src/include/storage/sync.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * sync.h
   4  *        File synchronization management code.
   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/sync.h
  10  *
  11  *-------------------------------------------------------------------------
  12  */
  13 #ifndef SYNC_H
  14 #define SYNC_H
  15
  16 #include "storage/relfilenode.h"
  17
  18 /*
  19  * Type of sync request.  These are used to manage the set of pending
  20  * requests to call a sync handler's sync or unlink functions at the next
  21  * checkpoint.
  22  */
  23 typedef enum SyncRequestType
  24 {
  25         SYNC_REQUEST,                           /* schedule a call of sync function */
  26         SYNC_UNLINK_REQUEST,            /* schedule a call of unlink function */
  27         SYNC_FORGET_REQUEST,            /* forget all calls for a tag */
  28         SYNC_FILTER_REQUEST                     /* forget all calls satisfying match fn */
  29 } SyncRequestType;
  30
  31 /*
  32  * Which set of functions to use to handle a given request.  The values of
  33  * the enumerators must match the indexes of the function table in sync.c.
  34  */
  35 typedef enum SyncRequestHandler
  36 {
  37         SYNC_HANDLER_MD = 0,
  38         SYNC_HANDLER_CLOG,
  39         SYNC_HANDLER_COMMIT_TS,
  40         SYNC_HANDLER_MULTIXACT_OFFSET,
  41         SYNC_HANDLER_MULTIXACT_MEMBER,
  42         SYNC_HANDLER_NONE
  43 } SyncRequestHandler;
  44
  45 /*
  46  * A tag identifying a file.  Currently it has the members required for md.c's
  47  * usage, but sync.c has no knowledge of the internal structure, and it is
  48  * liable to change as required by future handlers.
  49  */
  50 typedef struct FileTag
  51 {
  52         int16           handler;                /* SyncRequestHandler value, saving space */
  53         int16           forknum;                /* ForkNumber, saving space */
  54         RelFileNode rnode;
  55         uint32          segno;
  56 } FileTag;
  57
  58 extern void InitSync(void);
  59 extern void SyncPreCheckpoint(void);
  60 extern void SyncPostCheckpoint(void);
  61 extern void ProcessSyncRequests(void);
  62 extern void RememberSyncRequest(const FileTag *ftag, SyncRequestType type);
  63 extern bool RegisterSyncRequest(const FileTag *ftag, SyncRequestType type,
  64                                                                 bool retryOnError);
  65
  66 #endif                                                  /* SYNC_H */