Split out list of XLog resource managers

The new rmgrlist.h header, containing all necessary data
about built-in resource managers, allows other pieces of code to
access them.

In particular, this allows a future pg_xlogdump program to extract
rm_desc function pointers, without having to keep a duplicate list of
them.

Author: alvherre

src/backend/access/transam/rmgr.c

@@ -24,23 +24,10 @@
 #include "storage/standby.h"
 #include "utils/relmapper.h"
 
+/* must be kept in sync with RmgrData definition in xlog_internal.h */
+#define PG_RMGR(symname,name,redo,desc,startup,cleanup,restartpoint) \
+	{ name, redo, desc, startup, cleanup, restartpoint },
 
 const RmgrData RmgrTable[RM_MAX_ID + 1] = {
-	{"XLOG", xlog_redo, xlog_desc, NULL, NULL, NULL},
-	{"Transaction", xact_redo, xact_desc, NULL, NULL, NULL},
-	{"Storage", smgr_redo, smgr_desc, NULL, NULL, NULL},
-	{"CLOG", clog_redo, clog_desc, NULL, NULL, NULL},
-	{"Database", dbase_redo, dbase_desc, NULL, NULL, NULL},
-	{"Tablespace", tblspc_redo, tblspc_desc, NULL, NULL, NULL},
-	{"MultiXact", multixact_redo, multixact_desc, NULL, NULL, NULL},
-	{"RelMap", relmap_redo, relmap_desc, NULL, NULL, NULL},
-	{"Standby", standby_redo, standby_desc, NULL, NULL, NULL},
-	{"Heap2", heap2_redo, heap2_desc, NULL, NULL, NULL},
-	{"Heap", heap_redo, heap_desc, NULL, NULL, NULL},
-	{"Btree", btree_redo, btree_desc, btree_xlog_startup, btree_xlog_cleanup, btree_safe_restartpoint},
-	{"Hash", hash_redo, hash_desc, NULL, NULL, NULL},
-	{"Gin", gin_redo, gin_desc, gin_xlog_startup, gin_xlog_cleanup, gin_safe_restartpoint},
-	{"Gist", gist_redo, gist_desc, gist_xlog_startup, gist_xlog_cleanup, NULL},
-	{"Sequence", seq_redo, seq_desc, NULL, NULL, NULL},
-	{"SPGist", spg_redo, spg_desc, spg_xlog_startup, spg_xlog_cleanup, NULL}
+#include "access/rmgrlist.h"
 };

src/include/access/rmgr.h

@@ -13,27 +13,23 @@ typedef uint8 RmgrId;
 /*
  * Built-in resource managers
  *
- * Note: RM_MAX_ID could be as much as 255 without breaking the XLOG file
- * format, but we keep it small to minimize the size of RmgrTable[].
+ * The actual numerical values for each rmgr ID are defined by the order
+ * of entries in rmgrlist.h.
+ *
+ * Note: RM_MAX_ID must fit in RmgrId; widening that type will affect the XLOG
+ * file format.
  */
-#define RM_XLOG_ID				0
-#define RM_XACT_ID				1
-#define RM_SMGR_ID				2
-#define RM_CLOG_ID				3
-#define RM_DBASE_ID				4
-#define RM_TBLSPC_ID			5
-#define RM_MULTIXACT_ID			6
-#define RM_RELMAP_ID			7
-#define RM_STANDBY_ID			8
-#define RM_HEAP2_ID				9
-#define RM_HEAP_ID				10
-#define RM_BTREE_ID				11
-#define RM_HASH_ID				12
-#define RM_GIN_ID				13
-#define RM_GIST_ID				14
-#define RM_SEQ_ID				15
-#define RM_SPGIST_ID			16
+#define PG_RMGR(symname,name,redo,desc,startup,cleanup,restartpoint) \
+	symname,
+
+typedef enum RmgrIds
+{
+#include "access/rmgrlist.h"
+	RM_NEXT_ID
+} RmgrIds;
+
+#undef PG_RMGR
 
