Google-Guava Concurrent包里的Service框架浅析
概述
Guava包里的Service接口用于封装一个服务对象的运行状态、包括start和stop等方法。例如web服务器，RPC服务器、计时器等可以实现这个接口。对此类服务的状态管理并不轻松、需要对服务的开启/关闭进行妥善管理、特别是在多线程环境下尤为复杂。Guava包提供了一些基础类帮助你管理复杂的状态转换逻辑和同步细节。
使用一个服务
一个服务正常生命周期有：
- Service.State.NEW
- Service.State.STARTING
- Service.State.RUNNING
- Service.State.STOPPING
- Service.State.TERMINATED
服务一旦被停止就无法再重新启动了。如果服务在starting、running、stopping状态出现问题、会进入Service.State.FAILED.状态。调用 startAsync()方法可以异步开启一个服务,同时返回this对象形成方法调用链。注意：只有在当前服务的状态是NEW时才能调用startAsync()方法，因此最好在应用中有一个统一的地方初始化相关服务。停止一个服务也是类似的、使用异步方法stopAsync() 。但是不像startAsync(),多次调用这个方法是安全的。这是为了方便处理关闭服务时候的锁竞争问题。
Service也提供了一些方法用于等待服务状态转换的完成:
通过 addListener()方法异步添加监听器。此方法允许你添加一个 Service.Listener 、它会在每次服务状态转换的时候被调用。注意：最好在服务启动之前添加Listener（这时的状态是NEW）、否则之前已发生的状态转换事件是无法在新添加的Listener上被重新触发的。
同步使用awaitRunning()。这个方法不能被打断、不强制捕获异常、一旦服务启动就会返回。如果服务没有成功启动，会抛出IllegalStateException异常。同样的， awaitTerminated() 方法会等待服务达到终止状态（TERMINATED 或者 FAILED）。两个方法都有重载方法允许传入超时时间。
Service 接口本身实现起来会比较复杂、且容易碰到一些捉摸不透的问题。因此我们不推荐直接实现这个接口。而是请继承Guava包里已经封装好的基础抽象类。每个基础类支持一种特定的线程模型。
基础实现类
AbstractIdleService
AbstractIdleService 类简单实现了Service接口、其在running状态时不会执行任何动作–因此在running时也不需要启动线程–但需要处理开启/关闭动作。要实现一个此类的服务，只需继承AbstractIdleService类，然后自己实现startUp() 和shutDown()方法就可以了。
[code lang=”java”]
protected void startUp() {
servlets.add(new GcStatsServlet());
}
protected void shutDown() {}
[/code]
如上面的例子、由于任何请求到GcStatsServlet时已经会有现成线程处理了，所以在服务运行时就不需要做什么额外动作了。
AbstractExecutionThreadService
AbstractExecutionThreadService 通过单线程处理启动、运行、和关闭等操作。你必须重载run()方法，同时需要能响应停止服务的请求。具体的实现可以在一个循环内做处理：
[code lang=”java”]
public void run() {
while (isRunning()) {
// perform a unit of work
}
}
[/code]
另外，你还可以重载triggerShutdown()方法让run()方法结束返回。
重载startUp()和shutDown()方法是可选的，不影响服务本身状态的管理
[code lang=”java”]
protected void startUp() {
dispatcher.listenForConnections(port, queue);
}
protected void run() {
Connection connection;
while ((connection = queue.take() != POISON)) {
process(connection);
}
}
protected void triggerShutdown() {
dispatcher.stopListeningForConnections(queue);
queue.put(POISON);
}
[/code]
start()内部会调用startUp()方法，创建一个线程、然后在线程内调用run()方法。stop()会调用 triggerShutdown()方法并且等待线程终止。
AbstractScheduledService
AbstractScheduledService类用于在运行时处理一些周期性的任务。子类可以实现 runOneIteration()方法定义一个周期执行的任务，以及相应的startUp()和shutDown()方法。为了能够描述执行周期，你需要实现scheduler()方法。通常情况下，你可以使用AbstractScheduledService.Scheduler类提供的两种调度器：newFixedRateSchedule(initialDelay, delay, TimeUnit) 和newFixedDelaySchedule(initialDelay, delay, TimeUnit)，类似于JDK并发包中ScheduledExecutorService类提供的两种调度方式。如要自定义schedules则可以使用 CustomScheduler类来辅助实现；具体用法见javadoc。
AbstractService
如需要自定义的线程管理、可以通过扩展 AbstractService类来实现。一般情况下、使用上面的几个实现类就已经满足需求了，但如果在服务执行过程中有一些特定的线程处理需求、则建议继承AbstractService类。
继承AbstractService方法必须实现两个方法.
