1 /*-------------------------------------------------------------------------
4 * low-level dynamic shared memory primitives
6 * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
9 * src/include/storage/dsm_impl.h
11 *-------------------------------------------------------------------------
16 /* Dynamic shared memory implementations. */
17 #define DSM_IMPL_NONE 0
18 #define DSM_IMPL_POSIX 1
19 #define DSM_IMPL_SYSV 2
20 #define DSM_IMPL_WINDOWS 3
21 #define DSM_IMPL_MMAP 4
24 * Determine which dynamic shared memory implementations will be supported
25 * on this platform, and which one will be the default.
28 #define USE_DSM_WINDOWS
29 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_WINDOWS
33 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_POSIX
36 #ifndef DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE
37 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_SYSV
43 extern int dynamic_shared_memory_type;
46 * Directory for on-disk state.
48 * This is used by all implementations for crash recovery and by the mmap
49 * implementation for storage.
51 #define PG_DYNSHMEM_DIR "pg_dynshmem"
52 #define PG_DYNSHMEM_MMAP_FILE_PREFIX "mmap."
54 /* A "name" for a dynamic shared memory segment. */
55 typedef uint32 dsm_handle;
57 /* All the shared-memory operations we know about. */
67 /* Create, attach to, detach from, resize, or destroy a segment. */
68 extern bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size,
69 void **impl_private, void **mapped_address, Size *mapped_size,
72 /* Some implementations cannot resize segments. Can this one? */
73 extern bool dsm_impl_can_resize(void);
75 /* Implementation-dependent actions required to keep segment until shudown. */
76 extern void dsm_impl_pin_segment(dsm_handle handle, void *impl_private);
78 #endif /* DSM_IMPL_H */