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-rw-r--r--db2/txn/txn.c809
1 files changed, 809 insertions, 0 deletions
diff --git a/db2/txn/txn.c b/db2/txn/txn.c
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+++ b/db2/txn/txn.c
@@ -0,0 +1,809 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996, 1997
+ *	Sleepycat Software.  All rights reserved.
+ */
+/*
+ * Copyright (c) 1995, 1996
+ *	The President and Fellows of Harvard University.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Margo Seltzer.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include "config.h"
+
+#ifndef lint
+static const char sccsid[] = "@(#)txn.c	10.20 (Sleepycat) 8/24/97";
+#endif /* not lint */
+
+
+/*
+ * This file contains the top level routines of the transaction library.
+ * It assumes that a lock manager and log manager that conform to the db_log(3)
+ * and db_lock(3) interfaces exist.
+ */
+
+#ifndef NO_SYSTEM_INCLUDES
+#include <sys/types.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#endif
+
+#include "shqueue.h"
+#include "db_int.h"
+#include "db_page.h"
+#include "db_shash.h"
+#include "txn.h"
+#include "db_dispatch.h"
+#include "lock.h"
+#include "log.h"
+#include "db_am.h"
+#include "common_ext.h"
+
+static int __txn_check_running __P((const DB_TXN *));
+
+static int	__txn_create __P((DB_ENV *, const char *, u_int));
+static int	__txn_grow_region __P((DB_TXNMGR *));
+static int	__txn_validate_region __P((DB_TXNMGR *));
+static int      __txn_end __P((DB_TXN *, int));
+static int      __txn_undo __P((DB_TXN *));
+
+/*
+ * Create and initialize a transaction region in shared memory.
+ * 0 means, success.
+ * +1 means that the db_create failed, so we did not create the region.
+ * -1 means that we got some sort of system error.
+ */
+static int
+__txn_create(dbenv, path, mode)
+	DB_ENV *dbenv;
+	const char *path;
+	u_int mode;
+{
+	DB_TXNREGION *txn_region;
+	TXN_DETAIL *txnp;
+	time_t now;
+	int fd, i, maxtxns, ret;
+
+	maxtxns = dbenv->tx_max != 0 ? dbenv->tx_max : 1000;
+	(void)time(&now);
+
+	ret = __db_rcreate(dbenv, DB_APP_NONE, path,
+	    DEFAULT_TXN_FILE, mode, TXN_REGION_SIZE(maxtxns), &fd, &txn_region);
+
+	/* Region may have existed.  If it didn't, the open will fail. */
+	if (ret != 0)
+		return (ret);
+
+	txn_region->magic = DB_TXNMAGIC;
+	txn_region->version = DB_TXNVERSION;
+	txn_region->maxtxns = maxtxns;
+	txn_region->last_txnid = TXN_MINIMUM;
+	/* XXX If we ever do more types of locking and logging, this changes. */
+	txn_region->logtype = 0;
+	txn_region->locktype = 0;
+	txn_region->free_txn = 0;
+	txn_region->time_ckp = now;
+	ZERO_LSN(txn_region->last_ckp);
+	ZERO_LSN(txn_region->pending_ckp);
+
+	for (txnp = &txn_region->table[0], i = 0; i < maxtxns; i++, txnp++) {
