Java example source code file (ServiceManagerTest.java)

This example Java source code file (ServiceManagerTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

countdownlatch, failstartservice, illegalstateexception, log, logging, long, noopdelayedservice, noopservice, override, recordinglistener, service, servicemanager, snappyshutdownservice, string, testloghandler, threading, threads, timeoutexception, util

The ServiceManagerTest.java Java example source code

/*
 * Copyright (C) 2012 The Guava Authors
 *
 * 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.google.common.util.concurrent;

import static com.google.common.truth.Truth.assertThat;
import static java.util.Arrays.asList;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import com.google.common.testing.NullPointerTester;
import com.google.common.testing.TestLogHandler;
import com.google.common.util.concurrent.Service.State;
import com.google.common.util.concurrent.ServiceManager.Listener;

import junit.framework.TestCase;

import java.util.Arrays;
import java.util.Collection;
import java.util.List;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.logging.Formatter;
import java.util.logging.Level;
import java.util.logging.LogRecord;
import java.util.logging.Logger;

/**
 * Tests for {@link ServiceManager}.
 *
 * @author Luke Sandberg
 * @author Chris Nokleberg
 */
public class ServiceManagerTest extends TestCase {

  private static class NoOpService extends AbstractService {
    @Override protected void doStart() {
      notifyStarted();
    }

    @Override protected void doStop() {
      notifyStopped();
    }
  }

  /*
   * A NoOp service that will delay the startup and shutdown notification for a configurable amount
   * of time.
   */
  private static class NoOpDelayedService extends NoOpService {
    private long delay;

    public NoOpDelayedService(long delay) {
      this.delay = delay;
    }

    @Override protected void doStart() {
      new Thread() {
        @Override public void run() {
          Uninterruptibles.sleepUninterruptibly(delay, TimeUnit.MILLISECONDS);
          notifyStarted();
        }
      }.start();
    }

    @Override protected void doStop() {
      new Thread() {
        @Override public void run() {
          Uninterruptibles.sleepUninterruptibly(delay, TimeUnit.MILLISECONDS);
          notifyStopped();
        }
      }.start();
    }
  }

  private static class FailStartService extends NoOpService {
    @Override protected void doStart() {
      notifyFailed(new IllegalStateException("start failure"));
    }
  }

  private static class FailRunService extends NoOpService {
    @Override protected void doStart() {
      super.doStart();
      notifyFailed(new IllegalStateException("run failure"));
    }
  }

  private static class FailStopService extends NoOpService {
    @Override protected void doStop() {
      notifyFailed(new IllegalStateException("stop failure"));
    }
  }

  public void testServiceStartupTimes() {
    Service a = new NoOpDelayedService(150);
    Service b = new NoOpDelayedService(353);
    ServiceManager serviceManager = new ServiceManager(asList(a, b));
    serviceManager.startAsync().awaitHealthy();
    ImmutableMap<Service, Long> startupTimes = serviceManager.startupTimes();
    assertEquals(2, startupTimes.size());
    // TODO(kak): Use assertThat(startupTimes.get(a)).isAtLeast(150);
    assertTrue(startupTimes.get(a) >= 150);
    // TODO(kak): Use assertThat(startupTimes.get(b)).isAtLeast(353);
    assertTrue(startupTimes.get(b) >= 353);
  }

