src/include/replication/syncrep.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * syncrep.h
   4  *        Exports from replication/syncrep.c.
   5  *
   6  * Portions Copyright (c) 2010-2022, PostgreSQL Global Development Group
   7  *
   8  * IDENTIFICATION
   9  *              src/include/replication/syncrep.h
  10  *
  11  *-------------------------------------------------------------------------
  12  */
  13 #ifndef _SYNCREP_H
  14 #define _SYNCREP_H
  15
  16 #include "access/xlogdefs.h"
  17 #include "utils/guc.h"
  18
  19 #define SyncRepRequested() \
  20         (max_wal_senders > 0 && synchronous_commit > SYNCHRONOUS_COMMIT_LOCAL_FLUSH)
  21
  22 /* SyncRepWaitMode */
  23 #define SYNC_REP_NO_WAIT                (-1)
  24 #define SYNC_REP_WAIT_WRITE             0
  25 #define SYNC_REP_WAIT_FLUSH             1
  26 #define SYNC_REP_WAIT_APPLY             2
  27
  28 #define NUM_SYNC_REP_WAIT_MODE  3
  29
  30 /* syncRepState */
  31 #define SYNC_REP_NOT_WAITING            0
  32 #define SYNC_REP_WAITING                        1
  33 #define SYNC_REP_WAIT_COMPLETE          2
  34
  35 /* syncrep_method of SyncRepConfigData */
  36 #define SYNC_REP_PRIORITY               0
  37 #define SYNC_REP_QUORUM         1
  38
  39 /*
  40  * SyncRepGetCandidateStandbys returns an array of these structs,
  41  * one per candidate synchronous walsender.
  42  */
  43 typedef struct SyncRepStandbyData
  44 {
  45         /* Copies of relevant fields from WalSnd shared-memory struct */
  46         pid_t           pid;
  47         XLogRecPtr      write;
  48         XLogRecPtr      flush;
  49         XLogRecPtr      apply;
  50         int                     sync_standby_priority;
  51         /* Index of this walsender in the WalSnd shared-memory array */
  52         int                     walsnd_index;
  53         /* This flag indicates whether this struct is about our own process */
  54         bool            is_me;
  55 } SyncRepStandbyData;
  56
  57 /*
  58  * Struct for the configuration of synchronous replication.
  59  *
  60  * Note: this must be a flat representation that can be held in a single
  61  * chunk of malloc'd memory, so that it can be stored as the "extra" data
  62  * for the synchronous_standby_names GUC.
  63  */
  64 typedef struct SyncRepConfigData
  65 {
  66         int                     config_size;    /* total size of this struct, in bytes */
  67         int                     num_sync;               /* number of sync standbys that we need to
  68                                                                  * wait for */
  69         uint8           syncrep_method; /* method to choose sync standbys */
  70         int                     nmembers;               /* number of members in the following list */
  71         /* member_names contains nmembers consecutive nul-terminated C strings */
  72         char            member_names[FLEXIBLE_ARRAY_MEMBER];
  73 } SyncRepConfigData;
  74
  75 extern SyncRepConfigData *SyncRepConfig;
  76
  77 /* communication variables for parsing synchronous_standby_names GUC */
  78 extern SyncRepConfigData *syncrep_parse_result;
  79 extern char *syncrep_parse_error_msg;
  80
  81 /* user-settable parameters for synchronous replication */
  82 extern char *SyncRepStandbyNames;
  83
  84 /* called by user backend */
  85 extern void SyncRepWaitForLSN(XLogRecPtr lsn, bool commit);
  86
  87 /* called at backend exit */
  88 extern void SyncRepCleanupAtProcExit(void);
  89
  90 /* called by wal sender */
  91 extern void SyncRepInitConfig(void);
  92 extern void SyncRepReleaseWaiters(void);
  93
  94 /* called by wal sender and user backend */
  95 extern int      SyncRepGetCandidateStandbys(SyncRepStandbyData **standbys);
  96
  97 /* called by checkpointer */
  98 extern void SyncRepUpdateSyncStandbysDefined(void);
  99
 100 /* GUC infrastructure */
 101 extern bool check_synchronous_standby_names(char **newval, void **extra, GucSource source);
 102 extern void assign_synchronous_standby_names(const char *newval, void *extra);
 103 extern void assign_synchronous_commit(int newval, void *extra);
 104
 105 /*
 106  * Internal functions for parsing synchronous_standby_names grammar,
 107  * in syncrep_gram.y and syncrep_scanner.l
 108  */
 109 extern int      syncrep_yyparse(void);
 110 extern int      syncrep_yylex(void);
 111 extern void syncrep_yyerror(const char *str);
 112 extern void syncrep_scanner_init(const char *query_string);
 113 extern void syncrep_scanner_finish(void);
 114
 115 #endif                                                  /* _SYNCREP_H */