src/include/storage/dsm.h

   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 */