#Flexihash

Flexihash is a small PHP library which implements consistent hashing, which is most useful in distributed caching. It requires PHP5 and uses PHPUnit for unit testing.

##Installation

Composer is the recommended installation technique. You can find flexihash on Packagist so installation is as easy as

composer require flexihash/flexihash

or in your composer.json

{
    "require": {
        "flexihash/flexihash": "^2.0.0"
    }
}

##Usage

$hash = new Flexihash();

// bulk add
$hash->addTargets(array('cache-1', 'cache-2', 'cache-3'));

// simple lookup
$hash->lookup('object-a'); // "cache-1"
$hash->lookup('object-b'); // "cache-2"

// add and remove
$hash
  ->addTarget('cache-4')
  ->removeTarget('cache-1');

// lookup with next-best fallback (for redundant writes)
$hash->lookupList('object', 2); // ["cache-2", "cache-4"]

// remove cache-2, expect object to hash to cache-4
$hash->removeTarget('cache-2');
$hash->lookup('object'); // "cache-4"

##Further Reading

• http://www.spiteful.com/2008/03/17/programmers-toolbox-part-3-consistent-hashing/
• http://weblogs.java.net/blog/tomwhite/archive/2007/11/consistent_hash.html