* various consistent hash implementations that existed before this
* function was introduced.
*/
- static function consistentHashSort( &$array, $key, $separator = "\000" ) {
+ public static function consistentHashSort( &$array, $key, $separator = "\000" ) {
$hashes = array();
foreach ( $array as $elt ) {
$hashes[$elt] = md5( $elt . $separator . $key );
return strcmp( $hashes[$a], $hashes[$b] );
} );
}
+
+ /**
+ * Given an array of non-normalised probabilities, this function will select
+ * an element and return the appropriate key
+ *
+ * @param $weights array
+ *
+ * @return bool|int|string
+ */
+ 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;
+ }
}