txn.c

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		region->stat.st_ncommits++;
	else
		region->stat.st_naborts++;
	--region->stat.st_nactive;

	R_UNLOCK(dbenv, &mgr->reginfo);

	/*
	 * The transaction cannot get more locks, remove its locker info,
	 * if any.
	 */
	if (LOCKING_ON(dbenv) && (ret =
	    __lock_freefamilylocker(dbenv->lk_handle, txnp->txnid)) != 0)
		return (__db_panic(dbenv, ret));
	if (txnp->parent != NULL)
		TAILQ_REMOVE(&txnp->parent->kids, txnp, klinks);

	/* Free the space. */
	if (F_ISSET(txnp, TXN_MALLOC)) {
		MUTEX_THREAD_LOCK(dbenv, mgr->mutexp);
		TAILQ_REMOVE(&mgr->txn_chain, txnp, links);
		MUTEX_THREAD_UNLOCK(dbenv, mgr->mutexp);

		__os_free(dbenv, txnp);
	}

	if (do_closefiles) {
		F_SET((DB_LOG *)dbenv->lg_handle, DBLOG_RECOVER);
		(void)__dbreg_close_files(dbenv);
		F_CLR((DB_LOG *)dbenv->lg_handle, DBLOG_RECOVER);
		mgr->n_discards = 0;
		(void)dbenv->txn_checkpoint(dbenv, 0, 0, DB_FORCE);
	}
	return (0);
}

/*
 * __txn_undo --
 *	Undo the transaction with id txnid.  Returns 0 on success and
 *	errno on failure.
 */
static int
__txn_undo(txnp)
	DB_TXN *txnp;
{
	DBT rdbt;
	DB_ENV *dbenv;
	DB_LOGC *logc;
	DB_LSN key_lsn;
	DB_TXN *ptxn;
	DB_TXNMGR *mgr;
	int ret, t_ret;
	void *txnlist;

	mgr = txnp->mgrp;
	dbenv = mgr->dbenv;
	logc = NULL;
	txnlist = NULL;

	if (!DBENV_LOGGING(dbenv))
		return (0);

	/*
	 * This is the simplest way to code this, but if the mallocs during
	 * recovery turn out to be a performance issue, we can do the
	 * allocation here and use DB_DBT_USERMEM.
	 */
	memset(&rdbt, 0, sizeof(rdbt));

	key_lsn = txnp->last_lsn;

	/*
	 * Allocate a txnlist for children and aborted page allocs.
	 * We need to associate the list with the maximal parent
	 * so that aborted pages are recovered when that transaction
	 * is commited or aborted.
	 */
	for (ptxn = txnp->parent; ptxn != NULL && ptxn->parent != NULL;)
		ptxn = ptxn->parent;

	if (ptxn != NULL && ptxn->txn_list != NULL)
		txnlist = ptxn->txn_list;
	else if (txnp->txn_list != NULL)
		txnlist = txnp->txn_list;
	else if ((ret = __db_txnlist_init(dbenv, 0, 0, NULL, &txnlist)) != 0)
		return (ret);
	else if (ptxn != NULL)
		ptxn->txn_list = txnlist;

	if (F_ISSET(txnp, TXN_CHILDCOMMIT) &&
	    (ret = __db_txnlist_lsninit(dbenv, txnlist, &txnp->last_lsn)) != 0)
		return (ret);

	if ((ret = dbenv->log_cursor(dbenv, &logc, 0)) != 0)
		goto err;
	while (ret == 0 && !IS_ZERO_LSN(key_lsn)) {
		/*
		 * The dispatch routine returns the lsn of the record
		 * before the current one in the key_lsn argument.
		 */
		if ((ret = logc->get(logc, &key_lsn, &rdbt, DB_SET)) == 0) {
			ret = __db_dispatch(dbenv, dbenv->recover_dtab,
			    dbenv->recover_dtab_size, &rdbt, &key_lsn,
			    DB_TXN_ABORT, txnlist);
			if (F_ISSET(txnp, TXN_CHILDCOMMIT))
				(void)__db_txnlist_lsnadd(dbenv,
				    txnlist, &key_lsn, 0);
		}
		if (ret == DB_SURPRISE_KID) {
			if ((ret = __db_txnlist_lsninit(
			    dbenv, txnlist, &key_lsn)) == 0)
				F_SET(txnp, TXN_CHILDCOMMIT);
		} else if (ret != 0) {
			__db_err(txnp->mgrp->dbenv,
		    "DB_TXN->abort: Log undo failed for LSN: %lu %lu: %s",
			    (u_long)key_lsn.file, (u_long)key_lsn.offset,
			    db_strerror(ret));
			goto err;
		}
	}