- doStart(): 首次调用startAsync()时会同时调用doStart(),doStart()内部需要处理所有的初始化工作、如果启动成功则调用notifyStarted()方法；启动失败则调用notifyFailed()
- doStop(): 首次调用stopAsync()会同时调用doStop(),doStop()要做的事情就是停止服务，如果停止成功则调用 notifyStopped()方法；停止失败则调用 notifyFailed()方法。
doStart和doStop方法的实现需要考虑下性能，尽可能的低延迟。如果初始化的开销较大，如读文件，打开网络连接，或者其他任何可能引起阻塞的操作，建议移到另外一个单独的线程去处理。
使用ServiceManager
除了对Service接口提供基础的实现类，Guava还提供了 ServiceManager类使得涉及到多个Service集合的操作更加容易。通过实例化ServiceManager类来创建一个Service集合，你可以通过以下方法来管理它们：
- startAsync() ： 将启动所有被管理的服务。如果当前服务的状态都是NEW的话、那么你只能调用该方法一次、这跟 Service#startAsync()是一样的。
- stopAsync() ：将停止所有被管理的服务。
- addListener ：会添加一个ServiceManager.Listener，在服务状态转换中会调用该Listener
- awaitHealthy() ：会等待所有的服务达到Running状态
- awaitStopped()：会等待所有服务达到终止状态
检测类的方法有：
- isHealthy() ：如果所有的服务处于Running状态、会返回True
- servicesByState()：以状态为索引返回当前所有服务的快照
- startupTimes() ：返回一个Map对象，记录被管理的服务启动的耗时、以毫秒为单位，同时Map默认按启动时间排序。
我们建议整个服务的生命周期都能通过ServiceManager来管理，不过即使状态转换是通过其他机制触发的、也不影响ServiceManager方法的正确执行。例如：当一个服务不是通过startAsync()、而是其他机制启动时，listeners 仍然可以被正常调用、awaitHealthy()也能够正常工作。ServiceManager 唯一强制的要求是当其被创建时所有的服务必须处于New状态。
附：TestCase、也可以作为练习Demo
ServiceTest
[code lang=”java”]</pre>
/*
* Copyright (C) 2013 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.util.concurrent.Service.State.FAILED;
import static com.google.common.util.concurrent.Service.State.NEW;
import static com.google.common.util.concurrent.Service.State.RUNNING;
import static com.google.common.util.concurrent.Service.State.STARTING;
import static com.google.common.util.concurrent.Service.State.STOPPING;
import static com.google.common.util.concurrent.Service.State.TERMINATED;
import junit.framework.TestCase;
/**
* Unit tests for {@link Service}
*/
public class ServiceTest extends TestCase {
/** Assert on the comparison ordering of the State enum since we guarantee it. */
public void testStateOrdering() {
// List every valid (direct) state transition.
assertLessThan(NEW, STARTING);
assertLessThan(NEW, TERMINATED);
assertLessThan(STARTING, RUNNING);
assertLessThan(STARTING, STOPPING);
assertLessThan(STARTING, FAILED);
assertLessThan(RUNNING, STOPPING);
assertLessThan(RUNNING, FAILED);
assertLessThan(STOPPING, FAILED);
assertLessThan(STOPPING, TERMINATED);
}
private static <T extends Comparable<? super T>> void assertLessThan(T a, T b) {
if (a.compareTo(b) >= 0) {
fail(String.format("Expected %s to be less than %s", a, b));
}
}
}
<pre>
[/code]
AbstractIdleServiceTest
[code lang=”java”]
/*
* Copyright (C) 2009 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 org.truth0.Truth.ASSERT;
import com.google.common.collect.Lists;
import junit.framework.TestCase;
import java.util.List;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* Tests for {@link AbstractIdleService}.
*
* @author Chris Nokleberg
* @author Ben Yu
*/
public class AbstractIdleServiceTest extends TestCase {
// Functional tests using real thread. We only verify publicly visible state.
// Interaction assertions are done by the single-threaded unit tests.
