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/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1996-2009 Oracle. All rights reserved.
*
* $Id$
*/
#ifndef _DB_TXN_H_
#define _DB_TXN_H_
#if defined(__cplusplus)
extern "C" {
#endif
/* Operation parameters to the delayed commit processing code. */
typedef enum {
TXN_CLOSE, /* Close a DB handle whose close had failed. */
TXN_REMOVE, /* Remove a file. */
TXN_TRADE, /* Trade lockers. */
TXN_TRADED /* Already traded; downgrade lock. */
} TXN_EVENT_T;
struct __db_txnregion; typedef struct __db_txnregion DB_TXNREGION;
struct __txn_logrec; typedef struct __txn_logrec DB_TXNLOGREC;
/*
* !!!
* TXN_MINIMUM = (DB_LOCK_MAXID + 1) but this makes compilers complain.
*/
#define TXN_MINIMUM 0x80000000
#define TXN_MAXIMUM 0xffffffff /* Maximum number of txn ids. */
#define TXN_INVALID 0 /* Invalid transaction ID. */
#define DEF_MAX_TXNS 100 /* Default max transactions. */
#define TXN_NSLOTS 4 /* Initial slots to hold DB refs */
/*
* Internal data maintained in shared memory for each transaction.
*/
typedef struct __txn_detail {
u_int32_t txnid; /* current transaction id
used to link free list also */
pid_t pid; /* Process owning txn */
db_threadid_t tid; /* Thread owning txn */
DB_LSN last_lsn; /* Last LSN written for this txn. */
DB_LSN begin_lsn; /* LSN of begin record. */
roff_t parent; /* Offset of transaction's parent. */
roff_t name; /* Offset of txn name. */
u_int32_t nlog_dbs; /* Number of databases used. */
u_int32_t nlog_slots; /* Number of allocated slots. */
roff_t log_dbs; /* Databases used. */
DB_LSN read_lsn; /* Read LSN for MVCC. */
DB_LSN visible_lsn; /* LSN at which this transaction's
changes are visible. */
db_mutex_t mvcc_mtx; /* Version mutex. */
u_int32_t mvcc_ref; /* Number of buffers created by this
transaction still in cache. */
SH_TAILQ_HEAD(__tdkids) kids; /* Linked list of child txn detail. */
SH_TAILQ_ENTRY klinks;
/* TXN_{ABORTED, COMMITTED PREPARED, RUNNING} */
u_int32_t status; /* status of the transaction */
#define TXN_DTL_COLLECTED 0x1 /* collected during txn_recover */
#define TXN_DTL_RESTORED 0x2 /* prepared txn restored */
#define TXN_DTL_INMEMORY 0x4 /* uses in memory logs */
#define TXN_DTL_SNAPSHOT 0x8 /* On the list of snapshot txns. */
u_int32_t flags;
SH_TAILQ_ENTRY links; /* active/free/snapshot list */
u_int8_t gid[DB_GID_SIZE]; /* global transaction id */
roff_t slots[TXN_NSLOTS]; /* Initial DB slot allocation. */
} TXN_DETAIL;
/*
* DB_TXNMGR --
* The transaction manager encapsulates the transaction system.
*/
struct __db_txnmgr {
/*
* These fields need to be protected for multi-threaded support.
*
* Lock list of active transactions (including the content of each
* TXN_DETAIL structure on the list).
*/
db_mutex_t mutex;
/* List of active transactions. */
TAILQ_HEAD(_chain, __db_txn) txn_chain;
u_int32_t n_discards; /* Number of txns discarded. */
/* These fields are never updated after creation, so not protected. */
ENV *env; /* Environment. */
REGINFO reginfo; /* Region information. */
};
/* Macros to lock/unlock the transaction region as a whole. */
#define TXN_SYSTEM_LOCK(env) \
MUTEX_LOCK(env, ((DB_TXNREGION *) \
(env)->tx_handle->reginfo.primary)->mtx_region)
#define TXN_SYSTEM_UNLOCK(env) \
MUTEX_UNLOCK(env, ((DB_TXNREGION *) \
(env)->tx_handle->reginfo.primary)->mtx_region)
/*
* DB_TXNREGION --
* The primary transaction data structure in the shared memory region.
