Merge pull request #35 from mkristian/be-nice

Be nice

src/main/groovy/com/github/lookout/verspaetung/Delay.groovy

@@ -0,0 +1,40 @@
+package com.github.lookout.verspaetung
+
+/**
+ * abstract the logic on how to reduce the polling speed and get back to
+ * to full speed.
+ */
+class Delay {
+    static final Integer POLLER_DELAY_MIN = (1 * 1000)
+    static final Integer POLLER_DELAY_MAX = (2048 * 1000) // about half an hour
+
+    private Integer delay = POLLER_DELAY_MIN
+
+    boolean reset() {
+        if (delay != POLLER_DELAY_MIN) {
+            delay = POLLER_DELAY_MIN
+            true
+        }
+        else {
+            false
+        }
+    }
+
+    boolean slower() {
+        if (delay < POLLER_DELAY_MAX) {
+            delay += delay
+            true
+        }
+        else {
+            false
+        }
+    }
+
+    Integer value() {
+        delay
+    }
+
+    String toString() {
+        "Delay[ ${delay / 1000} sec ]"
+    }
+}

src/main/groovy/com/github/lookout/verspaetung/KafkaPoller.groovy

@@ -17,7 +17,7 @@ import scala.collection.JavaConversions
  * meta-data for them
  */
 class KafkaPoller extends Thread {
-    private static final Integer POLLER_DELAY = (1 * 1000)
+
     private static final String KAFKA_CLIENT_ID = 'VerspaetungClient'
     private static final Integer KAFKA_TIMEOUT = (5 * 1000)
     private static final Integer KAFKA_BUFFER = (100 * 1024)
@@ -29,7 +29,7 @@ class KafkaPoller extends Thread {
     private final AbstractMap<TopicPartition, Long> topicOffsetMap
     private final List<Closure> onDelta
     private final AbstractSet<String> currentTopics
-    private List<Broker> brokers
+    private final List<Broker> brokers
 
     KafkaPoller(AbstractMap map, AbstractSet topicSet) {
         this.topicOffsetMap = map
@@ -48,7 +48,8 @@ class KafkaPoller extends Thread {
     @SuppressWarnings(['LoggingSwallowsStacktrace', 'CatchException'])
     void run() {
         LOGGER.info('Starting wait loop')
-
+        Delay delay = new Delay()
+        LOGGER.error('polling ' + delay)
         while (keepRunning) {
             LOGGER.debug('poll loop')
 
@@ -62,21 +63,33 @@ class KafkaPoller extends Thread {
             if (this.currentTopics.size() > 0) {
                 try {
                     dumpMetadata()
+                    if (delay.reset()) {
+                        LOGGER.error('back to normal ' + delay)
+                    }
                 }
                 catch (KafkaException kex) {
                     LOGGER.error('Failed to interact with Kafka: {}', kex.message)
+                    slower(delay)
                 }
                 catch (Exception ex) {
                     LOGGER.error('Failed to fetch and dump Kafka metadata', ex)
+                    slower(delay)
                 }
             }
 
-            Thread.sleep(POLLER_DELAY)
+            Thread.sleep(delay.value())
+        }
+        disconnectConsumers()
+    }
+
+    private void slower(Delay delay) {
+        if (delay.slower()) {
+            LOGGER.error('using ' + delay)
         }
     }
 
     @SuppressWarnings(['CatchException'])
-    void dumpMetadata() {
+    private void dumpMetadata() {
         LOGGER.debug('dumping meta-data')
 
         Object metadata = fetchMetadataForCurrentTopics()
@@ -101,7 +114,7 @@ class KafkaPoller extends Thread {
      * The 'metadata' is the expected return from
      * kafka.client.ClientUtils.fetchTopicMetadata
      */
-    void withTopicsAndPartitions(Object metadata, Closure closure) {
+    private void withTopicsAndPartitions(Object metadata, Closure closure) {
         withScalaCollection(metadata.topicsMetadata).each { kafka.api.TopicMetadata f ->
             withScalaCollection(f.partitionsMetadata).each { p ->
                 TopicPartition tp = new TopicPartition(f.topic, p.partitionId)
@@ -113,7 +126,7 @@ class KafkaPoller extends Thread {
     /**
      * Fetch the leader metadata and update our data structures
      */
-    void captureLatestOffsetFor(TopicPartition tp, Object partitionMetadata) {
+    private void captureLatestOffsetFor(TopicPartition tp, Object partitionMetadata) {
         Integer leaderId = partitionMetadata.leader.get()?.id
         Integer partitionId = partitionMetadata.partitionId
 