  public void testServiceStartupTimes_selfStartingServices() {
    // This tests to ensure that:
    // 1. service times are accurate when the service is started by the manager
    // 2. service times are recorded when the service is not started by the manager (but they may
    // not be accurate).
    final Service b = new NoOpDelayedService(353) {
      @Override protected void doStart() {
        super.doStart();
        // This will delay service listener execution at least 150 milliseconds
        Uninterruptibles.sleepUninterruptibly(150, TimeUnit.MILLISECONDS);
      }
    };
    Service a = new NoOpDelayedService(150) {
      @Override protected void doStart() {
        b.startAsync();
        super.doStart();
      }
    };
    ServiceManager serviceManager = new ServiceManager(asList(a, b));
    serviceManager.startAsync().awaitHealthy();
    ImmutableMap<Service, Long> startupTimes = serviceManager.startupTimes();
    assertEquals(2, startupTimes.size());
    // TODO(kak): Use assertThat(startupTimes.get(a)).isAtLeast(150);
    assertTrue(startupTimes.get(a) >= 150);
    // Service b startup takes at least 353 millis, but starting the timer is delayed by at least
    // 150 milliseconds. so in a perfect world the timing would be 353-150=203ms, but since either
    // of our sleep calls can be arbitrarily delayed we should just assert that there is a time
    // recorded.
    assertThat(startupTimes.get(b)).isNotNull();
  }

  public void testServiceStartStop() {
    Service a = new NoOpService();
    Service b = new NoOpService();
    ServiceManager manager = new ServiceManager(asList(a, b));
    RecordingListener listener = new RecordingListener();
    manager.addListener(listener);
    assertState(manager, Service.State.NEW, a, b);
    assertFalse(manager.isHealthy());
    manager.startAsync().awaitHealthy();
    assertState(manager, Service.State.RUNNING, a, b);
    assertTrue(manager.isHealthy());
    assertTrue(listener.healthyCalled);
    assertFalse(listener.stoppedCalled);
    assertTrue(listener.failedServices.isEmpty());
    manager.stopAsync().awaitStopped();
    assertState(manager, Service.State.TERMINATED, a, b);
    assertFalse(manager.isHealthy());
    assertTrue(listener.stoppedCalled);
    assertTrue(listener.failedServices.isEmpty());
  }

  public void testFailStart() throws Exception {
    Service a = new NoOpService();
    Service b = new FailStartService();
    Service c = new NoOpService();
    Service d = new FailStartService();
    Service e = new NoOpService();
    ServiceManager manager = new ServiceManager(asList(a, b, c, d, e));
    RecordingListener listener = new RecordingListener();
    manager.addListener(listener);
    assertState(manager, Service.State.NEW, a, b, c, d, e);
    try {
      manager.startAsync().awaitHealthy();
      fail();
    } catch (IllegalStateException expected) {
    }
    assertFalse(listener.healthyCalled);
    assertState(manager, Service.State.RUNNING, a, c, e);
    assertEquals(ImmutableSet.of(b, d), listener.failedServices);
    assertState(manager, Service.State.FAILED, b, d);
    assertFalse(manager.isHealthy());

    manager.stopAsync().awaitStopped();
    assertFalse(manager.isHealthy());
    assertFalse(listener.healthyCalled);
    assertTrue(listener.stoppedCalled);
  }

  public void testFailRun() throws Exception {
    Service a = new NoOpService();
    Service b = new FailRunService();
    ServiceManager manager = new ServiceManager(asList(a, b));
    RecordingListener listener = new RecordingListener();
    manager.addListener(listener);
    assertState(manager, Service.State.NEW, a, b);
    try {
      manager.startAsync().awaitHealthy();
      fail();
    } catch (IllegalStateException expected) {
    }
    assertTrue(listener.healthyCalled);
    assertEquals(ImmutableSet.of(b), listener.failedServices);

    manager.stopAsync().awaitStopped();
    assertState(manager, Service.State.FAILED, b);
    assertState(manager, Service.State.TERMINATED, a);

    assertTrue(listener.stoppedCalled);
  }

  public void testFailStop() throws Exception {
    Service a = new NoOpService();
    Service b = new FailStopService();
    Service c = new NoOpService();
    ServiceManager manager = new ServiceManager(asList(a, b, c));
    RecordingListener listener = new RecordingListener();
    manager.addListener(listener);

    manager.startAsync().awaitHealthy();
    assertTrue(listener.healthyCalled);
    assertFalse(listener.stoppedCalled);
    manager.stopAsync().awaitStopped();

