+<?php
+/**
+ * Transaction profiling.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ * @ingroup Profiler
+ */
+
+/**
+ * Helper class that detects high-contention DB queries via profiling calls
+ *
+ * This class is meant to work with a Profiler, as the later already knows
+ * when methods start and finish (which may take place during transactions).
+ *
+ * @since 1.24
+ */
+class TransactionProfiler {
+ /** @var float Seconds */
+ protected $mDBLockThreshold = 3.0;
+ /** @var array DB/server name => (active trx count, time, DBs involved) */
+ protected $mDBTrxHoldingLocks = array();
+ /** @var array DB/server name => list of (function name, elapsed time) */
+ protected $mDBTrxMethodTimes = array();
+
+ /**
+ * Mark a DB as in a transaction with one or more writes pending
+ *
+ * Note that there can be multiple connections to a single DB.
+ *
+ * @param string $server DB server
+ * @param string $db DB name
+ * @param string $id ID string of transaction
+ */
+ public function transactionWritingIn( $server, $db, $id ) {
+ $name = "{$server} ({$db}) (TRX#$id)";
+ if ( isset( $this->mDBTrxHoldingLocks[$name] ) ) {
+ wfDebugLog( 'DBPerformance', "Nested transaction for '$name' - out of sync." );
+ }
+ $this->mDBTrxHoldingLocks[$name] = array(
+ 'start' => microtime( true ),
+ 'conns' => array(),
+ );
+ $this->mDBTrxMethodTimes[$name] = array();
+
+ foreach ( $this->mDBTrxHoldingLocks as $name => &$info ) {
+ // Track all DBs in transactions for this transaction
+ $info['conns'][$name] = 1;
+ }
+ }
+
+ /**
+ * Register the name and time of a method for slow DB trx detection
+ *
+ * This method is only to be called by the Profiler class as methods finish
+ *
+ * @param string $method Function name
+ * @param float $realtime Wal time ellapsed
+ */
+ public function recordFunctionCompletion( $method, $realtime ) {
+ if ( !$this->mDBTrxHoldingLocks ) {
+ // Short-circuit
+ return;
+ // @todo hardcoded check is a tad janky (what about FOR UPDATE?)
+ } elseif ( !preg_match( '/^query-m: (?!SELECT)/', $method )
+ && $realtime < $this->mDBLockThreshold
+ ) {
+ // Not a DB master query nor slow enough
+ return;
+ }
+ $now = microtime( true );
+ foreach ( $this->mDBTrxHoldingLocks as $name => $info ) {
+ // Hacky check to exclude entries from before the first TRX write
+ if ( ( $now - $realtime ) >= $info['start'] ) {
+ $this->mDBTrxMethodTimes[$name][] = array( $method, $realtime );
+ }
+ }
+ }
+
+ /**
+ * Mark a DB as no longer in a transaction
+ *
+ * This will check if locks are possibly held for longer than
+ * needed and log any affected transactions to a special DB log.
+ * Note that there can be multiple connections to a single DB.
+ *
+ * @param string $server DB server
+ * @param string $db DB name
+ * @param string $id ID string of transaction
+ */
+ public function transactionWritingOut( $server, $db, $id ) {
+ $name = "{$server} ({$db}) (TRX#$id)";
+ if ( !isset( $this->mDBTrxMethodTimes[$name] ) ) {
+ wfDebugLog( 'DBPerformance', "Detected no transaction for '$name' - out of sync." );
+ return;
+ }
+ $slow = false;
+ foreach ( $this->mDBTrxMethodTimes[$name] as $info ) {
+ $realtime = $info[1];
+ if ( $realtime >= $this->mDBLockThreshold ) {
+ $slow = true;
+ break;
+ }
+ }
+ if ( $slow ) {
+ $dbs = implode( ', ', array_keys( $this->mDBTrxHoldingLocks[$name]['conns'] ) );
+ $msg = "Sub-optimal transaction on DB(s) [{$dbs}]:\n";
+ foreach ( $this->mDBTrxMethodTimes[$name] as $i => $info ) {
+ list( $method, $realtime ) = $info;
+ $msg .= sprintf( "%d\t%.6f\t%s\n", $i, $realtime, $method );
+ }
+ wfDebugLog( 'DBPerformance', $msg );
+ }
+ unset( $this->mDBTrxHoldingLocks[$name] );
+ unset( $this->mDBTrxMethodTimes[$name] );
+ }
+}