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75 lines
2.4 KiB
C
75 lines
2.4 KiB
C
/*-------------------------------------------------------------------------
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*
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* shmem.h
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* shared memory management structures
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*
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* Historical note:
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* A long time ago, Postgres' shared memory region was allowed to be mapped
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* at a different address in each process, and shared memory "pointers" were
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* passed around as offsets relative to the start of the shared memory region.
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* That is no longer the case: each process must map the shared memory region
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* at the same address. This means shared memory pointers can be passed
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* around directly between different processes.
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*
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* Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* $PostgreSQL: pgsql/src/include/storage/shmem.h,v 1.57 2010/01/02 16:58:08 momjian Exp $
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef SHMEM_H
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#define SHMEM_H
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#include "utils/hsearch.h"
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/* shmqueue.c */
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typedef struct SHM_QUEUE
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{
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struct SHM_QUEUE *prev;
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struct SHM_QUEUE *next;
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} SHM_QUEUE;
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/* shmem.c */
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extern void InitShmemAccess(void *seghdr);
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extern void InitShmemAllocation(void);
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extern void *ShmemAlloc(Size size);
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extern bool ShmemAddrIsValid(void *addr);
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extern void InitShmemIndex(void);
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extern HTAB *ShmemInitHash(const char *name, long init_size, long max_size,
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HASHCTL *infoP, int hash_flags);
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extern void *ShmemInitStruct(const char *name, Size size, bool *foundPtr);
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extern Size add_size(Size s1, Size s2);
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extern Size mul_size(Size s1, Size s2);
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/* ipci.c */
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extern void RequestAddinShmemSpace(Size size);
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/* size constants for the shmem index table */
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/* max size of data structure string name */
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#define SHMEM_INDEX_KEYSIZE (48)
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/* estimated size of the shmem index table (not a hard limit) */
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#define SHMEM_INDEX_SIZE (32)
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/* this is a hash bucket in the shmem index table */
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typedef struct
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{
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char key[SHMEM_INDEX_KEYSIZE]; /* string name */
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void *location; /* location in shared mem */
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Size size; /* # bytes allocated for the structure */
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} ShmemIndexEnt;
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/*
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* prototypes for functions in shmqueue.c
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*/
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extern void SHMQueueInit(SHM_QUEUE *queue);
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extern void SHMQueueElemInit(SHM_QUEUE *queue);
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extern void SHMQueueDelete(SHM_QUEUE *queue);
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extern void SHMQueueInsertBefore(SHM_QUEUE *queue, SHM_QUEUE *elem);
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extern Pointer SHMQueueNext(SHM_QUEUE *queue, SHM_QUEUE *curElem,
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Size linkOffset);
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extern bool SHMQueueEmpty(SHM_QUEUE *queue);
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#endif /* SHMEM_H */
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