public static class FunctionalTest extends TestCase {
private static class DefaultService extends AbstractIdleService {
@Override protected void startUp() throws Exception {}
@Override protected void shutDown() throws Exception {}
}
public void testServiceStartStop() throws Exception {
AbstractIdleService service = new DefaultService();
service.startAsync().awaitRunning();
assertEquals(Service.State.RUNNING, service.state());
service.stopAsync().awaitTerminated();
assertEquals(Service.State.TERMINATED, service.state());
}
public void testStart_failed() throws Exception {
final Exception exception = new Exception("deliberate");
AbstractIdleService service = new DefaultService() {
@Override protected void startUp() throws Exception {
throw exception;
}
};
try {
service.startAsync().awaitRunning();
fail();
} catch (RuntimeException e) {
assertSame(exception, e.getCause());
}
assertEquals(Service.State.FAILED, service.state());
}
public void testStop_failed() throws Exception {
final Exception exception = new Exception("deliberate");
AbstractIdleService service = new DefaultService() {
@Override protected void shutDown() throws Exception {
throw exception;
}
};
service.startAsync().awaitRunning();
try {
service.stopAsync().awaitTerminated();
fail();
} catch (RuntimeException e) {
assertSame(exception, e.getCause());
}
assertEquals(Service.State.FAILED, service.state());
}
}
public void testStart() {
TestService service = new TestService();
assertEquals(0, service.startUpCalled);
service.startAsync().awaitRunning();
assertEquals(1, service.startUpCalled);
assertEquals(Service.State.RUNNING, service.state());
ASSERT.that(service.transitionStates).has().exactly(Service.State.STARTING).inOrder();
}
public void testStart_failed() {
final Exception exception = new Exception("deliberate");
TestService service = new TestService() {
@Override protected void startUp() throws Exception {
super.startUp();
throw exception;
}
};
assertEquals(0, service.startUpCalled);
try {
service.startAsync().awaitRunning();
fail();
} catch (RuntimeException e) {
assertSame(exception, e.getCause());
}
assertEquals(1, service.startUpCalled);
assertEquals(Service.State.FAILED, service.state());
ASSERT.that(service.transitionStates).has().exactly(Service.State.STARTING).inOrder();
}
public void testStop_withoutStart() {
TestService service = new TestService();
service.stopAsync().awaitTerminated();
assertEquals(0, service.startUpCalled);
assertEquals(0, service.shutDownCalled);
assertEquals(Service.State.TERMINATED, service.state());
ASSERT.that(service.transitionStates).isEmpty();
}
public void testStop_afterStart() {
TestService service = new TestService();
service.startAsync().awaitRunning();
assertEquals(1, service.startUpCalled);
assertEquals(0, service.shutDownCalled);
service.stopAsync().awaitTerminated();
assertEquals(1, service.startUpCalled);
assertEquals(1, service.shutDownCalled);
assertEquals(Service.State.TERMINATED, service.state());
ASSERT.that(service.transitionStates)
.has().exactly(Service.State.STARTING, Service.State.STOPPING).inOrder();
}
public void testStop_failed() {
final Exception exception = new Exception("deliberate");
TestService service = new TestService() {
@Override protected void shutDown() throws Exception {
super.shutDown();
throw exception;
}
};
service.startAsync().awaitRunning();
assertEquals(1, service.startUpCalled);
assertEquals(0, service.shutDownCalled);
try {
service.stopAsync().awaitTerminated();
fail();
} catch (RuntimeException e) {
assertSame(exception, e.getCause());
}
assertEquals(1, service.startUpCalled);
assertEquals(1, service.shutDownCalled);
assertEquals(Service.State.FAILED, service.state());
ASSERT.that(service.transitionStates)
.has().exactly(Service.State.STARTING, Service.State.STOPPING).inOrder();
}
public void testServiceToString() {
AbstractIdleService service = new TestService();
assertEquals("TestService [NEW]", service.toString());
service.startAsync().awaitRunning();
assertEquals("TestService [RUNNING]", service.toString());
service.stopAsync().awaitTerminated();
assertEquals("TestService [TERMINATED]", service.toString());
}
public void testTimeout() throws Exception {
// Create a service whose executor will never run its commands
Service service = new TestService() {
@Override protected Executor executor() {
return new Executor() {
@Override public void execute(Runnable command) {}
};
}
};
try {
service.startAsync().awaitRunning(1, TimeUnit.MILLISECONDS);
fail("Expected timeout");
} catch (TimeoutException e) {
ASSERT.that(e.getMessage()).contains(Service.State.STARTING.toString());
}
}
private static class TestService extends AbstractIdleService {
int startUpCalled = 0;
int shutDownCalled = 0;
final List<State> transitionStates = Lists.newArrayList();
@Override protected void startUp() throws Exception {
assertEquals(0, startUpCalled);
assertEquals(0, shutDownCalled);
startUpCalled++;
assertEquals(State.STARTING, state());
}
@Override protected void shutDown() throws Exception {
assertEquals(1, startUpCalled);
assertEquals(0, shutDownCalled);
shutDownCalled++;
assertEquals(State.STOPPING, state());
}
@Override protected Executor executor() {
transitionStates.add(state());
return MoreExecutors.sameThreadExecutor();
}
}
}
<pre>[/code]
AbstractScheduledServiceTest
[code lang=”java”]</pre>
/*
* Copyright (C) 2011 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 com.google.common.util.concurrent.AbstractScheduledService.Scheduler;
import com.google.common.util.concurrent.Service.State;
import junit.framework.TestCase;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicInteger;
/**
* Unit test for {@link AbstractScheduledService}.
