/
mock.clj
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/
mock.clj
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(ns jackdaw.test.transports.mock
(:require
[clojure.stacktrace :as stacktrace]
[clojure.tools.logging :as log]
[jackdaw.client :as kafka]
[jackdaw.test.journal :as j]
[jackdaw.test.transports :as t :refer [deftransport]]
[jackdaw.test.serde :refer [byte-array-serializer byte-array-deserializer
apply-serializers apply-deserializers serde-map]]
[manifold.stream :as s]
[manifold.deferred :as d])
(:import
(org.apache.kafka.common.record TimestampType)
(org.apache.kafka.clients.consumer ConsumerRecord)))
;; Unfortunately the terminology used in the test-machine clashes a bit with
;; the terminology used by the TopologyTestDriver so this looks a bit
;; confusing.
;;
;; While reviewing this code, bear in mind that the test machine has it's
;; own producer and consumer. The test-machine's producer is for producing
;; test input. The consumer is for consuming test output. On the other hand
;; when you feed records into the TopologyTestDriver, they are `ConsumerRecords`
;; (we're basically injecting the `ConsumerRecord` directly). This logic
;; is inverted on the other end where the test machine consumes the driver's
;; output `ProducerRecord`s directly
;;
;; For this reason, we try to make things a bit more meaningful by using
;; terms like "input-record" and "output-record".
(defn with-input-record
"Creates a kafka ConsumerRecord to be fed directly into a topology source
node by the TopologyTestDriver"
[topic-config]
(fn [m]
(let [record (ConsumerRecord. (get-in m [:topic :topic-name])
(int -1)
(long -1)
(:timestamp m)
TimestampType/CREATE_TIME,
(long ConsumerRecord/NULL_CHECKSUM)
(if-let [k (:key m)]
(count k)
0)
(if-let [v (:value m)]
(count v)
0)
(:key m)
(:value m))]
(assoc m :input-record record))))
(defn with-output-record
[topic-config]
(fn [r]
{:topic (.topic r)
:key (.key r)
:value (.value r)
:partition (or (.partition r) -1)}))
(defn- poller
"Returns a function for polling the results of a TopologyTestDriver
The returned function closes over the supplied `messages` channel
and `topic-config` to produce a function that can be invoked with
a TopologyTestDriver to gather any output generated by the topology
under test"
[messages topic-config]
(fn [driver]
(let [fetch (fn [[k t]]
{:topic k
:output (loop [collected []]
(if-let [o (.readOutput driver (:topic-name t)
byte-array-deserializer
byte-array-deserializer)]
(recur (conj collected o))
collected))})
topic-batches (->> topic-config
(map fetch)
(remove #(empty? (:output %)))
(map :output))]
(try
(when-not (empty? topic-batches)
(s/put-all! messages (apply concat topic-batches)))
(catch Throwable e
(log/error (Throwable->map e))
(s/put! messages {:error e}))))))
(defn mock-consumer
[driver topic-config deserializers]
(let [continue? (atom true)
messages (s/stream 1 (comp
(map (with-output-record topic-config))
(map #(apply-deserializers deserializers %))
(map #(assoc % :topic (j/reverse-lookup topic-config (:topic %))))))
started? (promise)
poll (poller messages topic-config)]
{:process (d/loop [cont? @continue?]
(d/chain cont? (fn [d]
(when-not (realized? started?)
(log/info "started mock consumer: %s" {:driver driver})
(deliver started? true))
(if @continue?
(d/future
(poll driver)
(Thread/sleep 100)
(d/recur @continue?))
(d/future
(s/close! messages)
(log/infof "stopped mock consumer: %s" {:driver driver}))))))
:started? started?
:messages messages
:continue? continue?}))
(defn mock-producer
[driver topic-config serializers on-input]
(let [build-record (with-input-record topic-config)
messages (s/stream 1 (map (fn [x]
(try
(-> (apply-serializers serializers x)
(build-record))
(catch Exception e
(let [trace (with-out-str
(stacktrace/print-cause-trace e))]
(log/error e trace))
(assoc x :serialization-error e))))))
_ (log/infof "started mock producer: %s" {:driver driver})
process (d/loop [message (s/take! messages)]
(d/chain message
(fn [{:keys [input-record ack serialization-error] :as message}]
(cond
serialization-error (do (deliver ack {:error :serialization-error
:message (.getMessage serialization-error)})
(d/recur (s/take! messages)))
input-record (do (on-input input-record)
(deliver ack {:topic (.topic input-record)
:partition (.partition input-record)
:offset (.offset input-record)})
(d/recur (s/take! messages)))
:else (do
(log/infof "stopped mock producer: %s" {:driver driver}))))))]
{:messages messages
:process process}))
(deftransport :mock
[{:keys [driver topics]}]
(let [serdes (serde-map topics)
test-consumer (mock-consumer driver topics (get serdes :deserializers))
record-fn (fn [input-record]
(try
(.pipeInput driver input-record)
(catch Exception e
(let [trace (with-out-str
(stacktrace/print-cause-trace e))]
(log/error e trace))
(throw e))))
test-producer (when @(:started? test-consumer)
(mock-producer driver topics (get serdes :serializers)
record-fn))]
{:consumer test-consumer
:producer test-producer
:serdes serdes
:topics topics
:exit-hooks [(fn []
(.close driver)
(s/close! (:messages test-producer))
(reset! (:continue? test-consumer) false)
@(:process test-producer)
@(:process test-consumer))]}))