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：
servers=$servers;
foreach($serversas$server){
for($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);
}
privatefunctiongetNodeIndex($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)){
return0;
}
$this->nodeTotalNum=count($this->nodeHashList);
return$this->binaryChopIndex(0,$this->nodeTotalNum);
}
privatefunctionbinaryChopIndex($l=0,$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;
}
}
publicfunctiongetServersByKey($key,$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'
);
$obj=newHashRing($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/