*
* @author Luke Sandberg
*/
public class AbstractScheduledServiceTest extends TestCase {
volatile Scheduler configuration = Scheduler.newFixedDelaySchedule(0, 10, TimeUnit.MILLISECONDS);
volatile ScheduledFuture<?> future = null;
volatile boolean atFixedRateCalled = false;
volatile boolean withFixedDelayCalled = false;
volatile boolean scheduleCalled = false;
final ScheduledExecutorService executor = new ScheduledThreadPoolExecutor(10) {
@Override
public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay,
long delay, TimeUnit unit) {
return future = super.scheduleWithFixedDelay(command, initialDelay, delay, unit);
}
};
public void testServiceStartStop() throws Exception {
NullService service = new NullService();
service.startAsync().awaitRunning();
assertFalse(future.isDone());
service.stopAsync().awaitTerminated();
assertTrue(future.isCancelled());
}
private class NullService extends AbstractScheduledService {
@Override protected void runOneIteration() throws Exception {}
@Override protected Scheduler scheduler() { return configuration; }
@Override protected ScheduledExecutorService executor() { return executor; }
}
public void testFailOnExceptionFromRun() throws Exception {
TestService service = new TestService();
service.runException = new Exception();
service.startAsync().awaitRunning();
service.runFirstBarrier.await();
service.runSecondBarrier.await();
try {
future.get();
fail();
} catch (ExecutionException e) {
// An execution exception holds a runtime exception (from throwables.propogate) that holds our
// original exception.
assertEquals(service.runException, e.getCause().getCause());
}
assertEquals(service.state(), Service.State.FAILED);
}
public void testFailOnExceptionFromStartUp() {
TestService service = new TestService();
service.startUpException = new Exception();
try {
service.startAsync().awaitRunning();
fail();
} catch (IllegalStateException e) {
assertEquals(service.startUpException, e.getCause());
}
assertEquals(0, service.numberOfTimesRunCalled.get());
assertEquals(Service.State.FAILED, service.state());
}
public void testFailOnExceptionFromShutDown() throws Exception {
TestService service = new TestService();
service.shutDownException = new Exception();
service.startAsync().awaitRunning();
service.runFirstBarrier.await();
service.stopAsync();
service.runSecondBarrier.await();
try {
service.awaitTerminated();
fail();
} catch (IllegalStateException e) {
assertEquals(service.shutDownException, e.getCause());
}
assertEquals(Service.State.FAILED, service.state());
}
public void testRunOneIterationCalledMultipleTimes() throws Exception {
TestService service = new TestService();
service.startAsync().awaitRunning();
for (int i = 1; i < 10; i++) {
service.runFirstBarrier.await();
assertEquals(i, service.numberOfTimesRunCalled.get());
service.runSecondBarrier.await();
}
service.runFirstBarrier.await();
service.stopAsync();
service.runSecondBarrier.await();
service.stopAsync().awaitTerminated();
}
public void testExecutorOnlyCalledOnce() throws Exception {
TestService service = new TestService();
service.startAsync().awaitRunning();
// It should be called once during startup.
assertEquals(1, service.numberOfTimesExecutorCalled.get());
for (int i = 1; i < 10; i++) {
service.runFirstBarrier.await();
assertEquals(i, service.numberOfTimesRunCalled.get());
service.runSecondBarrier.await();
}
service.runFirstBarrier.await();
service.stopAsync();
service.runSecondBarrier.await();
service.stopAsync().awaitTerminated();
// Only called once overall.
assertEquals(1, service.numberOfTimesExecutorCalled.get());
}
public void testDefaultExecutorIsShutdownWhenServiceIsStopped() throws Exception {
final CountDownLatch terminationLatch = new CountDownLatch(1);
AbstractScheduledService service = new AbstractScheduledService() {
volatile ScheduledExecutorService executorService;
@Override protected void runOneIteration() throws Exception {}
@Override protected ScheduledExecutorService executor() {
if (executorService == null) {
executorService = super.executor();
// Add a listener that will be executed after the listener that shuts down the executor.
addListener(new Listener() {
@Override public void terminated(State from) {
terminationLatch.countDown();
}
}, MoreExecutors.sameThreadExecutor());
}
return executorService;
}
@Override protected Scheduler scheduler() {
return Scheduler.newFixedDelaySchedule(0, 1, TimeUnit.MILLISECONDS);
}};
service.startAsync();
assertFalse(service.executor().isShutdown());
service.awaitRunning();
service.stopAsync();
terminationLatch.await();
assertTrue(service.executor().isShutdown());
assertTrue(service.executor().awaitTermination(100, TimeUnit.MILLISECONDS));
}
public void testDefaultExecutorIsShutdownWhenServiceFails() throws Exception {
final CountDownLatch failureLatch = new CountDownLatch(1);
AbstractScheduledService service = new AbstractScheduledService() {
volatile ScheduledExecutorService executorService;
@Override protected void runOneIteration() throws Exception {}
@Override protected void startUp() throws Exception {
throw new Exception("Failed");
}
@Override protected ScheduledExecutorService executor() {
if (executorService == null) {
executorService = super.executor();
// Add a listener that will be executed after the listener that shuts down the executor.