+		ZERO_LSN(txnp->begin_lsn);
+		txnp->status = TXN_UNALLOC;
+		txnp->txnid = i + 1;
+	}
+	txn_region->table[maxtxns - 1].txnid = TXN_INVALID;
+
+	/* Unlock the region. */
+	(void)__db_mutex_unlock(&txn_region->hdr.lock, fd);
+
+	/* Now unmap and close the region. */
+	if ((ret = __db_rclose(dbenv, fd, txn_region)) != 0) {
+		(void)txn_unlink(path, 1 /* force */, dbenv);
+		return (ret);
+	}
+
+	return (0);
+}
+
+int
+txn_open(path, flags, mode, dbenv, mgrpp)
+	const char *path;
+	int flags, mode;
+	DB_ENV *dbenv;
+	DB_TXNMGR **mgrpp;
+{
+	DB_TXNMGR *tmgrp;
+	DB_TXNREGION *txn_regionp;
+	int fd, ret, retry_cnt;
+
+	tmgrp = NULL;
+	txn_regionp = NULL;
+	fd = -1;
+
+	/* Validate arguments. */
+	if (dbenv == NULL)
+		return (EINVAL);
+#ifdef HAVE_SPINLOCKS
+#define	OKFLAGS	(DB_CREATE | DB_THREAD | DB_TXN_NOSYNC)
+#else
+#define	OKFLAGS	(DB_CREATE | DB_TXN_NOSYNC)
+#endif
+	if ((ret = __db_fchk(dbenv, "txn_open", flags, OKFLAGS)) != 0)
+		return (ret);
+
+	retry_cnt = 0;
+retry:	if (LF_ISSET(DB_CREATE) && (ret = __txn_create(dbenv, path, mode)) != 0)
+		if (ret == EAGAIN && ++retry_cnt < 0) {
+			(void)__db_sleep(1, 0);
+			goto retry;
+		} else	/* We did not really create the region */
+			flags &= ~DB_CREATE;
+
+	retry_cnt = 0;
+retry1:	if ((ret = __db_ropen(dbenv, DB_APP_NONE, path, DEFAULT_TXN_FILE,
+	    flags & ~(DB_CREATE | DB_THREAD | DB_TXN_NOSYNC),
+	    &fd, &txn_regionp)) != 0) {
+		if (ret == EAGAIN && ++retry_cnt < 3) {
+			(void)__db_sleep(1, 0);
+			goto retry1;
+		}
+		goto out;
+	}
+
+
+	/* Check if valid region. */
+	if (txn_regionp->magic != DB_TXNMAGIC) {
+		__db_err(dbenv, "txn_open: Bad magic number");
+		ret = EINVAL;
+		goto out;
+	}
+
+	/* Now, create the transaction manager structure and set its fields. */
+	if ((tmgrp = (DB_TXNMGR *)malloc(sizeof(DB_TXNMGR))) == NULL) {
+		__db_err(dbenv, "txn_open: %s", strerror(errno));
+		ret = ENOMEM;
+		goto out;
+	}
+
+	tmgrp->dbenv = dbenv;
+	tmgrp->recover =
+	    dbenv->tx_recover == NULL ? __db_dispatch : dbenv->tx_recover;
+	tmgrp->region = txn_regionp;
+	tmgrp->reg_size = txn_regionp->hdr.size;
+	tmgrp->fd = fd;
+	tmgrp->flags = LF_ISSET(DB_TXN_NOSYNC | DB_THREAD);
+	TAILQ_INIT(&tmgrp->txn_chain);
+	if (LF_ISSET(DB_THREAD))
+		__db_mutex_init(&tmgrp->mutex, -1);
+	*mgrpp = tmgrp;
+	return (0);
+
+out:	if (txn_regionp != NULL)
+		(void)__db_rclose(dbenv, fd, txn_regionp);
+	if (flags & DB_CREATE)
+		(void)txn_unlink(path, 1, dbenv);
+	if (tmgrp != NULL)
+		free(tmgrp);
+	return (ret);
+}
+
+/*
+ * Internally, we use TXN_DETAIL structures, but we allocate and return
+ * DB_TXN structures that provide access to the transaction ID and the
+ * offset in the transaction region of the TXN_DETAIL structure.
