Created listener for worker state change (#291)

* Created listener for worker state change
#275

src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/NoOpWorkerStateChangeListener.java

@@ -0,0 +1,16 @@
+package com.amazonaws.services.kinesis.clientlibrary.lib.worker;
+
+public class NoOpWorkerStateChangeListener implements WorkerStateChangeListener {
+
+	/**
+	 * Empty constructor for NoOp Worker State Change Listener
+	 */
+	public NoOpWorkerStateChangeListener() {
+
+	}
+
+	@Override
+	public void onWorkerStateChange(WorkerState newState) {
+
+	}
+}

src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java

@@ -71,6 +71,7 @@ public class Worker implements Runnable {
     private static final Log LOG = LogFactory.getLog(Worker.class);
 
     private static final int MAX_INITIALIZATION_ATTEMPTS = 20;
+    private static final WorkerStateChangeListener DEFAULT_WORKER_STATE_CHANGE_LISTENER = new NoOpWorkerStateChangeListener();
 
     private WorkerLog wlog = new WorkerLog();
 
@@ -93,7 +94,6 @@ public class Worker implements Runnable {
     private final Optional<Integer> retryGetRecordsInSeconds;
     private final Optional<Integer> maxGetRecordsThreadPool;
 
-    // private final KinesisClientLeaseManager leaseManager;
     private final KinesisClientLibLeaseCoordinator leaseCoordinator;
     private final ShardSyncTaskManager controlServer;
 
@@ -119,6 +119,8 @@ public class Worker implements Runnable {
     @VisibleForTesting
     protected GracefulShutdownCoordinator gracefulShutdownCoordinator = new GracefulShutdownCoordinator();
 
+    private WorkerStateChangeListener workerStateChangeListener;
+
     /**
      * Constructor.
      *
@@ -276,7 +278,8 @@ public Worker(
                 config.getSkipShardSyncAtWorkerInitializationIfLeasesExist(),
                 config.getShardPrioritizationStrategy(),
                 config.getRetryGetRecordsInSeconds(),
-                config.getMaxGetRecordsThreadPool());
+                config.getMaxGetRecordsThreadPool(),
+                DEFAULT_WORKER_STATE_CHANGE_LISTENER);
 
         // If a region name was explicitly specified, use it as the region for Amazon Kinesis and Amazon DynamoDB.
         if (config.getRegionName() != null) {
@@ -348,7 +351,7 @@ public Worker(
         this(applicationName, recordProcessorFactory, config, streamConfig, initialPositionInStream, parentShardPollIntervalMillis,
                 shardSyncIdleTimeMillis, cleanupLeasesUponShardCompletion, checkpoint, leaseCoordinator, execService,
                 metricsFactory, taskBackoffTimeMillis, failoverTimeMillis, skipShardSyncAtWorkerInitializationIfLeasesExist,
-                shardPrioritization, Optional.empty(), Optional.empty());
+                shardPrioritization, Optional.empty(), Optional.empty(), DEFAULT_WORKER_STATE_CHANGE_LISTENER);
     }
 
     /**
@@ -395,7 +398,7 @@ public Worker(
            KinesisClientLibLeaseCoordinator leaseCoordinator, ExecutorService execService,
            IMetricsFactory metricsFactory, long taskBackoffTimeMillis, long failoverTimeMillis,
            boolean skipShardSyncAtWorkerInitializationIfLeasesExist, ShardPrioritization shardPrioritization,
-           Optional<Integer> retryGetRecordsInSeconds, Optional<Integer> maxGetRecordsThreadPool) {
+           Optional<Integer> retryGetRecordsInSeconds, Optional<Integer> maxGetRecordsThreadPool, WorkerStateChangeListener workerStateChangeListener) {
         this.applicationName = applicationName;
         this.recordProcessorFactory = recordProcessorFactory;
         this.config = config;
@@ -417,6 +420,8 @@ public Worker(
         this.shardPrioritization = shardPrioritization;
         this.retryGetRecordsInSeconds = retryGetRecordsInSeconds;
         this.maxGetRecordsThreadPool = maxGetRecordsThreadPool;
+        this.workerStateChangeListener = workerStateChangeListener;
+        workerStateChangeListener.onWorkerStateChange(WorkerStateChangeListener.WorkerState.CREATED);
     }
 
     /**
@@ -494,6 +499,7 @@ void runProcessLoop() {
     }
 
     private void initialize() {
+        workerStateChangeListener.onWorkerStateChange(WorkerStateChangeListener.WorkerState.INITIALIZING);
         boolean isDone = false;
         Exception lastException = null;
 
@@ -543,6 +549,7 @@ private void initialize() {
         if (!isDone) {
             throw new RuntimeException(lastException);
         }
+        workerStateChangeListener.onWorkerStateChange(WorkerStateChangeListener.WorkerState.STARTED);
     }
 
