disk_quota_hooks_v4.patch

From 580ef70f73523d6ef654bf04296acb93c1009531 Mon Sep 17 00:00:00 2001
From: Hubert Zhang <hubertzhang@apache.org>
Date: Mon, 15 Jul 2019 11:34:24 +0800
Subject: [PATCH] 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 | 22 ++++++++++++++++++++++
 src/include/storage/smgr.h      | 19 +++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c
index dba8c397fe..5a1f7a3007 100644
--- a/src/backend/storage/smgr/smgr.c
+++ b/src/backend/storage/smgr/smgr.c
@@ -96,6 +96,16 @@ static dlist_head unowned_relns;
 /* local function prototypes */
 static void smgrshutdown(int code, Datum arg);
 
+/*
+ * 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
@@ -344,6 +354,9 @@ smgrcreate(SMgrRelation reln, ForkNumber forknum, bool isRedo)
 	if (isRedo && reln->md_num_open_segs[forknum] > 0)
 		return;
 
+	if (smgrcreate_hook)
+		(*smgrcreate_hook)(reln, forknum, isRedo);
+
 	/*
 	 * We may be using the target table space for the first time in this
 	 * database, so create a per-database subdirectory if needed.
@@ -439,6 +452,9 @@ smgrdounlinkall(SMgrRelation *rels, int nrels, bool isRedo)
 	if (nrels == 0)
 		return;
 
+	if (smgrdounlinkall_hook)
+		(*smgrdounlinkall_hook)(rels, nrels, isRedo);
+
 	/*
 	 * create an array which contains all relations to be dropped, and close
 	 * each relation's forks at the smgr level while at it
@@ -562,6 +578,9 @@ void
 smgrextend(SMgrRelation reln, ForkNumber forknum, BlockNumber blocknum,
 		   char *buffer, bool skipFsync)
 {
+	if (smgrextend_hook)
+		(*smgrextend_hook)(reln, forknum, blocknum, buffer, skipFsync);
+
 	smgrsw[reln->smgr_which].smgr_extend(reln, forknum, blocknum,
 										 buffer, skipFsync);
 }
@@ -645,6 +664,9 @@ smgrnblocks(SMgrRelation reln, ForkNumber forknum)
 void
 smgrtruncate(SMgrRelation reln, ForkNumber forknum, BlockNumber nblocks)
 {
+	if (smgrtruncate_hook)
+		(*smgrtruncate_hook)(reln, forknum, 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 d286c8c7b1..e473162a8b 100644
--- a/src/include/storage/smgr.h
+++ b/src/include/storage/smgr.h
@@ -107,4 +107,23 @@ extern void smgrtruncate(SMgrRelation reln, ForkNumber forknum,
 extern void smgrimmedsync(SMgrRelation reln, ForkNumber forknum);
 extern void AtEOXact_SMgr(void);
 
+/*
+ * 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,
+									 char *buffer, bool skipFsync);
+extern PGDLLIMPORT smgrextend_hook_type smgrextend_hook;
+typedef void (*smgrtruncate_hook_type)(SMgrRelation reln, ForkNumber forknum,
+									   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 */
-- 
2.11.0 (Apple Git-81)