From: Andrey Borodin <amborodin@acm.org>=0A=
Date: Mon, 28 Aug 2017 10:21:53 +0500=0A=
Subject: [PATCH] hooks to watch for changed pages=0A=
=0A=
---=0A=
 src/backend/access/transam/xlog.c       | 11 +++++++++++=0A=
 src/backend/access/transam/xloginsert.c |  7 +++++++=0A=
 src/include/access/xloginsert.h         |  6 ++++++=0A=
 3 files changed, 24 insertions(+)=0A=
=0A=
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam=
/xlog.c=0A=
index df4843f409..ffbd87e94e 100644=0A=
--- a/src/backend/access/transam/xlog.c=0A=
+++ b/src/backend/access/transam/xlog.c=0A=
@@ -7024,6 +7024,7 @@ StartupXLOG(void)=0A=
 			do=0A=
 			{=0A=
 				bool		switchedTLI =3D false;=0A=
+				int nblock;=0A=
=20=0A=
 #ifdef WAL_DEBUG=0A=
 				if (XLOG_DEBUG ||=0A=
@@ -7186,6 +7187,16 @@ StartupXLOG(void)=0A=
 				/* Pop the error context stack */=0A=
 				error_context_stack =3D errcallback.previous;=0A=
=20=0A=
+				if (xlog_insert_buffer_hook)=0A=
+					for(nblock =3D 0; nblock < xlogreader->max_block_id; nblock++)=0A=
+					{=0A=
+						if(xlogreader->blocks[nblock].forknum =3D=3D MAIN_FORKNUM)=0A=
+						{=0A=
+							xlog_insert_buffer_hook(xlogreader->blocks[nblock].blkno,=0A=
+											xlogreader->blocks[nblock].rnode, true);=0A=
+						}=0A=
+					}=0A=
+=0A=
 				/*=0A=
 				 * Update lastReplayedEndRecPtr after this record has been=0A=
 				 * successfully replayed.=0A=
diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/t=
ransam/xloginsert.c=0A=
index 3af03ecdb1..26dd72c21e 100644=0A=
--- a/src/backend/access/transam/xloginsert.c=0A=
+++ b/src/backend/access/transam/xloginsert.c=0A=
@@ -205,6 +205,9 @@ XLogResetInsertion(void)=0A=
 	begininsert_called =3D false;=0A=
 }=0A=
=20=0A=
+/* Hook for plugins to get control in during page insertion into xlog */=
=0A=
+PGDLLIMPORT xlog_insert_buffer_hook_type xlog_insert_buffer_hook =3D NULL;=
=0A=
+=0A=
 /*=0A=
  * Register a reference to a buffer with the WAL record being constructed.=
=0A=
  * This must be called for every page that the WAL-logged operation modifi=
es.=0A=
@@ -256,6 +259,10 @@ XLogRegisterBuffer(uint8 block_id, Buffer buffer, uint=
8 flags)=0A=
 #endif=0A=
=20=0A=
 	regbuf->in_use =3D true;=0A=
+	if (xlog_insert_buffer_hook && regbuf->forkno =3D=3D MAIN_FORKNUM)=0A=
+	{=0A=
+		xlog_insert_buffer_hook(regbuf->block, regbuf->rnode, false);=0A=
+	}=0A=
 }=0A=
=20=0A=
 /*=0A=
diff --git a/src/include/access/xloginsert.h b/src/include/access/xloginser=
t.h=0A=
index 174c88677f..c367669fa5 100644=0A=
--- a/src/include/access/xloginsert.h=0A=
+++ b/src/include/access/xloginsert.h=0A=
@@ -58,4 +58,10 @@ extern XLogRecPtr XLogSaveBufferForHint(Buffer buffer, b=
ool buffer_std);=0A=
=20=0A=
 extern void InitXLogInsert(void);=0A=
=20=0A=
+/* Hook for plugins to get control in during page insertion into xlog */=
=0A=
+typedef void (*xlog_insert_buffer_hook_type) (BlockNumber block_number, Re=
lFileNode rel, bool recovery);=0A=
+=0A=
+/* in xloginsert.c */=0A=
+extern PGDLLIMPORT xlog_insert_buffer_hook_type xlog_insert_buffer_hook;=
=0A=
+=0A=
 #endif							/* XLOGINSERT_H */=0A=
--=20=0A=
2.11.0 (Apple Git-81)=0A=
=0A=

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