From 977cea9451e602d8d3d5e4f0cf3cd7dfea11879e Mon Sep 17 00:00:00 2001
From: Nazir Bilal Yavuz <byavuz81@gmail.com>
Date: Sun, 7 Apr 2024 22:33:36 +0300
Subject: [PATCH v2 1/3] Refactor PinBufferForBlock() to remove if checks about
 persistence

There are if checks in PinBufferForBlock() function to set persistence
of the relation and this function is called for the each block in the
relation. Instead of that, set persistence of the relation before
PinBufferForBlock() function.
---
 src/include/storage/bufmgr.h          |  4 ++--
 src/backend/storage/aio/read_stream.c |  2 +-
 src/backend/storage/buffer/bufmgr.c   | 32 +++++++++++++--------------
 3 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h
index a1e71013d32..ba9a1a289a9 100644
--- a/src/include/storage/bufmgr.h
+++ b/src/include/storage/bufmgr.h
@@ -116,12 +116,12 @@ struct ReadBuffersOperation
 {
 	/*
 	 * The following members should be set by the caller.  If only smgr is
-	 * provided without rel, then smgr_persistence can be set to override the
+	 * provided without rel, then persistence can be set to override the
 	 * default assumption of RELPERSISTENCE_PERMANENT.
 	 */
 	Relation	rel;
 	struct SMgrRelationData *smgr;
-	char		smgr_persistence;
+	char		persistence;
 	ForkNumber	forknum;
 	BufferAccessStrategy strategy;
 
diff --git a/src/backend/storage/aio/read_stream.c b/src/backend/storage/aio/read_stream.c
index 74b9bae6313..58221649f27 100644
--- a/src/backend/storage/aio/read_stream.c
+++ b/src/backend/storage/aio/read_stream.c
@@ -551,7 +551,7 @@ read_stream_begin_relation(int flags,
 	{
 		stream->ios[i].op.rel = rel;
 		stream->ios[i].op.smgr = RelationGetSmgr(rel);
-		stream->ios[i].op.smgr_persistence = 0;
+		stream->ios[i].op.persistence = rel->rd_rel->relpersistence;
 		stream->ios[i].op.forknum = forknum;
 		stream->ios[i].op.strategy = strategy;
 	}
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 61816730955..7cbcdc63a6f 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -1104,7 +1104,7 @@ ZeroAndLockBuffer(Buffer buffer, ReadBufferMode mode, bool already_valid)
 static pg_attribute_always_inline Buffer
 PinBufferForBlock(Relation rel,
 				  SMgrRelation smgr,
-				  char smgr_persistence,
+				  char persistence,
 				  ForkNumber forkNum,
 				  BlockNumber blockNum,
 				  BufferAccessStrategy strategy,
@@ -1113,22 +1113,12 @@ PinBufferForBlock(Relation rel,
 	BufferDesc *bufHdr;
 	IOContext	io_context;
 	IOObject	io_object;
-	char		persistence;
 
 	Assert(blockNum != P_NEW);
 
-	/*
-	 * If there is no Relation it usually implies recovery and thus permanent,
-	 * but we take an argument because CreateAndCopyRelationData can reach us
-	 * with only an SMgrRelation for an unlogged relation that we don't want
-	 * to flag with BM_PERMANENT.
-	 */
-	if (rel)
-		persistence = rel->rd_rel->relpersistence;
-	else if (smgr_persistence == 0)
-		persistence = RELPERSISTENCE_PERMANENT;
-	else
-		persistence = smgr_persistence;
+	Assert((persistence == RELPERSISTENCE_TEMP ||
+			persistence == RELPERSISTENCE_PERMANENT ||
+			persistence == RELPERSISTENCE_UNLOGGED));
 
 	if (persistence == RELPERSISTENCE_TEMP)
 	{
@@ -1203,6 +1193,7 @@ ReadBuffer_common(Relation rel, SMgrRelation smgr, char smgr_persistence,
 	ReadBuffersOperation operation;
 	Buffer		buffer;
 	int			flags;
+	char		persistence;
 
 	/*
 	 * Backward compatibility path, most code should use ExtendBufferedRel()
@@ -1224,12 +1215,19 @@ ReadBuffer_common(Relation rel, SMgrRelation smgr, char smgr_persistence,
 		return ExtendBufferedRel(BMR_REL(rel), forkNum, strategy, flags);
 	}
 
+	if (rel)
+		persistence = rel->rd_rel->relpersistence;
+	else if (smgr_persistence == 0)
+		persistence = RELPERSISTENCE_PERMANENT;
+	else
+		persistence = smgr_persistence;
+
 	if (unlikely(mode == RBM_ZERO_AND_CLEANUP_LOCK ||
 				 mode == RBM_ZERO_AND_LOCK))
 	{
 		bool		found;
 
-		buffer = PinBufferForBlock(rel, smgr, smgr_persistence,
+		buffer = PinBufferForBlock(rel, smgr, persistence,
 								   forkNum, blockNum, strategy, &found);
 		ZeroAndLockBuffer(buffer, mode, found);
 		return buffer;
@@ -1241,7 +1239,7 @@ ReadBuffer_common(Relation rel, SMgrRelation smgr, char smgr_persistence,
 		flags = 0;
 	operation.smgr = smgr;
 	operation.rel = rel;
-	operation.smgr_persistence = smgr_persistence;
+	operation.persistence = persistence;
 	operation.forknum = forkNum;
 	operation.strategy = strategy;
 	if (StartReadBuffer(&operation,
@@ -1272,7 +1270,7 @@ StartReadBuffersImpl(ReadBuffersOperation *operation,
 
 		buffers[i] = PinBufferForBlock(operation->rel,
 									   operation->smgr,
-									   operation->smgr_persistence,
+									   operation->persistence,
 									   operation->forknum,
 									   blockNum + i,
 									   operation->strategy,
-- 
2.45.2