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/*-------------------------------------------------------------------------
*
* shmem.h
* shared memory management structures
*
*
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: shmem.h,v 1.33 2001/10/05 17:28:13 tgl Exp $
*
*-------------------------------------------------------------------------
*/
#ifndef SHMEM_H
#define SHMEM_H
#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)
#define BAD_LOCATION (-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 DLLIMPORT 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))
/* shmemqueue.c */
typedef struct SHM_QUEUE
{
SHMEM_OFFSET prev;
SHMEM_OFFSET next;
} SHM_QUEUE;
/* shmem.c */
extern void InitShmemAllocation(void *seghdr);
extern void *ShmemAlloc(Size size);
extern bool ShmemIsValid(unsigned long addr);
extern void InitShmemIndex(void);
extern HTAB *ShmemInitHash(const char *name, long init_size, long max_size,
HASHCTL *infoP, int hash_flags);
extern void *ShmemInitStruct(const char *name, Size size, bool *foundPtr);
/* size constants for the shmem index table */
/* max size of data structure string name */
#define SHMEM_INDEX_KEYSIZE (48)
/* maximum size of the shmem index table */
#define SHMEM_INDEX_SIZE (100)
/* 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 */
} ShmemIndexEnt;
/*
* prototypes for functions in shmqueue.c
*/
extern void SHMQueueInit(SHM_QUEUE *queue);
extern void SHMQueueElemInit(SHM_QUEUE *queue);
extern void SHMQueueDelete(SHM_QUEUE *queue);
extern void SHMQueueInsertBefore(SHM_QUEUE *queue, SHM_QUEUE *elem);
extern Pointer SHMQueueNext(SHM_QUEUE *queue, SHM_QUEUE *curElem,
Size linkOffset);
extern bool SHMQueueEmpty(SHM_QUEUE *queue);
#endif /* SHMEM_H */
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