greenplumn mem 源码
greenplumn mem 代码
文件路径：/src/include/portability/mem.h
/*-------------------------------------------------------------------------
*
* mem.h
* portability definitions for various memory operations
*
* Copyright (c) 2001-2019, PostgreSQL Global Development Group
*
* src/include/portability/mem.h
*
*-------------------------------------------------------------------------
*/
#ifndef MEM_H
#define MEM_H
#define IPCProtection (0600) /* access/modify by user only */
#ifdef SHM_SHARE_MMU /* use intimate shared memory on Solaris */
#define PG_SHMAT_FLAGS SHM_SHARE_MMU
#else
#define PG_SHMAT_FLAGS 0
#endif
/* Linux prefers MAP_ANONYMOUS, but the flag is called MAP_ANON on other systems. */
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
/* BSD-derived systems have MAP_HASSEMAPHORE, but it's not present (or needed) on Linux. */
#ifndef MAP_HASSEMAPHORE
#define MAP_HASSEMAPHORE 0
#endif
/*
* BSD-derived systems use the MAP_NOSYNC flag to prevent dirty mmap(2)
* pages from being gratuitously flushed to disk.
*/
#ifndef MAP_NOSYNC
#define MAP_NOSYNC 0
#endif
#define PG_MMAP_FLAGS (MAP_SHARED|MAP_ANONYMOUS|MAP_HASSEMAPHORE)
/* Some really old systems don't define MAP_FAILED. */
#ifndef MAP_FAILED
#define MAP_FAILED ((void *) -1)
#endif
#endif /* MEM_H */
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