src/include/storage/lockdefs.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * lockdefs.h
   4  *         Frontend exposed parts of postgres' low level lock mechanism
   5  *
   6  * The split between lockdefs.h and lock.h is not very principled. This file
   7  * contains definition that have to (indirectly) be available when included by
   8  * FRONTEND code.
   9  *
  10  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
  11  * Portions Copyright (c) 1994, Regents of the University of California
  12  *
  13  * src/include/storage/lockdefs.h
  14  *
  15  *-------------------------------------------------------------------------
  16  */
  17 #ifndef LOCKDEFS_H_
  18 #define LOCKDEFS_H_
  19
  20 /*
  21  * LOCKMODE is an integer (1..N) indicating a lock type.  LOCKMASK is a bit
  22  * mask indicating a set of held or requested lock types (the bit 1<<mode
  23  * corresponds to a particular lock mode).
  24  */
  25 typedef int LOCKMASK;
  26 typedef int LOCKMODE;
  27
  28 /*
  29  * These are the valid values of type LOCKMODE for all the standard lock
  30  * methods (both DEFAULT and USER).
  31  */
  32
  33 /* NoLock is not a lock mode, but a flag value meaning "don't get a lock" */
  34 #define NoLock                                  0
  35
  36 #define AccessShareLock                 1       /* SELECT */
  37 #define RowShareLock                    2       /* SELECT FOR UPDATE/FOR SHARE */
  38 #define RowExclusiveLock                3       /* INSERT, UPDATE, DELETE */
  39 #define ShareUpdateExclusiveLock 4      /* VACUUM (non-FULL), ANALYZE, CREATE
  40                                                                          * INDEX CONCURRENTLY */
  41 #define ShareLock                               5       /* CREATE INDEX (WITHOUT CONCURRENTLY) */
  42 #define ShareRowExclusiveLock   6       /* like EXCLUSIVE MODE, but allows ROW
  43                                                                          * SHARE */
  44 #define ExclusiveLock                   7       /* blocks ROW SHARE/SELECT...FOR UPDATE */
  45 #define AccessExclusiveLock             8       /* ALTER TABLE, DROP TABLE, VACUUM FULL,
  46                                                                          * and unqualified LOCK TABLE */
  47
  48 #define MaxLockMode                             8       /* highest standard lock mode */
  49
  50 /* See README.tuplock section "Locking to write inplace-updated tables" */
  51 #define InplaceUpdateTupleLock ExclusiveLock
  52
  53 /* WAL representation of an AccessExclusiveLock on a table */
  54 typedef struct xl_standby_lock
  55 {
  56         TransactionId xid;                      /* xid of holder of AccessExclusiveLock */
  57         Oid                     dbOid;                  /* DB containing table */
  58         Oid                     relOid;                 /* OID of table */
  59 } xl_standby_lock;
  60
  61 #endif                                                  /* LOCKDEFS_H_ */