = InvalidOid;
-	MyProc->isBackgroundWorker = true;
+	MyProc->isRegularBackend = false;
 	MyProc->delayChkptFlags = 0;
 	MyProc->statusFlags = 0;
 	MyProc->lwWaiting = LW_WS_NOT_WAITING;

src/include/storage/proc.h

@@ -149,7 +149,7 @@ typedef enum
  * but its myProcLocks[] lists are valid.
  *
  * We allow many fields of this struct to be accessed without locks, such as
- * delayChkptFlags and isBackgroundWorker. However, keep in mind that writing
+ * delayChkptFlags and isRegularBackend. However, keep in mind that writing
  * mirrored ones (see below) requires holding ProcArrayLock or XidGenLock in
  * at least shared mode, so that pgxactoff does not change concurrently.
  *
@@ -216,7 +216,7 @@ struct PGPROC
 	Oid			tempNamespaceId;	/* OID of temp schema this backend is
 									 * using */
 
-	bool		isBackgroundWorker; /* true if not a regular backend. */
+	bool		isRegularBackend;	/* true if it's a regular backend. */
 
 	/*
 	 * While in hot standby mode, shows that a conflict signal has been sent