WT-2104 Backport a form of log_flush to 3.0.

11 files changed, 183 insertions, 77 deletions

diff --git a/dist/api_data.py b/dist/api_data.py
index 215e3f81803..3b14fae427c 100644
--- a/dist/api_data.py
+++ b/dist/api_data.py
@@ -662,6 +662,15 @@ methods = {
         type='boolean'),
 ]),
 
+'session.log_flush' : Method([
+    Config('sync', 'on', r'''
+        forcibly flush the log and wait for it to synchronize.  If
+        using \c off, then wait for the log to be written to the file
+        system.  If using \c on, wait for the log to be synchronized
+        to the backing store.''',
+        choices=['off', 'on']),
+]),
+
 'session.log_printf' : Method([]),
 
 'session.open_cursor' : Method(cursor_runtime_config + [
diff --git a/dist/stat_data.py b/dist/stat_data.py
index d27840d3fbc..37843acb188 100644
--- a/dist/stat_data.py
+++ b/dist/stat_data.py
@@ -228,6 +228,7 @@ connection_stats = [
     LogStat('log_compress_small', 'log records too small to compress'),
     LogStat('log_compress_writes', 'log records compressed'),
     LogStat('log_compress_write_fails', 'log records not compressed'),
+    LogStat('log_flush', 'log flush operations'),
     LogStat('log_max_filesize', 'maximum log file size', 'no_clear,no_scale'),
     LogStat('log_prealloc_files', 'pre-allocated log files prepared'),
     LogStat('log_prealloc_max',
diff --git a/lang/java/java_doc.i b/lang/java/java_doc.i
index 53785a3bab4..d997306d87f 100644
--- a/lang/java/java_doc.i
+++ b/lang/java/java_doc.i
@@ -33,6 +33,7 @@ COPYDOC(__wt_session, WT_SESSION, open_cursor)
 COPYDOC(__wt_session, WT_SESSION, create)
 COPYDOC(__wt_session, WT_SESSION, compact)
 COPYDOC(__wt_session, WT_SESSION, drop)
+COPYDOC(__wt_session, WT_SESSION, log_flush)
 COPYDOC(__wt_session, WT_SESSION, log_printf)
 COPYDOC(__wt_session, WT_SESSION, rename)
 COPYDOC(__wt_session, WT_SESSION, salvage)
diff --git a/src/config/config_def.c b/src/config/config_def.c
index 2dfcf862cc8..75252afae34 100644
--- a/src/config/config_def.c
+++ b/src/config/config_def.c
@@ -299,6 +299,11 @@ static const WT_CONFIG_CHECK confchk_session_drop[] = {
 	{ NULL, NULL, NULL, NULL, NULL }
 };
 
+static const WT_CONFIG_CHECK confchk_session_log_flush[] = {
+	{ "sync", "string", NULL, "choices=[\"off\",\"on\"]", NULL },
+	{ NULL, NULL, NULL, NULL, NULL }
+};
+
 static const WT_CONFIG_CHECK confchk_session_open_cursor[] = {
 	{ "append", "boolean", NULL, NULL, NULL },
 	{ "bulk", "string", NULL, NULL, NULL },
@@ -742,6 +747,10 @@ static const WT_CONFIG_ENTRY config_entries[] = {
 	  "force=0,remove_files=",
 	  confchk_session_drop
 	},
+	{ "session.log_flush",
+	  "sync=on",
+	  confchk_session_log_flush
+	},
 	{ "session.log_printf",
 	  "",
 	  NULL
diff --git a/src/include/config.h b/src/include/config.h
index 1f30667b8d6..8cb793b799c 100644
--- a/src/include/config.h
+++ b/src/include/config.h
@@ -68,21 +68,22 @@ struct __wt_config_parser_impl {
 #define	WT_CONFIG_ENTRY_session_compact			18
 #define	WT_CONFIG_ENTRY_session_create			19
 #define	WT_CONFIG_ENTRY_session_drop			20
-#define	WT_CONFIG_ENTRY_session_log_printf		21
-#define	WT_CONFIG_ENTRY_session_open_cursor		22
