From: Thomas Munro <thomas.munro@gmail.com>
Date: Wed, 17 Jul 2019 02:15:27 +0000 (+1200)
Subject: Prepare to support multiple SMGR implementations.
X-Git-Url: http://git.postgresql.org/gitweb/static/developers.postgresql.org?a=commitdiff_plain;h=e3f1fb93eb7a8c5fad276c7dd6d82087135ae015;p=users%2Frhaas%2Fpostgres.git

Prepare to support multiple SMGR implementations.

Move the "which" decision into a function that later patches can add
to.

Author: Thomas Munro
---

diff --git a/src/backend/storage/smgr/smgr.c b/src/backend/storage/smgr/smgr.c
index b0d9f21e68..d00b275e46 100644
--- a/src/backend/storage/smgr/smgr.c
+++ b/src/backend/storage/smgr/smgr.c
@@ -97,6 +97,18 @@ static dlist_head unowned_relns;
 /* local function prototypes */
 static void smgrshutdown(int code, Datum arg);
 
+/*
+ * Which implementation should handle a given RelFileNode?
+ */
+static int
+smgrwhich(RelFileNode rnode)
+{
+	switch (rnode.dbNode)
+	{
+		default:
+			return 0;			/* md.c */
+	}
+}
 
 /*
  *	smgrinit(), smgrshutdown() -- Initialize or shut down storage
@@ -176,7 +188,7 @@ smgropen(RelFileNode rnode, BackendId backend)
 		reln->smgr_targblock = InvalidBlockNumber;
 		reln->smgr_fsm_nblocks = InvalidBlockNumber;
 		reln->smgr_vm_nblocks = InvalidBlockNumber;
-		reln->smgr_which = 0;	/* we only have md.c at present */
+		reln->smgr_which = smgrwhich(rnode);
 
 		/* implementation-specific initialization */
 		smgrsw[reln->smgr_which].smgr_open(reln);