    assertTrue(listener.stoppedCalled);
    assertEquals(ImmutableSet.of(b), listener.failedServices);
    assertState(manager, Service.State.FAILED, b);
    assertState(manager, Service.State.TERMINATED, a, c);
  }

  public void testToString() throws Exception {
    Service a = new NoOpService();
    Service b = new FailStartService();
    ServiceManager manager = new ServiceManager(asList(a, b));
    String toString = manager.toString();
    assertThat(toString).contains("NoOpService");
    assertThat(toString).contains("FailStartService");
  }

  public void testTimeouts() throws Exception {
    Service a = new NoOpDelayedService(50);
    ServiceManager manager = new ServiceManager(asList(a));
    manager.startAsync();
    try {
      manager.awaitHealthy(1, TimeUnit.MILLISECONDS);
      fail();
    } catch (TimeoutException expected) {
    }
    manager.awaitHealthy(100, TimeUnit.MILLISECONDS); // no exception thrown

    manager.stopAsync();
    try {
      manager.awaitStopped(1, TimeUnit.MILLISECONDS);
      fail();
    } catch (TimeoutException expected) {
    }
    manager.awaitStopped(100, TimeUnit.MILLISECONDS);  // no exception thrown
  }

  /**
   * This covers a case where if the last service to stop failed then the stopped callback would
   * never be called.
   */
  public void testSingleFailedServiceCallsStopped() {
    Service a = new FailStartService();
    ServiceManager manager = new ServiceManager(asList(a));
    RecordingListener listener = new RecordingListener();
    manager.addListener(listener);
    try {
      manager.startAsync().awaitHealthy();
      fail();
    } catch (IllegalStateException expected) {
    }
    assertTrue(listener.stoppedCalled);
  }

  /**
   * This covers a bug where listener.healthy would get called when a single service failed during
   * startup (it occurred in more complicated cases also).
   */
  public void testFailStart_singleServiceCallsHealthy() {
    Service a = new FailStartService();
    ServiceManager manager = new ServiceManager(asList(a));
    RecordingListener listener = new RecordingListener();
    manager.addListener(listener);
    try {
      manager.startAsync().awaitHealthy();
      fail();
    } catch (IllegalStateException expected) {
    }
    assertFalse(listener.healthyCalled);
  }

  /**
   * This covers a bug where if a listener was installed that would stop the manager if any service
   * fails and something failed during startup before service.start was called on all the services,
   * then awaitStopped would deadlock due to an IllegalStateException that was thrown when trying to
   * stop the timer(!).
   */
  public void testFailStart_stopOthers() throws TimeoutException {
    Service a = new FailStartService();
    Service b = new NoOpService();
    final ServiceManager manager = new ServiceManager(asList(a, b));
    manager.addListener(new Listener() {
      @Override public void failure(Service service) {
        manager.stopAsync();
      }});
    manager.startAsync();
    manager.awaitStopped(10, TimeUnit.MILLISECONDS);
  }

  private static void assertState(
      ServiceManager manager, Service.State state, Service... services) {
    Collection<Service> managerServices = manager.servicesByState().get(state);
    for (Service service : services) {
      assertEquals(service.toString(), state, service.state());
      assertEquals(service.toString(), service.isRunning(), state == Service.State.RUNNING);
      assertTrue(managerServices + " should contain " + service, managerServices.contains(service));
    }
  }

