Make FP_LOCK_SLOTS_PER_BACKEND look like a function

The FP_LOCK_SLOTS_PER_BACKEND macro looks like a constant, but it
depends on the max_locks_per_transaction GUC, and thus can change. This
is non-obvious and confusing, so make it look more like a function by
renaming it to FastPathLockSlotsPerBackend().

While at it, use the macro when initializing fast-path shared memory,
instead of using the formula.

Reported-by: Andres Freund
Discussion: https://postgr.es/m/ffiwtzc6vedo6wb4gbwelon5nefqg675t5c7an2ta7pcz646cg%40qwmkdb3l4ett

1 files changed, 2 insertions, 2 deletions

diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 49204f91a20..749a79d48ef 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -116,7 +116,7 @@ ProcGlobalShmemSize(void)
 	 * nicely aligned in each backend.
 	 */
 	fpLockBitsSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(uint64));
-	fpRelIdSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(Oid) * FP_LOCK_SLOTS_PER_GROUP);
+	fpRelIdSize = MAXALIGN(FastPathLockSlotsPerBackend() * sizeof(Oid));
 
 	size = add_size(size, mul_size(TotalProcs, (fpLockBitsSize + fpRelIdSize)));
 
@@ -231,7 +231,7 @@ InitProcGlobal(void)
 	 * shared memory and then divide that between backends.
 	 */
 	fpLockBitsSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(uint64));
-	fpRelIdSize = MAXALIGN(FastPathLockGroupsPerBackend * sizeof(Oid) * FP_LOCK_SLOTS_PER_GROUP);
+	fpRelIdSize = MAXALIGN(FastPathLockSlotsPerBackend() * sizeof(Oid));
 
 	fpPtr = ShmemAlloc(TotalProcs * (fpLockBitsSize + fpRelIdSize));
 	MemSet(fpPtr, 0, TotalProcs * (fpLockBitsSize + fpRelIdSize));