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

<?php
/**
 * Arbitrary section name based PHP 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
 * @author Aaron Schulz
 */
use Wikimedia\ScopedCallback;

/**
 * Custom PHP profiler for parser/DB type section names that xhprof/xdebug can't handle
 *
 * @since 1.25
 */
class SectionProfiler {
        /** @var array Map of (mem,real,cpu) */
        protected $start;
        /** @var array Map of (mem,real,cpu) */
        protected $end;
        /** @var array List of resolved profile calls with start/end data */
        protected $stack = [];
        /** @var array Queue of open profile calls with start data */
        protected $workStack = [];

        /** @var array Map of (function name => aggregate data array) */
        protected $collated = [];
        /** @var bool */
        protected $collateDone = false;

        /** @var bool Whether to collect the full stack trace or just aggregates */
        protected $collateOnly = true;
        /** @var array Cache of a standard broken collation entry */
        protected $errorEntry;

        /**
         * @param array $params
         */
        public function __construct( array $params = [] ) {
                $this->errorEntry = $this->getErrorEntry();
                $this->collateOnly = empty( $params['trace'] );
        }

        /**
         * @param string $section
         * @return SectionProfileCallback
         */
        public function scopedProfileIn( $section ) {
                $this->profileInInternal( $section );

                return new SectionProfileCallback( $this, $section );
        }

        /**
         * @param ScopedCallback $section
         */
        public function scopedProfileOut( ScopedCallback &$section ) {
                $section = null;
        }

        /**
         * Get the aggregated inclusive profiling data for each method
         *
         * The percent time for each time is based on the current "total" time
         * used is based on all methods so far. This method can therefore be
         * called several times in between several profiling calls without the
         * delays in usage of the profiler skewing the results. A "-total" entry
         * is always included in the results.
         *
         * @return array List of method entries arrays, each having:
         *   - name    : method name
         *   - calls   : the number of invoking calls
         *   - real    : real time elapsed (ms)
         *   - %real   : percent real time
         *   - cpu     : real time elapsed (ms)
         *   - %cpu    : percent real time
         *   - memory  : memory used (bytes)
         *   - %memory : percent memory used
         *   - min_real : min real time in a call (ms)
         *   - max_real : max real time in a call (ms)
         */
        public function getFunctionStats() {
                $this->collateData();

                $totalCpu = max( $this->end['cpu'] - $this->start['cpu'], 0 );
                $totalReal = max( $this->end['real'] - $this->start['real'], 0 );
                $totalMem = max( $this->end['memory'] - $this->start['memory'], 0 );

                $profile = [];
                foreach ( $this->collated as $fname => $data ) {
                        $profile[] = [
                                'name' => $fname,
                                'calls' => $data['count'],
                                'real' => $data['real'] * 1000,
                                '%real' => $totalReal ? 100 * $data['real'] / $totalReal : 0,
                                'cpu' => $data['cpu'] * 1000,
                                '%cpu' => $totalCpu ? 100 * $data['cpu'] / $totalCpu : 0,
                                'memory' => $data['memory'],
                                '%memory' => $totalMem ? 100 * $data['memory'] / $totalMem : 0,
                                'min_real' => 1000 * $data['min_real'],
                                'max_real' => 1000 * $data['max_real']
                        ];
                }

                $profile[] = [
                        'name' => '-total',
                        'calls' => 1,
                        'real' => 1000 * $totalReal,
                        '%real' => 100,
                        'cpu' => 1000 * $totalCpu,
                        '%cpu' => 100,
                        'memory' => $totalMem,
                        '%memory' => 100,
                        'min_real' => 1000 * $totalReal,
                        'max_real' => 1000 * $totalReal
                ];

                return $profile;
        }

        /**
         * Clear all of the profiling data for another run
         */
        public function reset() {
                $this->start = null;
                $this->end = null;
                $this->stack = [];
                $this->workStack = [];
                $this->collated = [];
                $this->collateDone = false;
        }

        /**
         * @return array Initial collation entry
         */
        protected function getZeroEntry() {
                return [
                        'cpu'      => 0.0,
                        'real'     => 0.0,
                        'memory'   => 0,
                        'count'    => 0,
                        'min_real' => 0.0,
                        'max_real' => 0.0
                ];
        }

        /**
         * @return array Initial collation entry for errors
         */
        protected function getErrorEntry() {
                $entry = $this->getZeroEntry();
                $entry['count'] = 1;
                return $entry;
        }

        /**
         * Update the collation entry for a given method name
         *
         * @param string $name
         * @param float $elapsedCpu
         * @param float $elapsedReal
         * @param int $memChange
         */
        protected function updateEntry( $name, $elapsedCpu, $elapsedReal, $memChange ) {
                $entry =& $this->collated[$name];
                if ( !is_array( $entry ) ) {
                        $entry = $this->getZeroEntry();
                        $this->collated[$name] =& $entry;
                }
                $entry['cpu'] += $elapsedCpu;
                $entry['real'] += $elapsedReal;
                $entry['memory'] += $memChange > 0 ? $memChange : 0;
                $entry['count']++;
                $entry['min_real'] = min( $entry['min_real'], $elapsedReal );
                $entry['max_real'] = max( $entry['max_real'], $elapsedReal );
        }