+ */
+int
+txn_begin(tmgrp, parent, txnpp)
+	DB_TXNMGR *tmgrp;
+	DB_TXN *parent;
+	DB_TXN **txnpp;
+{
+	TXN_DETAIL *txnp;
+	DB_TXN *retp;
+	int id, index, ret;
+
+	LOCK_TXNREGION(tmgrp);
+
+	if ((ret = __txn_validate_region(tmgrp)) != 0) {
+		UNLOCK_TXNREGION(tmgrp);
+		return (ret);
+	}
+
+	/* Remove element from free list. */
+	if (tmgrp->region->free_txn == TXN_INVALID &&
+	    (ret = __txn_grow_region(tmgrp)) != 0) {
+		UNLOCK_TXNREGION(tmgrp);
+		return (ret);
+	}
+
+	index = tmgrp->region->free_txn;
+	txnp = &tmgrp->region->table[index];
+	tmgrp->region->free_txn = txnp->txnid;
+
+	if (txnp->status != TXN_UNALLOC) {
+		UNLOCK_TXNREGION(tmgrp);
+		return (EINVAL);
+	}
+
+	/* Make sure that last_txnid is not going to wrap around. */
+	if (tmgrp->region->last_txnid == TXN_INVALID)
+		return (EINVAL);
+
+	if ((retp = (DB_TXN *)malloc(sizeof(DB_TXN))) == NULL) {
+		__db_err(tmgrp->dbenv, "txn_begin : %s", strerror(ENOMEM));
+		UNLOCK_TXNREGION(tmgrp);
+		return (ENOMEM);
+	}
+
+	id = ++tmgrp->region->last_txnid;
+	tmgrp->region->nbegins++;
+
+	txnp->txnid = id;
+	txnp->last_lock = 0;
+	txnp->status = TXN_RUNNING;
+	ZERO_LSN(txnp->last_lsn);
+	ZERO_LSN(txnp->begin_lsn);
+
+	UNLOCK_TXNREGION(tmgrp);
+
+	ZERO_LSN(retp->last_lsn);
+	retp->txnid = id;
+	retp->parent = parent;
+	retp->off = (u_int8_t *)txnp - (u_int8_t *)tmgrp->region;
+	retp->mgrp = tmgrp;
+
+	if (tmgrp->dbenv->lg_info != NULL &&
+	    (ret = __txn_regop_log(tmgrp->dbenv->lg_info,
+	        retp, &txnp->begin_lsn, 0, TXN_BEGIN)) != 0) {
+
+		/* Deallocate transaction. */
+		LOCK_TXNREGION(tmgrp);
+		txnp->txnid = tmgrp->region->free_txn;
+		tmgrp->region->free_txn = txnp - &tmgrp->region->table[0];
+		UNLOCK_TXNREGION(tmgrp);
+		free (retp);
+		return (ret);
+	}
+
+	LOCK_TXNTHREAD(tmgrp);
+	TAILQ_INSERT_TAIL(&tmgrp->txn_chain, retp, links);
+	UNLOCK_TXNTHREAD(tmgrp);
+
+	*txnpp  = retp;
+	return (0);
+}
+
+/* The db_txn(3) man page describes txn_commit. */
+int
+txn_commit(txnp)
+	DB_TXN *txnp;
+{
+	DB_LOG *logp;
+	int ret;
+
+	if ((ret = __txn_check_running(txnp)) != 0)
+		return (ret);
+
+	/* Sync the log. */
+	if ((logp = txnp->mgrp->dbenv->lg_info) != NULL &&
+	    (ret = __txn_regop_log(logp,
+	    txnp, &txnp->last_lsn,
+	    F_ISSET(txnp->mgrp, DB_TXN_NOSYNC) ? 0 : DB_FLUSH, TXN_COMMIT))
+	    != 0)
+		return (ret);
+
+	return (__txn_end(txnp, 1));
+}
+
+/* The db_txn(3) man page describes txn_abort. */
+int
+txn_abort(txnp)
+	DB_TXN *txnp;
+{
+	int ret;
+
+	if ((ret = __txn_check_running(txnp)) != 0)
+		return (ret);
+
+	if ((ret = __txn_undo(txnp)) != 0) {
+		__db_err(txnp->mgrp->dbenv,
+		    "txn_abort: Log undo failed %s", strerror(ret));
+		return (ret);
+	}
+	return (__txn_end(txnp, 0));
+}
+
+/*
+ * Flush the log so a future commit is guaranteed to succeed.
