From: Thomas Munro <tmunro@postgresql.org>
Date: Sat, 12 Jul 2025 01:47:59 +0000 (+1200)
Subject: aio: Remove obsolete IO worker ID references.
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b4c19da93a08f767f88de9696af0de3b1715d40e;p=thirdparty%2Fpostgresql.git

aio: Remove obsolete IO worker ID references.

In an ancient ancestor of this code, the postmaster assigned IDs to IO
workers.  Now it tracks them in an unordered array and doesn't know
their IDs, so it might be confusing to readers that it still referred to
their indexes as IDs.

No change in behavior, just variable name and error message cleanup.

Back-patch to 18.

Discussion: https://postgr.es/m/CA%2BhUKG%2BwbaZZ9Nwc_bTopm4f-7vDmCwLk80uKDHj9mq%2BUp0E%2Bg%40mail.gmail.com
---

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 490f7ce3664..cca9b946e53 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -4337,15 +4337,15 @@ maybe_start_bgworkers(void)
 static bool
 maybe_reap_io_worker(int pid)
 {
-	for (int id = 0; id < MAX_IO_WORKERS; ++id)
+	for (int i = 0; i < MAX_IO_WORKERS; ++i)
 	{
-		if (io_worker_children[id] &&
-			io_worker_children[id]->pid == pid)
+		if (io_worker_children[i] &&
+			io_worker_children[i]->pid == pid)
 		{
-			ReleasePostmasterChildSlot(io_worker_children[id]);
+			ReleasePostmasterChildSlot(io_worker_children[i]);
 
 			--io_worker_count;
-			io_worker_children[id] = NULL;
+			io_worker_children[i] = NULL;
 			return true;
 		}
 	}
@@ -4389,22 +4389,22 @@ maybe_adjust_io_workers(void)
 	while (io_worker_count < io_workers)
 	{
 		PMChild    *child;
-		int			id;
+		int			i;
 
 		/* find unused entry in io_worker_children array */
-		for (id = 0; id < MAX_IO_WORKERS; ++id)
+		for (i = 0; i < MAX_IO_WORKERS; ++i)
 		{
-			if (io_worker_children[id] == NULL)
+			if (io_worker_children[i] == NULL)
 				break;
 		}
-		if (id == MAX_IO_WORKERS)
-			elog(ERROR, "could not find a free IO worker ID");
+		if (i == MAX_IO_WORKERS)
+			elog(ERROR, "could not find a free IO worker slot");
 
 		/* Try to launch one. */
 		child = StartChildProcess(B_IO_WORKER);
 		if (child != NULL)
 		{
-			io_worker_children[id] = child;
+			io_worker_children[i] = child;
 			++io_worker_count;
 		}
 		else
@@ -4415,11 +4415,11 @@ maybe_adjust_io_workers(void)
 	if (io_worker_count > io_workers)
 	{
 		/* ask the IO worker in the highest slot to exit */
-		for (int id = MAX_IO_WORKERS - 1; id >= 0; --id)
+		for (int i = MAX_IO_WORKERS - 1; i >= 0; --i)
 		{
-			if (io_worker_children[id] != NULL)
+			if (io_worker_children[i] != NULL)
 			{
-				kill(io_worker_children[id]->pid, SIGUSR2);
+				kill(io_worker_children[i]->pid, SIGUSR2);
 				break;
 			}
 		}