-#define	WT_CONFIG_ENTRY_session_reconfigure		23
-#define	WT_CONFIG_ENTRY_session_rename			24
-#define	WT_CONFIG_ENTRY_session_rollback_transaction	25
-#define	WT_CONFIG_ENTRY_session_salvage			26
-#define	WT_CONFIG_ENTRY_session_strerror		27
-#define	WT_CONFIG_ENTRY_session_truncate		28
-#define	WT_CONFIG_ENTRY_session_upgrade			29
-#define	WT_CONFIG_ENTRY_session_verify			30
-#define	WT_CONFIG_ENTRY_table_meta			31
-#define	WT_CONFIG_ENTRY_wiredtiger_open			32
-#define	WT_CONFIG_ENTRY_wiredtiger_open_all		33
-#define	WT_CONFIG_ENTRY_wiredtiger_open_basecfg		34
-#define	WT_CONFIG_ENTRY_wiredtiger_open_usercfg		35
+#define	WT_CONFIG_ENTRY_session_log_flush		21
+#define	WT_CONFIG_ENTRY_session_log_printf		22
+#define	WT_CONFIG_ENTRY_session_open_cursor		23
+#define	WT_CONFIG_ENTRY_session_reconfigure		24
+#define	WT_CONFIG_ENTRY_session_rename			25
+#define	WT_CONFIG_ENTRY_session_rollback_transaction	26
+#define	WT_CONFIG_ENTRY_session_salvage			27
+#define	WT_CONFIG_ENTRY_session_strerror		28
+#define	WT_CONFIG_ENTRY_session_truncate		29
+#define	WT_CONFIG_ENTRY_session_upgrade			30
+#define	WT_CONFIG_ENTRY_session_verify			31
+#define	WT_CONFIG_ENTRY_table_meta			32
+#define	WT_CONFIG_ENTRY_wiredtiger_open			33
+#define	WT_CONFIG_ENTRY_wiredtiger_open_all		34
+#define	WT_CONFIG_ENTRY_wiredtiger_open_basecfg		35
+#define	WT_CONFIG_ENTRY_wiredtiger_open_usercfg		36
 /*
  * configuration section: END
  * DO NOT EDIT: automatically built by dist/flags.py.
diff --git a/src/include/extern.h b/src/include/extern.h
index a11f3dcd73c..447a74d2d67 100644
--- a/src/include/extern.h
+++ b/src/include/extern.h
@@ -332,6 +332,7 @@ extern int __wt_log_read(WT_SESSION_IMPL *session, WT_ITEM *record, WT_LSN *lsnp
 extern int __wt_log_scan(WT_SESSION_IMPL *session, WT_LSN *lsnp, uint32_t flags, int (*func)(WT_SESSION_IMPL *session, WT_ITEM *record, WT_LSN *lsnp, WT_LSN *next_lsnp, void *cookie, int firstrecord), void *cookie);
 extern int __wt_log_write(WT_SESSION_IMPL *session, WT_ITEM *record, WT_LSN *lsnp, uint32_t flags);
 extern int __wt_log_vprintf(WT_SESSION_IMPL *session, const char *fmt, va_list ap);
+extern int __wt_log_flush(WT_SESSION_IMPL *session, uint32_t flags);
 extern int __wt_logrec_alloc(WT_SESSION_IMPL *session, size_t size, WT_ITEM **logrecp);
 extern void __wt_logrec_free(WT_SESSION_IMPL *session, WT_ITEM **logrecp);
 extern int __wt_logrec_read(WT_SESSION_IMPL *session, const uint8_t **pp, const uint8_t *end, uint32_t *rectypep);
diff --git a/src/include/stat.h b/src/include/stat.h
index df8f950f330..64d5c4bc71e 100644
--- a/src/include/stat.h
+++ b/src/include/stat.h
@@ -214,6 +214,7 @@ struct __wt_connection_stats {
 	WT_STATS log_compress_small;
 	WT_STATS log_compress_write_fails;
 	WT_STATS log_compress_writes;
+	WT_STATS log_flush;
 	WT_STATS log_max_filesize;
 	WT_STATS log_prealloc_files;
 	WT_STATS log_prealloc_max;
diff --git a/src/include/wiredtiger.in b/src/include/wiredtiger.in
index ab03d2d27ad..2667e02c5b6 100644
--- a/src/include/wiredtiger.in
+++ b/src/include/wiredtiger.in
@@ -1213,6 +1213,16 @@ struct __wt_session {
 	    const char *name, const char *config);
 
 	/*!
