1 /*------------------------------------------------------------------------- 2 * 3 * dsm.h 4 * manage dynamic shared memory segments 5 * 6 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group 7 * Portions Copyright (c) 1994, Regents of the University of California 8 * 9 * src/include/storage/dsm.h 10 * 11 *------------------------------------------------------------------------- 12 */ 13 #ifndef DSM_H 14 #define DSM_H 15 16 #include "storage/dsm_impl.h" 17 18 typedef struct dsm_segment dsm_segment; 19 20 #define DSM_CREATE_NULL_IF_MAXSEGMENTS 0x0001 21 22 /* A sentinel value for an invalid DSM handle. */ 23 #define DSM_HANDLE_INVALID 0 24 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); 31 32 extern size_t dsm_estimate_size(void); 33 extern void dsm_shmem_init(void); 34 35 #ifdef EXEC_BACKEND 36 extern void dsm_set_control_handle(dsm_handle h); 37 #endif 38 39 /* Functions that create or remove mappings. */ 40 extern dsm_segment *dsm_create(Size size, int flags); 41 extern dsm_segment *dsm_attach(dsm_handle h); 42 extern void dsm_detach(dsm_segment *seg); 43 44 /* Resource management functions. */ 45 extern void dsm_pin_mapping(dsm_segment *seg); 46 extern void dsm_unpin_mapping(dsm_segment *seg); 47 extern void dsm_pin_segment(dsm_segment *seg); 48 extern void dsm_unpin_segment(dsm_handle h); 49 extern dsm_segment *dsm_find_mapping(dsm_handle h); 50 51 /* Informational functions. */ 52 extern void *dsm_segment_address(dsm_segment *seg); 53 extern Size dsm_segment_map_length(dsm_segment *seg); 54 extern dsm_handle dsm_segment_handle(dsm_segment *seg); 55 56 /* Cleanup hooks. */ 57 typedef void (*on_dsm_detach_callback) (dsm_segment *, Datum arg); 58 extern void on_dsm_detach(dsm_segment *seg, 59 on_dsm_detach_callback function, Datum arg); 60 extern void cancel_on_dsm_detach(dsm_segment *seg, 61 on_dsm_detach_callback function, Datum arg); 62 extern void reset_on_dsm_detach(void); 63 64 #endif /* DSM_H */ 65