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Subject: [PATCH v2 4/9] use Buffer instead of buffer ID for startup's buffer pin wait
Date: Wed, 22 Jul 2026 11:32:05 -0400
---
src/backend/storage/buffer/bufmgr.c | 16 ++++++++--------
src/backend/storage/lmgr/proc.c | 20 ++++++++++----------
src/include/storage/proc.h | 9 +++++----
3 files changed, 23 insertions(+), 22 deletions(-)
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 3908529872a..a85547fa492 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -6806,12 +6806,12 @@ LockBufferForCleanup(Buffer buffer)
if (log_recovery_conflict_waits && waitStart == 0)
waitStart = GetCurrentTimestamp();
- /* Publish the bufid that Startup process waits on */
- SetStartupBufferPinWaitBufId(buffer - 1);
+ /* Publish the buffer that Startup process waits on */
+ SetStartupBufferPinWaitBuf(buffer);
/* Set alarm and then wait to be signaled by UnpinBuffer() */
ResolveRecoveryConflictWithBufferPin();
- /* Reset the published bufid */
- SetStartupBufferPinWaitBufId(-1);
+ /* Reset the published buffer */
+ SetStartupBufferPinWaitBuf(InvalidBuffer);
}
else
ProcWaitForSignal(WAIT_EVENT_BUFFER_CLEANUP);
@@ -6865,18 +6865,18 @@ cleanup_lock_acquired:
bool
HoldingBufferPinThatDelaysRecovery(void)
{
- int bufid = GetStartupBufferPinWaitBufId();
+ Buffer buffer = GetStartupBufferPinWaitBuf();
/*
* If we get woken slowly then it's possible that the Startup process was
* already woken by other backends before we got here. Also possible that
* we get here by multiple interrupts or interrupts at inappropriate
- * times, so make sure we do nothing if the bufid is not set.
+ * times, so make sure we do nothing if the buffer is not set.
*/
- if (bufid < 0)
+ if (buffer == InvalidBuffer)
return false;
- if (GetPrivateRefCount(bufid + 1) > 0)
+ if (GetPrivateRefCount(buffer) > 0)
return true;
return false;
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 9d6e69175a5..f973494abb1 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -239,7 +239,7 @@ ProcGlobalShmemInit(void *arg)
dlist_init(&ProcGlobal->autovacFreeProcs);
dlist_init(&ProcGlobal->bgworkerFreeProcs);
dlist_init(&ProcGlobal->walsenderFreeProcs);
- ProcGlobal->startupBufferPinWaitBufId = -1;
+ ProcGlobal->startupBufferPinWaitBuf = InvalidBuffer;
pg_atomic_init_u32(&ProcGlobal->avLauncherProc, INVALID_PROC_NUMBER);
pg_atomic_init_u32(&ProcGlobal->walwriterProc, INVALID_PROC_NUMBER);
pg_atomic_init_u32(&ProcGlobal->checkpointerProc, INVALID_PROC_NUMBER);
@@ -760,30 +760,30 @@ InitAuxiliaryProcess(void)
/*
* Used from bufmgr to share the value of the buffer that Startup waits on,
- * or to reset the value to "not waiting" (-1). This allows processing
- * of recovery conflicts for buffer pins. Set is made before backends look
- * at this value, so locking not required, especially since the set is
- * an atomic integer set operation.
+ * or to reset the value to "not waiting" (InvalidBuffer). This allows
+ * processing of recovery conflicts for buffer pins. Set is made before
+ * backends look at this value, so locking not required, especially since
+ * the set is an atomic integer set operation.
*/
void
-SetStartupBufferPinWaitBufId(int bufid)
+SetStartupBufferPinWaitBuf(Buffer buffer)
{
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
- procglobal->startupBufferPinWaitBufId = bufid;
+ procglobal->startupBufferPinWaitBuf = buffer;
}
/*
* Used by backends when they receive a request to check for buffer pin waits.
*/
-int
-GetStartupBufferPinWaitBufId(void)
+Buffer
+GetStartupBufferPinWaitBuf(void)
{
/* use volatile pointer to prevent code rearrangement */
volatile PROC_HDR *procglobal = ProcGlobal;
- return procglobal->startupBufferPinWaitBufId;
+ return procglobal->startupBufferPinWaitBuf;
}
/*
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 03a1a466fa8..4c3f431b4eb 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -17,6 +17,7 @@
#include "access/xlogdefs.h"
#include "lib/ilist.h"
#include "miscadmin.h"
+#include "storage/buf.h"
#include "storage/latch.h"
#include "storage/lock.h"
#include "storage/pg_sema.h"
@@ -498,8 +499,8 @@ typedef struct PROC_HDR
/* Current shared estimate of appropriate spins_per_delay value */
int spins_per_delay;
- /* Buffer id of the buffer that Startup process waits for pin on, or -1 */
- int startupBufferPinWaitBufId;
+ /* Buffer that Startup process waits for pin on, or InvalidBuffer */
+ Buffer startupBufferPinWaitBuf;
} PROC_HDR;
extern PGDLLIMPORT PROC_HDR *ProcGlobal;
@@ -558,8 +559,8 @@ extern void InitProcess(void);
extern void InitProcessPhase2(void);
extern void InitAuxiliaryProcess(void);
-extern void SetStartupBufferPinWaitBufId(int bufid);
-extern int GetStartupBufferPinWaitBufId(void);
+extern void SetStartupBufferPinWaitBuf(Buffer buffer);
+extern Buffer GetStartupBufferPinWaitBuf(void);
extern bool HaveNFreeProcs(int n, int *nfree);
extern void ProcReleaseLocks(bool isCommit);
--
2.50.1 (Apple Git-155)
--Xf36GNcW+0xZNily
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
filename=v2-0005-convert-PROC_HDR-startupBufferPinWaitBuf-to-an-at.patch
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Subject: Re: [PATCH v2 4/9] use Buffer instead of buffer ID for startup's buffer pin wait
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