-#define RM_MAX_ID				RM_SPGIST_ID
+#define RM_MAX_ID				(RM_NEXT_ID - 1)
 
 #endif   /* RMGR_H */

src/include/access/rmgrlist.h

@@ -0,0 +1,44 @@
+/*---------------------------------------------------------------------------
+ * rmgrlist.h
+ *
+ * The resource manager list is kept in its own source file for possible
+ * use by automatic tools.	The exact representation of a rmgr is determined
+ * by the PG_RMGR macro, which is not defined in this file; it can be
+ * defined by the caller for special purposes.
+ *
+ * Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/access/rmgrlist.h
+ *---------------------------------------------------------------------------
+ */
+
+/* there is deliberately not an #ifndef RMGRLIST_H here */
+
+/*
+ * List of resource manager entries.  Note that order of entries defines the
+ * numerical values of each rmgr's ID, which is stored in WAL records.  New
+ * entries should be added at the end, to avoid changing IDs of existing
+ * entries.
+ *
+ * Changes to this list possibly need a XLOG_PAGE_MAGIC bump.
+ */
+
+/* symbol name, textual name, redo, desc, startup, cleanup, restartpoint */
+PG_RMGR(RM_XLOG_ID, "XLOG", xlog_redo, xlog_desc, NULL, NULL, NULL)
+PG_RMGR(RM_XACT_ID, "Transaction", xact_redo, xact_desc, NULL, NULL, NULL)
+PG_RMGR(RM_SMGR_ID, "Storage", smgr_redo, smgr_desc, NULL, NULL, NULL)
+PG_RMGR(RM_CLOG_ID, "CLOG", clog_redo, clog_desc, NULL, NULL, NULL)
+PG_RMGR(RM_DBASE_ID, "Database", dbase_redo, dbase_desc, NULL, NULL, NULL)
+PG_RMGR(RM_TBLSPC_ID, "Tablespace", tblspc_redo, tblspc_desc, NULL, NULL, NULL)
+PG_RMGR(RM_MULTIXACT_ID, "MultiXact", multixact_redo, multixact_desc, NULL, NULL, NULL)
+PG_RMGR(RM_RELMAP_ID, "RelMap", relmap_redo, relmap_desc, NULL, NULL, NULL)
+PG_RMGR(RM_STANDBY_ID, "Standby", standby_redo, standby_desc, NULL, NULL, NULL)
+PG_RMGR(RM_HEAP2_ID, "Heap2", heap2_redo, heap2_desc, NULL, NULL, NULL)
+PG_RMGR(RM_HEAP_ID, "Heap", heap_redo, heap_desc, NULL, NULL, NULL)
+PG_RMGR(RM_BTREE_ID, "Btree", btree_redo, btree_desc, btree_xlog_startup, btree_xlog_cleanup, btree_safe_restartpoint)
+PG_RMGR(RM_HASH_ID, "Hash", hash_redo, hash_desc, NULL, NULL, NULL)
+PG_RMGR(RM_GIN_ID, "Gin", gin_redo, gin_desc, gin_xlog_startup, gin_xlog_cleanup, gin_safe_restartpoint)
+PG_RMGR(RM_GIST_ID, "Gist", gist_redo, gist_desc, gist_xlog_startup, gist_xlog_cleanup, NULL)
+PG_RMGR(RM_SEQ_ID, "Sequence", seq_redo, seq_desc, NULL, NULL, NULL)
+PG_RMGR(RM_SPGIST_ID, "SPGist", spg_redo, spg_desc, spg_xlog_startup, spg_xlog_cleanup, NULL)

src/include/access/xlog_internal.h

@@ -233,7 +233,10 @@ struct XLogRecord;
 /*
  * Method table for resource managers.
  *
- * RmgrTable[] is indexed by RmgrId values (see rmgr.h).
+ * This struct must be kept in sync with the PG_RMGR definition in
+ * rmgr.c.
+ *
+ * RmgrTable[] is indexed by RmgrId values (see rmgrlist.h).
  */
 typedef struct RmgrData
 {