addListener(new Listener() {
@Override public void failed(State from, Throwable failure) {
failureLatch.countDown();
}
}, MoreExecutors.sameThreadExecutor());
}
return executorService;
}
@Override protected Scheduler scheduler() {
return Scheduler.newFixedDelaySchedule(0, 1, TimeUnit.MILLISECONDS);
}};
try {
service.startAsync().awaitRunning();
fail("Expected service to fail during startup");
} catch (IllegalStateException expected) {}
failureLatch.await();
assertTrue(service.executor().isShutdown());
assertTrue(service.executor().awaitTermination(100, TimeUnit.MILLISECONDS));
}
public void testSchedulerOnlyCalledOnce() throws Exception {
TestService service = new TestService();
service.startAsync().awaitRunning();
// It should be called once during startup.
assertEquals(1, service.numberOfTimesSchedulerCalled.get());
for (int i = 1; i < 10; i++) {
service.runFirstBarrier.await();
assertEquals(i, service.numberOfTimesRunCalled.get());
service.runSecondBarrier.await();
}
service.runFirstBarrier.await();
service.stopAsync();
service.runSecondBarrier.await();
service.awaitTerminated();
// Only called once overall.
assertEquals(1, service.numberOfTimesSchedulerCalled.get());
}
private class TestService extends AbstractScheduledService {
CyclicBarrier runFirstBarrier = new CyclicBarrier(2);
CyclicBarrier runSecondBarrier = new CyclicBarrier(2);
volatile boolean startUpCalled = false;
volatile boolean shutDownCalled = false;
AtomicInteger numberOfTimesRunCalled = new AtomicInteger(0);
AtomicInteger numberOfTimesExecutorCalled = new AtomicInteger(0);
AtomicInteger numberOfTimesSchedulerCalled = new AtomicInteger(0);
volatile Exception runException = null;
volatile Exception startUpException = null;
volatile Exception shutDownException = null;
@Override
protected void runOneIteration() throws Exception {
assertTrue(startUpCalled);
assertFalse(shutDownCalled);
numberOfTimesRunCalled.incrementAndGet();
assertEquals(State.RUNNING, state());
runFirstBarrier.await();
runSecondBarrier.await();
if (runException != null) {
throw runException;
}
}
@Override
protected void startUp() throws Exception {
assertFalse(startUpCalled);
assertFalse(shutDownCalled);
startUpCalled = true;
assertEquals(State.STARTING, state());
if (startUpException != null) {
throw startUpException;
}
}
@Override
protected void shutDown() throws Exception {
assertTrue(startUpCalled);
assertFalse(shutDownCalled);
shutDownCalled = true;
if (shutDownException != null) {
throw shutDownException;
}
}
@Override
protected ScheduledExecutorService executor() {
numberOfTimesExecutorCalled.incrementAndGet();
return executor;
}
@Override
protected Scheduler scheduler() {
numberOfTimesSchedulerCalled.incrementAndGet();
return configuration;
}
}
public static class SchedulerTest extends TestCase {
// These constants are arbitrary and just used to make sure that the correct method is called
// with the correct parameters.
private static final int initialDelay = 10;
private static final int delay = 20;
private static final TimeUnit unit = TimeUnit.MILLISECONDS;
// Unique runnable object used for comparison.
final Runnable testRunnable = new Runnable() {@Override public void run() {}};
boolean called = false;
private void assertSingleCallWithCorrectParameters(Runnable command, long initialDelay,
long delay, TimeUnit unit) {
assertFalse(called); // only called once.
