ArrayUtils.php

Go to the documentation of this file.

<?php

class ArrayUtils {
    public static function consistentHashSort( &$array, $key, $separator = "\000" ) {
        $hashes = array();
        foreach ( $array as $elt ) {
            $hashes[$elt] = md5( $elt . $separator . $key );
        }
        uasort( $array, function ( $a, $b ) use ( $hashes ) {
            return strcmp( $hashes[$a], $hashes[$b] );
        } );
    }

    public static function pickRandom( $weights ) {
        if ( !is_array( $weights ) || count( $weights ) == 0 ) {
            return false;
        }

        $sum = array_sum( $weights );
        if ( $sum == 0 ) {
            # No loads on any of them
            # In previous versions, this triggered an unweighted random selection,
            # but this feature has been removed as of April 2006 to allow for strict
            # separation of query groups.
            return false;
        }
        $max = mt_getrandmax();
        $rand = mt_rand( 0, $max ) / $max * $sum;

        $sum = 0;
        foreach ( $weights as $i => $w ) {
            $sum += $w;
            # Do not return keys if they have 0 weight.
            # Note that the "all 0 weight" case is handed above
            if ( $w > 0 && $sum >= $rand ) {
                break;
            }
        }
        return $i;
    }
}