Split the shared-memory array of PGPROC pointers out of the sinval

communication structure, and make it its own module with its own lock.
This should reduce contention at least a little, and it definitely makes
the code seem cleaner.  Per my recent proposal.

src/include/storage/sinvaladt.h

@@ -7,16 +7,16 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/storage/sinvaladt.h,v 1.37 2004/12/31 22:03:42 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/storage/sinvaladt.h,v 1.38 2005/05/19 21:35:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 #ifndef SINVALADT_H
 #define SINVALADT_H
 
-#include "storage/shmem.h"
 #include "storage/sinval.h"
 
+
 /*
  * The shared cache invalidation manager is responsible for transmitting
  * invalidation messages between backends.	Any message sent by any backend
@@ -71,7 +71,6 @@ typedef struct ProcState
 	/* nextMsgNum is -1 in an inactive ProcState array entry. */
 	int			nextMsgNum;		/* next message number to read, or -1 */
 	bool		resetState;		/* true, if backend has to reset its state */
-	SHMEM_OFFSET procStruct;	/* location of backend's PGPROC struct */
 } ProcState;
 
 /* Shared cache invalidation memory segment */