	ret = __db_do_the_limbo(dbenv, ptxn, txnp, txnlist);

err:	if (logc != NULL && (t_ret = logc->close(logc, 0)) != 0 && ret == 0)
		ret = t_ret;

	if (ptxn == NULL && txnlist != NULL)
		__db_txnlist_end(dbenv, txnlist);
	return (ret);
}

/*
 * Transaction checkpoint.
 * If either kbytes or minutes is non-zero, then we only take the checkpoint
 * more than "minutes" minutes have passed since the last checkpoint or if
 * more than "kbytes" of log data have been written since the last checkpoint.
 * When taking a checkpoint, find the oldest active transaction and figure out
 * its first LSN.  This is the lowest LSN we can checkpoint, since any record
 * written after since that point may be involved in a transaction and may
 * therefore need to be undone in the case of an abort.
 *
 * PUBLIC: int __txn_checkpoint
 * PUBLIC:     __P((DB_ENV *, u_int32_t, u_int32_t, u_int32_t));
 */
int
__txn_checkpoint(dbenv, kbytes, minutes, flags)
	DB_ENV *dbenv;
	u_int32_t kbytes, minutes, flags;
{
	DB_LSN ckp_lsn, last_ckp;
	DB_TXNMGR *mgr;
	DB_TXNREGION *region;
	TXN_DETAIL *txnp;
	time_t last_ckp_time, now;
	u_int32_t bytes, mbytes;
	int ret;

	PANIC_CHECK(dbenv);
	ENV_REQUIRES_CONFIG(dbenv,
	    dbenv->tx_handle, "txn_checkpoint", DB_INIT_TXN);

	/*
	 * On a replication client, all transactions are read-only;  therefore,
	 * a checkpoint is a null-op.
	 *
	 * We permit txn_checkpoint, instead of just rendering it illegal,
	 * so that an application can just let a checkpoint thread continue
	 * to operate as it gets promoted or demoted between being a
	 * master and a client.
	 */
	if (F_ISSET(dbenv, DB_ENV_REP_CLIENT))
		return (0);

	mgr = dbenv->tx_handle;
	region = mgr->reginfo.primary;

	/*
	 * The checkpoint LSN is an LSN such that all transactions begun before
	 * it are complete.  Our first guess (corrected below based on the list
	 * of active transactions) is the last-written LSN.
	 */
	__log_txn_lsn(dbenv, &ckp_lsn, &mbytes, &bytes);

	if (!LF_ISSET(DB_FORCE)) {
		/* Don't checkpoint a quiescent database. */
		if (bytes == 0 && mbytes == 0)
			return (0);

		if (kbytes != 0 &&
		    mbytes * 1024 + bytes / 1024 >= (u_int32_t)kbytes)
			goto do_ckp;

		if (minutes != 0) {
			(void)time(&now);

			R_LOCK(dbenv, &mgr->reginfo);
			last_ckp_time = region->time_ckp;
			R_UNLOCK(dbenv, &mgr->reginfo);

			if (now - last_ckp_time >= (time_t)(minutes * 60))
				goto do_ckp;
		}

		/*
		 * If we checked time and data and didn't go to checkpoint,
		 * we're done.
		 */
		if (minutes != 0 || kbytes != 0)
			return (0);
	}

do_ckp:	/* Look through the active transactions for the lowest begin LSN. */
	R_LOCK(dbenv, &mgr->reginfo);
	for (txnp = SH_TAILQ_FIRST(&region->active_txn, __txn_detail);
	    txnp != NULL;
	    txnp = SH_TAILQ_NEXT(txnp, links, __txn_detail))
		if (!IS_ZERO_LSN(txnp->begin_lsn) &&
		    log_compare(&txnp->begin_lsn, &ckp_lsn) < 0)
			ckp_lsn = txnp->begin_lsn;
	R_UNLOCK(dbenv, &mgr->reginfo);

	if (MPOOL_ON(dbenv) && (ret = dbenv->memp_sync(dbenv, NULL)) != 0) {
		__db_err(dbenv,
		    "txn_checkpoint: failed to flush the buffer cache %s",
		    db_strerror(ret));
		return (ret);
	}

