db2/include/txn.h

   1 /*-
   2  * See the file LICENSE for redistribution information.
   3  *
   4  * Copyright (c) 1996, 1997, 1998
   5  *      Sleepycat Software.  All rights reserved.
   6  *
   7  *      @(#)txn.h       10.15 (Sleepycat) 4/21/98
   8  */
   9 #ifndef _TXN_H_
  10 #define _TXN_H_
  11
  12 /*
  13  * The name of the transaction shared memory region is DEFAULT_TXN_FILE and
  14  * the region is always created group RW of the group owning the directory.
  15  */
  16 #define DEFAULT_TXN_FILE        "__db_txn.share"
  17 /* TXN_MINIMUM = (DB_LOCK_MAXID + 1) but this makes compilers complain. */
  18 #define TXN_MINIMUM             0x80000000
  19 #define TXN_INVALID             0xffffffff /* Maximum number of txn ids. */
  20
  21 /*
  22  * Transaction type declarations.
  23  */
  24
  25 /*
  26  * Internal data maintained in shared memory for each transaction.
  27  */
  28 typedef struct __txn_detail {
  29         u_int32_t txnid;                /* current transaction id
  30                                            used to link free list also */
  31         DB_LSN  last_lsn;               /* last lsn written for this txn */
  32         DB_LSN  begin_lsn;              /* lsn of begin record */
  33         size_t  last_lock;              /* offset in lock region of last lock
  34                                            for this transaction. */
  35 #define TXN_UNALLOC     0
  36 #define TXN_RUNNING     1
  37 #define TXN_ABORTED     2
  38 #define TXN_PREPARED    3
  39         u_int32_t status;               /* status of the transaction */
  40         SH_TAILQ_ENTRY  links;          /* free/active list */
  41 } TXN_DETAIL;
  42
  43 /*
  44  * The transaction manager encapsulates the transaction system.  It contains
  45  * references to the log and lock managers as well as the state that keeps
  46  * track of the shared memory region.
  47  */
  48 struct __db_txnmgr {
  49 /* These fields need to be protected for multi-threaded support. */
  50         db_mutex_t      *mutexp;        /* Synchronization. */
  51                                         /* list of active transactions */
  52         TAILQ_HEAD(_chain, __db_txn)    txn_chain;
  53
  54 /* These fields are not protected. */
  55         REGINFO         reginfo;        /* Region information. */
  56         DB_ENV          *dbenv;         /* Environment. */
  57         int (*recover)                  /* Recovery dispatch routine */
  58             __P((DB_LOG *, DBT *, DB_LSN *, int, void *));
  59         u_int32_t        flags;         /* DB_TXN_NOSYNC, DB_THREAD */
  60         DB_TXNREGION    *region;        /* address of shared memory region */
  61         void            *mem;           /* address of the shalloc space */
  62 };
  63
  64 /*
  65  * Layout of the shared memory region.
  66  * The region consists of a DB_TXNREGION structure followed by a large
  67  * pool of shalloc'd memory which is used to hold TXN_DETAIL structures
  68  * and thread mutexes (which are dynamically allocated).
  69  */
  70 struct __db_txnregion {
  71         RLAYOUT         hdr;            /* Shared memory region header. */
  72         u_int32_t       magic;          /* transaction magic number */
  73         u_int32_t       version;        /* version number */
  74         u_int32_t       maxtxns;        /* maximum number of active txns */
  75         u_int32_t       last_txnid;     /* last transaction id given out */
  76         DB_LSN          pending_ckp;    /* last checkpoint did not finish */
  77         DB_LSN          last_ckp;       /* lsn of the last checkpoint */
  78         time_t          time_ckp;       /* time of last checkpoint */
  79         u_int32_t       logtype;        /* type of logging */
  80         u_int32_t       locktype;       /* lock type */
  81         u_int32_t       naborts;        /* number of aborted transactions */
  82         u_int32_t       ncommits;       /* number of committed transactions */
  83         u_int32_t       nbegins;        /* number of begun transactions */
  84         SH_TAILQ_HEAD(_active) active_txn;      /* active transaction list */
  85 };
  86
  87 /*
  88  * Make the region large enough to hold N  transaction detail structures
  89  * plus some space to hold thread handles and the beginning of the shalloc
  90  * region.
  91  */
  92 #define TXN_REGION_SIZE(N)                                              \
  93         (sizeof(DB_TXNREGION) + N * sizeof(TXN_DETAIL) + 1000)
  94
  95 /* Macros to lock/unlock the region and threads. */
  96 #define LOCK_TXNTHREAD(tmgrp)                                           \
  97         if (F_ISSET(tmgrp, DB_THREAD))                                  \
  98                 (void)__db_mutex_lock((tmgrp)->mutexp, -1)
  99 #define UNLOCK_TXNTHREAD(tmgrp)                                         \
 100         if (F_ISSET(tmgrp, DB_THREAD))                                  \
 101                 (void)__db_mutex_unlock((tmgrp)->mutexp, -1)
 102
 103 #define LOCK_TXNREGION(tmgrp)                                           \
 104         (void)__db_mutex_lock(&(tmgrp)->region->hdr.lock, (tmgrp)->reginfo.fd)
 105 #define UNLOCK_TXNREGION(tmgrp)                                         \
 106         (void)__db_mutex_unlock(&(tmgrp)->region->hdr.lock, (tmgrp)->reginfo.fd)
 107
 108 /*
 109  * Log record types.
 110  */
 111 #define TXN_COMMIT      1
 112 #define TXN_PREPARE     2
 113 #define TXN_CHECKPOINT  3
 114
 115 #include "txn_auto.h"
 116 #include "txn_ext.h"
 117 #endif /* !_TXN_H_ */