called = true;
assertEquals(SchedulerTest.initialDelay, initialDelay);
assertEquals(SchedulerTest.delay, delay);
assertEquals(SchedulerTest.unit, unit);
assertEquals(testRunnable, command);
}
public void testFixedRateSchedule() {
Scheduler schedule = Scheduler.newFixedRateSchedule(initialDelay, delay, unit);
schedule.schedule(null, new ScheduledThreadPoolExecutor(1) {
@Override
public ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay,
long period, TimeUnit unit) {
assertSingleCallWithCorrectParameters(command, initialDelay, delay, unit);
return null;
}
}, testRunnable);
assertTrue(called);
}
public void testFixedDelaySchedule() {
Scheduler schedule = Scheduler.newFixedDelaySchedule(initialDelay, delay, unit);
schedule.schedule(null, new ScheduledThreadPoolExecutor(10) {
@Override
public ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay,
long delay, TimeUnit unit) {
assertSingleCallWithCorrectParameters(command, initialDelay, delay, unit);
return null;
}
}, testRunnable);
assertTrue(called);
}
private class TestCustomScheduler extends AbstractScheduledService.CustomScheduler {
public AtomicInteger scheduleCounter = new AtomicInteger(0);
@Override
protected Schedule getNextSchedule() throws Exception {
scheduleCounter.incrementAndGet();
return new Schedule(0, TimeUnit.SECONDS);
}
}
public void testCustomSchedule_startStop() throws Exception {
final CyclicBarrier firstBarrier = new CyclicBarrier(2);
final CyclicBarrier secondBarrier = new CyclicBarrier(2);
final AtomicBoolean shouldWait = new AtomicBoolean(true);
Runnable task = new Runnable() {
@Override public void run() {
try {
if (shouldWait.get()) {
firstBarrier.await();
secondBarrier.await();
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
};
TestCustomScheduler scheduler = new TestCustomScheduler();
Future<?> future = scheduler.schedule(null, Executors.newScheduledThreadPool(10), task);
firstBarrier.await();
assertEquals(1, scheduler.scheduleCounter.get());
secondBarrier.await();
firstBarrier.await();
assertEquals(2, scheduler.scheduleCounter.get());
shouldWait.set(false);
secondBarrier.await();
future.cancel(false);
}
public void testCustomSchedulerServiceStop() throws Exception {
TestAbstractScheduledCustomService service = new TestAbstractScheduledCustomService();
service.startAsync().awaitRunning();
service.firstBarrier.await();
assertEquals(1, service.numIterations.get());
service.stopAsync();
service.secondBarrier.await();
service.awaitTerminated();
// Sleep for a while just to ensure that our task wasn’t called again.
Thread.sleep(unit.toMillis(3 * delay));
assertEquals(1, service.numIterations.get());
}
public void testBig() throws Exception {
TestAbstractScheduledCustomService service = new TestAbstractScheduledCustomService() {
@Override protected Scheduler scheduler() {
return new AbstractScheduledService.CustomScheduler() {
@Override
protected Schedule getNextSchedule() throws Exception {
// Explicitly yield to increase the probability of a pathological scheduling.
Thread.yield();
return new Schedule(0, TimeUnit.SECONDS);
}
};
}
};
service.useBarriers = false;
service.startAsync().awaitRunning();
Thread.sleep(50);
service.useBarriers = true;
service.firstBarrier.await();
int numIterations = service.numIterations.get();
service.stopAsync();
service.secondBarrier.await();
service.awaitTerminated();
assertEquals(numIterations, service.numIterations.get());
}
private static class TestAbstractScheduledCustomService extends AbstractScheduledService {
final AtomicInteger numIterations = new AtomicInteger(0);
volatile boolean useBarriers = true;
final CyclicBarrier firstBarrier = new CyclicBarrier(2);
final CyclicBarrier secondBarrier = new CyclicBarrier(2);
@Override protected void runOneIteration() throws Exception {
numIterations.incrementAndGet();
if (useBarriers) {
firstBarrier.await();
secondBarrier.await();
}
}
@Override protected ScheduledExecutorService executor() {
// use a bunch of threads so that weird overlapping schedules are more likely to happen.
return Executors.newScheduledThreadPool(10);
}
@Override protected void startUp() throws Exception {}
@Override protected void shutDown() throws Exception {}
@Override protected Scheduler scheduler() {
return new CustomScheduler() {
@Override
protected Schedule getNextSchedule() throws Exception {
return new Schedule(delay, unit);
}};
}
}
public void testCustomSchedulerFailure() throws Exception {
TestFailingCustomScheduledService service = new TestFailingCustomScheduledService();
service.startAsync().awaitRunning();
for (int i = 1; i < 4; i++) {
service.firstBarrier.await();
assertEquals(i, service.numIterations.get());
service.secondBarrier.await();
}
Thread.sleep(1000);
try {
service.stopAsync().awaitTerminated(100, TimeUnit.SECONDS);
fail();
} catch (IllegalStateException e) {
assertEquals(State.FAILED, service.state());
}
}
private static class TestFailingCustomScheduledService extends AbstractScheduledService {
final AtomicInteger numIterations = new AtomicInteger(0);
final CyclicBarrier firstBarrier = new CyclicBarrier(2);
final CyclicBarrier secondBarrier = new CyclicBarrier(2);
@Override protected void runOneIteration() throws Exception {
numIterations.incrementAndGet();
firstBarrier.await();
secondBarrier.await();
}
@Override protected ScheduledExecutorService executor() {
// use a bunch of threads so that weird overlapping schedules are more likely to happen.
