src/include/access/multixact.h

   1 /*
   2  * multixact.h
   3  *
   4  * PostgreSQL multi-transaction-log manager
   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/access/multixact.h
  10  */
  11 #ifndef MULTIXACT_H
  12 #define MULTIXACT_H
  13
  14 #include "access/xlogreader.h"
  15 #include "lib/stringinfo.h"
  16 #include "storage/sync.h"
  17
  18
  19 /*
  20  * The first two MultiXactId values are reserved to store the truncation Xid
  21  * and epoch of the first segment, so we start assigning multixact values from
  22  * 2.
  23  */
  24 #define InvalidMultiXactId      ((MultiXactId) 0)
  25 #define FirstMultiXactId        ((MultiXactId) 1)
  26 #define MaxMultiXactId          ((MultiXactId) 0xFFFFFFFF)
  27
  28 #define MultiXactIdIsValid(multi) ((multi) != InvalidMultiXactId)
  29
  30 #define MaxMultiXactOffset      ((MultiXactOffset) 0xFFFFFFFF)
  31
  32 /* Number of SLRU buffers to use for multixact */
  33 #define NUM_MULTIXACTOFFSET_BUFFERS             8
  34 #define NUM_MULTIXACTMEMBER_BUFFERS             16
  35
  36 /*
  37  * Possible multixact lock modes ("status").  The first four modes are for
  38  * tuple locks (FOR KEY SHARE, FOR SHARE, FOR NO KEY UPDATE, FOR UPDATE); the
  39  * next two are used for update and delete modes.
  40  */
  41 typedef enum
  42 {
  43         MultiXactStatusForKeyShare = 0x00,
  44         MultiXactStatusForShare = 0x01,
  45         MultiXactStatusForNoKeyUpdate = 0x02,
  46         MultiXactStatusForUpdate = 0x03,
  47         /* an update that doesn't touch "key" columns */
  48         MultiXactStatusNoKeyUpdate = 0x04,
  49         /* other updates, and delete */
  50         MultiXactStatusUpdate = 0x05
  51 } MultiXactStatus;
  52
  53 #define MaxMultiXactStatus MultiXactStatusUpdate
  54
  55 /* does a status value correspond to a tuple update? */
  56 #define ISUPDATE_from_mxstatus(status) \
  57                         ((status) > MultiXactStatusForUpdate)
  58
  59
  60 typedef struct MultiXactMember
  61 {
  62         TransactionId xid;
  63         MultiXactStatus status;
  64 } MultiXactMember;
  65
  66
  67 /* ----------------
  68  *              multixact-related XLOG entries
  69  * ----------------
  70  */
  71
  72 #define XLOG_MULTIXACT_ZERO_OFF_PAGE    0x00
  73 #define XLOG_MULTIXACT_ZERO_MEM_PAGE    0x10
  74 #define XLOG_MULTIXACT_CREATE_ID                0x20
  75 #define XLOG_MULTIXACT_TRUNCATE_ID              0x30
  76
  77 typedef struct xl_multixact_create
  78 {
  79         MultiXactId mid;                        /* new MultiXact's ID */
  80         MultiXactOffset moff;           /* its starting offset in members file */
  81         int32           nmembers;               /* number of member XIDs */
  82         MultiXactMember members[FLEXIBLE_ARRAY_MEMBER];
  83 } xl_multixact_create;
  84
  85 #define SizeOfMultiXactCreate (offsetof(xl_multixact_create, members))
  86
  87 typedef struct xl_multixact_truncate
  88 {
  89         Oid                     oldestMultiDB;
  90
  91         /* to-be-truncated range of multixact offsets */
  92         MultiXactId startTruncOff;      /* just for completeness' sake */
  93         MultiXactId endTruncOff;
  94
  95         /* to-be-truncated range of multixact members */
  96         MultiXactOffset startTruncMemb;
  97         MultiXactOffset endTruncMemb;
  98 } xl_multixact_truncate;
  99
 100 #define SizeOfMultiXactTruncate (sizeof(xl_multixact_truncate))
 101
 102
 103 extern MultiXactId MultiXactIdCreate(TransactionId xid1,
 104                                                                          MultiXactStatus status1, TransactionId xid2,
 105                                                                          MultiXactStatus status2);
 106 extern MultiXactId MultiXactIdExpand(MultiXactId multi, TransactionId xid,
