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dsm_impl.h
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1 /*-------------------------------------------------------------------------
2  *
3  * dsm_impl.h
4  * low-level dynamic shared memory primitives
5  *
6  * Portions Copyright (c) 1996-2019, 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_POSIX 1
18 #define DSM_IMPL_SYSV 2
19 #define DSM_IMPL_WINDOWS 3
20 #define DSM_IMPL_MMAP 4
21 
22 /*
23  * Determine which dynamic shared memory implementations will be supported
24  * on this platform, and which one will be the default.
25  */
26 #ifdef WIN32
27 #define USE_DSM_WINDOWS
28 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_WINDOWS
29 #else
30 #ifdef HAVE_SHM_OPEN
31 #define USE_DSM_POSIX
32 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_POSIX
33 #endif
34 #define USE_DSM_SYSV
35 #ifndef DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE
36 #define DEFAULT_DYNAMIC_SHARED_MEMORY_TYPE DSM_IMPL_SYSV
37 #endif
38 #define USE_DSM_MMAP
39 #endif
40 
41 /* GUC. */
43 
44 /*
45  * Directory for on-disk state.
46  *
47  * This is used by all implementations for crash recovery and by the mmap
48  * implementation for storage.
49  */
50 #define PG_DYNSHMEM_DIR "pg_dynshmem"
51 #define PG_DYNSHMEM_MMAP_FILE_PREFIX "mmap."
52 
53 /* A "name" for a dynamic shared memory segment. */
55 
56 /* All the shared-memory operations we know about. */
57 typedef enum
58 {
63 } dsm_op;
64 
65 /* Create, attach to, detach from, resize, or destroy a segment. */
66 extern bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size,
67  void **impl_private, void **mapped_address, Size *mapped_size,
68  int elevel);
69 
70 /* Implementation-dependent actions required to keep segment until shutdown. */
71 extern void dsm_impl_pin_segment(dsm_handle handle, void *impl_private,
72  void **impl_private_pm_handle);
73 extern void dsm_impl_unpin_segment(dsm_handle handle, void **impl_private);
74 
75 #endif /* DSM_IMPL_H */
uint32 dsm_handle
Definition: dsm_impl.h:54
void dsm_impl_unpin_segment(dsm_handle handle, void **impl_private)
Definition: dsm_impl.c:993
void dsm_impl_pin_segment(dsm_handle handle, void *impl_private, void **impl_private_pm_handle)
Definition: dsm_impl.c:943
bool dsm_impl_op(dsm_op op, dsm_handle handle, Size request_size, void **impl_private, void **mapped_address, Size *mapped_size, int elevel)
Definition: dsm_impl.c:158
unsigned int uint32
Definition: c.h:358
static int elevel
Definition: vacuumlazy.c:143
size_t Size
Definition: c.h:466
int dynamic_shared_memory_type
Definition: dsm_impl.c:114
dsm_op
Definition: dsm_impl.h:57