v8-0001-Add-smgr-hooks-to-extend-the-logic-of-storage-man.patch

From 6479e1ccc92c53468dc879d33fa1a93f66ae4521 Mon Sep 17 00:00:00 2001
From: Hubert Zhang <hubertzhang@apache.org>
Date: Mon, 26 Feb 2024 19:24:43 +0800
Subject: [PATCH v8] Add smgr hooks to extend the logic of storage management

One example is that these hooks could be used by diskquota extension
to detect heap table change(create/extend/truncate/unlink).

Co-authored-by: Haozhou Wang <hawang@pivotal.io>
Co-authored-by: Hubert Zhang <hzhang@pivotal.io>
Co-authored-by: Hao Wu <gfphoenix78@gmail.com>
---
 src/backend/storage/smgr/smgr.c | 21 +++++++++++++++++++++
 src/include/storage/smgr.h      | 16 ++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c
index f7f7fe30b6..7992da84ce 100644
--- a/src/backend/storage/smgr/smgr.c
+++ b/src/backend/storage/smgr/smgr.c
@@ -142,6 +142,15 @@ static dlist_head unpinned_relns;
 static void smgrshutdown(int code, Datum arg);
 static void smgrdestroy(SMgrRelation reln);
 
+/*
+ * Hook for plugins to extend smgr functions.
+ * for example, collect statistics from smgr functions
+ * via recording the active relfilenode information.
+ */
+smgrcreate_hook_type smgrcreate_hook = NULL;
+smgrextend_hook_type smgrextend_hook = NULL;
+smgrtruncate_hook_type smgrtruncate_hook = NULL;
+smgrdounlinkall_hook_type smgrdounlinkall_hook = NULL;
 
 /*
  * smgrinit(), smgrshutdown() -- Initialize or shut down storage
@@ -413,6 +422,9 @@ smgrexists(SMgrRelation reln, ForkNumber forknum)
 void
 smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo)
 {
+	if (smgrcreate_hook)
+		(*smgrcreate_hook)(reln, forknum, isRedo);
+
 	smgrsw[reln->smgr_which].smgr_create(reln, forknum, isRedo);
 }
 
@@ -471,6 +483,9 @@ smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo)
 	if (nrels == 0)
 		return;
 
+	if (smgrdounlinkall_hook)
+		(*smgrdounlinkall_hook)(rels, nrels, isRedo);
+
 	/*
 	 * Get rid of any remaining buffers for the relations.  bufmgr will just
 	 * drop them without bothering to write the contents.
@@ -538,6 +553,9 @@ void
 smgrextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
 		   const void *buffer, bool skipFsync)
 {
+	if (smgrextend_hook)
+		(*smgrextend_hook)(reln, forknum, blocknum, buffer, skipFsync);
+
 	smgrsw[reln->smgr_which].smgr_extend(reln, forknum, blocknum,
 										 buffer, skipFsync);
 
@@ -706,6 +724,9 @@ smgrtruncate(SMgrRelation reln, ForkNumber *forknum, int nforks, BlockNumber *nb
 {
 	int			i;
 
+	if (smgrtruncate_hook)
+		(*smgrtruncate_hook)(reln, forknum, nforks, nblocks);
+
 	/*
 	 * Get rid of any buffers for the about-to-be-deleted blocks. bufmgr will
 	 * just drop them without bothering to write the contents.
diff --git a/src/include/storage/smgr.h b/src/include/storage/smgr.h
index 2b57addbdb..0ac1ed8f93 100644
--- a/src/include/storage/smgr.h
+++ b/src/include/storage/smgr.h
@@ -124,4 +124,20 @@ smgrwrite(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
 	smgrwritev(reln, forknum, blocknum, &buffer, 1, skipFsync);
 }
 
+/*
+ * Hook for plugins to extend smgr functions.
+ * for example, collect statistics from smgr functions
+ * via recording the active relfilenode information.
+ */
+typedef void (*smgrcreate_hook_type)(SMgrRelation reln, ForkNumber forknum, bool isRedo);
+extern PGDLLIMPORT smgrcreate_hook_type smgrcreate_hook;
+typedef void (*smgrextend_hook_type)(SMgrRelation reln, ForkNumber forknum,
+									 BlockNumber blocknum, const void *buffer, bool skipFsync);
+extern PGDLLIMPORT smgrextend_hook_type smgrextend_hook;
+typedef void (*smgrtruncate_hook_type)(SMgrRelation reln, ForkNumber *forknum,
+									   int nforks, BlockNumber *nblocks);
+extern PGDLLIMPORT smgrtruncate_hook_type smgrtruncate_hook;
+typedef void (*smgrdounlinkall_hook_type)(SMgrRelation *rels, int nrels, bool isRedo);
+extern PGDLLIMPORT smgrdounlinkall_hook_type smgrdounlinkall_hook;
+
 #endif							/* SMGR_H */
-- 
2.43.2