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PHP Consistency hash Distributed Algorithm Encapsulation Class Definition and Usage Example

  • 2021-10-25 06:15:24
  • OfStack

This paper illustrates the definition and usage of PHP1-induced hash distributed algorithm encapsulation class. Share it for your reference, as follows:

1. No virtual node implementation 


<?php
/**
 * 1 Pathogenic hash Distributed algorithm 
 * @param $key
 * @return int
 *  Implementation steps 
 * 1. First put 0~  Yes 32 Bitwise maximum signed integer ( 0x7FFFFFFF )   Imagine 1 Closed loop 
 * 2. Pass the server list through hash Algorithms are distributed in   In the ring 
 * 3. Will key Values are also distributed in the ring 
 * 4. Pass _isSorted Determine whether the server needs to be sorted in reverse order   Traverse the server after sorting   Find the nearest server   Return 
 * hash The algorithm does not guarantee balance   In order to ensure the balance as much as possible,   We should add the number of virtual nodes   Will 1 Server nodes are virtualized into multiple   The balance is ensured to a great extent 
 */
class FlexiHash{
  private $_serverList = array();
  private $_isSorted = false;
  private $_virtual_node_num = 20;// Number of virtual nodes   The fewer servers   The more virtual nodes should be added 
  // Pass hash Algorithm return 1 Integer value 
  protected function myHash($key){
    $md5 = substr(md5($key),0,8);
    $seed = 31; // Seed value 
    $hash=0;
    for($i=0;$i<8;$i++){
      $hash = $hash*$seed+ord($md5{$i}); //ord  Return ascii Value 
      $i++;
    }
    return $hash&0x7FFFFFFF; //0x7FFFFFFF Represents the maximum value 
  }
  // Add Server 
  function addServer($server){
    $hash =$this->myHash($server. '#1');
    if(!isset($this->_serverList[$hash])) {
      for ($i = 1; $i <= $this->_virtual_node_num; $i++) {
        $hash = $this->myHash($server . '#' . $i);
        $this->_serverList[$hash] = $server;
      }
    }
    $this->_isSorted = false;
    return true;
  }
  // Delete a server 
  function removeServer($server){
    for ($i = 1; $i <= $this->_virtual_node_num; $i++) {
      $hash = $this->myHash($server . '#' . $i);
      unset($this->_serverList[$hash]);
    }
    $this->_isSorted = false;
    return true;
  }
  // Get the server 
  function lookup($key){
    $hash =$this->myHash($key);
    if(!$this->_isSorted){
      krsort($this->_serverList,SORT_NUMERIC);
      $this->_isSorted = true;
    }
    foreach($this->_serverList as $pos=>$server){
      if($hash >= $pos) return $server;
    }
    return end($this->_serverList);
  }
  public function getServerList(){
    krsort($this->_serverList,SORT_NUMERIC);
    return $this->_serverList;
  }
}
//demo test
$hserver = new FlexiHash();
// Add Server 
$hserver->addServer('192.168.1.1');
$hserver->addServer('192.168.1.2');
$hserver->addServer('192.168.1.3');
$hserver->addServer('192.168.1.4');
$hserver->addServer('192.168.1.5');
$key1='Key1111';
$key2='Key2222';
$key2='Key3333';
$key2='Key4444';
$key2='Key5555';
$key2='Key6666';
echo "save key1 in server: ".$hserver->lookup($key1).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key2).PHP_EOL;
echo "save key1 in server: ".$hserver->lookup($key3).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key4).PHP_EOL;
echo "save key1 in server: ".$hserver->lookup($key5).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key6).PHP_EOL;
echo "================================================".PHP_EOL;
// Remove Server  key Values are automatically escaped to the following 1 Taiwan server 
$hserver->removeServer('192.168.1.4');
echo "save key1 in server: ".$hserver->lookup($key1).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key2).PHP_EOL;
echo "save key1 in server: ".$hserver->lookup($key3).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key4).PHP_EOL;
echo "save key1 in server: ".$hserver->lookup($key5).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key6).PHP_EOL;
echo "================================================".PHP_EOL;
// Recovery of failed servers  key Value will restore the original server 
$hserver->addServer('192.168.1.4');
echo "save key1 in server: ".$hserver->lookup($key1).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key2).PHP_EOL;
echo "save key1 in server: ".$hserver->lookup($key3).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key4).PHP_EOL;
echo "save key1 in server: ".$hserver->lookup($key5).PHP_EOL;
echo "save key2 in server: ".$hserver->lookup($key6).PHP_EOL;

2. Running results:

save key1 in server: 192.168.1.4
save key2 in server: 192.168.1.4
save key1 in server: 192.168.1.3
save key2 in server: 192.168.1.3
save key1 in server: 192.168.1.3
save key2 in server: 192.168.1.3
================================================
save key1 in server: 192.168.1.2
save key2 in server: 192.168.1.5
save key1 in server: 192.168.1.3
save key2 in server: 192.168.1.3
save key1 in server: 192.168.1.3
save key2 in server: 192.168.1.3
================================================
save key1 in server: 192.168.1.4
save key2 in server: 192.168.1.4
save key1 in server: 192.168.1.3
save key2 in server: 192.168.1.3
save key1 in server: 192.168.1.3
save key2 in server: 192.168.1.3

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.

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