+	 * Flush the log.
+	 *
+	 * @param session the session handle
+	 * @configstart{WT_SESSION.log_flush, see dist/api_data.py}
+	 * @configend
+	 * @errors
+	 */
+	int __F(log_flush)(WT_SESSION *session, const char *config);
+
+	/*!
 	 * Insert a ::WT_LOGREC_MESSAGE type record in the database log files
 	 * (the database must be configured for logging when this method is
 	 * called).
@@ -3369,130 +3379,132 @@ extern int wiredtiger_extension_terminate(WT_CONNECTION *connection);
 #define	WT_STAT_CONN_LOG_COMPRESS_WRITE_FAILS		1080
 /*! log: log records compressed */
 #define	WT_STAT_CONN_LOG_COMPRESS_WRITES		1081
+/*! log: log flush operations */
+#define	WT_STAT_CONN_LOG_FLUSH				1082
 /*! log: maximum log file size */
-#define	WT_STAT_CONN_LOG_MAX_FILESIZE			1082
+#define	WT_STAT_CONN_LOG_MAX_FILESIZE			1083
 /*! log: pre-allocated log files prepared */
-#define	WT_STAT_CONN_LOG_PREALLOC_FILES			1083
+#define	WT_STAT_CONN_LOG_PREALLOC_FILES			1084
 /*! log: number of pre-allocated log files to create */
-#define	WT_STAT_CONN_LOG_PREALLOC_MAX			1084
+#define	WT_STAT_CONN_LOG_PREALLOC_MAX			1085
 /*! log: pre-allocated log files used */
-#define	WT_STAT_CONN_LOG_PREALLOC_USED			1085
+#define	WT_STAT_CONN_LOG_PREALLOC_USED			1086
 /*! log: log read operations */
-#define	WT_STAT_CONN_LOG_READS				1086
+#define	WT_STAT_CONN_LOG_READS				1087
 /*! log: log release advances write LSN */
-#define	WT_STAT_CONN_LOG_RELEASE_WRITE_LSN		1087
+#define	WT_STAT_CONN_LOG_RELEASE_WRITE_LSN		1088
 /*! log: records processed by log scan */
-#define	WT_STAT_CONN_LOG_SCAN_RECORDS			1088
+#define	WT_STAT_CONN_LOG_SCAN_RECORDS			1089
 /*! log: log scan records requiring two reads */
-#define	WT_STAT_CONN_LOG_SCAN_REREADS			1089
+#define	WT_STAT_CONN_LOG_SCAN_REREADS			1090
 /*! log: log scan operations */
-#define	WT_STAT_CONN_LOG_SCANS				1090
+#define	WT_STAT_CONN_LOG_SCANS				1091
 /*! log: consolidated slot closures */
-#define	WT_STAT_CONN_LOG_SLOT_CLOSES			1091
+#define	WT_STAT_CONN_LOG_SLOT_CLOSES			1092
 /*! log: logging bytes consolidated */
-#define	WT_STAT_CONN_LOG_SLOT_CONSOLIDATED		1092
+#define	WT_STAT_CONN_LOG_SLOT_CONSOLIDATED		1093
 /*! log: consolidated slot joins */
-#define	WT_STAT_CONN_LOG_SLOT_JOINS			1093
+#define	WT_STAT_CONN_LOG_SLOT_JOINS			1094
 /*! log: consolidated slot join races */
-#define	WT_STAT_CONN_LOG_SLOT_RACES			1094
+#define	WT_STAT_CONN_LOG_SLOT_RACES			1095
 /*! log: slots selected for switching that were unavailable */