  /**
   * This is for covering a case where the ServiceManager would behave strangely if constructed
   * with no service under management.  Listeners would never fire because the ServiceManager was
   * healthy and stopped at the same time.  This test ensures that listeners fire and isHealthy
   * makes sense.
   */
  public void testEmptyServiceManager() {
    Logger logger = Logger.getLogger(ServiceManager.class.getName());
    logger.setLevel(Level.FINEST);
    TestLogHandler logHandler = new TestLogHandler();
    logger.addHandler(logHandler);
    ServiceManager manager = new ServiceManager(Arrays.<Service>asList());
    RecordingListener listener = new RecordingListener();
    manager.addListener(listener);
    manager.startAsync().awaitHealthy();
    assertTrue(manager.isHealthy());
    assertTrue(listener.healthyCalled);
    assertFalse(listener.stoppedCalled);
    assertTrue(listener.failedServices.isEmpty());
    manager.stopAsync().awaitStopped();
    assertFalse(manager.isHealthy());
    assertTrue(listener.stoppedCalled);
    assertTrue(listener.failedServices.isEmpty());
    // check that our NoOpService is not directly observable via any of the inspection methods or
    // via logging.
    assertEquals("ServiceManager{services=[]}", manager.toString());
    assertTrue(manager.servicesByState().isEmpty());
    assertTrue(manager.startupTimes().isEmpty());
    Formatter logFormatter = new Formatter() {
      @Override public String format(LogRecord record) {
        return formatMessage(record);
      }
    };
    for (LogRecord record : logHandler.getStoredLogRecords()) {
      assertThat(logFormatter.format(record)).doesNotContain("NoOpService");
    }
  }

  /**
   * Tests that a ServiceManager can be fully shut down if one of its failure listeners is slow or
   * even permanently blocked.
   */

  public void testListenerDeadlock() throws InterruptedException {
    final CountDownLatch failEnter = new CountDownLatch(1);
    final CountDownLatch failLeave = new CountDownLatch(1);
    final CountDownLatch afterStarted = new CountDownLatch(1);
    Service failRunService = new AbstractService() {
      @Override protected void doStart() {
        new Thread() {
          @Override public void run() {
            notifyStarted();
            // We need to wait for the main thread to leave the ServiceManager.startAsync call to
            // ensure that the thread running the failure callbacks is not the main thread.
            Uninterruptibles.awaitUninterruptibly(afterStarted);
            notifyFailed(new Exception("boom"));
          }
        }.start();
      }
      @Override protected void doStop() {
        notifyStopped();
      }
    };
    final ServiceManager manager = new ServiceManager(
        Arrays.asList(failRunService, new NoOpService()));
    manager.addListener(new ServiceManager.Listener() {
      @Override public void failure(Service service) {
        failEnter.countDown();
        // block until after the service manager is shutdown
        Uninterruptibles.awaitUninterruptibly(failLeave);
      }
    });
    manager.startAsync();
    afterStarted.countDown();
    // We do not call awaitHealthy because, due to races, that method may throw an exception.  But
    // we really just want to wait for the thread to be in the failure callback so we wait for that
    // explicitly instead.
    failEnter.await();
    assertFalse("State should be updated before calling listeners", manager.isHealthy());
    // now we want to stop the services.
    Thread stoppingThread = new Thread() {
      @Override public void run() {
        manager.stopAsync().awaitStopped();
      }
    };
    stoppingThread.start();
    // this should be super fast since the only non stopped service is a NoOpService
    stoppingThread.join(1000);
    assertFalse("stopAsync has deadlocked!.", stoppingThread.isAlive());
    failLeave.countDown();  // release the background thread
  }

  /**
   * Catches a bug where when constructing a service manager failed, later interactions with the
   * service could cause IllegalStateExceptions inside the partially constructed ServiceManager.
   * This ISE wouldn't actually bubble up but would get logged by ExecutionQueue.  This obfuscated
   * the original error (which was not constructing ServiceManager correctly).
   */
  public void testPartiallyConstructedManager() {
    Logger logger = Logger.getLogger("global");
    logger.setLevel(Level.FINEST);
    TestLogHandler logHandler = new TestLogHandler();
    logger.addHandler(logHandler);
    NoOpService service = new NoOpService();
    service.startAsync();
    try {
      new ServiceManager(Arrays.asList(service));
      fail();
    } catch (IllegalArgumentException expected) {}
    service.stopAsync();
    // Nothing was logged!
    assertEquals(0, logHandler.getStoredLogRecords().size());
  }