return Executors.newScheduledThreadPool(10);
}
@Override protected Scheduler scheduler() {
return new CustomScheduler() {
@Override
protected Schedule getNextSchedule() throws Exception {
if (numIterations.get() > 2) {
throw new IllegalStateException("Failed");
}
return new Schedule(delay, unit);
}};
}
}
}
}
<pre>[/code]
AbstractServiceTest
[code lang=”java”]</pre>
/*
* Copyright (C) 2009 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 java.lang.Thread.currentThread;
import static java.util.concurrent.TimeUnit.SECONDS;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.util.concurrent.Service.Listener;
import com.google.common.util.concurrent.Service.State;
import junit.framework.TestCase;
import java.lang.Thread.UncaughtExceptionHandler;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;
import javax.annotation.concurrent.GuardedBy;
/**
* Unit test for {@link AbstractService}.
*
* @author Jesse Wilson
*/
public class AbstractServiceTest extends TestCase {
private Thread executionThread;
private Throwable thrownByExecutionThread;
public void testNoOpServiceStartStop() throws Exception {
NoOpService service = new NoOpService();
RecordingListener listener = RecordingListener.record(service);
assertEquals(State.NEW, service.state());
assertFalse(service.isRunning());
assertFalse(service.running);
service.startAsync();
assertEquals(State.RUNNING, service.state());
assertTrue(service.isRunning());
assertTrue(service.running);
service.stopAsync();
assertEquals(State.TERMINATED, service.state());
assertFalse(service.isRunning());
assertFalse(service.running);
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.STOPPING,
State.TERMINATED),
listener.getStateHistory());
}
public void testNoOpServiceStartAndWaitStopAndWait() throws Exception {
NoOpService service = new NoOpService();
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.stopAsync().awaitTerminated();
assertEquals(State.TERMINATED, service.state());
}
public void testNoOpServiceStartAsyncAndAwaitStopAsyncAndAwait() throws Exception {
NoOpService service = new NoOpService();
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.stopAsync().awaitTerminated();
assertEquals(State.TERMINATED, service.state());
}
public void testNoOpServiceStopIdempotence() throws Exception {
NoOpService service = new NoOpService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.stopAsync();
service.stopAsync();
assertEquals(State.TERMINATED, service.state());
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.STOPPING,
State.TERMINATED),
listener.getStateHistory());
}
public void testNoOpServiceStopIdempotenceAfterWait() throws Exception {
NoOpService service = new NoOpService();
service.startAsync().awaitRunning();
service.stopAsync().awaitTerminated();
service.stopAsync();
assertEquals(State.TERMINATED, service.state());
}
public void testNoOpServiceStopIdempotenceDoubleWait() throws Exception {
NoOpService service = new NoOpService();
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.stopAsync().awaitTerminated();
service.stopAsync().awaitTerminated();
assertEquals(State.TERMINATED, service.state());
}
public void testNoOpServiceStartStopAndWaitUninterruptible()
throws Exception {
NoOpService service = new NoOpService();
currentThread().interrupt();
try {
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.stopAsync().awaitTerminated();
assertEquals(State.TERMINATED, service.state());
assertTrue(currentThread().isInterrupted());
} finally {
Thread.interrupted(); // clear interrupt for future tests
}
}
private static class NoOpService extends AbstractService {
boolean running = false;
@Override protected void doStart() {
assertFalse(running);
running = true;
notifyStarted();
}
@Override protected void doStop() {
assertTrue(running);
running = false;
notifyStopped();
}
}
public void testManualServiceStartStop() throws Exception {
ManualSwitchedService service = new ManualSwitchedService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync();
assertEquals(State.STARTING, service.state());
assertFalse(service.isRunning());
assertTrue(service.doStartCalled);
service.notifyStarted(); // usually this would be invoked by another thread
assertEquals(State.RUNNING, service.state());
assertTrue(service.isRunning());
service.stopAsync();
assertEquals(State.STOPPING, service.state());
assertFalse(service.isRunning());
assertTrue(service.doStopCalled);
service.notifyStopped(); // usually this would be invoked by another thread
assertEquals(State.TERMINATED, service.state());
assertFalse(service.isRunning());
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.STOPPING,
State.TERMINATED),
listener.getStateHistory());
}
public void testManualServiceNotifyStoppedWhileRunning() throws Exception {
ManualSwitchedService service = new ManualSwitchedService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync();
service.notifyStarted();
service.notifyStopped();
assertEquals(State.TERMINATED, service.state());
assertFalse(service.isRunning());
assertFalse(service.doStopCalled);
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.TERMINATED),
listener.getStateHistory());
}
public void testManualServiceStopWhileStarting() throws Exception {
ManualSwitchedService service = new ManualSwitchedService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync();
assertEquals(State.STARTING, service.state());
assertFalse(service.isRunning());
assertTrue(service.doStartCalled);
service.stopAsync();
assertEquals(State.STOPPING, service.state());
assertFalse(service.isRunning());
assertFalse(service.doStopCalled);
service.notifyStarted();
assertEquals(State.STOPPING, service.state());
assertFalse(service.isRunning());
assertTrue(service.doStopCalled);
service.notifyStopped();
assertEquals(State.TERMINATED, service.state());
assertFalse(service.isRunning());
assertEquals(
ImmutableList.of(
State.STARTING,
State.STOPPING,
State.TERMINATED),
listener.getStateHistory());
}
/**
* This tests for a bug where if {@link Service#stopAsync()} was called while the service was
* {@link State#STARTING} more than once, the {@link Listener#stopping(State)} callback would get
* called multiple times.
