Java tutorial
/** * Copyright (C) 2014-2015 LinkedIn Corp. (pinot-core@linkedin.com) * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.linkedin.pinot.transport.common; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.util.concurrent.ImmediateExecutor; import java.util.Map; import java.util.concurrent.CountDownLatch; import java.util.concurrent.ExecutionException; import java.util.concurrent.Executor; import java.util.concurrent.LinkedBlockingQueue; import java.util.concurrent.ThreadPoolExecutor; import java.util.concurrent.TimeUnit; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.testng.Assert; import org.testng.annotations.Test; import com.linkedin.pinot.Checkable; import com.linkedin.pinot.TestUtils; import com.linkedin.pinot.common.response.ServerInstance; public class ResponseFutureTest { protected static Logger LOGGER = LoggerFactory.getLogger(ResponseFutureTest.class); /* * Future Handle provided to the request sender to asynchronously wait for response. * We use guava API for implementing Futures. */ public static class ResponseFuture extends AsyncResponseFuture<ServerInstance, ByteBuf> { public ResponseFuture(ServerInstance key) { super(key, ""); } } @Test public void testResponseFutureOtherCases() throws Exception { ServerInstance s = new ServerInstance("localhost", 8080); // A Future is cancelled but gets a message after that. get() called before cancellation { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); f.cancel(false); String message = "dummy Message"; setResponse(f, message); runner.waitForDone(); Assert.assertTrue(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // A Future is cancelled but gets a message after that. get() called after cancellation { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); f.cancel(false); String message = "dummy Message"; setResponse(f, message); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); runner.waitForDone(); Assert.assertTrue(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // A Future is cancelled but gets an exception after that. get() called before cancellation { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); f.cancel(false); f.onError(new Exception("dummy")); runner.waitForDone(); Assert.assertTrue(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // A Future is cancelled but gets an exception after that. get() called after cancellation { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); f.cancel(false); f.onError(new Exception("dummy")); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); runner.waitForDone(); Assert.assertTrue(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // Throw Exception. Then we try to cancel. Future Client calls get() before exception { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); Exception expectedError = new Exception("error processing"); f.onError(expectedError); f.cancel(false); runner.waitForDone(); // Now we know listener executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertEquals(runner.getError(), expectedError, "Error"); executor.shutdown(); } // Throw Exception. Then we try to cancel. Future Client calls get() after exception { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); Exception expectedError = new Exception("error processing"); f.onError(expectedError); f.cancel(false); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); runner.waitForDone(); // Now we know listener executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertEquals(runner.getError(), expectedError, "Error"); executor.shutdown(); } // Set Response. Then we try to cancel. Future Client calls get() before response { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); String message = "dummy Message"; setResponse(f, message); f.cancel(false); runner.waitForDone(); // Now we know runner executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertEquals(runner.getMessage(), message, "Response Check:"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // Set Response. Then we try to cancel. Future Client calls get() after response { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); String message = "dummy Message"; setResponse(f, message); f.cancel(false); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); runner.waitForDone(); // Now we know runner executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertEquals(runner.getMessage(), message, "Response Check:"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // Set Response. Then an exception happens. Future Client calls get() before response { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); String message = "dummy Message"; setResponse(f, message); f.onError(new Exception("dummy")); runner.waitForDone(); // Now we know runner executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertEquals(runner.getMessage(), message, "Response Check:"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // Set Response. then an exception gets processed. Future Client calls get() after response { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); String message = "dummy Message"; setResponse(f, message); f.onError(new Exception("dummy")); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); runner.waitForDone(); // Now we know runner executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertEquals(runner.getMessage(), message, "Response Check:"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // Throw Exception. Then a valid response arrives. Future Client calls get() before exception { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); Exception expectedError = new