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Remove the last vestiges of the MAKE_PTR/MAKE_OFFSET mechanism. We haven't

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allowed different processes to have different addresses for the shmem segment
in quite a long time, but there were still a few places left that used the
old coding convention.  Clean them up to reduce confusion and improve the
compiler's ability to detect pointer type mismatches.

Kris Jurka
This commit is contained in:
Tom Lane
2008-11-02 21:24:52 +00:00
parent 902d1cb35f
commit d7112cfa88
10 changed files with 153 additions and 268 deletions
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56
src/include/storage/shmem.h
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@@ -3,11 +3,18 @@
* shmem.h
* shared memory management structures
*
* Historical note:
* A long time ago, Postgres' shared memory region was allowed to be mapped
* at a different address in each process, and shared memory "pointers" were
* passed around as offsets relative to the start of the shared memory region.
* That is no longer the case: each process must map the shared memory region
* at the same address. This means shared memory pointers can be passed
* around directly between different processes.
*
* Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/include/storage/shmem.h,v 1.53 2008/01/01 19:45:59 momjian Exp $
* $PostgreSQL: pgsql/src/include/storage/shmem.h,v 1.54 2008/11/02 21:24:52 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -17,53 +24,18 @@
#include "utils/hsearch.h"
/*
* The shared memory region can start at a different address
* in every process. Shared memory "pointers" are actually
* offsets relative to the start of the shared memory region(s).
*
* In current usage, this is not actually a problem, but we keep
* the code that used to handle it...
*/
typedef unsigned long SHMEM_OFFSET;
#define INVALID_OFFSET (-1)
/*
* Start of the primary shared memory region, in this process' address space.
* The macros in this header file can only cope with offsets into this
* shared memory region!
*/
extern PGDLLIMPORT SHMEM_OFFSET ShmemBase;
/* coerce an offset into a pointer in this process's address space */
#define MAKE_PTR(xx_offs)\
(ShmemBase+((unsigned long)(xx_offs)))
/* coerce a pointer into a shmem offset */
#define MAKE_OFFSET(xx_ptr)\
((SHMEM_OFFSET) (((unsigned long)(xx_ptr))-ShmemBase))
#define SHM_PTR_VALID(xx_ptr)\
(((unsigned long)(xx_ptr)) > ShmemBase)
/* cannot have an offset to ShmemFreeStart (offset 0) */
#define SHM_OFFSET_VALID(xx_offs)\
(((xx_offs) != 0) && ((xx_offs) != INVALID_OFFSET))
/* shmqueue.c */
typedef struct SHM_QUEUE
{
SHMEM_OFFSET prev;
SHMEM_OFFSET next;
struct SHM_QUEUE *prev;
struct SHM_QUEUE *next;
} SHM_QUEUE;
/* shmem.c */
extern void InitShmemAccess(void *seghdr);
extern void InitShmemAllocation(void);
extern void *ShmemAlloc(Size size);
extern bool ShmemIsValid(unsigned long addr);
extern bool ShmemAddrIsValid(void *addr);
extern void InitShmemIndex(void);
extern HTAB *ShmemInitHash(const char *name, long init_size, long max_size,
HASHCTL *infoP, int hash_flags);
@@ -77,15 +49,15 @@ extern void RequestAddinShmemSpace(Size size);
/* size constants for the shmem index table */
/* max size of data structure string name */
#define SHMEM_INDEX_KEYSIZE (48)
/* max size of the shmem index table (not a hard limit) */
/* estimated size of the shmem index table (not a hard limit) */
#define SHMEM_INDEX_SIZE (32)
/* this is a hash bucket in the shmem index table */
typedef struct
{
char key[SHMEM_INDEX_KEYSIZE]; /* string name */
unsigned long location; /* location in shared mem */
unsigned long size; /* numbytes allocated for the structure */
void *location; /* location in shared mem */
Size size; /* # bytes allocated for the structure */
} ShmemIndexEnt;
/*