        /**
         * This method should not be called outside SectionProfiler
         *
         * @param string $functionname
         */
        public function profileInInternal( $functionname ) {
                // Once the data is collated for reports, any future calls
                // should clear the collation cache so the next report will
                // reflect them. This matters when trace mode is used.
                $this->collateDone = false;

                $cpu = $this->getTime( 'cpu' );
                $real = $this->getTime( 'wall' );
                $memory = memory_get_usage();

                if ( $this->start === null ) {
                        $this->start = [ 'cpu' => $cpu, 'real' => $real, 'memory' => $memory ];
                }

                $this->workStack[] = [
                        $functionname,
                        count( $this->workStack ),
                        $real,
                        $cpu,
                        $memory
                ];
        }

        /**
         * This method should not be called outside SectionProfiler
         *
         * @param string $functionname
         */
        public function profileOutInternal( $functionname ) {
                $item = array_pop( $this->workStack );
                if ( $item === null ) {
                        $this->debugGroup( 'profileerror', "Profiling error: $functionname" );
                        return;
                }
                list( $ofname, /* $ocount */, $ortime, $octime, $omem ) = $item;

                if ( $functionname === 'close' ) {
                        $message = "Profile section ended by close(): {$ofname}";
                        $this->debugGroup( 'profileerror', $message );
                        if ( $this->collateOnly ) {
                                $this->collated[$message] = $this->errorEntry;
                        } else {
                                $this->stack[] = [ $message, 0, 0.0, 0.0, 0, 0.0, 0.0, 0 ];
                        }
                        $functionname = $ofname;
                } elseif ( $ofname !== $functionname ) {
                        $message = "Profiling error: in({$ofname}), out($functionname)";
                        $this->debugGroup( 'profileerror', $message );
                        if ( $this->collateOnly ) {
                                $this->collated[$message] = $this->errorEntry;
                        } else {
                                $this->stack[] = [ $message, 0, 0.0, 0.0, 0, 0.0, 0.0, 0 ];
                        }
                }

                $realTime = $this->getTime( 'wall' );
                $cpuTime = $this->getTime( 'cpu' );
                $memUsage = memory_get_usage();

                if ( $this->collateOnly ) {
                        $elapsedcpu = $cpuTime - $octime;
                        $elapsedreal = $realTime - $ortime;
                        $memchange = $memUsage - $omem;
                        $this->updateEntry( $functionname, $elapsedcpu, $elapsedreal, $memchange );
                } else {
                        $this->stack[] = array_merge( $item, [ $realTime, $cpuTime, $memUsage ] );
                }

                $this->end = [
                        'cpu'      => $cpuTime,
                        'real'     => $realTime,
                        'memory'   => $memUsage
                ];
        }

        /**
         * Returns a tree of function calls with their real times
         * @return string
         * @throws Exception
         */
        public function getCallTreeReport() {
                if ( $this->collateOnly ) {
                        throw new Exception( "Tree is only available for trace profiling." );
                }
                return implode( '', array_map(
                        [ $this, 'getCallTreeLine' ], $this->remapCallTree( $this->stack )
                ) );
        }

        /**
         * Recursive function the format the current profiling array into a tree
         *
         * @param array $stack Profiling array
         * @return array
         */
        protected function remapCallTree( array $stack ) {
                if ( count( $stack ) < 2 ) {
                        return $stack;
                }
                $outputs = [];
                for ( $max = count( $stack ) - 1; $max > 0; ) {
                        /* Find all items under this entry */
                        $level = $stack[$max][1];
                        $working = [];
                        for ( $i = $max -1; $i >= 0; $i-- ) {
                                if ( $stack[$i][1] > $level ) {
                                        $working[] = $stack[$i];
                                } else {
                                        break;
                                }
                        }
                        $working = $this->remapCallTree( array_reverse( $working ) );
                        $output = [];
                        foreach ( $working as $item ) {
                                array_push( $output, $item );
                        }
                        array_unshift( $output, $stack[$max] );
                        $max = $i;

                        array_unshift( $outputs, $output );
                }
                $final = [];
                foreach ( $outputs as $output ) {
                        foreach ( $output as $item ) {
                                $final[] = $item;
                        }
                }
                return $final;
        }