 107                                                                          MultiXactStatus status);
 108 extern MultiXactId MultiXactIdCreateFromMembers(int nmembers,
 109                                                                                                 MultiXactMember *members);
 110
 111 extern MultiXactId ReadNextMultiXactId(void);
 112 extern void ReadMultiXactIdRange(MultiXactId *oldest, MultiXactId *next);
 113 extern bool MultiXactIdIsRunning(MultiXactId multi, bool isLockOnly);
 114 extern void MultiXactIdSetOldestMember(void);
 115 extern int      GetMultiXactIdMembers(MultiXactId multi, MultiXactMember **xids,
 116                                                                   bool allow_old, bool isLockOnly);
 117 extern bool MultiXactIdPrecedes(MultiXactId multi1, MultiXactId multi2);
 118 extern bool MultiXactIdPrecedesOrEquals(MultiXactId multi1,
 119                                                                                 MultiXactId multi2);
 120
 121 extern int      multixactoffsetssyncfiletag(const FileTag *ftag, char *path);
 122 extern int      multixactmemberssyncfiletag(const FileTag *ftag, char *path);
 123
 124 extern void AtEOXact_MultiXact(void);
 125 extern void AtPrepare_MultiXact(void);
 126 extern void PostPrepare_MultiXact(TransactionId xid);
 127
 128 extern Size MultiXactShmemSize(void);
 129 extern void MultiXactShmemInit(void);
 130 extern void BootStrapMultiXact(void);
 131 extern void StartupMultiXact(void);
 132 extern void TrimMultiXact(void);
 133 extern void SetMultiXactIdLimit(MultiXactId oldest_datminmxid,
 134                                                                 Oid oldest_datoid,
 135                                                                 bool is_startup);
 136 extern void MultiXactGetCheckptMulti(bool is_shutdown,
 137                                                                          MultiXactId *nextMulti,
 138                                                                          MultiXactOffset *nextMultiOffset,
 139                                                                          MultiXactId *oldestMulti,
 140                                                                          Oid *oldestMultiDB);
 141 extern void CheckPointMultiXact(void);
 142 extern MultiXactId GetOldestMultiXactId(void);
 143 extern void TruncateMultiXact(MultiXactId oldestMulti, Oid oldestMultiDB);
 144 extern void MultiXactSetNextMXact(MultiXactId nextMulti,
 145                                                                   MultiXactOffset nextMultiOffset);
 146 extern void MultiXactAdvanceNextMXact(MultiXactId minMulti,
 147                                                                           MultiXactOffset minMultiOffset);
 148 extern void MultiXactAdvanceOldest(MultiXactId oldestMulti, Oid oldestMultiDB);
 149 extern int      MultiXactMemberFreezeThreshold(void);
 150
 151 extern void multixact_twophase_recover(TransactionId xid, uint16 info,
 152                                                                            void *recdata, uint32 len);
 153 extern void multixact_twophase_postcommit(TransactionId xid, uint16 info,
 154                                                                                   void *recdata, uint32 len);
 155 extern void multixact_twophase_postabort(TransactionId xid, uint16 info,
 156                                                                                  void *recdata, uint32 len);
 157
 158 extern void multixact_redo(XLogReaderState *record);
 159 extern void multixact_desc(StringInfo buf, XLogReaderState *record);
 160 extern const char *multixact_identify(uint8 info);
 161 extern char *mxid_to_string(MultiXactId multi, int nmembers,
 162                                                         MultiXactMember *members);
 163
 164 #endif                                                  /* MULTIXACT_H */