PHP实现的服务器一致性hash分布算法示例
本文实例讲述了PHP实现的服务器一致性hash分布算法。分享给大家供大家参考，具体如下：
<?php
/**
* 对服务器进行一致性hash分布算法
*/
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;
}
}
//示例
$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";
运行结果：
Array
(
[0] => 127.0.0.1:11214
[1] => 127.0.0.1:11211
)
PS：这里再为大家提供2款hash相关在线工具供大家参考使用：
在线散列/哈希算法加密工具：
http://tools.jb51.net/password/hash_encrypt
在线MD5/hash/SHA-1/SHA-2/SHA-256/SHA-512/SHA-3/RIPEMD-160加密工具：
http://tools.jb51.net/password/hash_md5_sha
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希望本文所述对大家PHP程序设计有所帮助。
