src/include/replication/syncrep.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * syncrep.h
   4  *        Exports from replication/syncrep.c.
   5  *
   6  * Portions Copyright (c) 2010-2025, 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
  18 #define SyncRepRequested() \
  19         (max_wal_senders > 0 && synchronous_commit > SYNCHRONOUS_COMMIT_LOCAL_FLUSH)
  20
  21 /* SyncRepWaitMode */
  22 #define SYNC_REP_NO_WAIT                (-1)
  23 #define SYNC_REP_WAIT_WRITE             0
  24 #define SYNC_REP_WAIT_FLUSH             1
  25 #define SYNC_REP_WAIT_APPLY             2
  26
  27 #define NUM_SYNC_REP_WAIT_MODE  3
  28
  29 /* syncRepState */
  30 #define SYNC_REP_NOT_WAITING            0
  31 #define SYNC_REP_WAITING                        1
  32 #define SYNC_REP_WAIT_COMPLETE          2
  33
  34 /* syncrep_method of SyncRepConfigData */
  35 #define SYNC_REP_PRIORITY               0
  36 #define SYNC_REP_QUORUM         1
  37
  38 /*
  39  * SyncRepGetCandidateStandbys returns an array of these structs,
  40  * one per candidate synchronous walsender.
  41  */
  42 typedef struct SyncRepStandbyData
  43 {
  44         /* Copies of relevant fields from WalSnd shared-memory struct */
  45         pid_t           pid;
  46         XLogRecPtr      write;
  47         XLogRecPtr      flush;
  48         XLogRecPtr      apply;
  49         int                     sync_standby_priority;
  50         /* Index of this walsender in the WalSnd shared-memory array */
  51         int                     walsnd_index;
  52         /* This flag indicates whether this struct is about our own process */
  53         bool            is_me;
  54 } SyncRepStandbyData;
  55
  56 /*
  57  * Struct for the configuration of synchronous replication.
  58  *
  59  * Note: this must be a flat representation that can be held in a single
  60  * chunk of malloc'd memory, so that it can be stored as the "extra" data
  61  * for the synchronous_standby_names GUC.
  62  */
  63 typedef struct SyncRepConfigData
  64 {
  65         int                     config_size;    /* total size of this struct, in bytes */
  66         int                     num_sync;               /* number of sync standbys that we need to
  67                                                                  * wait for */
  68         uint8           syncrep_method; /* method to choose sync standbys */
  69         int                     nmembers;               /* number of members in the following list */
  70         /* member_names contains nmembers consecutive nul-terminated C strings */
  71         char            member_names[FLEXIBLE_ARRAY_MEMBER];
  72 } SyncRepConfigData;
  73
  74 extern PGDLLIMPORT SyncRepConfigData *SyncRepConfig;
  75
  76 /* user-settable parameters for synchronous replication */
  77 extern PGDLLIMPORT char *SyncRepStandbyNames;
  78
  79 /* called by user backend */
  80 extern void SyncRepWaitForLSN(XLogRecPtr lsn, bool commit);
  81
  82 /* called at backend exit */
  83 extern void SyncRepCleanupAtProcExit(void);
  84
  85 /* called by wal sender */
  86 extern void SyncRepInitConfig(void);
  87 extern void SyncRepReleaseWaiters(void);
  88
  89 /* called by wal sender and user backend */
  90 extern int      SyncRepGetCandidateStandbys(SyncRepStandbyData **standbys);
  91
  92 /* called by checkpointer */
  93 extern void SyncRepUpdateSyncStandbysDefined(void);
  94
  95 /*
  96  * Internal functions for parsing synchronous_standby_names grammar,
  97  * in syncrep_gram.y and syncrep_scanner.l
  98  */
  99 union YYSTYPE;
 100 #ifndef YY_TYPEDEF_YY_SCANNER_T
 101 #define YY_TYPEDEF_YY_SCANNER_T
 102 typedef void *yyscan_t;
 103 #endif
 104 extern int      syncrep_yyparse(SyncRepConfigData **syncrep_parse_result_p, char **syncrep_parse_error_msg_p, yyscan_t yyscanner);
 105 extern int      syncrep_yylex(union YYSTYPE *yylval_param, char **syncrep_parse_error_msg_p, yyscan_t yyscanner);
 106 extern void syncrep_yyerror(SyncRepConfigData **syncrep_parse_result_p, char **syncrep_parse_error_msg_p, yyscan_t yyscanner, const char *str);
 107 extern void syncrep_scanner_init(const char *str, yyscan_t *yyscannerp);
 108 extern void syncrep_scanner_finish(yyscan_t yyscanner);
 109
 110 #endif                                                  /* _SYNCREP_H */