-#define	WT_STAT_CONN_LOG_SLOT_SWITCH_FAILS		1095
+#define	WT_STAT_CONN_LOG_SLOT_SWITCH_FAILS		1096
 /*! log: record size exceeded maximum */
-#define	WT_STAT_CONN_LOG_SLOT_TOOBIG			1096
+#define	WT_STAT_CONN_LOG_SLOT_TOOBIG			1097
 /*! log: failed to find a slot large enough for record */
-#define	WT_STAT_CONN_LOG_SLOT_TOOSMALL			1097
+#define	WT_STAT_CONN_LOG_SLOT_TOOSMALL			1098
 /*! log: consolidated slot join transitions */
-#define	WT_STAT_CONN_LOG_SLOT_TRANSITIONS		1098
+#define	WT_STAT_CONN_LOG_SLOT_TRANSITIONS		1099
 /*! log: log sync operations */
-#define	WT_STAT_CONN_LOG_SYNC				1099
+#define	WT_STAT_CONN_LOG_SYNC				1100
 /*! log: log sync_dir operations */
-#define	WT_STAT_CONN_LOG_SYNC_DIR			1100
+#define	WT_STAT_CONN_LOG_SYNC_DIR			1101
 /*! log: log server thread advances write LSN */
-#define	WT_STAT_CONN_LOG_WRITE_LSN			1101
+#define	WT_STAT_CONN_LOG_WRITE_LSN			1102
 /*! log: log write operations */
-#define	WT_STAT_CONN_LOG_WRITES				1102
+#define	WT_STAT_CONN_LOG_WRITES				1103
 /*! LSM: sleep for LSM checkpoint throttle */
-#define	WT_STAT_CONN_LSM_CHECKPOINT_THROTTLE		1103
+#define	WT_STAT_CONN_LSM_CHECKPOINT_THROTTLE		1104
 /*! LSM: sleep for LSM merge throttle */
-#define	WT_STAT_CONN_LSM_MERGE_THROTTLE			1104
+#define	WT_STAT_CONN_LSM_MERGE_THROTTLE			1105
 /*! LSM: rows merged in an LSM tree */
-#define	WT_STAT_CONN_LSM_ROWS_MERGED			1105
+#define	WT_STAT_CONN_LSM_ROWS_MERGED			1106
 /*! LSM: application work units currently queued */
-#define	WT_STAT_CONN_LSM_WORK_QUEUE_APP			1106
+#define	WT_STAT_CONN_LSM_WORK_QUEUE_APP			1107
 /*! LSM: merge work units currently queued */
-#define	WT_STAT_CONN_LSM_WORK_QUEUE_MANAGER		1107
+#define	WT_STAT_CONN_LSM_WORK_QUEUE_MANAGER		1108
 /*! LSM: tree queue hit maximum */
-#define	WT_STAT_CONN_LSM_WORK_QUEUE_MAX			1108
+#define	WT_STAT_CONN_LSM_WORK_QUEUE_MAX			1109
 /*! LSM: switch work units currently queued */
-#define	WT_STAT_CONN_LSM_WORK_QUEUE_SWITCH		1109
+#define	WT_STAT_CONN_LSM_WORK_QUEUE_SWITCH		1110
 /*! LSM: tree maintenance operations scheduled */
-#define	WT_STAT_CONN_LSM_WORK_UNITS_CREATED		1110
+#define	WT_STAT_CONN_LSM_WORK_UNITS_CREATED		1111
 /*! LSM: tree maintenance operations discarded */
-#define	WT_STAT_CONN_LSM_WORK_UNITS_DISCARDED		1111
+#define	WT_STAT_CONN_LSM_WORK_UNITS_DISCARDED		1112
 /*! LSM: tree maintenance operations executed */
-#define	WT_STAT_CONN_LSM_WORK_UNITS_DONE		1112
+#define	WT_STAT_CONN_LSM_WORK_UNITS_DONE		1113