	/*
	 * Because we can't be a replication client here, and because
	 * recovery (somewhat unusually) calls txn_checkpoint and expects
	 * it to write a log message, LOGGING_ON is the correct macro here.
	 */
	if (LOGGING_ON(dbenv)) {
		R_LOCK(dbenv, &mgr->reginfo);
		last_ckp = region->last_ckp;
		R_UNLOCK(dbenv, &mgr->reginfo);

		/*
		 * Put out records for the open files before we log
		 * the checkpoint.  The records are certain to be at
		 * or after ckp_lsn, but before the checkpoint record
		 * itself, so they're sure to be included if we start
		 * recovery from the ckp_lsn contained in this
		 * checkpoint.
		 */
		if ((ret = __dbreg_open_files(dbenv)) != 0 ||
		    (ret = __txn_ckp_log(dbenv,
		    NULL, &ckp_lsn, DB_PERMANENT | DB_FLUSH, &ckp_lsn,
		    &last_ckp, (int32_t)time(NULL))) != 0) {
			__db_err(dbenv,
			    "txn_checkpoint: log failed at LSN [%ld %ld] %s",
			    (long)ckp_lsn.file, (long)ckp_lsn.offset,
			    db_strerror(ret));
			return (ret);
		}

		__txn_updateckp(dbenv, &ckp_lsn);
	}
	return (0);
}

/*
 * __txn_getckp --
 *	Get the LSN of the last transaction checkpoint.
 *
 * PUBLIC: int __txn_getckp __P((DB_ENV *, DB_LSN *));
 */
int
__txn_getckp(dbenv, lsnp)
	DB_ENV *dbenv;
	DB_LSN *lsnp;
{
	DB_LSN lsn;
	DB_TXNMGR *mgr;
	DB_TXNREGION *region;

	mgr = dbenv->tx_handle;
	region = mgr->reginfo.primary;

	R_LOCK(dbenv, &mgr->reginfo);
	lsn = region->last_ckp;
	R_UNLOCK(dbenv, &mgr->reginfo);

	if (IS_ZERO_LSN(lsn))
		return (DB_NOTFOUND);

	*lsnp = lsn;
	return (0);
}

/*
 * __txn_activekids --
 *	Return if this transaction has any active children.
 *
 * PUBLIC: int __txn_activekids __P((DB_ENV *, u_int32_t, DB_TXN *));
 */
int
__txn_activekids(dbenv, rectype, txnp)
	DB_ENV *dbenv;
	u_int32_t rectype;
	DB_TXN *txnp;
{
	/*
	 * On a child commit, we know that there are children (i.e., the
	 * commiting child at the least.  In that case, skip this check.
	 */
	if (F_ISSET(txnp, TXN_COMPENSATE) || rectype == DB___txn_child)
		return (0);

	if (TAILQ_FIRST(&txnp->kids) != NULL) {
		__db_err(dbenv, "Child transaction is active");
		return (EPERM);
	}
	return (0);
}

/*
 * __txn_force_abort --
 *	Force an abort record into the log if the commit record
 *	failed to get to disk.
 *
 * PUBLIC: int __txn_force_abort __P((DB_ENV *, u_int8_t *));
 */
int
__txn_force_abort(dbenv, buffer)
	DB_ENV *dbenv;
	u_int8_t *buffer;
{
	DB_CIPHER *db_cipher;
	HDR *hdr;
	u_int32_t offset, opcode, rec_len, rec_type, sum_len;
	u_int8_t *bp, *key, chksum[DB_MAC_KEY];
	size_t hdrsize;
	int ret;

	db_cipher = dbenv->crypto_handle;