+ */
+int
+txn_prepare(txnp)
+	DB_TXN *txnp;
+{
+	int ret;
+	TXN_DETAIL *tp;
+
+	ret = 0;
+	if ((ret = __txn_check_running(txnp)) != 0)
+		return (ret);
+
+	if (txnp->mgrp->dbenv->lg_info) {
+		ret = log_flush(txnp->mgrp->dbenv->lg_info, &txnp->last_lsn);
+		if (ret)
+			__db_err(txnp->mgrp->dbenv,
+			    "txn_prepare: log_flush failed %s\n",
+			    strerror(errno));
+		return (ret);
+	}
+
+	LOCK_TXNTHREAD(txnp->mgrp);
+	tp = (TXN_DETAIL *)((u_int8_t *)txnp->mgrp->region + txnp->off);
+	tp->status = TXN_PREPARED;
+	UNLOCK_TXNTHREAD(txnp->mgrp);
+	return (ret);
+}
+
+/*
+ * Return the transaction ID associated with a particular transaction
+ */
+u_int32_t
+txn_id(txnp)
+	DB_TXN *txnp;
+{
+	return (txnp->txnid);
+}
+
+/*
+ * The db_txn(3) man page describes txn_close. Currently the caller should
+ * arrange a checkpoint before calling txn_close.
+ */
+int
+txn_close(tmgrp)
+	DB_TXNMGR *tmgrp;
+{
+	DB_TXN *txnp;
+	int ret, t_ret;
+
+	/*
+	 * This function had better only be called once per process
+	 * (i.e., not per thread), so there should be no synchronization
+	 * required.
+	 */
+	for (ret = 0, txnp = TAILQ_FIRST(&tmgrp->txn_chain);
+	    txnp != TAILQ_END(&tmgrp->txn_chain);
+	    txnp = TAILQ_FIRST(&tmgrp->txn_chain)) {
+		if ((t_ret = txn_abort(txnp)) != 0 && ret == 0)
+			ret = t_ret;
+	}
+
+	if (tmgrp->dbenv->lg_info && (t_ret =
+	    log_flush(tmgrp->dbenv->lg_info, NULL)) != 0 &&
+	    ret == 0)
+		ret = t_ret;
+
+	if ((t_ret = __db_rclose(tmgrp->dbenv, tmgrp->fd, tmgrp->region)) != 0
+	    && ret == 0)
+		ret = t_ret;
+
+	if (ret == 0)
+		free (tmgrp);
+	return (ret);
+}
+
+/*
+ * The db_txn(3) man page describes txn_unlink.  Right now it is up to
+ * txn_close to write the final checkpoint record.
+ */
+int
+txn_unlink(path, force, dbenv)
+	const char *path;
+	int force;
+	DB_ENV *dbenv;
+{
+	return (__db_runlink(dbenv,
+	    DB_APP_NONE, path, DEFAULT_TXN_FILE, force));
+}
+
+/* Internal routines. */
+
+/*
+ * Return 0 if the txnp is reasonable, otherwise returns EINVAL.