 /*! connection: memory allocations */
-#define	WT_STAT_CONN_MEMORY_ALLOCATION			1113
+#define	WT_STAT_CONN_MEMORY_ALLOCATION			1114
 /*! connection: memory frees */
-#define	WT_STAT_CONN_MEMORY_FREE			1114
+#define	WT_STAT_CONN_MEMORY_FREE			1115
 /*! connection: memory re-allocations */
-#define	WT_STAT_CONN_MEMORY_GROW			1115
+#define	WT_STAT_CONN_MEMORY_GROW			1116
 /*! thread-yield: page acquire busy blocked */
-#define	WT_STAT_CONN_PAGE_BUSY_BLOCKED			1116
+#define	WT_STAT_CONN_PAGE_BUSY_BLOCKED			1117
 /*! thread-yield: page acquire eviction blocked */
-#define	WT_STAT_CONN_PAGE_FORCIBLE_EVICT_BLOCKED	1117
+#define	WT_STAT_CONN_PAGE_FORCIBLE_EVICT_BLOCKED	1118
 /*! thread-yield: page acquire locked blocked */
-#define	WT_STAT_CONN_PAGE_LOCKED_BLOCKED		1118
+#define	WT_STAT_CONN_PAGE_LOCKED_BLOCKED		1119
 /*! thread-yield: page acquire read blocked */
-#define	WT_STAT_CONN_PAGE_READ_BLOCKED			1119
+#define	WT_STAT_CONN_PAGE_READ_BLOCKED			1120
 /*! thread-yield: page acquire time sleeping (usecs) */
-#define	WT_STAT_CONN_PAGE_SLEEP				1120
+#define	WT_STAT_CONN_PAGE_SLEEP				1121
 /*! connection: total read I/Os */
-#define	WT_STAT_CONN_READ_IO				1121
+#define	WT_STAT_CONN_READ_IO				1122
 /*! reconciliation: page reconciliation calls */
-#define	WT_STAT_CONN_REC_PAGES				1122
+#define	WT_STAT_CONN_REC_PAGES				1123
 /*! reconciliation: page reconciliation calls for eviction */
-#define	WT_STAT_CONN_REC_PAGES_EVICTION			1123
+#define	WT_STAT_CONN_REC_PAGES_EVICTION			1124
 /*! reconciliation: split bytes currently awaiting free */
-#define	WT_STAT_CONN_REC_SPLIT_STASHED_BYTES		1124
+#define	WT_STAT_CONN_REC_SPLIT_STASHED_BYTES		1125
 /*! reconciliation: split objects currently awaiting free */
-#define	WT_STAT_CONN_REC_SPLIT_STASHED_OBJECTS		1125
+#define	WT_STAT_CONN_REC_SPLIT_STASHED_OBJECTS		1126
 /*! connection: pthread mutex shared lock read-lock calls */
-#define	WT_STAT_CONN_RWLOCK_READ			1126
+#define	WT_STAT_CONN_RWLOCK_READ			1127
 /*! connection: pthread mutex shared lock write-lock calls */
-#define	WT_STAT_CONN_RWLOCK_WRITE			1127
+#define	WT_STAT_CONN_RWLOCK_WRITE			1128
 /*! session: open cursor count */
-#define	WT_STAT_CONN_SESSION_CURSOR_OPEN		1128
+#define	WT_STAT_CONN_SESSION_CURSOR_OPEN		1129
 /*! session: open session count */
-#define	WT_STAT_CONN_SESSION_OPEN			1129
+#define	WT_STAT_CONN_SESSION_OPEN			1130
 /*! transaction: transaction begins */
-#define	WT_STAT_CONN_TXN_BEGIN				1130
