2002-05-05 02:03:29 +02:00
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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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2002-09-04 22:31:48 +02:00
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* terms). Other platforms may ignore the second value if they need
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2002-05-05 02:03:29 +02:00
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* only one ID number.
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*
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*
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2002-06-20 22:29:54 +02:00
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* Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
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2002-05-05 02:03:29 +02:00
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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2003-05-07 01:34:56 +02:00
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* $Id: pg_shmem.h,v 1.5 2003/05/06 23:34:56 momjian Exp $
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2002-05-05 02:03:29 +02:00
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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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2003-05-07 01:34:56 +02:00
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typedef uint32 IpcMemoryKey; /* shared memory key passed to shmget(2) */
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2002-05-05 02:03:29 +02:00
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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 679834892
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pid_t creatorPID; /* PID of creating process */
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uint32 totalsize; /* total size of segment */
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uint32 freeoffset; /* offset to first free space */
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} PGShmemHeader;
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2003-05-07 01:34:56 +02:00
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#ifdef EXEC_BACKEND
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extern IpcMemoryKey UsedShmemSegID;
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#endif
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2002-05-05 02:03:29 +02:00
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extern PGShmemHeader *PGSharedMemoryCreate(uint32 size, bool makePrivate,
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2002-09-04 22:31:48 +02:00
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int port);
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2002-05-05 02:03:29 +02:00
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extern bool PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2);
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#endif /* PG_SHMEM_H */
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