        /**
         * Callback to get a formatted line for the call tree
         * @param array $entry
         * @return string
         */
        protected function getCallTreeLine( $entry ) {
                // $entry has (name, level, stime, scpu, smem, etime, ecpu, emem)
                list( $fname, $level, $startreal, , , $endreal ) = $entry;
                $delta = $endreal - $startreal;
                $space = str_repeat( ' ', $level );
                # The ugly double sprintf is to work around a PHP bug,
                # which has been fixed in recent releases.
                return sprintf( "%10s %s %s\n",
                        trim( sprintf( "%7.3f", $delta * 1000.0 ) ), $space, $fname );
        }

        /**
         * Populate collated data
         */
        protected function collateData() {
                if ( $this->collateDone ) {
                        return;
                }
                $this->collateDone = true;
                // Close opened profiling sections
                while ( count( $this->workStack ) ) {
                        $this->profileOutInternal( 'close' );
                }

                if ( $this->collateOnly ) {
                        return; // already collated as methods exited
                }

                $this->collated = [];

                # Estimate profiling overhead
                $oldEnd = $this->end;
                $profileCount = count( $this->stack );
                $this->calculateOverhead( $profileCount );

                # First, subtract the overhead!
                $overheadTotal = $overheadMemory = $overheadInternal = [];
                foreach ( $this->stack as $entry ) {
                        // $entry is (name,pos,rtime0,cputime0,mem0,rtime1,cputime1,mem1)
                        $fname = $entry[0];
                        $elapsed = $entry[5] - $entry[2];
                        $memchange = $entry[7] - $entry[4];

                        if ( $fname === '-overhead-total' ) {
                                $overheadTotal[] = $elapsed;
                                $overheadMemory[] = max( 0, $memchange );
                        } elseif ( $fname === '-overhead-internal' ) {
                                $overheadInternal[] = $elapsed;
                        }
                }
                $overheadTotal = $overheadTotal ?
                        array_sum( $overheadTotal ) / count( $overheadInternal ) : 0;
                $overheadMemory = $overheadMemory ?
                        array_sum( $overheadMemory ) / count( $overheadInternal ) : 0;
                $overheadInternal = $overheadInternal ?
                        array_sum( $overheadInternal ) / count( $overheadInternal ) : 0;

                # Collate
                foreach ( $this->stack as $index => $entry ) {
                        // $entry is (name,pos,rtime0,cputime0,mem0,rtime1,cputime1,mem1)
                        $fname = $entry[0];
                        $elapsedCpu = $entry[6] - $entry[3];
                        $elapsedReal = $entry[5] - $entry[2];
                        $memchange = $entry[7] - $entry[4];
                        $subcalls = $this->calltreeCount( $this->stack, $index );

                        if ( substr( $fname, 0, 9 ) !== '-overhead' ) {
                                # Adjust for profiling overhead (except special values with elapsed=0)
                                if ( $elapsed ) {
                                        $elapsed -= $overheadInternal;
                                        $elapsed -= ( $subcalls * $overheadTotal );
                                        $memchange -= ( $subcalls * $overheadMemory );
                                }
                        }

                        $this->updateEntry( $fname, $elapsedCpu, $elapsedReal, $memchange );
                }

                $this->collated['-overhead-total']['count'] = $profileCount;
                arsort( $this->collated, SORT_NUMERIC );

                // Unclobber the end info map (the overhead checking alters it)
                $this->end = $oldEnd;
        }

        /**
         * Dummy calls to calculate profiling overhead
         *
         * @param int $profileCount
         */
        protected function calculateOverhead( $profileCount ) {
                $this->profileInInternal( '-overhead-total' );
                for ( $i = 0; $i < $profileCount; $i++ ) {
                        $this->profileInInternal( '-overhead-internal' );
                        $this->profileOutInternal( '-overhead-internal' );
                }
                $this->profileOutInternal( '-overhead-total' );
        }

        /**
         * Counts the number of profiled function calls sitting under
         * the given point in the call graph. Not the most efficient algo.
         *
         * @param array $stack
         * @param int $start
         * @return int
         */
        protected function calltreeCount( $stack, $start ) {
                $level = $stack[$start][1];
                $count = 0;
                for ( $i = $start -1; $i >= 0 && $stack[$i][1] > $level; $i-- ) {
                        $count ++;
                }
                return $count;
        }

        /**
         * Get the initial time of the request, based on getrusage()
         *
         * @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
         */
        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 );
                }
        }

        /**
         * 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 );
                }
        }
}

/**
 * Subclass ScopedCallback to avoid call_user_func_array(), which is slow
 *
 * This class should not be used outside of SectionProfiler
 */
class SectionProfileCallback extends ScopedCallback {
        /** @var SectionProfiler */
        protected $profiler;
        /** @var string */
        protected $section;

        /**
         * @param SectionProfiler $profiler
         * @param string $section
         */
        public function __construct( SectionProfiler $profiler, $section ) {
                parent::__construct( null );
                $this->profiler = $profiler;
                $this->section = $section;
        }

        function __destruct() {
                $this->profiler->profileOutInternal( $this->section );
        }
}