+ */
+static int
+__txn_check_running(txnp)
+	const DB_TXN *txnp;
+{
+	TXN_DETAIL *tp;
+
+	tp = NULL;
+	if (txnp != NULL && txnp->mgrp != NULL && txnp->mgrp->region != NULL) {
+		tp = (TXN_DETAIL *)((u_int8_t *)txnp->mgrp->region + txnp->off);
+		if (tp->status != TXN_RUNNING)
+			tp = NULL;
+	}
+
+	return (tp == NULL ? EINVAL : 0);
+}
+
+static int
+__txn_end(txnp, is_commit)
+	DB_TXN *txnp;
+	int is_commit;
+{
+	DB_TXNMGR *mgr;
+	TXN_DETAIL *tp;
+	DB_LOCKREQ request;
+	int ret;
+	u_int32_t locker;
+
+	mgr = txnp->mgrp;
+
+	LOCK_TXNTHREAD(mgr);
+	TAILQ_REMOVE(&mgr->txn_chain, txnp, links);
+	UNLOCK_TXNTHREAD(mgr);
+
+	/* Release the locks. */
+	locker = txnp->txnid;
+	request.op = DB_LOCK_PUT_ALL;
+
+	if (mgr->dbenv->lk_info) {
+		ret = lock_vec(mgr->dbenv->lk_info, locker, 0,
+		    &request, 1, NULL);
+		if (ret != 0 && (ret != DB_LOCK_DEADLOCK || is_commit)) {
+			__db_err(mgr->dbenv, "%s: release locks failed %s",
+			    is_commit ? "txn_commit" : "txn_abort",
+			    strerror(ret));
+			return (ret);
+		}
+	}
+
+	/* End the transaction. */
+	LOCK_TXNREGION(mgr);
+	tp = (TXN_DETAIL *)((u_int8_t *)mgr->region + txnp->off);
+	tp->status = TXN_UNALLOC;
+	tp->txnid = mgr->region->free_txn;
+	mgr->region->free_txn = tp - &mgr->region->table[0];
+	if (is_commit)
+		mgr->region->ncommits++;
+	else
+		mgr->region->naborts++;
+	UNLOCK_TXNREGION(mgr);
+
+	FREE(txnp, sizeof(*txnp));
+
+	return (0);
+}
+
+
+/*
+ * Undo the transaction with id txnid.  Returns 0 on success and sets
+ * errno and returns -1 on failure.
+ */
+static int
+__txn_undo(txnp)
+	DB_TXN *txnp;
+{
+	DB_TXNMGR *mgr;
+	DB_LOG *logp;
+	DBT rdbt;
+	DB_LSN key_lsn;
+	int ret;
+
+	mgr = txnp->mgrp;
+	logp = mgr->dbenv->lg_info;
+	if (logp == NULL)
+		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));
+	if (F_ISSET(logp, DB_AM_THREAD))
+		F_SET(&rdbt, DB_DBT_MALLOC);
+
+	key_lsn = txnp->last_lsn;		/* structure assignment */
+	for (ret = 0; 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 = log_get(logp, &key_lsn, &rdbt, DB_SET)) == 0) {
+			ret =
+			    mgr->recover(logp, &rdbt, &key_lsn, TXN_UNDO, NULL);
+			if (F_ISSET(logp, DB_AM_THREAD) && rdbt.data != NULL) {
+				free(rdbt.data);
+				rdbt.data = NULL;
+			}
+		}
+		if (ret != 0)
+			return (ret);
+	}
+
+	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.
+ */
+int
+txn_checkpoint(mgr, kbytes, minutes)
+	const DB_TXNMGR *mgr;
+	long kbytes, minutes;
+{
+	TXN_DETAIL *txnp;
+	DB_LSN ckp_lsn, last_ckp;
+	DB_LOG *dblp;
+	u_int32_t bytes_written, i;
+	time_t last_ckp_time, now;
+	int ret;
+
+	/* Check usage. */
+	if (kbytes < 0 || minutes < 0)
+		return (EINVAL);
+
+	/*
+	 * Check if we need to run recovery.
