src/include/access/xact.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * xact.h
   4  *        postgres transaction system definitions
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #ifndef XACT_H
  15 #define XACT_H
  16
  17 #include "access/xlog.h"
  18 #include "nodes/pg_list.h"
  19 #include "storage/relfilenode.h"
  20 #include "utils/timestamp.h"
  21
  22
  23 /*
  24  * Xact isolation levels
  25  */
  26 #define XACT_READ_UNCOMMITTED   0
  27 #define XACT_READ_COMMITTED             1
  28 #define XACT_REPEATABLE_READ    2
  29 #define XACT_SERIALIZABLE               3
  30
  31 extern int      DefaultXactIsoLevel;
  32 extern int      XactIsoLevel;
  33
  34 /*
  35  * We only implement two isolation levels internally.  This macro should
  36  * be used to check which one is selected.
  37  */
  38 #define IsXactIsoLevelSerializable (XactIsoLevel >= XACT_REPEATABLE_READ)
  39
  40 /* Xact read-only state */
  41 extern bool DefaultXactReadOnly;
  42 extern bool XactReadOnly;
  43
  44 /* Asynchronous commits */
  45 extern bool XactSyncCommit;
  46
  47 /* Kluge for 2PC support */
  48 extern bool MyXactAccessedTempRel;
  49
  50 /*
  51  *      start- and end-of-transaction callbacks for dynamically loaded modules
  52  */
  53 typedef enum
  54 {
  55         XACT_EVENT_COMMIT,
  56         XACT_EVENT_ABORT,
  57         XACT_EVENT_PREPARE
  58 } XactEvent;
  59
  60 typedef void (*XactCallback) (XactEvent event, void *arg);
  61
  62 typedef enum
  63 {
  64         SUBXACT_EVENT_START_SUB,
  65         SUBXACT_EVENT_COMMIT_SUB,
  66         SUBXACT_EVENT_ABORT_SUB
  67 } SubXactEvent;
  68
  69 typedef void (*SubXactCallback) (SubXactEvent event, SubTransactionId mySubid,
  70                                                                         SubTransactionId parentSubid, void *arg);
  71
  72
  73 /* ----------------
  74  *              transaction-related XLOG entries
  75  * ----------------
  76  */
  77
  78 /*
  79  * XLOG allows to store some information in high 4 bits of log
  80  * record xl_info field
  81  */
  82 #define XLOG_XACT_COMMIT                        0x00
  83 #define XLOG_XACT_PREPARE                       0x10
  84 #define XLOG_XACT_ABORT                         0x20
  85 #define XLOG_XACT_COMMIT_PREPARED       0x30
  86 #define XLOG_XACT_ABORT_PREPARED        0x40
  87
  88 typedef struct xl_xact_commit
  89 {
  90         TimestampTz xact_time;          /* time of commit */
  91         int                     nrels;                  /* number of RelFileForks */
  92         int                     nsubxacts;              /* number of subtransaction XIDs */
  93         /* Array of RelFileFork(s) to drop at commit */
  94         RelFileFork     xnodes[1];              /* VARIABLE LENGTH ARRAY */
  95         /* ARRAY OF COMMITTED SUBTRANSACTION XIDs FOLLOWS */
  96 } xl_xact_commit;
  97
  98 #define MinSizeOfXactCommit offsetof(xl_xact_commit, xnodes)
  99
 100 typedef struct xl_xact_abort
 101 {
 102         TimestampTz xact_time;          /* time of abort */
 103         int                     nrels;                  /* number of RelFileForks */
 104         int                     nsubxacts;              /* number of subtransaction XIDs */
 105         /* Array of RelFileFork(s) to drop at abort */
 106         RelFileFork     xnodes[1];              /* VARIABLE LENGTH ARRAY */
 107         /* ARRAY OF ABORTED SUBTRANSACTION XIDs FOLLOWS */
 108 } xl_xact_abort;
 109
 110 #define MinSizeOfXactAbort offsetof(xl_xact_abort, xnodes)
 111
 112 /*
 113  * COMMIT_PREPARED and ABORT_PREPARED are identical to COMMIT/ABORT records
 114  * except that we have to store the XID of the prepared transaction explicitly
 115  * --- the XID in the record header will be for the transaction doing the
 116  * COMMIT PREPARED or ABORT PREPARED command.
