Profiler: Call getContentType() only once in logData()

[mediawiki.git] / includes / profiler / Profiler.php

<?php
/**
 * Base class and functions for 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
 * @defgroup Profiler Profiler
 */

/**
 * Get system resource usage of current request context.
 * Invokes the getrusage(2) system call, requesting RUSAGE_SELF if on PHP5
 * or RUSAGE_THREAD if on HHVM. Returns false if getrusage is not available.
 *
 * @since 1.24
 * @return array|bool Resource usage data or false if no data available.
 */
function wfGetRusage() {
        if ( !function_exists( 'getrusage' ) ) {
                return false;
        } elseif ( defined ( 'HHVM_VERSION' ) ) {
                return getrusage( 2 /* RUSAGE_THREAD */ );
        } else {
                return getrusage( 0 /* RUSAGE_SELF */ );
        }
}

/**
 * Begin profiling of a function
 * @param string $functionname Name of the function we will profile
 */
function wfProfileIn( $functionname ) {
        if ( Profiler::$__instance === null ) { // use this directly to reduce overhead
                Profiler::instance();
        }
        if ( !( Profiler::$__instance instanceof ProfilerStub ) ) {
                Profiler::$__instance->profileIn( $functionname );
        }
}

/**
 * Stop profiling of a function
 * @param string $functionname Name of the function we have profiled
 */
function wfProfileOut( $functionname = 'missing' ) {
        if ( Profiler::$__instance === null ) { // use this directly to reduce overhead
                Profiler::instance();
        }
        if ( !( Profiler::$__instance instanceof ProfilerStub ) ) {
                Profiler::$__instance->profileOut( $functionname );
        }
}

/**
 * Class for handling function-scope profiling
 *
 * @since 1.22
 */
class ProfileSection {
        protected $name; // string; method name
        protected $enabled = false; // boolean; whether profiling is enabled

        /**
         * Begin profiling of a function and return an object that ends profiling of
         * the function when that object leaves scope. As long as the object is not
         * specifically linked to other objects, it will fall out of scope at the same
         * moment that the function to be profiled terminates.
         *
         * This is typically called like:
         * <code>$section = new ProfileSection( __METHOD__ );</code>
         *
         * @param string $name Name of the function to profile
         */
        public function __construct( $name ) {
                $this->name = $name;
                if ( Profiler::$__instance === null ) { // use this directly to reduce overhead
                        Profiler::instance();
                }
                if ( !( Profiler::$__instance instanceof ProfilerStub ) ) {
                        $this->enabled = true;
                        Profiler::$__instance->profileIn( $this->name );
                }
        }

        function __destruct() {
                if ( $this->enabled ) {
                        Profiler::$__instance->profileOut( $this->name );
                }
        }
}

/**
 * Profiler base class that defines the interface and some trivial functionality
 *
 * @ingroup Profiler
 */
abstract class Profiler {
        /** @var string|bool Profiler ID for bucketing data */
        protected $mProfileID = false;
        /** @var bool Whether MediaWiki is in a SkinTemplate output context */
        protected $mTemplated = false;

        /** @var TransactionProfiler */
        protected $trxProfiler;

        // @codingStandardsIgnoreStart PSR2.Classes.PropertyDeclaration.Underscore
        /** @var Profiler Do not call this outside Profiler and ProfileSection */
        public static $__instance = null;
        // @codingStandardsIgnoreEnd

        /**
         * @param array $params
         */
        public function __construct( array $params ) {
                if ( isset( $params['profileID'] ) ) {
                        $this->mProfileID = $params['profileID'];
                }
                $this->trxProfiler = new TransactionProfiler();
        }

        /**
         * Singleton
         * @return Profiler
         */
        final public static function instance() {
                if ( self::$__instance === null ) {
                        global $wgProfiler;
                        if ( is_array( $wgProfiler ) ) {
                                if ( !isset( $wgProfiler['class'] ) ) {
                                        $class = 'ProfilerStub';
                                } else {
                                        $class = $wgProfiler['class'];
                                }
                                self::$__instance = new $class( $wgProfiler );
                        } else {
                                self::$__instance = new ProfilerStub( array() );
                        }
                }
                return self::$__instance;
        }

        /**
         * Set the profiler to a specific profiler instance. Mostly for dumpHTML
         * @param Profiler $p
         */
        final public static function setInstance( Profiler $p ) {
                self::$__instance = $p;
        }

        /**
         * Return whether this a stub profiler
         *
         * @return bool
         */
        abstract public function isStub();

        /**
         * Return whether this profiler stores data
         *
         * Called by Parser::braceSubstitution. If true, the parser will not
         * generate per-title profiling sections, to avoid overloading the
         * profiling data collector.
         *
         * @see Profiler::logData()
         * @return bool
         */
        abstract public function isPersistent();