Exception("error processing"); f.onError(expectedError); String message = "dummy Message"; setResponse(f, message); runner.waitForDone(); // Now we know listener executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertEquals(runner.getError(), expectedError, "Error"); executor.shutdown(); } // Throw Exception. Then a valid response arrives. Future Client calls get() after exception { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); Exception expectedError = new Exception("error processing"); f.onError(expectedError); String message = "dummy Message"; setResponse(f, message); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); runner.waitForDone(); // Now we know listener executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertEquals(runner.getError(), expectedError, "Error"); executor.shutdown(); } } @Test public void testResponseFuture() throws Exception { ServerInstance s = new ServerInstance("localhost", 8080); //Cancelled Future. Future Client calls get() before cancel() { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); f.cancel(false); runner.waitForDone(); Assert.assertTrue(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } //Cancelled Future. Future Client calls get() after cancel() { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); f.cancel(false); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForDone(); Assert.assertTrue(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // Throw Exception. Future Client calls get() before exception { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); Exception expectedError = new Exception("error processing"); f.onError(expectedError); runner.waitForDone(); // Now we know listener executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertEquals(runner.getError(), expectedError, "Error"); executor.shutdown(); } // Throw Exception. Future Client calls get() after exception { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); Exception expectedError = new Exception("error processing"); f.onError(expectedError); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForDone(); // Now we know listener executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertNull(runner.getMessage(), "No Reponse :"); Assert.assertEquals(runner.getError(), expectedError, "Error"); executor.shutdown(); } // Set Response. Future Client calls get() before response { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForAboutToGet(); // No guarantees as this only ensures the thread is started but not blocking in get(). Thread.sleep(100); String message = "dummy Message"; setResponse(f, message); runner.waitForDone(); // Now we know runner executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertEquals(runner.getMessage(), message, "Response Check:"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } // Set Response. Future Client calls get() after response { ResponseFuture f = new ResponseFuture(s); ResponseFutureClientRunner runner = new ResponseFutureClientRunner(f); String message = "dummy Message"; setResponse(f, message); ThreadPoolExecutor executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>()); executor.execute(runner); runner.waitForDone(); // Now we know runner executed Assert.assertFalse(runner.isCancelled(), "Cancelled ?"); Assert.assertTrue(runner.isDone(), "Is Done ? "); Assert.assertEquals(runner.getMessage(), message, "Response Check:"); Assert.assertNull(runner.getError(), "No Error :"); executor.shutdown(); } } @Test public void testResponseFutureListener() throws Exception { ServerInstance s = new ServerInstance("localhost", 8080); // Cancelled future. Listener added before cancelling { ResponseFuture f = new ResponseFuture(s); FutureListener listener = new FutureListener(f); WaitForCompletion w = new WaitForCompletion(listener); f.cancel(false); TestUtils.assertWithBackoff(w, 10, 1000, 2, 1, 2); // Now we know listener executed Assert.assertTrue(listener.isCancelled(), "Cancelled ?"); Assert.assertEquals(listener.getNumRuns(), 1, "Num Runs of listener"); Assert.assertTrue(listener.isDone(), "Is Done ? "); Assert.assertNull(listener.getMessage(), "No Reponse :"); Assert.assertNull(listener.getError(), "No Error :"); listener.close(); } // Cancelled future. Listener added after cancelling { ResponseFuture f = new ResponseFuture(s); FutureListener listener = new FutureListener(f); WaitForCompletion w = new WaitForCompletion(listener); f.cancel(false); TestUtils.assertWithBackoff(w, 10, 1000, 2, 1, 2); // Now we know listener executed Assert.assertTrue(listener.isCancelled(), "Cancelled ?"); Assert.assertEquals(listener.getNumRuns(), 1, "Num Runs of listener"); Assert.assertTrue(listener.isDone(), "Is Done ? "); Assert.assertNull(listener.getMessage(), "No Reponse :"); Assert.assertNull(listener.getError(), "No Error :"); listener.close(); } // Throw Exception. Listener added before exception { ResponseFuture f = new ResponseFuture(s); FutureListener listener = new FutureListener(f); WaitForCompletion w = new WaitForCompletion(listener); Exception expectedError = new Exception("error processing"); f.onError(expectedError); TestUtils.assertWithBackoff(w, 10, 1000, 2, 1, 2); // Now we know listener executed Assert.assertFalse(listener.isCancelled(), "Cancelled ?"); Assert.assertEquals(listener.getNumRuns(), 1, "Num Runs of listener"); Assert.assertTrue(listener.isDone(), "Is Done ? "); Assert.assertNull(listener.getMessage(), "No Reponse :"); Assert.assertEquals(listener.getError(), expectedError, "Error"); } // Throw Exception. Listener added after exception { ResponseFuture f = new