PHPSessionHandler: Implement SessionHandlerInterface

[mediawiki.git] / includes / libs / Xhprof.php

<?php
/**
 * 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
 */

use RunningStat\RunningStat;

/**
 * Convenience class for working with XHProf
 * <https://github.com/phacility/xhprof>. XHProf can be installed as a PECL
 * package for use with PHP5 (Zend PHP) and is built-in to HHVM 3.3.0.
 *
 * @author Bryan Davis <bd808@wikimedia.org>
 * @copyright © 2014 Bryan Davis and Wikimedia Foundation.
 * @since 1.25
 */
class Xhprof {

        /**
         * @var array $config
         */
        protected $config;

        /**
         * Hierarchical profiling data returned by xhprof.
         * @var array $hieraData
         */
        protected $hieraData;

        /**
         * Per-function inclusive data.
         * @var array $inclusive
         */
        protected $inclusive;

        /**
         * Per-function inclusive and exclusive data.
         * @var array $complete
         */
        protected $complete;

        /**
         * Configuration data can contain:
         * - flags:   Optional flags to add additional information to the
         *            profiling data collected.
         *            (XHPROF_FLAGS_NO_BUILTINS, XHPROF_FLAGS_CPU,
         *            XHPROF_FLAGS_MEMORY)
         * - exclude: Array of function names to exclude from profiling.
         * - include: Array of function names to include in profiling.
         * - sort:    Key to sort per-function reports on.
         *
         * Note: When running under HHVM, xhprof will always behave as though the
         * XHPROF_FLAGS_NO_BUILTINS flag has been used unless the
         * Eval.JitEnableRenameFunction option is enabled for the HHVM process.
         *
         * @param array $config
         */
        public function __construct( array $config = array() ) {
                $this->config = array_merge(
                        array(
                                'flags' => 0,
                                'exclude' => array(),
                                'include' => null,
                                'sort' => 'wt',
                        ),
                        $config
                );

                xhprof_enable( $this->config['flags'], array(
                        'ignored_functions' => $this->config['exclude']
                ) );
        }

        /**
         * Stop collecting profiling data.
         *
         * Only the first invocation of this method will effect the internal
         * object state. Subsequent calls will return the data collected by the
         * initial call.
         *
         * @return array Collected profiling data (possibly cached)
         */
        public function stop() {
                if ( $this->hieraData === null ) {
                        $this->hieraData = $this->pruneData( xhprof_disable() );
                }
                return $this->hieraData;
        }

        /**
         * Load raw data from a prior run for analysis.
         * Stops any existing data collection and clears internal caches.
         *
         * Any 'include' filters configured for this Xhprof instance will be
         * enforced on the data as it is loaded. 'exclude' filters will however
         * not be enforced as they are an XHProf intrinsic behavior.
         *
         * @param array $data
         * @see getRawData()
         */
        public function loadRawData( array $data ) {
                $this->stop();
                $this->inclusive = null;
                $this->complete = null;
                $this->hieraData = $this->pruneData( $data );
        }

        /**
         * Get raw data collected by xhprof.
         *
         * If data collection has not been stopped yet this method will halt
         * collection to gather the profiling data.
         *
         * Each key in the returned array is an edge label for the call graph in
         * the form "caller==>callee". There is once special case edge labled
         * simply "main()" which represents the global scope entry point of the
         * application.
         *
         * XHProf will collect different data depending on the flags that are used:
         * - ct:    Number of matching events seen.
         * - wt:    Inclusive elapsed wall time for this event in microseconds.
         * - cpu:   Inclusive elapsed cpu time for this event in microseconds.
         *          (XHPROF_FLAGS_CPU)
         * - mu:    Delta of memory usage from start to end of callee in bytes.
         *          (XHPROF_FLAGS_MEMORY)
         * - pmu:   Delta of peak memory usage from start to end of callee in
         *          bytes. (XHPROF_FLAGS_MEMORY)
         * - alloc: Delta of amount memory requested from malloc() by the callee,
         *          in bytes. (XHPROF_FLAGS_MALLOC)
         * - free:  Delta of amount of memory passed to free() by the callee, in
         *          bytes. (XHPROF_FLAGS_MALLOC)
         *
         * @return array
         * @see stop()
         * @see getInclusiveMetrics()
         * @see getCompleteMetrics()
         */
        public function getRawData() {
                return $this->stop();
        }