+	 */
+	ZERO_LSN(ckp_lsn);
+	if (minutes != 0) {
+		(void)time(&now);
+
+		LOCK_TXNREGION(mgr);
+		last_ckp_time = mgr->region->time_ckp;
+		UNLOCK_TXNREGION(mgr);
+
+		if (now - last_ckp_time >= (time_t)(minutes * 60))
+			goto do_ckp;
+	}
+
+	if (kbytes != 0) {
+		dblp = mgr->dbenv->lg_info;
+		LOCK_LOGREGION(dblp);
+		bytes_written = dblp->lp->written;
+		ckp_lsn = dblp->lp->lsn;
+		UNLOCK_LOGREGION(dblp);
+		if (bytes_written >= (u_int32_t)(kbytes * 1024))
+			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);
+
+	if (IS_ZERO_LSN(ckp_lsn)) {
+		dblp = mgr->dbenv->lg_info;
+		LOCK_LOGREGION(dblp);
+		ckp_lsn = dblp->lp->lsn;
+		UNLOCK_LOGREGION(dblp);
+	}
+
+	/*
+	 * We have to find an LSN such that all transactions begun
+	 * before that LSN are complete.
+	 */
+do_ckp:
+	LOCK_TXNREGION(mgr);
+
+	if (!IS_ZERO_LSN(mgr->region->pending_ckp))
+		ckp_lsn = mgr->region->pending_ckp;
+	else
+		for (txnp = &mgr->region->table[0], i = 0;
+		    i < mgr->region->maxtxns; i++, txnp++) {
+
+			/*
+			 * Look through the transaction table for the LSN of
+			 * the transaction that is in-use (e.g., not
+			 * TXN_UNALLOC) and whose begin lsn is the lowest.
+			 */
+			if (txnp->status != TXN_UNALLOC &&
+			    !IS_ZERO_LSN(txnp->begin_lsn) &&
+			    log_compare(&txnp->begin_lsn, &ckp_lsn) < 0)
+				ckp_lsn = txnp->begin_lsn;
+		}
+
+	mgr->region->pending_ckp = ckp_lsn;
+	UNLOCK_TXNREGION(mgr);
+
+	ret = memp_sync(mgr->dbenv->mp_info, &ckp_lsn);
+	if (ret > 0) {
+		__db_err(mgr->dbenv,
+		    "txn_checkpoint: system failure in memp_sync %s\n",
+		    strerror(ret));
+	} else if (ret == 0 && mgr->dbenv->lg_info != NULL) {
+		LOCK_TXNREGION(mgr);
+		last_ckp = mgr->region->last_ckp;
+		ZERO_LSN(mgr->region->pending_ckp);
+		UNLOCK_TXNREGION(mgr);
+
+		if ((ret = __txn_ckp_log(mgr->dbenv->lg_info,
+		   NULL, &ckp_lsn, DB_CHECKPOINT, &ckp_lsn, &last_ckp)) != 0) {
+			__db_err(mgr->dbenv,
+			    "txn_checkpoint: log failed at LSN [%ld %ld] %s\n",
+			    (long)ckp_lsn.file, (long)ckp_lsn.offset,
+			    strerror(ret));
+			return (ret);
+		}
+
+		LOCK_TXNREGION(mgr);
+		mgr->region->last_ckp = ckp_lsn;
+		(void)time(&mgr->region->time_ckp);
+		UNLOCK_TXNREGION(mgr);
+	}
+	/*
+	 * ret < 0 means that there are still buffers to flush; the
+	 * checkpoint is not complete. Back off and try again.
+	 */
+	return (ret);
+}
+
+/*
+ * This is called at every interface to verify if the region
+ * has changed size, and if so, to remap the region in and
+ * reset the process pointers.
