Rename StartBackgroundWorker() to BackgroundWorkerMain().

The comment claimed that it is "called from postmaster", but it is
actually called in the child process, pretty early in the process
initialization. I guess you could interpret "called from postmaster"
to mean that, but it seems wrong to me. Rename the function to be
consistent with other functions with similar role.

Reviewed-by: Thomas Munro
Discussion: https://www.postgresql.org/message-id/4f95c1fc-ad3c-7974-3a8c-6faa3931804c@iki.fi

src/backend/postmaster/bgworker.c

@@ -741,13 +741,10 @@ bgworker_die(SIGNAL_ARGS)
 }
 
 /*
- * Start a new background worker
- *
- * This is the main entry point for background worker, to be called from
- * postmaster.
+ * Main entry point for background worker processes.
  */
 void
-StartBackgroundWorker(void)
+BackgroundWorkerMain(void)
 {
 	sigjmp_buf	local_sigjmp_buf;
 	BackgroundWorker *worker = MyBgworkerEntry;

src/backend/postmaster/postmaster.c

@@ -4982,7 +4982,7 @@ SubPostmasterMain(int argc, char *argv[])
 		shmem_slot = atoi(argv[1] + 15);
 		MyBgworkerEntry = BackgroundWorkerEntry(shmem_slot);
 
-		StartBackgroundWorker();
+		BackgroundWorkerMain();
 	}
 	if (strcmp(argv[1], "--forklog") == 0)
 	{
@@ -5721,7 +5721,7 @@ do_start_bgworker(RegisteredBgWorker *rw)
 			MemoryContextDelete(PostmasterContext);
 			PostmasterContext = NULL;
 
-			StartBackgroundWorker();
+			BackgroundWorkerMain();
 
 			exit(1);			/* should not get here */
 			break;

src/include/postmaster/bgworker_internals.h

@@ -54,8 +54,8 @@ extern void BackgroundWorkerStopNotifications(pid_t pid);
 extern void ForgetUnstartedBackgroundWorkers(void);
 extern void ResetBackgroundWorkerCrashTimes(void);
 
-/* Function to start a background worker, called from postmaster.c */
-extern void StartBackgroundWorker(void) pg_attribute_noreturn();
+/* Entry point for background worker processes */
+extern void BackgroundWorkerMain(void) pg_attribute_noreturn();
 
 #ifdef EXEC_BACKEND
 extern BackgroundWorker *BackgroundWorkerEntry(int slotno);