+#define	WT_STAT_CONN_TXN_BEGIN				1131
 /*! transaction: transaction checkpoints */
-#define	WT_STAT_CONN_TXN_CHECKPOINT			1131
+#define	WT_STAT_CONN_TXN_CHECKPOINT			1132
 /*! transaction: transaction checkpoint generation */
-#define	WT_STAT_CONN_TXN_CHECKPOINT_GENERATION		1132
+#define	WT_STAT_CONN_TXN_CHECKPOINT_GENERATION		1133
 /*! transaction: transaction checkpoint currently running */
-#define	WT_STAT_CONN_TXN_CHECKPOINT_RUNNING		1133
+#define	WT_STAT_CONN_TXN_CHECKPOINT_RUNNING		1134
 /*! transaction: transaction checkpoint max time (msecs) */
-#define	WT_STAT_CONN_TXN_CHECKPOINT_TIME_MAX		1134
+#define	WT_STAT_CONN_TXN_CHECKPOINT_TIME_MAX		1135
 /*! transaction: transaction checkpoint min time (msecs) */
-#define	WT_STAT_CONN_TXN_CHECKPOINT_TIME_MIN		1135
+#define	WT_STAT_CONN_TXN_CHECKPOINT_TIME_MIN		1136
 /*! transaction: transaction checkpoint most recent time (msecs) */
-#define	WT_STAT_CONN_TXN_CHECKPOINT_TIME_RECENT		1136
+#define	WT_STAT_CONN_TXN_CHECKPOINT_TIME_RECENT		1137
 /*! transaction: transaction checkpoint total time (msecs) */
-#define	WT_STAT_CONN_TXN_CHECKPOINT_TIME_TOTAL		1137
+#define	WT_STAT_CONN_TXN_CHECKPOINT_TIME_TOTAL		1138
 /*! transaction: transactions committed */
-#define	WT_STAT_CONN_TXN_COMMIT				1138
+#define	WT_STAT_CONN_TXN_COMMIT				1139
 /*! transaction: transaction failures due to cache overflow */
-#define	WT_STAT_CONN_TXN_FAIL_CACHE			1139
+#define	WT_STAT_CONN_TXN_FAIL_CACHE			1140
 /*! transaction: transaction range of IDs currently pinned by a checkpoint */
-#define	WT_STAT_CONN_TXN_PINNED_CHECKPOINT_RANGE	1140
+#define	WT_STAT_CONN_TXN_PINNED_CHECKPOINT_RANGE	1141
 /*! transaction: transaction range of IDs currently pinned */
-#define	WT_STAT_CONN_TXN_PINNED_RANGE			1141
+#define	WT_STAT_CONN_TXN_PINNED_RANGE			1142
 /*! transaction: transactions rolled back */
-#define	WT_STAT_CONN_TXN_ROLLBACK			1142
+#define	WT_STAT_CONN_TXN_ROLLBACK			1143
 /*! connection: total write I/Os */
-#define	WT_STAT_CONN_WRITE_IO				1143
+#define	WT_STAT_CONN_WRITE_IO				1144
 
 /*!
  * @}
diff --git a/src/log/log.c b/src/log/log.c
index 76cf5f55f7b..567200ffa0b 100644
--- a/src/log/log.c
+++ b/src/log/log.c
@@ -1920,3 +1920,36 @@ __wt_log_vprintf(WT_SESSION_IMPL *session, const char *fmt, va_list ap)
 err:	__wt_scr_free(session, &logrec);
 	return (ret);
 }
+
+/*
+ * __wt_log_flush --
+ *	Forcibly flush the log to the synchronization level specified.
+ *	Wait until it has been completed.