     /**
@@ -593,10 +600,10 @@ private List<ShardInfo> getShardInfoForAssignments() {
 
     /**
      * Starts the requestedShutdown process, and returns a future that can be used to track the process.
-     * 
+     *
      * This is deprecated in favor of {@link #startGracefulShutdown()}, which returns a more complete future, and
      * indicates the process behavior
-     * 
+     *
      * @return a future that will be set once shutdown is completed.
      */
     @Deprecated
@@ -640,7 +647,7 @@ public Void get(long timeout, TimeUnit unit)
      * Requests a graceful shutdown of the worker, notifying record processors, that implement
      * {@link IShutdownNotificationAware}, of the impending shutdown. This gives the record processor a final chance to
      * checkpoint.
-     * 
+     *
      * This will only create a single shutdown future. Additional attempts to start a graceful shutdown will return the
      * previous future.
      *
@@ -755,6 +762,10 @@ ConcurrentMap<ShardInfo, ShardConsumer> getShardInfoShardConsumerMap() {
         return shardInfoShardConsumerMap;
     }
 
+    WorkerStateChangeListener getWorkerStateChangeListener() {
+        return workerStateChangeListener;
+    }
+
     /**
      * Signals worker to shutdown. Worker will try initiating shutdown of all record processors. Note that if executor
      * services were passed to the worker by the user, worker will not attempt to shutdown those resources.
@@ -785,6 +796,7 @@ public void shutdown() {
         // Lost leases will force Worker to begin shutdown process for all shard consumers in
         // Worker.run().
         leaseCoordinator.stop();
+        workerStateChangeListener.onWorkerStateChange(WorkerStateChangeListener.WorkerState.SHUT_DOWN);
     }
 
     /**
@@ -807,7 +819,7 @@ private void finalShutdown() {
     /**
      * Returns whether worker can shutdown immediately. Note that this method is called from Worker's {{@link #run()}
      * method before every loop run, so method must do minimum amount of work to not impact shard processing timings.
-     * 
+     *
      * @return Whether worker should shutdown immediately.
      */
     @VisibleForTesting
@@ -1012,7 +1024,7 @@ StreamConfig getStreamConfig() {
 
     /**
      * Given configuration, returns appropriate metrics factory.
-     * 
+     *
      * @param cloudWatchClient
      *            Amazon CloudWatch client
      * @param config
@@ -1039,7 +1051,7 @@ private static IMetricsFactory getMetricsFactory(AmazonCloudWatch cloudWatchClie
 
     /**
      * Returns default executor service that should be used by the worker.
-     * 
+     *
      * @return Default executor service that should be used by the worker.
      */
     private static ExecutorService getExecutorService() {
@@ -1089,6 +1101,7 @@ public static class Builder {
         private ExecutorService execService;
         private ShardPrioritization shardPrioritization;
         private IKinesisProxy kinesisProxy;
+        private WorkerStateChangeListener workerStateChangeListener;
 
         /**
          * Default constructor.
@@ -1209,10 +1222,10 @@ public Builder execService(ExecutorService execService) {
 
         /**
          * Provides logic how to prioritize shard processing.
-         * 
+         *
          * @param shardPrioritization
          *            shardPrioritization is responsible to order shards before processing
-         * 
+         *
          * @return A reference to this updated object so that method calls can be chained together.
          */
         public Builder shardPrioritization(ShardPrioritization shardPrioritization) {
@@ -1233,6 +1246,17 @@ public Builder kinesisProxy(IKinesisProxy kinesisProxy) {
             return this;
         }
 
+        /**
+         * Set WorkerStateChangeListener for the worker
+         * @param workerStateChangeListener
+         *             Sets the WorkerStateChangeListener
+         * @return A reference to this updated object so that method calls can be chained together.
+         */
+        public Builder workerStateChangeListener(WorkerStateChangeListener workerStateChangeListener) {
+            this.workerStateChangeListener = workerStateChangeListener;
+            return this;
+        }
+
         /**
          * Build the Worker instance.
          *
@@ -1305,6 +1329,10 @@ public Worker build() {
                 kinesisProxy = new KinesisProxy(config, kinesisClient);
             }
 
+            if (workerStateChangeListener == null) {
+                workerStateChangeListener = DEFAULT_WORKER_STATE_CHANGE_LISTENER;
+            }
+
             return new Worker(config.getApplicationName(),
                     recordProcessorFactory,
                     config,
@@ -1336,9 +1364,8 @@ public Worker build() {
                     config.getSkipShardSyncAtWorkerInitializationIfLeasesExist(),
                     shardPrioritization,
                     config.getRetryGetRecordsInSeconds(),
-                    config.getMaxGetRecordsThreadPool());
-
+                    config.getMaxGetRecordsThreadPool(),
+                    workerStateChangeListener);
         }
-
     }
 }

src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/WorkerStateChangeListener.java

@@ -0,0 +1,16 @@
+package com.amazonaws.services.kinesis.clientlibrary.lib.worker;
+
+/**
+ * A listener for callbacks on changes worker state
+ */
+@FunctionalInterface
+public interface WorkerStateChangeListener {
+	enum WorkerState {
+		CREATED,
+		INITIALIZING,
+		STARTED,
+		SHUT_DOWN
+	}
+
+	void onWorkerStateChange(WorkerState newState);
+}