        /**
         * @param string $id
         */
        public function setProfileID( $id ) {
                $this->mProfileID = $id;
        }

        /**
         * @return string
         */
        public function getProfileID() {
                if ( $this->mProfileID === false ) {
                        return wfWikiID();
                } else {
                        return $this->mProfileID;
                }
        }

        /**
         * Called by wfProfieIn()
         *
         * @param string $functionname
         */
        abstract public function profileIn( $functionname );

        /**
         * Called by wfProfieOut()
         *
         * @param string $functionname
         */
        abstract public function profileOut( $functionname );

        /**
         * 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 Resource ID string of connection
         */
        public function transactionWritingIn( $server, $db, $id = '' ) {
                $this->trxProfiler->transactionWritingIn( $server, $db, $id );
        }

        /**
         * 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 Resource ID string of connection
         */
        public function transactionWritingOut( $server, $db, $id = '' ) {
                $this->trxProfiler->transactionWritingOut( $server, $db, $id );
        }

        /**
         * Close opened profiling sections
         */
        abstract public function close();

        /**
         * Log the data to some store or even the page output
         */
        abstract public function logData();

        /**
         * Mark this call as templated or not
         *
         * @param bool $t
         */
        public function setTemplated( $t ) {
                $this->mTemplated = $t;
        }

        /**
         * Returns a profiling output to be stored in debug file
         *
         * @return string
         */
        abstract public function getOutput();

        /**
         * @return array
         */
        abstract public function getRawData();

        /**
         * Get the initial time of the request, based either on $wgRequestTime or
         * $wgRUstart. Will return null if not able to find data.
         *
         * @param string|bool $metric Metric to use, with the following possibilities:
         *   - user: User CPU time (without system calls)
         *   - cpu: Total CPU time (user and system calls)
         *   - wall (or any other string): elapsed time
         *   - false (default): will fall back to default metric
         * @return float|null
         */
        protected function getTime( $metric = 'wall' ) {
                if ( $metric === 'cpu' || $metric === 'user' ) {
                        $ru = wfGetRusage();
                        if ( !$ru ) {
                                return 0;
                        }
                        $time = $ru['ru_utime.tv_sec'] + $ru['ru_utime.tv_usec'] / 1e6;
                        if ( $metric === 'cpu' ) {
                                # This is the time of system calls, added to the user time
                                # it gives the total CPU time
                                $time += $ru['ru_stime.tv_sec'] + $ru['ru_stime.tv_usec'] / 1e6;
                        }
                        return $time;
                } else {
                        return microtime( true );
                }
        }

        /**
         * Get the initial time of the request, based either on $wgRequestTime or
         * $wgRUstart. Will return null if not able to find data.
         *
         * @param string|bool $metric Metric to use, with the following possibilities:
         *   - user: User CPU time (without system calls)
         *   - cpu: Total CPU time (user and system calls)
         *   - wall (or any other string): elapsed time
         *   - false (default): will fall back to default metric
         * @return float|null
         */
        protected function getInitialTime( $metric = 'wall' ) {
                global $wgRequestTime, $wgRUstart;

                if ( $metric === 'cpu' || $metric === 'user' ) {
                        if ( !count( $wgRUstart ) ) {
                                return null;
                        }

                        $time = $wgRUstart['ru_utime.tv_sec'] + $wgRUstart['ru_utime.tv_usec'] / 1e6;
                        if ( $metric === 'cpu' ) {
                                # This is the time of system calls, added to the user time
                                # it gives the total CPU time
                                $time += $wgRUstart['ru_stime.tv_sec'] + $wgRUstart['ru_stime.tv_usec'] / 1e6;
                        }
                        return $time;
                } else {
                        if ( empty( $wgRequestTime ) ) {
                                return null;
                        } else {
                                return $wgRequestTime;
                        }
                }
        }

        /**
         * Add an entry in the debug log file
         *
         * @param string $s String to output
         */
        protected function debug( $s ) {
                if ( function_exists( 'wfDebug' ) ) {
                        wfDebug( $s );
                }
        }

        /**
         * Add an entry in the debug log group
         *
         * @param string $group Group to send the message to
         * @param string $s String to output
         */
        protected function debugGroup( $group, $s ) {
                if ( function_exists( 'wfDebugLog' ) ) {
                        wfDebugLog( $group, $s );
                }
        }
}

/**
 * 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 ) {
                        $info['conns'][$name] = 1; // track all DBs in transactions for this transaction
                }
        }

        /**
         * 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 ) {
                        return; // short-circuit
                // @todo hardcoded check is a tad janky (what about FOR UPDATE?)
                } elseif ( !preg_match( '/^query-m: (?!SELECT)/', $method )
                        && $realtime < $this->mDBLockThreshold
                ) {
                        return; // not a DB master query nor slow enough
                }
                $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] );
        }
}