*/
struct __db_txnregion {
db_mutex_t mtx_region; /* Region mutex. */
u_int32_t maxtxns; /* maximum number of active TXNs */
u_int32_t last_txnid; /* last transaction id given out */
u_int32_t cur_maxid; /* current max unused id. */
db_mutex_t mtx_ckp; /* Single thread checkpoints. */
DB_LSN last_ckp; /* lsn of the last checkpoint */
time_t time_ckp; /* time of last checkpoint */
DB_TXN_STAT stat; /* Statistics for txns. */
#define TXN_IN_RECOVERY 0x01 /* environment is being recovered */
u_int32_t flags;
/* active TXN list */
SH_TAILQ_HEAD(__active) active_txn;
SH_TAILQ_HEAD(__mvcc) mvcc_txn;
};
/*
* DB_TXNLOGREC --
* An in-memory, linked-list copy of a log record.
*/
struct __txn_logrec {
STAILQ_ENTRY(__txn_logrec) links;/* Linked list. */
u_int8_t data[1]; /* Log record. */
};
/*
* Log record types. Note that these are *not* alphabetical. This is
* intentional so that we don't change the meaning of values between
* software upgrades.
*
* EXPECTED, UNEXPECTED, IGNORE, and OK are used in the txnlist functions.
* Here is an explanation of how the statuses are used.
*
* TXN_OK
* BEGIN records for transactions found on the txnlist during
* OPENFILES (BEGIN records are those with a prev_lsn of 0,0)
*
* TXN_COMMIT
* Transaction committed and should be rolled forward.
*
* TXN_ABORT
* This transaction's changes must be undone. Either there was
* never a prepare or commit record for this transaction OR there
* was a commit, but we are recovering to a timestamp or particular
* LSN and that point is before this transaction's commit.
*
* TXN_PREPARE
* Prepare record, but no commit record is in the log.
*
* TXN_IGNORE
* Generic meaning is that this transaction should not be
* processed during later recovery passes. We use it in a
* number of different manners:
*
* 1. We never saw its BEGIN record. Therefore, the logs have
* been reclaimed and we *know* that this transaction doesn't
* need to be aborted, because in order for it to be
* reclaimed, there must have been a subsequent checkpoint
* (and any dirty pages for this transaction made it to
* disk).
*
* 2. This is a child transaction that created a database.
* For some reason, we don't want to recreate that database
* (i.e., it already exists or some other database created
* after it exists).
*
* 3. During recovery open of subdatabases, if the master check fails,
* we use a TXN_IGNORE on the create of the subdb in the nested
* transaction.
*
* 4. During a remove, the file with the name being removed isn't
* the file for which we are recovering a remove.
*
* TXN_EXPECTED
* After a successful open during recovery, we update the
* transaction's status to TXN_EXPECTED. The open was done
* in the parent, but in the open log record, we record the
* child transaction's ID if we also did a create. When there
* is a valid ID in that field, we use it and mark the child's
* status as TXN_EXPECTED (indicating that we don't need to redo
* a create for this file).
*
* When recovering a remove, if we don't find or can't open
* the file, the child (which does the remove) gets marked
* EXPECTED (indicating that we don't need to redo the remove).
*
* TXN_UNEXPECTED
* During recovery, we attempted an open that should have succeeded
* and we got ENOENT, so like with the EXPECTED case, we indicate
* in the child that we got the UNEXPECTED return so that we do redo
* the creating/deleting operation.
*
*/
#define TXN_OK 0
#define TXN_COMMIT 1
#define TXN_PREPARE 2
#define TXN_ABORT 3
#define TXN_IGNORE 4
#define TXN_EXPECTED 5
#define TXN_UNEXPECTED 6
#if defined(__cplusplus)
}
#endif
#include "dbinc_auto/txn_auto.h"
#include "dbinc_auto/txn_ext.h"
#endif /* !_DB_TXN_H_ */
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