240 lines
7.6 KiB
C
240 lines
7.6 KiB
C
/*-
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* See the file LICENSE for redistribution information.
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*
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* Copyright (c) 1996,2008 Oracle. All rights reserved.
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*
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* $Id: txn.h 63573 2008-05-23 21:43:21Z trent.nelson $
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*/
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#ifndef _DB_TXN_H_
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#define _DB_TXN_H_
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#include "dbinc/xa.h"
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#if defined(__cplusplus)
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extern "C" {
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#endif
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/* Operation parameters to the delayed commit processing code. */
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typedef enum {
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TXN_CLOSE, /* Close a DB handle whose close had failed. */
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TXN_REMOVE, /* Remove a file. */
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TXN_TRADE, /* Trade lockers. */
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TXN_TRADED /* Already traded; downgrade lock. */
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} TXN_EVENT_T;
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struct __db_txnregion; typedef struct __db_txnregion DB_TXNREGION;
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struct __txn_logrec; typedef struct __txn_logrec DB_TXNLOGREC;
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/*
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* !!!
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* TXN_MINIMUM = (DB_LOCK_MAXID + 1) but this makes compilers complain.
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*/
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#define TXN_MINIMUM 0x80000000
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#define TXN_MAXIMUM 0xffffffff /* Maximum number of txn ids. */
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#define TXN_INVALID 0 /* Invalid transaction ID. */
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#define DEF_MAX_TXNS 100 /* Default max transactions. */
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#define TXN_NSLOTS 4 /* Initial slots to hold DB refs */
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/*
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* Internal data maintained in shared memory for each transaction.
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*/
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typedef struct __txn_detail {
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u_int32_t txnid; /* current transaction id
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used to link free list also */
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pid_t pid; /* Process owning txn */
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db_threadid_t tid; /* Thread owning txn */
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DB_LSN last_lsn; /* Last LSN written for this txn. */
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DB_LSN begin_lsn; /* LSN of begin record. */
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roff_t parent; /* Offset of transaction's parent. */
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roff_t name; /* Offset of txn name. */
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u_int32_t nlog_dbs; /* Number of databases used. */
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u_int32_t nlog_slots; /* Number of allocated slots. */
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roff_t log_dbs; /* Databases used. */
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DB_LSN read_lsn; /* Read LSN for MVCC. */
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DB_LSN visible_lsn; /* LSN at which this transaction's
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changes are visible. */
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db_mutex_t mvcc_mtx; /* Version mutex. */
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u_int32_t mvcc_ref; /* Number of buffers created by this
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transaction still in cache. */
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SH_TAILQ_HEAD(__tdkids) kids; /* Linked list of child txn detail. */
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SH_TAILQ_ENTRY klinks;
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/* TXN_{ABORTED, COMMITTED PREPARED, RUNNING} */
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u_int32_t status; /* status of the transaction */
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#define TXN_DTL_COLLECTED 0x1 /* collected during txn_recover */
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#define TXN_DTL_RESTORED 0x2 /* prepared txn restored */
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#define TXN_DTL_INMEMORY 0x4 /* uses in memory logs */
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u_int32_t flags;
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/* TXN_XA_{ABORTED, DEADLOCKED, ENDED, PREPARED, STARTED, SUSPENDED} */
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SH_TAILQ_ENTRY links; /* active/free/snapshot list */
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u_int32_t xa_status; /* XA status */
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/*
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* XID (xid_t) structure: because these fields are logged, the
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* sizes have to be explicit.
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*/
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u_int8_t xid[XIDDATASIZE]; /* XA global transaction id */
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u_int32_t bqual; /* bqual_length from XID */
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u_int32_t gtrid; /* gtrid_length from XID */
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int32_t format; /* XA format */
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roff_t slots[TXN_NSLOTS]; /* Initial DB slot allocation. */
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} TXN_DETAIL;
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/*
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* DB_TXNMGR --
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* The transaction manager encapsulates the transaction system.
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*/
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struct __db_txnmgr {
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/*
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* These fields need to be protected for multi-threaded support.
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*
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* Lock list of active transactions (including the content of each
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* TXN_DETAIL structure on the list).
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*/
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db_mutex_t mutex;
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/* List of active transactions. */
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TAILQ_HEAD(_chain, __db_txn) txn_chain;
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u_int32_t n_discards; /* Number of txns discarded. */
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/* These fields are never updated after creation, so not protected. */
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ENV *env; /* Environment. */
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REGINFO reginfo; /* Region information. */
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};
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/* Macros to lock/unlock the transaction region as a whole. */
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#define TXN_SYSTEM_LOCK(env) \
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MUTEX_LOCK(env, ((DB_TXNREGION *) \
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(env)->tx_handle->reginfo.primary)->mtx_region)
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#define TXN_SYSTEM_UNLOCK(env) \
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MUTEX_UNLOCK(env, ((DB_TXNREGION *) \
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(env)->tx_handle->reginfo.primary)->mtx_region)
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/*
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* DB_TXNREGION --
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* The primary transaction data structure in the shared memory region.