ResponseFuture(s); FutureListener listener = new FutureListener(f); Exception expectedError = new Exception("error processing"); f.onError(expectedError); WaitForCompletion w = new WaitForCompletion(listener); TestUtils.assertWithBackoff(w, 10, 1000, 2, 1, 2); // Now we know listener executed Assert.assertFalse(listener.isCancelled(), "Cancelled ?"); Assert.assertEquals(listener.getNumRuns(), 1, "Num Runs of listener"); Assert.assertTrue(listener.isDone(), "Is Done ? "); Assert.assertNull(listener.getMessage(), "No Reponse :"); Assert.assertEquals(listener.getError(), expectedError, "Error"); } // Set Response. Listener added before response { ResponseFuture f = new ResponseFuture(s); FutureListener listener = new FutureListener(f); WaitForCompletion w = new WaitForCompletion(listener); String message = "dummy Message"; setResponse(f, message); TestUtils.assertWithBackoff(w, 10, 1000, 2, 1, 2); // Now we know listener executed Assert.assertFalse(listener.isCancelled(), "Cancelled ?"); Assert.assertEquals(listener.getNumRuns(), 1, "Num Runs of listener"); Assert.assertTrue(listener.isDone(), "Is Done ? "); Assert.assertEquals(listener.getMessage(), message, "Response Check:"); Assert.assertNull(listener.getError(), "No Error :"); listener.close(); } // Set Response. Listener added after response { ResponseFuture f = new ResponseFuture(s); FutureListener listener = new FutureListener(f); String message = "dummy Message"; setResponse(f, message); WaitForCompletion w = new WaitForCompletion(listener); TestUtils.assertWithBackoff(w, 10, 1000, 2, 1, 2); // Now we know listener executed Assert.assertFalse(listener.isCancelled(), "Cancelled ?"); Assert.assertEquals(listener.getNumRuns(), 1, "Num Runs of listener"); Assert.assertTrue(listener.isDone(), "Is Done ? "); Assert.assertEquals(listener.getMessage(), message, "Response Check:"); Assert.assertNull(listener.getError(), "No Error :"); listener.close(); } } private static void setResponse(ResponseFuture f, String message) { ByteBuf b = Unpooled.wrappedBuffer(message.getBytes()); f.onSuccess(b); } private static class WaitForCompletion implements Checkable { private final FutureListener _listener; public WaitForCompletion(FutureListener f) { _listener = f; } @Override public boolean runCheck() throws AssertionError { boolean isCalled = false; synchronized (_listener) { isCalled = _listener.isCalled(); } return isCalled; } } private static class ResponseFutureClientRunner implements Runnable { private boolean _isDone; private boolean _isCancelled; private String _message; private Throwable _error; private final ResponseFuture _future; private final CountDownLatch _latch = new CountDownLatch(1); private final CountDownLatch _endLatch = new CountDownLatch(1); public ResponseFutureClientRunner(ResponseFuture f) { _future = f; } public void waitForAboutToGet() throws InterruptedException { _latch.await(); } public void waitForDone() throws InterruptedException { _endLatch.await(); } @Override public synchronized void run() { LOGGER.info("Running Future runner !!"); ByteBuf message = null; try { _latch.countDown(); message = _future.getOne(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ExecutionException e) { // TODO Auto-generated catch block e.printStackTrace(); } _isDone = _future.isDone(); _isCancelled = _future.isCancelled(); if (null != message) { byte[] m = new byte[message.readableBytes()]; message.readBytes(m); _message = new String(m); } Map<ServerInstance, Throwable> errorMap = _future.getError(); if ((null != errorMap) && (!errorMap.isEmpty())) { _error = errorMap.values().iterator().next(); } _endLatch.countDown(); LOGGER.info("End Running Listener !!"); } public boolean isDone() { return _isDone; } public boolean isCancelled() { return _isCancelled; } public String getMessage() { return _message; } public Throwable getError() { return _error; } public ResponseFuture getFuture() { return _future; } } private static class FutureListener implements Runnable { private int _numRuns = 0; private boolean _isCalled; private boolean _isDone; private boolean _isCancelled; private String _message; private Throwable _error; private final ResponseFuture _future; private Executor _executor = null; public FutureListener(ResponseFuture f) { _future = f; LinkedBlockingQueue<Runnable> queue = new LinkedBlockingQueue<Runnable>(); queue.add(this); //_executor = new ThreadPoolExecutor(1, 1, 1, TimeUnit.HOURS, queue); _executor = ImmediateExecutor.INSTANCE; f.addListener(this, _executor); } @Override public synchronized void run() { _isCalled = true; _numRuns++; LOGGER.info("Running Listener !!"); //try{ throw new Exception("dummy"); } catch(Exception e) {e.printStackTrace();} _isDone = _future.isDone(); _isCancelled = _future.isCancelled(); ByteBuf message = null; try { message = _future.getOne(); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (ExecutionException e) { // TODO Auto-generated catch block e.printStackTrace(); } if (null != message) { byte[] m = new byte[message.readableBytes()]; message.readBytes(m); _message = new String(m); } Map<ServerInstance, Throwable> errorMap = _future.getError(); if ((null != errorMap) && (!errorMap.isEmpty())) { _error = errorMap.values().iterator().next(); } LOGGER.info("End Running Listener !!"); } public void close() { //_executor.shutdown(); } public boolean isCalled() { return _isCalled; } public boolean isDone() { return _isDone; } public boolean isCancelled() { return _isCancelled; } public String getMessage() { return _message; } public Throwable getError() { return _error; } public int getNumRuns() { return _numRuns; } } }