@@ -122,7 +135,7 @@ class KafkaPoller extends Thread {
         this.topicOffsetMap[tp] = offset
     }
 
-    Long latestFromLeader(Integer leaderId, String topic, Integer partition) {
+    private Long latestFromLeader(Integer leaderId, String topic, Integer partition) {
         SimpleConsumer consumer = this.brokerConsumerMap[leaderId]
 
         /* If we don't have a proper SimpleConsumer instance (e.g. null) then
@@ -137,24 +150,26 @@ class KafkaPoller extends Thread {
         return consumer.earliestOrLatestOffset(topicAndPart, -1, 0)
     }
 
-    Iterable withScalaCollection(scala.collection.Iterable iter) {
+    private Iterable withScalaCollection(scala.collection.Iterable iter) {
         return JavaConversions.asJavaIterable(iter)
     }
 
     /**
      * Blocking reconnect to the Kafka brokers
      */
-    void reconnect() {
+    private void reconnect() {
         disconnectConsumers()
         LOGGER.info('Creating SimpleConsumer connections for brokers')
-        this.brokers.each { Broker b ->
-            SimpleConsumer consumer = new SimpleConsumer(b.host,
-                                                         b.port,
-                                                         KAFKA_TIMEOUT,
-                                                         KAFKA_BUFFER,
-                                                         KAFKA_CLIENT_ID)
-            consumer.connect()
-            this.brokerConsumerMap[b.id] = consumer
+        synchronized(this.brokers) {
+            this.brokers.each { Broker b ->
+                SimpleConsumer consumer = new SimpleConsumer(b.host,
+                                                             b.port,
+                                                             KAFKA_TIMEOUT,
+                                                             KAFKA_BUFFER,
+                                                             KAFKA_CLIENT_ID)
+                consumer.connect()
+                this.brokerConsumerMap[b.id] = consumer
+            }
         }
         this.shouldReconnect = false
     }
@@ -164,7 +179,6 @@ class KafkaPoller extends Thread {
      */
     void die() {
         this.keepRunning = false
-        disconnectConsumers()
     }
 
     private void disconnectConsumers() {
@@ -178,8 +192,11 @@ class KafkaPoller extends Thread {
      * Store a new list of KafkaBroker objects and signal a reconnection
      */
     void refresh(List<KafkaBroker> brokers) {
-        this.brokers = brokers.collect { KafkaBroker b ->
-            new Broker(b.brokerId, b.host, b.port)
+        synchronized(this.brokers) {
+            this.brokers.clear()
+            this.brokers.addAll(brokers.collect { KafkaBroker b ->
+                new Broker(b.brokerId, b.host, b.port)
+            })
         }
         this.shouldReconnect = true
     }
@@ -189,7 +206,9 @@ class KafkaPoller extends Thread {
      * scala underpinnings
      */
     private scala.collection.immutable.Seq getBrokersSeq() {
-        return JavaConversions.asScalaBuffer(this.brokers).toList()
+        synchronized(this.brokers) {
+            return JavaConversions.asScalaBuffer(this.brokers).toList()
+        }
     }
 
     /**

src/main/groovy/com/github/lookout/verspaetung/Main.groovy

@@ -126,8 +126,9 @@ class Main {
         /* Assuming that most people aren't needing to run Storm-based watchers
          * as well
          */
+        KafkaSpoutTreeWatcher stormWatcher = null
         if (cli.hasOption('s')) {
-            KafkaSpoutTreeWatcher stormWatcher = new KafkaSpoutTreeWatcher(client,
+            stormWatcher = new KafkaSpoutTreeWatcher(client,
                                                                            watchedTopics,
                                                                            consumerOffsets)
             stormWatcher.onConsumerData << gaugeRegistrar
@@ -155,6 +156,18 @@ class Main {
         /* Start the reporter if we've got it */
         reporter?.start(delayInSeconds, TimeUnit.SECONDS)
 