+ */
+static int
+__txn_validate_region(tp)
+	DB_TXNMGR *tp;
+{
+	int ret;
+
+	if (tp->reg_size == tp->region->hdr.size)
+		return (0);
+
+	/* Grow the region. */
+	if ((ret = __db_rremap(tp->dbenv, tp->region,
+	    tp->reg_size, tp->region->hdr.size, tp->fd, &tp->region)) != 0)
+		return (ret);
+
+	tp->reg_size = tp->region->hdr.size;
+
+	return (0);
+}
+
+static int
+__txn_grow_region(tp)
+	DB_TXNMGR *tp;
+{
+	TXN_DETAIL *tx;
+	size_t incr;
+	u_int32_t i, oldmax;
+	int ret;
+
+	oldmax = tp->region->maxtxns;
+	incr = oldmax * sizeof(DB_TXN);
+
+	if ((ret = __db_rgrow(tp->dbenv, tp->fd, incr)) != 0)
+		return (ret);
+
+	if ((ret = __db_rremap(tp->dbenv, tp->region,
+	    tp->reg_size, tp->reg_size + incr, tp->fd, &tp->region)) != 0)
+		return (ret);
+	tp->reg_size += incr;
+
+	/*
+	 * Initialize all the new transactions and up the transaction count.
+	 */
+	for (i = 0, tx = &tp->region->table[oldmax]; i < oldmax; i++, tx++) {
+		ZERO_LSN(tx->begin_lsn);
+		tx->status = TXN_UNALLOC;
+		tx->txnid = oldmax + i + 1;
+	}
+	tp->region->free_txn = oldmax;
+	tp->region->maxtxns = 2 * oldmax;
+	tp->region->table[tp->region->maxtxns - 1].txnid = TXN_INVALID;
+
+	return (0);
+}
+
+int
+txn_stat(mgr, statp, db_malloc)
+	DB_TXNMGR *mgr;
+	DB_TXN_STAT **statp;
+	void *(*db_malloc) __P((size_t));
+{
+	DB_TXN_STAT *stats;
+	size_t nbytes;
+	u_int32_t nactive;
+	unsigned int i, ndx;
+
+	LOCK_TXNREGION(mgr);
+	nactive = mgr->region->nbegins -
+	    mgr->region->naborts - mgr->region->ncommits;
+	UNLOCK_TXNREGION(mgr);
+
+	/*
+	 * Allocate a bunch of extra active structures to handle any
+	 * that have been created since we unlocked the region.
+	 */
+	nbytes = sizeof(DB_TXN_STAT) + sizeof(DB_TXN_ACTIVE) * (nactive + 200);
+	if (db_malloc == NULL)
+		stats = (DB_TXN_STAT *)malloc(nbytes);
+	else
+		stats = (DB_TXN_STAT *)db_malloc(nbytes);
+
+	if (stats == NULL)
+		return (ENOMEM);
+
+	LOCK_TXNREGION(mgr);
+	stats->st_last_txnid = mgr->region->last_txnid;
+	stats->st_last_ckp = mgr->region->last_ckp;
+	stats->st_maxtxns = mgr->region->maxtxns;
+	stats->st_naborts = mgr->region->naborts;
+	stats->st_nbegins = mgr->region->nbegins;
+	stats->st_ncommits = mgr->region->ncommits;
+	stats->st_pending_ckp = mgr->region->pending_ckp;
+	stats->st_time_ckp = mgr->region->time_ckp;
+	stats->st_nactive = stats->st_nbegins -
+	    stats->st_naborts - stats->st_ncommits;
+	if (stats->st_nactive > nactive + 200)
+		stats->st_nactive = nactive + 200;
+	stats->st_txnarray = (DB_TXN_ACTIVE *)&stats[1];
+
+	for (ndx = 0, i = 0; i < mgr->region->maxtxns; i++)
+		if (mgr->region->table[i].status != TXN_UNALLOC) {
+			stats->st_txnarray[ndx].txnid =
+			    mgr->region->table[i].txnid;
+			stats->st_txnarray[ndx].lsn =
+			    mgr->region->table[i].begin_lsn;
+			ndx++;
+
+			if (ndx >= stats->st_nactive)
+				break;
+		}
+
+	UNLOCK_TXNREGION(mgr);
+	*statp = stats;
+	return (0);
+}