  public void testPartiallyConstructedManager_transitionAfterAddListenerBeforeStateIsReady() {
    // The implementation of this test is pretty sensitive to the implementation :( but we want to
    // ensure that if weird things happen during construction then we get exceptions.
    final NoOpService service1 = new NoOpService();
    // This service will start service1 when addListener is called.  This simulates service1 being
    // started asynchronously.
    Service service2 = new Service() {
      final NoOpService delegate = new NoOpService();
      @Override public final void addListener(Listener listener, Executor executor) {
        service1.startAsync();
        delegate.addListener(listener, executor);
      }
      // Delegates from here on down
      @Override public final Service startAsync() {
        return delegate.startAsync();
      }

      @Override public final Service stopAsync() {
        return delegate.stopAsync();
      }

      @Override public final void awaitRunning() {
        delegate.awaitRunning();
      }

      @Override public final void awaitRunning(long timeout, TimeUnit unit)
          throws TimeoutException {
        delegate.awaitRunning(timeout, unit);
      }

      @Override public final void awaitTerminated() {
        delegate.awaitTerminated();
      }

      @Override public final void awaitTerminated(long timeout, TimeUnit unit)
          throws TimeoutException {
        delegate.awaitTerminated(timeout, unit);
      }

      @Override public final boolean isRunning() {
        return delegate.isRunning();
      }

      @Override public final State state() {
        return delegate.state();
      }

      @Override public final Throwable failureCause() {
        return delegate.failureCause();
      }
    };
    try {
      new ServiceManager(Arrays.asList(service1, service2));
      fail();
    } catch (IllegalArgumentException expected) {
      assertThat(expected.getMessage()).contains("started transitioning asynchronously");
    }
  }

  /**
   * This test is for a case where two Service.Listener callbacks for the same service would call
   * transitionService in the wrong order due to a race.  Due to the fact that it is a race this
   * test isn't guaranteed to expose the issue, but it is at least likely to become flaky if the
   * race sneaks back in, and in this case flaky means something is definitely wrong.
   *
   * <p>Before the bug was fixed this test would fail at least 30% of the time.
   */

  public void testTransitionRace() throws TimeoutException {
    for (int k = 0; k < 1000; k++) {
      List<Service> services = Lists.newArrayList();
      for (int i = 0; i < 5; i++) {
        services.add(new SnappyShutdownService(i));
      }
      ServiceManager manager = new ServiceManager(services);
      manager.startAsync().awaitHealthy();
      manager.stopAsync().awaitStopped(1, TimeUnit.SECONDS);
    }
  }

  /**
   * This service will shutdown very quickly after stopAsync is called and uses a background thread
   * so that we know that the stopping() listeners will execute on a different thread than the
   * terminated() listeners.
   */
  private static class SnappyShutdownService extends AbstractExecutionThreadService {
    final int index;
    final CountDownLatch latch = new CountDownLatch(1);

    SnappyShutdownService(int index) {
      this.index = index;
    }

    @Override protected void run() throws Exception {
      latch.await();
    }

    @Override protected void triggerShutdown() {
      latch.countDown();
    }

    @Override protected String serviceName() {
      return this.getClass().getSimpleName() + "[" + index + "]";
    }
  }

  public void testNulls() {
    ServiceManager manager = new ServiceManager(Arrays.<Service>asList());
    new NullPointerTester()
        .setDefault(ServiceManager.Listener.class, new RecordingListener())
        .testAllPublicInstanceMethods(manager);
  }

  private static final class RecordingListener extends ServiceManager.Listener {
    volatile boolean healthyCalled;
    volatile boolean stoppedCalled;
    final Set<Service> failedServices = Sets.newConcurrentHashSet();

    @Override public void healthy() {
      healthyCalled = true;
    }

    @Override public void stopped() {
      stoppedCalled = true;
    }

    @Override public void failure(Service service) {
      failedServices.add(service);
    }
  }
}