1 /*-------------------------------------------------------------------------
4 * manage dynamic shared memory segments
6 * Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
7 * Portions Copyright (c) 1994, Regents of the University of California
9 * src/include/storage/dsm.h
11 *-------------------------------------------------------------------------
16 #include "storage/dsm_impl.h"
18 typedef struct dsm_segment dsm_segment;
20 #define DSM_CREATE_NULL_IF_MAXSEGMENTS 0x0001
22 /* A sentinel value for an invalid DSM handle. */
23 #define DSM_HANDLE_INVALID 0
25 /* Startup and shutdown functions. */
26 struct PGShmemHeader; /* avoid including pg_shmem.h */
27 extern void dsm_cleanup_using_control_segment(dsm_handle old_control_handle);
28 extern void dsm_postmaster_startup(struct PGShmemHeader *);
29 extern void dsm_backend_shutdown(void);
30 extern void dsm_detach_all(void);
33 extern void dsm_set_control_handle(dsm_handle h);
36 /* Functions that create, update, or remove mappings. */
37 extern dsm_segment *dsm_create(Size size, int flags);
38 extern dsm_segment *dsm_attach(dsm_handle h);
39 extern void *dsm_resize(dsm_segment *seg, Size size);
40 extern void *dsm_remap(dsm_segment *seg);
41 extern void dsm_detach(dsm_segment *seg);
43 /* Resource management functions. */
44 extern void dsm_pin_mapping(dsm_segment *seg);
45 extern void dsm_unpin_mapping(dsm_segment *seg);
46 extern void dsm_pin_segment(dsm_segment *seg);
47 extern void dsm_unpin_segment(dsm_handle h);
48 extern dsm_segment *dsm_find_mapping(dsm_handle h);
50 /* Informational functions. */
51 extern void *dsm_segment_address(dsm_segment *seg);
52 extern Size dsm_segment_map_length(dsm_segment *seg);
53 extern dsm_handle dsm_segment_handle(dsm_segment *seg);
56 typedef void (*on_dsm_detach_callback) (dsm_segment *, Datum arg);
57 extern void on_dsm_detach(dsm_segment *seg,
58 on_dsm_detach_callback function, Datum arg);
59 extern void cancel_on_dsm_detach(dsm_segment *seg,
60 on_dsm_detach_callback function, Datum arg);
61 extern void reset_on_dsm_detach(void);