Onyx plugin for reading from a seq. The seq will be read from in way that is approriate for use with lazy-seqs. Therefore, this plugin can be useful for use with datomic.api/datoms calls, slow lazy calculations, line-seq / buffered reading, etc.
[THIS PROJECT IS ARCHIVED AS THE PLUGIN IS NOW INCLUDED IN ONYX CORE:] (https://github.com/onyx-platform/onyx/blob/0.12.x/src/onyx/plugin/seq.clj)
In your project file:
[org.onyxplatform/onyx-seq "0.9.15.1-SNAPSHOT"](:require [onyx.plugin.seq])Catalog entry:
{:onyx/name :in
:onyx/plugin :onyx.plugin.seq/input
:onyx/type :input
:onyx/medium :seq
:seq/checkpoint? true
:onyx/batch-size batch-size
:onyx/max-peers 1
:onyx/doc "Reads segments from seq"}Lifecycle entry:
[{:lifecycle/task :in
:lifecycle/calls :onyx.plugin.seq/reader-calls}]Ensure that the elements of your seq are maps. If they are not, in may help to bundle them into maps via a map over the seq returned before returning it from the lifecycle.
e.g. (map (fn [a] {:val a}) ["A" "B" "C"])
onyx-seq will checkpoint the state of the read results. In the case of a virtual peer crash, the new virtual peer will drop from the seq until it has reached the first non fully acked segment. In order for this process to work, the seq that is read from must be reproducible on restart. If it is not, please disable checkpointing via :seq/checkpoint?.
(defn inject-in-reader [event lifecycle]
(let [rdr (FileReader. (:buffered-reader/filename lifecycle))]
{:seq/rdr rdr
:seq/seq (line-seq (BufferedReader. rdr))}))
(defn close-reader [event lifecycle]
(.close (:seq/rdr event)))
(def in-calls
{:lifecycle/before-task-start inject-in-reader
:lifecycle/after-task-stop close-reader})
;; lifecycles
(def lifecycles
[{:lifecycle/task :in
:buffered-reader/filename "test-resources/lines.txt"
:lifecycle/calls ::in-calls}
{:lifecycle/task :in
:lifecycle/calls :onyx.plugin.seq/reader-calls}])Pull requests into the master branch are welcomed.
Copyright © 2015 Distributed Masonry LLC
Distributed under the Eclipse Public License, the same as Clojure.