60 lines
2.1 KiB
C
60 lines
2.1 KiB
C
/*-------------------------------------------------------------------------
|
|
*
|
|
* 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) 1996-2024, PostgreSQL Global Development Group
|
|
* Portions Copyright (c) 1994, Regents of the University of California
|
|
*
|
|
* src/include/storage/shmem.h
|
|
*
|
|
*-------------------------------------------------------------------------
|
|
*/
|
|
#ifndef SHMEM_H
|
|
#define SHMEM_H
|
|
|
|
#include "utils/hsearch.h"
|
|
|
|
|
|
/* shmem.c */
|
|
extern void InitShmemAccess(void *seghdr);
|
|
extern void InitShmemAllocation(void);
|
|
extern void *ShmemAlloc(Size size);
|
|
extern void *ShmemAllocNoError(Size size);
|
|
extern void *ShmemAllocUnlocked(Size size);
|
|
extern bool ShmemAddrIsValid(const void *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);
|
|
extern Size add_size(Size s1, Size s2);
|
|
extern Size mul_size(Size s1, Size s2);
|
|
|
|
/* ipci.c */
|
|
extern void RequestAddinShmemSpace(Size size);
|
|
|
|
/* size constants for the shmem index table */
|
|
/* max size of data structure string name */
|
|
#define SHMEM_INDEX_KEYSIZE (48)
|
|
/* estimated size of the shmem index table (not a hard limit) */
|
|
#define SHMEM_INDEX_SIZE (64)
|
|
|
|
/* this is a hash bucket in the shmem index table */
|
|
typedef struct
|
|
{
|
|
char key[SHMEM_INDEX_KEYSIZE]; /* string name */
|
|
void *location; /* location in shared mem */
|
|
Size size; /* # bytes requested for the structure */
|
|
Size allocated_size; /* # bytes actually allocated */
|
|
} ShmemIndexEnt;
|
|
|
|
#endif /* SHMEM_H */
|