Zookeeper Atom

Looks and behaves like a Clojure atom but works distributed across many machines by storing it's data as EDN in a Zookeeper node.

Features

• Simple API: atom (to create), deref/@, swap, and reset. Just like Clojure's API.
• Reads don't block, they just return a cached value. All updates from Zookeeper get applied in the background.
• Values are encoded as EDN.

Releases and Dependency Information

zookeeper-atom is released via Clojars. The Latest stable release is 1.0.0

Leiningen dependency information:

[zookeeper-atom "1.0.0"]

Maven dependency information:

<dependency>
  <groupId>zookeeper-atom</groupId>
  <artifactId>zookeeper-atom</artifactId>
  <version>1.0.0</version>
</dependency>

Usage

This example requires that you have Zookeeper installed and running:

(require '[zookeeper-atom.core :as zk])

(def client (zk/connect "127.0.0.1"))
(def a-atom (zk/atom client "/some/znode/path"))

@a-atom
;; => nil

(zk/swap a-atom assoc :foo "bar")
;; => {:foo "bar"}

(zk/reset a-atom {})
;; => {}

Alternatively to the code above, a zookeeper-atom can be initialized:

(def b-atom (zk/atom client "/some/path" [1 2 3]))

@b-atom
;; => [1 2 3]

However, if there already exists a node at the given path, it's value will not be overwritten:

(def c-atom (zk/atom client "/some/path" "WAT?!"))

@c-atom
;; => [1 2 3]

Contributing

Reporting bugs and pull requests are very welcome!

Here is a little snippet to get you started in your REPL in case you want to extend zookeeper-atom:

(use 'clj-logging-config.log4j 'midje.repl)
(set-loggers! :root {:level :warn} "zookeeper-atom.core" {:level :debug})
(autotest)
; hack!

License

Copyright © 2014 Torsten Becker.

Distributed under the Eclipse Public License, the same as Clojure.