/*- * See the file LICENSE for redistribution information. * * Copyright (c) 1996,2008 Oracle. All rights reserved. * * $Id: txn.h,v 12.20 2008/01/08 20:58:18 bostic Exp $ */ #ifndef _DB_TXN_H_ #define _DB_TXN_H_ #include "dbinc/xa.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 */ u_int32_t flags; /* TXN_XA_{ABORTED, DEADLOCKED, ENDED, PREPARED, STARTED, SUSPENDED} */ SH_TAILQ_ENTRY links; /* active/free/snapshot list */ u_int32_t xa_status; /* XA status */ /* * XID (xid_t) structure: because these fields are logged, the * sizes have to be explicit. */ u_int8_t xid[XIDDATASIZE]; /* XA global transaction id */ u_int32_t bqual; /* bqual_length from XID */ u_int32_t gtrid; /* gtrid_length from XID */ int32_t format; /* XA format */ 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" #include "dbinc_auto/xa_ext.h" #endif /* !_DB_TXN_H_ */