+ */
+int
+__wt_log_flush(WT_SESSION_IMPL *session, uint32_t flags)
+{
+	WT_CONNECTION_IMPL *conn;
+	WT_LOG *log;
+	WT_LSN last_lsn, lsn;
+
+	conn = S2C(session);
+	WT_ASSERT(session, FLD_ISSET(conn->log_flags, WT_CONN_LOG_ENABLED));
+	log = conn->log;
+	last_lsn = log->alloc_lsn;
+	lsn = log->write_lsn;
+	/*
+	 * Wait until all current outstanding writes have been written
+	 * to the file system.
+	 */
+	while (LOG_CMP(&last_lsn, &lsn) > 0) {
+		__wt_yield();
+		lsn = log->write_lsn;
+	}
+	/*
+	 * If the user wants sync, force it now.
+	 */
+	if (LF_ISSET(WT_LOG_FSYNC))
+		WT_RET(__wt_log_force_sync(session, &lsn));
+	return (0);
+}
diff --git a/src/session/session_api.c b/src/session/session_api.c
index 881be7428e5..af30edb9251 100644
--- a/src/session/session_api.c
+++ b/src/session/session_api.c
@@ -439,6 +439,41 @@ err:	API_END_RET_NOTFOUND_MAP(session, ret);
 }
 
 /*
+ * __session_log_flush --
+ *	WT_SESSION->log_flush method.
+ */
+static int
+__session_log_flush(WT_SESSION *wt_session, const char *config)
+{
+	WT_CONFIG_ITEM cval;
+	WT_CONNECTION_IMPL *conn;
+	WT_DECL_RET;
+	WT_SESSION_IMPL *session;
+	uint32_t flags;
+
+	session = (WT_SESSION_IMPL *)wt_session;
+	SESSION_API_CALL(session, log_flush, config, cfg);
+	WT_STAT_FAST_CONN_INCR(session, log_flush);
+
+	conn = S2C(session);
+	flags = 0;
+	/*
+	 * If logging is not enabled there is nothing to do.
+	 */
+	if (!FLD_ISSET(conn->log_flags, WT_CONN_LOG_ENABLED))
+		WT_ERR_MSG(session, EINVAL, "logging not enabled");
+
+	WT_ERR(__wt_config_gets_def(session, cfg, "sync", 0, &cval));
+	if (WT_STRING_MATCH("on", cval.str, cval.len))
+		flags = WT_LOG_FSYNC;
+	else if (WT_STRING_MATCH("off", cval.str, cval.len))
+		flags = WT_LOG_FLUSH;
+	ret = __wt_log_flush(session, flags);
+
+err:	API_END_RET(session, ret);
+}
+
+/*
  * __session_log_printf --
  *	WT_SESSION->log_printf method.
  */
@@ -1008,6 +1043,7 @@ __wt_open_session(WT_CONNECTION_IMPL *conn,
 		__session_create,
 		__session_compact,
 		__session_drop,
+		__session_log_flush,
 		__session_log_printf,
 		__session_rename,
 		__session_salvage,
diff --git a/src/support/stat.c b/src/support/stat.c
index 476566b227f..a95cfcdafbb 100644
--- a/src/support/stat.c
+++ b/src/support/stat.c
@@ -455,6 +455,7 @@ __wt_stat_init_connection_stats(WT_CONNECTION_STATS *stats)
 	    "log: failed to find a slot large enough for record";
 	stats->log_bytes_payload.desc = "log: log bytes of payload data";
 	stats->log_bytes_written.desc = "log: log bytes written";
+	stats->log_flush.desc = "log: log flush operations";
 	stats->log_reads.desc = "log: log read operations";
 	stats->log_compress_writes.desc = "log: log records compressed";
 	stats->log_compress_write_fails.desc =
@@ -630,6 +631,7 @@ __wt_stat_refresh_connection_stats(void *stats_arg)
 	stats->log_slot_toosmall.v = 0;
 	stats->log_bytes_payload.v = 0;
 	stats->log_bytes_written.v = 0;
+	stats->log_flush.v = 0;
 	stats->log_reads.v = 0;
 	stats->log_compress_writes.v = 0;
 	stats->log_compress_write_fails.v = 0;