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*/
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struct __db_txnregion {
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db_mutex_t mtx_region; /* Region mutex. */
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u_int32_t maxtxns; /* maximum number of active TXNs */
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u_int32_t last_txnid; /* last transaction id given out */
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u_int32_t cur_maxid; /* current max unused id. */
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db_mutex_t mtx_ckp; /* Single thread checkpoints. */
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DB_LSN last_ckp; /* lsn of the last checkpoint */
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time_t time_ckp; /* time of last checkpoint */
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DB_TXN_STAT stat; /* Statistics for txns. */
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#define TXN_IN_RECOVERY 0x01 /* environment is being recovered */
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u_int32_t flags;
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/* active TXN list */
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SH_TAILQ_HEAD(__active) active_txn;
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SH_TAILQ_HEAD(__mvcc) mvcc_txn;
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};
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/*
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* DB_TXNLOGREC --
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* An in-memory, linked-list copy of a log record.
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*/
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struct __txn_logrec {
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STAILQ_ENTRY(__txn_logrec) links;/* Linked list. */
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u_int8_t data[1]; /* Log record. */
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};
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/*
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* Log record types. Note that these are *not* alphabetical. This is
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* intentional so that we don't change the meaning of values between
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* software upgrades.
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*
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* EXPECTED, UNEXPECTED, IGNORE, and OK are used in the txnlist functions.
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* Here is an explanation of how the statuses are used.
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*
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* TXN_OK
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* BEGIN records for transactions found on the txnlist during
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* OPENFILES (BEGIN records are those with a prev_lsn of 0,0)
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*
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* TXN_COMMIT
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* Transaction committed and should be rolled forward.
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*
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* TXN_ABORT
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* This transaction's changes must be undone. Either there was
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* never a prepare or commit record for this transaction OR there
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* was a commit, but we are recovering to a timestamp or particular
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* LSN and that point is before this transaction's commit.
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*
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* TXN_PREPARE
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* Prepare record, but no commit record is in the log.
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*
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* TXN_IGNORE
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* Generic meaning is that this transaction should not be
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* processed during later recovery passes. We use it in a
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* number of different manners:
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*
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* 1. We never saw its BEGIN record. Therefore, the logs have
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* been reclaimed and we *know* that this transaction doesn't
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* need to be aborted, because in order for it to be
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* reclaimed, there must have been a subsequent checkpoint
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* (and any dirty pages for this transaction made it to
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* disk).
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*
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* 2. This is a child transaction that created a database.
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* For some reason, we don't want to recreate that database
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* (i.e., it already exists or some other database created
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* after it exists).
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*
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* 3. During recovery open of subdatabases, if the master check fails,
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* we use a TXN_IGNORE on the create of the subdb in the nested
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* transaction.
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*
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* 4. During a remove, the file with the name being removed isn't
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* the file for which we are recovering a remove.
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*
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* TXN_EXPECTED
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* After a successful open during recovery, we update the
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* transaction's status to TXN_EXPECTED. The open was done
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* in the parent, but in the open log record, we record the
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* child transaction's ID if we also did a create. When there
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* is a valid ID in that field, we use it and mark the child's
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* status as TXN_EXPECTED (indicating that we don't need to redo
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* a create for this file).
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*
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* When recovering a remove, if we don't find or can't open
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* the file, the child (which does the remove) gets marked
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* EXPECTED (indicating that we don't need to redo the remove).
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*
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* TXN_UNEXPECTED
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* During recovery, we attempted an open that should have succeeded
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* and we got ENOENT, so like with the EXPECTED case, we indicate
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* in the child that we got the UNEXPECTED return so that we do redo
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* the creating/deleting operation.
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*
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*/
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#define TXN_OK 0
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#define TXN_COMMIT 1
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#define TXN_PREPARE 2
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#define TXN_ABORT 3
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#define TXN_IGNORE 4
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#define TXN_EXPECTED 5
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#define TXN_UNEXPECTED 6
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#if defined(__cplusplus)
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}
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#endif
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#include "dbinc_auto/txn_auto.h"
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#include "dbinc_auto/txn_ext.h"
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#include "dbinc_auto/xa_ext.h"
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#endif /* !_DB_TXN_H_ */
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