        /**
         * Convert an xhprof data key into an array of ['parent', 'child']
         * function names.
         *
         * The resulting array is left padded with nulls, so a key
         * with no parent (eg 'main()') will return [null, 'function'].
         *
         * @return array
         */
        public static function splitKey( $key ) {
                return array_pad( explode( '==>', $key, 2 ), -2, null );
        }

        /**
         * Remove data for functions that are not included in the 'include'
         * configuration array.
         *
         * @param array $data Raw xhprof data
         * @return array
         */
        protected function pruneData( $data ) {
                if ( !$this->config['include'] ) {
                        return $data;
                }

                $want = array_fill_keys( $this->config['include'], true );
                $want['main()'] = true;

                $keep = array();
                foreach ( $data as $key => $stats ) {
                        list( $parent, $child ) = self::splitKey( $key );
                        if ( isset( $want[$parent] ) || isset( $want[$child] ) ) {
                                $keep[$key] = $stats;
                        }
                }
                return $keep;
        }

        /**
         * Get the inclusive metrics for each function call. Inclusive metrics
         * for given function include the metrics for all functions that were
         * called from that function during the measurement period.
         *
         * If data collection has not been stopped yet this method will halt
         * collection to gather the profiling data.
         *
         * See getRawData() for a description of the metric that are returned for
         * each funcition call. The values for the wt, cpu, mu and pmu metrics are
         * arrays with these values:
         * - total: Cumulative value
         * - min: Minimum value
         * - mean: Mean (average) value
         * - max: Maximum value
         * - variance: Variance (spread) of the values
         *
         * @return array
         * @see getRawData()
         * @see getCompleteMetrics()
         */
        public function getInclusiveMetrics() {
                if ( $this->inclusive === null ) {
                        // Make sure we have data to work with
                        $this->stop();

                        $main = $this->hieraData['main()'];
                        $hasCpu = isset( $main['cpu'] );
                        $hasMu = isset( $main['mu'] );
                        $hasAlloc = isset( $main['alloc'] );

                        $this->inclusive = array();
                        foreach ( $this->hieraData as $key => $stats ) {
                                list( $parent, $child ) = self::splitKey( $key );
                                if ( !isset( $this->inclusive[$child] ) ) {
                                        $this->inclusive[$child] = array(
                                                'ct' => 0,
                                                'wt' => new RunningStat(),
                                        );
                                        if ( $hasCpu ) {
                                                $this->inclusive[$child]['cpu'] = new RunningStat();
                                        }
                                        if ( $hasMu ) {
                                                $this->inclusive[$child]['mu'] = new RunningStat();
                                                $this->inclusive[$child]['pmu'] = new RunningStat();
                                        }
                                        if ( $hasAlloc ) {
                                                $this->inclusive[$child]['alloc'] = new RunningStat();
                                                $this->inclusive[$child]['free'] = new RunningStat();
                                        }
                                }

                                $this->inclusive[$child]['ct'] += $stats['ct'];
                                foreach ( $stats as $stat => $value ) {
                                        if ( $stat === 'ct' ) {
                                                continue;
                                        }

                                        if ( !isset( $this->inclusive[$child][$stat] ) ) {
                                                // Ignore unknown stats
                                                continue;
                                        }

                                        for ( $i = 0; $i < $stats['ct']; $i++ ) {
                                                $this->inclusive[$child][$stat]->addObservation(
                                                        $value / $stats['ct']
                                                );
                                        }
                                }
                        }

                        // Convert RunningStat instances to static arrays and add
                        // percentage stats.
                        foreach ( $this->inclusive as $func => $stats ) {
                                foreach ( $stats as $name => $value ) {
                                        if ( $value instanceof RunningStat ) {
                                                $total = $value->m1 * $value->n;
                                                $percent = ( isset( $main[$name] ) && $main[$name] )
                                                        ? 100 * $total / $main[$name]
                                                        : 0;
                                                $this->inclusive[$func][$name] = array(
                                                        'total' => $total,
                                                        'min' => $value->min,
                                                        'mean' => $value->m1,
                                                        'max' => $value->max,
                                                        'variance' => $value->m2,
                                                        'percent' => $percent,
                                                );
                                        }
                                }
                        }

                        uasort( $this->inclusive, self::makeSortFunction(
                                $this->config['sort'], 'total'
                        ) );
                }
                return $this->inclusive;
        }

