Example of server consistency hash distribution algorithm implemented by PHP

In this paper, an example is given to describe the server 1-induced hash distribution algorithm implemented by PHP. Share it for your reference, as follows:

<?php
/**
 *  To the server 1 Pathogenic hash Distribution algorithm 
 */
class HashRing
{
  private $servers = array();
  private $nodeList = array();
  private $nodeHashList = array();
  private $nodeTotalNum = 0;
  private $virtualNodeNum = 32;
  private $keyHash = '';
  public function __construct($servers)
  {
    $this->servers = $servers;
    foreach ($servers as $server) {
      for ($i = 0; $i < $this->virtualNodeNum; $i++) {
        $this->nodeList[sprintf("%u", crc32($server.'-'.$i))] = array($server, $i);
      }
    }
    ksort($this->nodeList);
    $this->nodeHashList = array_keys($this->nodeList);
  }
  private function getNodeIndex($key)
  {
    $this->keyHash = sprintf("%u", crc32($key));
    if ($this->keyHash > end($this->nodeHashList)) {
      $this->keyHash = $this->keyHash % end($this->nodeHashList);
    }
    if ($this->keyHash <= reset($this->nodeHashList)) {
      return 0;
    }
    $this->nodeTotalNum = count($this->nodeHashList);
    return $this->binaryChopIndex(0, $this->nodeTotalNum);
  }
  private function binaryChopIndex($l=0, $r=0)
  {
    if ($l < $r) {
      $avg = intval(($l+$r) / 2);
      if ($this->nodeHashList[$avg] == $this->keyHash) {
        return $avg;
      } elseif ($this->keyHash < $this->nodeHashList[$avg] && ($avg > 0)) {
        return $this->binaryChopIndex($l, $avg-1);
      } else {
        return $this->binaryChopIndex($avg+1, $r);
      }
    } else {
      return $l;
    }
  }
  public function getServersByKey($key, $num=1)
  {
    $index = $this->getNodeIndex($key);
    $server = $this->nodeList[$this->nodeHashList[$index]];
    if ($num == 1) {
      return $server[0];
    }
    if ($num >= count($this->servers)) {
      $num = count($this->servers);
    }
    $result = array($server[0]);
    for ($i=$index+1; true; $i++) {
      if ($i >= $this->nodeTotalNum) {
        $i = 0;
      }
      $nextServer = $this->nodeList[$this->nodeHashList[$i]];
      if (!in_array($nextServer[0], $result)) {
        $result[] = $nextServer[0];
      }
      if (count($result) == $num) {
        break;
      }
    }
    return $result;
  }
}
// Example 
$servers = array(
  '127.0.0.1:11211',
  '127.0.0.1:11212',
  '127.0.0.1:11213',
  '127.0.0.1:11214',
  '127.0.0.1:11215'
);
$obj = new HashRing($servers);
$servers = $obj->getServersByKey('testkey', 2);
print_r($servers);
echo "\n";

Run results:

Array
(
[0] = > 127.0.0.1:11214
[1] = > 127.0.0.1:11211
)

PS: Here are two online tools related to hash for your reference:

Online hash/hash algorithm encryption tool:
http://tools.ofstack.com/password/hash_encrypt

Online MD5/hash/SHA-1/SHA-2/SHA-256/SHA-512/SHA-3/RIPEMD-160 Encryption Tool:
http://tools.ofstack.com/password/hash_md5_sha

For more readers interested in PHP related contents, please check the special topics of this site: "Summary of php Encryption Methods", "Summary of PHP Encoding and Transcoding Operation Skills", "Summary of PHP Mathematical Operation Skills", "Encyclopedia of PHP Array (Array) Operation Skills", "Summary of php String (string) Usage", "Tutorial of PHP Data Structure and Algorithm", "Summary of php Programming Algorithm" and "Summary of php Regular Expression Usage"

I hope this article is helpful to everyone's PHP programming.