 117  */
 118
 119 typedef struct xl_xact_commit_prepared
 120 {
 121         TransactionId xid;                      /* XID of prepared xact */
 122         xl_xact_commit crec;            /* COMMIT record */
 123         /* MORE DATA FOLLOWS AT END OF STRUCT */
 124 } xl_xact_commit_prepared;
 125
 126 #define MinSizeOfXactCommitPrepared offsetof(xl_xact_commit_prepared, crec.xnodes)
 127
 128 typedef struct xl_xact_abort_prepared
 129 {
 130         TransactionId xid;                      /* XID of prepared xact */
 131         xl_xact_abort arec;                     /* ABORT record */
 132         /* MORE DATA FOLLOWS AT END OF STRUCT */
 133 } xl_xact_abort_prepared;
 134
 135 #define MinSizeOfXactAbortPrepared offsetof(xl_xact_abort_prepared, arec.xnodes)
 136
 137
 138 /* ----------------
 139  *              extern definitions
 140  * ----------------
 141  */
 142 extern bool IsTransactionState(void);
 143 extern bool IsAbortedTransactionBlockState(void);
 144 extern TransactionId GetTopTransactionId(void);
 145 extern TransactionId GetTopTransactionIdIfAny(void);
 146 extern TransactionId GetCurrentTransactionId(void);
 147 extern TransactionId GetCurrentTransactionIdIfAny(void);
 148 extern SubTransactionId GetCurrentSubTransactionId(void);
 149 extern CommandId GetCurrentCommandId(bool used);
 150 extern TimestampTz GetCurrentTransactionStartTimestamp(void);
 151 extern TimestampTz GetCurrentStatementStartTimestamp(void);
 152 extern TimestampTz GetCurrentTransactionStopTimestamp(void);
 153 extern void SetCurrentStatementStartTimestamp(void);
 154 extern int      GetCurrentTransactionNestLevel(void);
 155 extern bool TransactionIdIsCurrentTransactionId(TransactionId xid);
 156 extern void CommandCounterIncrement(void);
 157 extern void ForceSyncCommit(void);
 158 extern void StartTransactionCommand(void);
 159 extern void CommitTransactionCommand(void);
 160 extern void AbortCurrentTransaction(void);
 161 extern void BeginTransactionBlock(void);
 162 extern bool EndTransactionBlock(void);
 163 extern bool PrepareTransactionBlock(char *gid);
 164 extern void UserAbortTransactionBlock(void);
 165 extern void ReleaseSavepoint(List *options);
 166 extern void DefineSavepoint(char *name);
 167 extern void RollbackToSavepoint(List *options);
 168 extern void BeginInternalSubTransaction(char *name);
 169 extern void ReleaseCurrentSubTransaction(void);
 170 extern void RollbackAndReleaseCurrentSubTransaction(void);
 171 extern bool IsSubTransaction(void);
 172 extern bool IsTransactionBlock(void);
 173 extern bool IsTransactionOrTransactionBlock(void);
 174 extern char TransactionBlockStatusCode(void);
 175 extern void AbortOutOfAnyTransaction(void);
 176 extern void PreventTransactionChain(bool isTopLevel, const char *stmtType);
 177 extern void RequireTransactionChain(bool isTopLevel, const char *stmtType);
 178 extern bool IsInTransactionChain(bool isTopLevel);
 179 extern void RegisterXactCallback(XactCallback callback, void *arg);
 180 extern void UnregisterXactCallback(XactCallback callback, void *arg);
 181 extern void RegisterSubXactCallback(SubXactCallback callback, void *arg);
 182 extern void UnregisterSubXactCallback(SubXactCallback callback, void *arg);
 183
 184 extern TransactionId RecordTransactionCommit(void);
 185
 186 extern int      xactGetCommittedChildren(TransactionId **ptr);
 187
 188 extern void xact_redo(XLogRecPtr lsn, XLogRecord *record);
 189 extern void xact_desc(StringInfo buf, uint8 xl_info, char *rec);
 190
 191 #endif   /* XACT_H */