]> granicus.if.org Git - postgresql/blob - src/include/storage/dsm_impl.h
Centralize definition of integer limits.
[postgresql] / src / include / storage / dsm_impl.h
1 /*-------------------------------------------------------------------------
2  *
3  * dsm_impl.h
4  *        low-level dynamic shared memory primitives
5  *
6  * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
7  * Portions Copyright (c) 1994, Regents of the University of California
8  *
9  * src/include/storage/dsm_impl.h
10  *
11  *-------------------------------------------------------------------------
12  */
13 #ifndef DSM_IMPL_H
14 #define DSM_IMPL_H
15
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
22
23 /*
24  * Determine which dynamic shared memory implementations will be supported
25  * on this platform, and which one will be the default.
26  */
27 #ifdef WIN32
28 #define USE_DSM_WINDOWS
29 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE              DSM_IMPL_WINDOWS
30 #else
31 #ifdef HAVE_SHM_OPEN
32 #define USE_DSM_POSIX
33 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE              DSM_IMPL_POSIX
34 #endif
35 #define USE_DSM_SYSV
36 #ifndef DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE
37 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE              DSM_IMPL_SYSV
38 #endif
39 #define USE_DSM_MMAP
40 #endif
41
42 /* GUC. */
43 extern int      dynamic_shared_memory_type;
44
45 /*
46  * Directory for on-disk state.
47  *
48  * This is used by all implementations for crash recovery and by the mmap
49  * implementation for storage.
50  */
51 #define PG_DYNSHMEM_DIR                                 "pg_dynshmem"
52 #define PG_DYNSHMEM_MMAP_FILE_PREFIX    "mmap."
53
54 /* A "name" for a dynamic shared memory segment. */
55 typedef uint32 dsm_handle;
56
57 /* All the shared-memory operations we know about. */
58 typedef enum
59 {
60         DSM_OP_CREATE,
61         DSM_OP_ATTACH,
62         DSM_OP_DETACH,
63         DSM_OP_RESIZE,
64         DSM_OP_DESTROY
65 } dsm_op;
66
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,
70                         int elevel);
71
72 /* Some implementations cannot resize segments.  Can this one? */
73 extern bool dsm_impl_can_resize(void);
74
75 /* Implementation-dependent actions required to keep segment until shudown. */
76 extern void dsm_impl_pin_segment(dsm_handle handle, void *impl_private);
77
78 #endif   /* DSM_IMPL_H */