From 7fc0e7de9fb8306e84d1c15211aba4308f694455 Mon Sep 17 00:00:00 2001
From: Robert Haas
Date: Tue, 12 Apr 2022 14:45:23 -0400
Subject: Revert the addition of GetMaxBackends() and related stuff.

This reverts commits 0147fc7, 4567596, aa64f23, and 5ecd018.
There is no longer agreement that introducing this function
was the right way to address the problem. The consensus now
seems to favor trying to make a correct value for MaxBackends
available to mdules executing their _PG_init() functions.

Nathan Bossart

Discussion: http://postgr.es/m/20220323045229.i23skfscdbvrsuxa@jrouhaud
---
 src/backend/commands/async.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

(limited to 'src/backend/commands/async.c')

diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c
index 455d895a44a..3e1b92df030 100644
--- a/src/backend/commands/async.c
+++ b/src/backend/commands/async.c
@@ -518,7 +518,7 @@ AsyncShmemSize(void)
 	Size		size;
 
 	/* This had better match AsyncShmemInit */
-	size = mul_size(GetMaxBackends() + 1, sizeof(QueueBackendStatus));
+	size = mul_size(MaxBackends + 1, sizeof(QueueBackendStatus));
 	size = add_size(size, offsetof(AsyncQueueControl, backend));
 
 	size = add_size(size, SimpleLruShmemSize(NUM_NOTIFY_BUFFERS, 0));
@@ -534,7 +534,6 @@ AsyncShmemInit(void)
 {
 	bool		found;
 	Size		size;
-	int			max_backends = GetMaxBackends();
 
 	/*
 	 * Create or attach to the AsyncQueueControl structure.
@@ -542,7 +541,7 @@ AsyncShmemInit(void)
 	 * The used entries in the backend[] array run from 1 to MaxBackends; the
 	 * zero'th entry is unused but must be allocated.
 	 */
-	size = mul_size(max_backends + 1, sizeof(QueueBackendStatus));
+	size = mul_size(MaxBackends + 1, sizeof(QueueBackendStatus));
 	size = add_size(size, offsetof(AsyncQueueControl, backend));
 
 	asyncQueueControl = (AsyncQueueControl *)
@@ -557,7 +556,7 @@ AsyncShmemInit(void)
 		QUEUE_FIRST_LISTENER = InvalidBackendId;
 		asyncQueueControl->lastQueueFillWarn = 0;
 		/* zero'th entry won't be used, but let's initialize it anyway */
-		for (int i = 0; i <= max_backends; i++)
+		for (int i = 0; i <= MaxBackends; i++)
 		{
 			QUEUE_BACKEND_PID(i) = InvalidPid;
 			QUEUE_BACKEND_DBOID(i) = InvalidOid;
@@ -1633,7 +1632,6 @@ SignalBackends(void)
 	int32	   *pids;
 	BackendId  *ids;
 	int			count;
-	int			max_backends = GetMaxBackends();
 
 	/*
 	 * Identify backends that we need to signal.  We don't want to send
@@ -1643,8 +1641,8 @@ SignalBackends(void)
 	 * XXX in principle these pallocs could fail, which would be bad. Maybe
 	 * preallocate the arrays?  They're not that large, though.
 	 */
-	pids = (int32 *) palloc(max_backends * sizeof(int32));
-	ids = (BackendId *) palloc(max_backends * sizeof(BackendId));
+	pids = (int32 *) palloc(MaxBackends * sizeof(int32));
+	ids = (BackendId *) palloc(MaxBackends * sizeof(BackendId));
 	count = 0;
 
 	LWLockAcquire(NotifyQueueLock, LW_EXCLUSIVE);
-- 
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