ConsistentHashingで本当に分散できているのかを検証するためのプログラム

inspectConsistentHasher.php

<?php

error_reporting(E_ALL);

require_once '../class/ConsistentHasher.php';

$start_time = microtime(TRUE);
$nodes = array('1', '2', '3', '4');
$another_nodes = array('1', '2', '3', '4', '5');
$ids = range(1, 10000);

$hasher = new ConsistentHasher($nodes);

//結果を格納する配列を作る
$count_results = array();
foreach ($nodes as $name) {
    $count_results[$name] = 0;
}
$node_results = array();

//実行
foreach ($ids as $id) {
	$name = $hasher->getNode($id);
	$count_results[$name]++;
	$node_results[$id] = $name;
}

//実行結果表示(個数)
echo "CountPerNode\n";
foreach ($count_results as $name => $count) {
	echo 'node' . $name . ':' . $count . "\n";
}
echo "\n";
echo "\n";

//ここからノード増やしたときにどの程度変わるかチェック
$hit_count = 0;
$added_hasher = new ConsistentHasher($another_nodes);
foreach ($ids as $id) {
	$added_name = $added_hasher->getNode($id);
	if ($node_results[$id] === $added_name) {
		$hit_count++;
	}
}
echo 'node diff:' . (count($another_nodes) - count($nodes)) . ':' . $hit_count * 100 / count($ids) . "%\n";
echo "\n";
echo "\n";
//比較用に単なる剰余のバージョンも計算しておく
$hit_count = 0;
$before_num = count($nodes);
$after_num = count($another_nodes);
foreach ($ids as $id) {
	if ($id % $before_num === $id % $after_num) {
		$hit_count++;
	}
}
echo '(remainder)node diff:' . (count($another_nodes) - count($nodes)) . ':' . $hit_count * 100 / count($ids) . "%\n";
echo "\n";
echo "\n";
//終了！
echo "Time:" . (microtime(TRUE) - $start_time) . "sec\n";
echo "Memory:" . memory_get_peak_usage() / 1024 / 1024 . "MB\n";