An example of a consistent hash distribution algorithm

This article describes the implementation of a consistent hash algorithm using PHP.

Create a Flexihash class that has two member variables and three methods:

$serverlist: Save the list of servers.

$isSorted: Records whether the server list has been sequenced.

Addserver: Add a server to the server list;

Removeserver: Remove a server from the server list;

Lookup: Find the right server to store data in the current server.

"Example":

<span style= "Font-family:microsoft yahei;font-size:18px;"       ><?              Class flexihash{Private $serverList = Array ();                           Private $isSorted =false;                     Public Functionaddserver ($server) {$hash =mhash ($server);                     if (!isset ($this-serverlist[$hash]) {$this, serverlist[$hash] = $server;                     } $this->issorted = FALSE;              return TRUE;                     } functionremoveserver ($server) {$hash =mhash ($server);                     if (!isset ($this-serverlist[$hash]) {$this, serverlist[$hash] = $server;                     } $this->issorted = FALSE;              return TRUE;                     } functionlookup ($key) {$hash =mhash ($key);                  if (! $this-issorted) {          Krsort ($this-serverlist,sort_numeric);                            $this-issorted = TRUE; foreach ($this-serverlist as $pos = + $server) {if ($hash >= $pos) return $server                            ;                     } return$this-Serverlist[count ($this-ServerList)-1];       }}} $server = new Flexihash ();       $server->addserver ("192.168.1.1");       $server->addserver ("192.168.1.2");       $server->addserver ("192.168.1.3");       $server->addserver ("192.168.1.4");       $server->addserver ("192.168.1.5");       echo "Save Key1 Inserver:". $server->lookup (' Key1 ');       echo "Save Key2 Inserver:". $server->lookup (' Key2 ');       echo "+++++++++++++++++++++++++++++++++++++++++++++";       $server->removeserver ("192.168.1.4");       echo "Save Key1 Inserver:". $server->lookup (' Key1 '); echo "Save Key2 Inserver: ". $server->lookup (' Key2 ');       echo "+++++++++++++++++++++++++++++++++++++++++++++";       $server->addserver ("192.168.1.6");       echo "Save Key1 Inserver:". $server->lookup (' Key1 ');       echo "Save Key2 Inserver:". $server->lookup (' Key2 ');    echo "+++++++++++++++++++++++++++++++++++++++++++++"; </span>

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An example of a consistent hash distribution algorithm