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Viewing changes to src/include/storage/pg_shmem.h

  • Committer: Bazaar Package Importer
  • Author(s): Martin Pitt
  • Date: 2011-05-11 10:41:53 UTC
  • Revision ID: james.westby@ubuntu.com-20110511104153-psbh2o58553fv1m0
Tags: upstream-9.1~beta1
Import upstream version 9.1~beta1

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src/include/storage/pg_shmem.h
 
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/*-------------------------------------------------------------------------
 
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 *
 
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 * pg_shmem.h
 
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 *        Platform-independent API for shared memory support.
 
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 *
 
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 * Every port is expected to support shared memory with approximately
 
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 * SysV-ish semantics; in particular, a memory block is not anonymous
 
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 * but has an ID, and we must be able to tell whether there are any
 
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 * remaining processes attached to a block of a specified ID.
 
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 *
 
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 * To simplify life for the SysV implementation, the ID is assumed to
 
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 * consist of two unsigned long values (these are key and ID in SysV
 
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 * terms).      Other platforms may ignore the second value if they need
 
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 * only one ID number.
 
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 *
 
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 *
 
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 * Portions Copyright (c) 1996-2011, 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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 * src/include/storage/pg_shmem.h
 
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 *
 
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 *-------------------------------------------------------------------------
 
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 */
 
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#ifndef PG_SHMEM_H
 
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#define PG_SHMEM_H
 
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typedef struct PGShmemHeader    /* standard header for all Postgres shmem */
 
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{
 
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        int32           magic;                  /* magic # to identify Postgres segments */
 
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#define PGShmemMagic  679834894
 
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        pid_t           creatorPID;             /* PID of creating process */
 
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        Size            totalsize;              /* total size of segment */
 
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        Size            freeoffset;             /* offset to first free space */
 
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        void       *index;                      /* pointer to ShmemIndex table */
 
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#ifndef WIN32                                   /* Windows doesn't have useful inode#s */
 
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        dev_t           device;                 /* device data directory is on */
 
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        ino_t           inode;                  /* inode number of data directory */
 
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#endif
 
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} PGShmemHeader;
 
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#ifdef EXEC_BACKEND
 
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#ifndef WIN32
 
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extern unsigned long UsedShmemSegID;
 
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#else
 
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extern HANDLE UsedShmemSegID;
 
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#endif
 
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extern void *UsedShmemSegAddr;
 
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extern void PGSharedMemoryReAttach(void);
 
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#endif
 
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extern PGShmemHeader *PGSharedMemoryCreate(Size size, bool makePrivate,
 
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                                         int port);
 
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extern bool PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2);
 
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extern void PGSharedMemoryDetach(void);
 
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#endif   /* PG_SHMEM_H */