NeverSleep is an immutable data structure server, written in Clojure
Follow instructions at https://github.com/raspasov/neversleep
Add the necessary dependency to your Leiningen project.clj and require the library in your ns:
[com.raspasov/neversleep-clojure-client "1.0.0-alpha5"] ;project.clj
(ns my-app.core
(:require [neversleep-clojure-client.core :as nvrslp :refer :all]))Write to an entity "user-1" while preserving all past history:
;connect to server
(nvrslp/init "localhost" 10000)
;first write
(io-assoc "user-1" :currency-balance 100)
=> {:result {:timestamp "1427531747415000000"}} ;t-1
;second write
(io-assoc "user-1" :currency-balance 200)
=> {:result {:timestamp "1427531776863000000"}} ;t-2
;read "user-1" as of t-1
(io-get-entity-as-of "user-1" "1427531747415000000")
=> {:result {:currency-balance 100}}
;read "user-1" as of t-2
(io-get-entity-as-of "user-1" "1427531776863000000")
=> {:result {:currency-balance 200}}
;get all versions of an entity
;the last parameter is the maximum number of versions returned (limit)
;this lookup is currently implemented in linear time, so the limit should be kept low
(io-get-all-versions-between "user-1" latest-server-timestamp end-of-times 25)
=> {:result [["1427531776863000000" {:currency-balance 200}]
["1427531747415000000" {:currency-balance 100}]]}
;"delete" from an entity
(io-dissoc "user-1" :currency-balance)
=> {:result {:timestamp "1427533314969000000"}}
;get the current state of the entity
(io-get-entity "user-1")
=> {:result {}} ;entity is empty
;of course, reading "user-1" at a previous timestamp is intact
(io-get-entity-as-of "user-1" "1427531776863000000")
=> {:result {:currency-balance 200}}
;we can see that the history has grown by one item
(io-get-all-versions-between "user-1" latest-server-timestamp end-of-times 25)
=> {:result [["1427533314969000000" {}]
["1427531776863000000" {:currency-balance 200}]
["1427531747415000000" {:currency-balance 100}]]}
Copyright © 2015 Rangel Spasov
Distributed under the MIT License