        /**
         * Get the inclusive and exclusive metrics for each function call.
         *
         * If data collection has not been stopped yet this method will halt
         * collection to gather the profiling data.
         *
         * In addition to the normal data contained in the inclusive metrics, the
         * metrics have an additional 'exclusive' measurement which is the total
         * minus the totals of all child function calls.
         *
         * @return array
         * @see getRawData()
         * @see getInclusiveMetrics()
         */
        public function getCompleteMetrics() {
                if ( $this->complete === null ) {
                        // Start with inclusive data
                        $this->complete = $this->getInclusiveMetrics();

                        foreach ( $this->complete as $func => $stats ) {
                                foreach ( $stats as $stat => $value ) {
                                        if ( $stat === 'ct' ) {
                                                continue;
                                        }
                                        // Initialize exclusive data with inclusive totals
                                        $this->complete[$func][$stat]['exclusive'] = $value['total'];
                                }
                                // Add sapce for call tree information to be filled in later
                                $this->complete[$func]['calls'] = array();
                                $this->complete[$func]['subcalls'] = array();
                        }

                        foreach ( $this->hieraData as $key => $stats ) {
                                list( $parent, $child ) = self::splitKey( $key );
                                if ( $parent !== null ) {
                                        // Track call tree information
                                        $this->complete[$child]['calls'][$parent] = $stats;
                                        $this->complete[$parent]['subcalls'][$child] = $stats;
                                }

                                if ( isset( $this->complete[$parent] ) ) {
                                        // Deduct child inclusive data from exclusive data
                                        foreach ( $stats as $stat => $value ) {
                                                if ( $stat === 'ct' ) {
                                                        continue;
                                                }

                                                if ( !isset( $this->complete[$parent][$stat] ) ) {
                                                        // Ignore unknown stats
                                                        continue;
                                                }

                                                $this->complete[$parent][$stat]['exclusive'] -= $value;
                                        }
                                }
                        }

                        uasort( $this->complete, self::makeSortFunction(
                                $this->config['sort'], 'exclusive'
                        ) );
                }
                return $this->complete;
        }

        /**
         * Get a list of all callers of a given function.
         *
         * @param string $function Function name
         * @return array
         * @see getEdges()
         */
        public function getCallers( $function ) {
                $edges = $this->getCompleteMetrics();
                if ( isset( $edges[$function]['calls'] ) ) {
                        return array_keys( $edges[$function]['calls'] );
                } else {
                        return array();
                }
        }

        /**
         * Get a list of all callees from a given function.
         *
         * @param string $function Function name
         * @return array
         * @see getEdges()
         */
        public function getCallees( $function ) {
                $edges = $this->getCompleteMetrics();
                if ( isset( $edges[$function]['subcalls'] ) ) {
                        return array_keys( $edges[$function]['subcalls'] );
                } else {
                        return array();
                }
        }

        /**
         * Find the critical path for the given metric.
         *
         * @param string $metric Metric to find critical path for
         * @return array
         */
        public function getCriticalPath( $metric = 'wt' ) {
                $this->stop();
                $func = 'main()';
                $path = array(
                        $func => $this->hieraData[$func],
                );
                while ( $func ) {
                        $callees = $this->getCallees( $func );
                        $maxCallee = null;
                        $maxCall = null;
                        foreach ( $callees as $callee ) {
                                $call = "{$func}==>{$callee}";
                                if ( $maxCall === null ||
                                        $this->hieraData[$call][$metric] >
                                                $this->hieraData[$maxCall][$metric]
                                ) {
                                        $maxCallee = $callee;
                                        $maxCall = $call;
                                }
                        }
                        if ( $maxCall !== null ) {
                                $path[$maxCall] = $this->hieraData[$maxCall];
                        }
                        $func = $maxCallee;
                }
                return $path;
        }

        /**
         * Make a closure to use as a sort function. The resulting function will
         * sort by descending numeric values (largest value first).
         *
         * @param string $key Data key to sort on
         * @param string $sub Sub key to sort array values on
         * @return Closure
         */
        public static function makeSortFunction( $key, $sub ) {
                return function ( $a, $b ) use ( $key, $sub ) {
                        if ( isset( $a[$key] ) && isset( $b[$key] ) ) {
                                // Descending sort: larger values will be first in result.
                                // Assumes all values are numeric.
                                // Values for 'main()' will not have sub keys
                                $valA = is_array( $a[$key] ) ? $a[$key][$sub] : $a[$key];
                                $valB = is_array( $b[$key] ) ? $b[$key][$sub] : $b[$key];
                                return $valB - $valA;
                        } else {
                                // Sort datum with the key before those without
                                return isset( $a[$key] ) ? -1 : 1;
                        }
                };
        }
}