+        // shutdown threads
+        Runtime.getRuntime().addShutdownHook(new Thread() {
+                                                 public void run() {
+                                                     Main.logger.info("showdown threads")
+                                                     poller.die()
+                                                     consumerWatcher.close()
+                                                     if (stormWatcher != null) {
+                                                         stormWatcher.close()
+                                                     }
+                                                     poller.join()
+                                                 }
+                                             });
         logger.info('Starting wait loop...')
         synchronized(this) {
             wait()

src/main/groovy/com/github/lookout/verspaetung/zk/AbstractTreeWatcher.groovy

@@ -47,5 +47,13 @@ abstract class AbstractTreeWatcher implements TreeCacheListener {
         return this
     }
 
+    /**
+     * Close our internal cache and return ourselves for API cleanliness
+     */
+    AbstractTreeWatcher close() {
+        this.cache?.close()
+        return this
+    }
+
     abstract void childEvent(CuratorFramework client, TreeCacheEvent event)
 }

src/main/groovy/com/github/lookout/verspaetung/zk/BrokerTreeWatcher.groovy

@@ -28,7 +28,7 @@ class BrokerTreeWatcher extends AbstractTreeWatcher {
         super(client)
 
         this.json = new JsonSlurper()
-        this.brokers = []
+        this.brokers = Collections.synchronizedList([])
         this.onBrokerUpdates = []
     }
 
@@ -47,9 +47,8 @@ class BrokerTreeWatcher extends AbstractTreeWatcher {
          */
         if (event.type == TreeCacheEvent.Type.INITIALIZED) {
             this.isTreeInitialized = true
-            List threadsafeBrokers = Collections.synchronizedList(this.brokers)
             this.onBrokerUpdates.each { Closure c ->
-                c?.call(threadsafeBrokers)
+                c?.call(this.brokers)
             }
             return
         }
@@ -68,6 +67,12 @@ class BrokerTreeWatcher extends AbstractTreeWatcher {
         Object brokerData = json.parseText(new String(nodeData.data, 'UTF-8'))
 
         this.brokers << new KafkaBroker(brokerData, brokerId)
+
+        if (this.isTreeInitialized) {
+            this.onBrokerUpdates.each { Closure c ->
+                c?.call(this.brokers)
+            }
+        }
     }
 
     /**

src/test/groovy/com/github/lookout/verspaetung/DelaySpec.groovy

@@ -0,0 +1,55 @@
+package com.github.lookout.verspaetung
+
+import spock.lang.*
+
+class DelaySpec extends Specification {
+    Delay delay = new Delay()
+    
+    def "it should give default on first use"() {
+        given:
+
+        expect:
+        delay.value() == Delay.POLLER_DELAY_MIN
+    }
+
+    def "slower has an upper bound"() {
+        given:
+        for(int i = 1; i < 20; i++) { delay.slower() }
+        def firstLast = delay.value()
+        def result = delay.slower()
+        def secondLast = delay.value()
+        
+        expect:
+        firstLast == secondLast
+        firstLast == Delay.POLLER_DELAY_MAX
+        result == false
+    }
+
+    def "increasing delay gives true"() {
+        def result = true
+        for(int i = 1; delay.value() < Delay.POLLER_DELAY_MAX; i++) {
+            result = result && delay.slower()
+        }
+        def last = delay.slower()
+
+        expect:
+        result == true
+        last == false
+    }
+
+    def "reset on min value gives false"() {
+        given:
+        def result = delay.reset()
+        
+        expect:
+        result == false
+    }
+    def "reset on none min value gives true"() {
+        given:
+        delay.slower()
+        def result = delay.reset()
+        
+        expect:
+        result == true
+    }
+}