	/*
	 * This routine depends on the layout of HDR and the __txn_regop
	 * record in txn.src.  We are passed the beginning of the commit
	 * record in the log buffer and overwrite the commit with an abort
	 * and recalculate the checksum.  We may be passed a txn_xa_regop
	 * that is, an XA prepare), there's no need to overwrite that one.
	 */
	hdr = (HDR *)buffer;
	memcpy(&rec_type, hdr, sizeof(rec_type));
	if (rec_type == DB___txn_xa_regop)
		return (0);

	offset = sizeof(u_int32_t) + sizeof(u_int32_t) + sizeof(DB_LSN);
	rec_len = offset + sizeof(u_int32_t) + sizeof(int32_t);
	if (CRYPTO_ON(dbenv)) {
		key = db_cipher->mac_key;
		hdrsize = HDR_CRYPTO_SZ;
		sum_len = DB_MAC_KEY;
		if ((ret = db_cipher->decrypt(dbenv, db_cipher->data,
		    &hdr->iv[0], buffer + hdrsize, rec_len)) != 0)
			return (__db_panic(dbenv, ret));
	} else {
		key = NULL;
		hdrsize = HDR_NORMAL_SZ;
		sum_len = sizeof(u_int32_t);
	}
	bp = buffer + hdrsize + offset;
	opcode = TXN_ABORT;
	memcpy(bp, &opcode, sizeof(opcode));

	if (CRYPTO_ON(dbenv) &&
	    (ret = db_cipher->encrypt(dbenv,
	    db_cipher->data, &hdr->iv[0], buffer + hdrsize, rec_len)) != 0)
		return (__db_panic(dbenv, ret));

	__db_chksum(buffer + hdrsize, rec_len, key, chksum);
	memcpy(buffer + SSZ(HDR, chksum), &chksum, sum_len);

	return (0);
}

/*
 * __txn_preclose
 *	Before we can close an environment, we need to check if we
 * were in the midst of taking care of restored transactions.  If
 * so, then we need to close the files that we opened.
 *
 * PUBLIC: int __txn_preclose __P((DB_ENV *));
 */
int
__txn_preclose(dbenv)
	DB_ENV *dbenv;
{
	DB_TXNMGR *mgr;
	DB_TXNREGION *region;
	int do_closefiles, ret;

	mgr = (DB_TXNMGR *)dbenv->tx_handle;
	region = mgr->reginfo.primary;
	do_closefiles = 0;

	R_LOCK(dbenv, &mgr->reginfo);
	if (region != NULL &&
	    region->stat.st_nrestores
	    <= mgr->n_discards && mgr->n_discards != 0)
		do_closefiles = 1;
	R_UNLOCK(dbenv, &mgr->reginfo);

	if (do_closefiles) {
		/*
		 * Set the DBLOG_RECOVER flag while closing these
		 * files so they do not create additional log records
		 * that will confuse future recoveries.
		 */
		F_SET((DB_LOG *)dbenv->lg_handle, DBLOG_RECOVER);
		ret = __dbreg_close_files(dbenv);
		F_CLR((DB_LOG *)dbenv->lg_handle, DBLOG_RECOVER);
	} else
		ret = 0;

	return (ret);
}

/*
 * __txn_reset --
 *	Reset the last txnid to its minimum value, and log the reset.
 *
 * PUBLIC: int __txn_reset __P((DB_ENV *));
 */
int
__txn_reset(dbenv)
	DB_ENV *dbenv;
{
	DB_LSN scrap;
	DB_TXNREGION *region;

	region = ((DB_TXNMGR *)dbenv->tx_handle)->reginfo.primary;
	region->last_txnid = TXN_MINIMUM;

	DB_ASSERT(LOGGING_ON(dbenv));
	return (__txn_recycle_log(dbenv,
	    NULL, &scrap, 0, TXN_MINIMUM, TXN_MAXIMUM));
}

/*
 * __txn_updateckp --
 *	Update the last_ckp field in the transaction region.  This happens
 * at the end of a normal checkpoint and also when a replication client
 * receives a checkpoint record.
 *
 * PUBLIC: void __txn_updateckp __P((DB_ENV *, DB_LSN *));
 */
void
__txn_updateckp(dbenv, lsnp)
	DB_ENV *dbenv;
	DB_LSN *lsnp;
{
	DB_TXNMGR *mgr;
	DB_TXNREGION *region;

	mgr = dbenv->tx_handle;
	region = mgr->reginfo.primary;

	/*
	 * We want to make sure last_ckp only moves forward;  since
	 * we drop locks above and in log_put, it's possible
	 * for two calls to __txn_ckp_log to finish in a different
	 * order from how they were called.
	 */
	R_LOCK(dbenv, &mgr->reginfo);
	if (log_compare(&region->last_ckp, lsnp) < 0) {
		region->last_ckp = *lsnp;
		(void)time(&region->time_ckp);
	}
	R_UNLOCK(dbenv, &mgr->reginfo);
}