Ticket #17019: perftest_17019.php

<?php
// performance test for WP ticket #17019
//
// purpose: evaluate performance penalties for extra call_user_func_array() calls by current apply_filters_ref_array(),
//                      versus an additional empty statement in proposed patch


add_action( 'init', 'run_multiple_perf_tests' );
//add_action( 'init', 'run_single_perf_test' );

function run_single_perf_test() {
        $num_queries = 5;
        $num_filters = 10;
        run_perf_test( $num_queries, $num_filters, true );
        die( 'test done' );
}

function run_multiple_perf_tests() {
        // array( num_queries, num_filters )
        $a = array();
        $a[] = array( 1, 0 );
        $a[] = array( 5, 0 );
        $a[] = array( 2, 5 );
        $a[] = array( 5, 5 );
        $a[] = array( 5, 10 );
        $a[] = array( 5, 20 );
        $a[] = array( 10, 5 );
        $a[] = array( 10, 10 );
        $a[] = array( 10, 20 );
        $a[] = array( 10, 50 );
        $a[] = array( 20, 50 );
        $a[] = array( 100, 100 );
        
        echo '<p>Running performance test for WP ticket #17019 to show:</p><ul><li>cost of superfluous call_user_func_array() calls in apply_filters_ref_array()</li><li>cost of context check to avoid them</li></ul>';
        echo '<table border=1><thead><th>Queries</th><th>Filters</th><th>superfluous<br />call_user_func()<br />(current)</th><th>additional<br />empty()<br />(proposed)</th></thead><tbody>';
        
        echo "<p>Premise:</p><ul><li>M filters are added to 'post_where'</li><li>but each filter only applies to only 1 of the N queries, and will return an unaltered WHERE clause for all other queries.</li></ul>";
        
        echo "<p>Results:</p>";
        
        foreach( $a as $arg ) {
                $result = perf_test( $arg[0], $arg[1], false );

                echo '<tr><td>' . $arg[0] . '</td><td>' . $arg[1] . '</td><td>' . round( $result['savings'], 2 ) . ' msec</td><td>' . round( $result['cost'], 2 ) . ' msec</td></tr>';
        }
        
        echo '</tbody></table>';
        
        die( '<br />test done.' );
}

function perf_test_where( $where, &$query ) {
        if ( ! empty( $query->query_vars['context'] ) && ( 'blahblah' == $query->query_vars['context'] ) ) {
                return $where . ' blah';
        }
        return $where;
}

function perf_test( $num_queries, $num_filters, $verbose = true ) {
        if ( $verbose )
                echo "running performance test with $num_filters 'posts_where' filters added and $num_queries 'posts_where' hook applications:<br /><br />";
        
        for ( $i = 0; $i < $num_filters; $i++ ) {
                add_filter( 'posts_where', 'perf_test_where', $i, 2 );
        }
        
        global $wp_query;
        $where = 'TEST CLAUSE';
        
        if ( ( $num_filters < 2 ) || ( $num_queries < 2 ) ) {
                $extra_call_user_func_time = 0;
        } else {
                // ==== measure time to apply M out-of-context filters for N get_posts() executions ====
                $start = microtime(true);
                for ( $i = 0; $i < $num_queries; $i++ ) {
                        $test = apply_filters_ref_array( 'posts_where', array( $where, &$wp_query )  );
                }
                $all_filters_time = ( microtime(true) - $start ) * 1000;
                
                for ( $i = 0; $i < $num_filters - 1; $i++ )
                        remove_filter( 'posts_where', 'perf_test_where', $i, 2 );
                
                // ==== subtract out time to apply a single in-context filter for N different get_posts() executions ====
                $start = microtime(true);
                for ( $i = 0; $i < $num_queries; $i++ ) {
                        $test = apply_filters_ref_array( 'posts_where', array( $where, &$wp_query )  );
                }
                $one_filter_time = ( microtime(true) - $start ) * 1000;
                
                $extra_call_user_func_time = $all_filters_time - $one_filter_time;
        }
        
        // ==== measure time to execute proposed if statement (with empty check) in every apply_filters_ref_array() call ====
        $arr = array( 'key1' => 'blah' );
        $context = '';
        
        $start = microtime();
        for ( $i = 0; $i < $num_queries * 26; $i++ ) {
                if ( ! is_null( $arr['key1'] ) && ( empty( $arr['key2'] ) || ( $arr['key2'] == $context ) ) ) {
                        $j = 0;
                }
        }
        $if_empty_time = ( microtime(true) - $start ) * 1000;
        
        // ==== subtract out time to execute current if statement in every apply_filters_ref_array() call ====
        $start = microtime();
        for ( $i = 0; $i < $num_queries * 26; $i++ ) {
                if ( ! is_null( $arr['key1'] ) ) {
                        $j = 0;
                }
        }
        $if_time = ( microtime(true) - $start ) * 1000;

        $extra_empty_time = $if_empty_time - $if_time;
        
        if ( $verbose ) {
                echo( "time incurred for out-of-context filter applications (current API): <br />$extra_call_user_func_time msec" . '<br /><br />' );
                echo( "time incurred for context check in apply_filters_ref_array (revised API): <br />$extra_empty_time msec" . '<br /><br />' );
        }
        
        return array( 'savings' => $extra_call_user_func_time, 'cost' => $extra_empty_time );
}
?>