*/
public void testManualServiceStopMultipleTimesWhileStarting() throws Exception {
ManualSwitchedService service = new ManualSwitchedService();
final AtomicInteger stopppingCount = new AtomicInteger();
service.addListener(new Listener() {
@Override public void stopping(State from) {
stopppingCount.incrementAndGet();
}
}, MoreExecutors.sameThreadExecutor());
service.startAsync();
service.stopAsync();
assertEquals(1, stopppingCount.get());
service.stopAsync();
assertEquals(1, stopppingCount.get());
}
public void testManualServiceStopWhileNew() throws Exception {
ManualSwitchedService service = new ManualSwitchedService();
RecordingListener listener = RecordingListener.record(service);
service.stopAsync();
assertEquals(State.TERMINATED, service.state());
assertFalse(service.isRunning());
assertFalse(service.doStartCalled);
assertFalse(service.doStopCalled);
assertEquals(ImmutableList.of(State.TERMINATED), listener.getStateHistory());
}
public void testManualServiceFailWhileStarting() throws Exception {
ManualSwitchedService service = new ManualSwitchedService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync();
service.notifyFailed(EXCEPTION);
assertEquals(ImmutableList.of(State.STARTING, State.FAILED), listener.getStateHistory());
}
public void testManualServiceFailWhileRunning() throws Exception {
ManualSwitchedService service = new ManualSwitchedService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync();
service.notifyStarted();
service.notifyFailed(EXCEPTION);
assertEquals(ImmutableList.of(State.STARTING, State.RUNNING, State.FAILED),
listener.getStateHistory());
}
public void testManualServiceFailWhileStopping() throws Exception {
ManualSwitchedService service = new ManualSwitchedService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync();
service.notifyStarted();
service.stopAsync();
service.notifyFailed(EXCEPTION);
assertEquals(ImmutableList.of(State.STARTING, State.RUNNING, State.STOPPING, State.FAILED),
listener.getStateHistory());
}
public void testManualServiceUnrequestedStop() {
ManualSwitchedService service = new ManualSwitchedService();
service.startAsync();
service.notifyStarted();
assertEquals(State.RUNNING, service.state());
assertTrue(service.isRunning());
assertFalse(service.doStopCalled);
service.notifyStopped();
assertEquals(State.TERMINATED, service.state());
assertFalse(service.isRunning());
assertFalse(service.doStopCalled);
}
/**
* The user of this service should call {@link #notifyStarted} and {@link
* #notifyStopped} after calling {@link #startAsync} and {@link #stopAsync}.
*/
private static class ManualSwitchedService extends AbstractService {
boolean doStartCalled = false;
boolean doStopCalled = false;
@Override protected void doStart() {
assertFalse(doStartCalled);
doStartCalled = true;
}
@Override protected void doStop() {
assertFalse(doStopCalled);
doStopCalled = true;
}
}
public void testAwaitTerminated() throws Exception {
final NoOpService service = new NoOpService();
Thread waiter = new Thread() {
@Override public void run() {
service.awaitTerminated();
}
};
waiter.start();
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.stopAsync();
waiter.join(100); // ensure that the await in the other thread is triggered
assertFalse(waiter.isAlive());
}
public void testAwaitTerminated_FailedService() throws Exception {
final ManualSwitchedService service = new ManualSwitchedService();
final AtomicReference<Throwable> exception = Atomics.newReference();
Thread waiter = new Thread() {
@Override public void run() {
try {
service.awaitTerminated();
fail("Expected an IllegalStateException");
} catch (Throwable t) {
exception.set(t);
}
}
};
waiter.start();
service.startAsync();
service.notifyStarted();
assertEquals(State.RUNNING, service.state());
service.notifyFailed(EXCEPTION);
assertEquals(State.FAILED, service.state());
waiter.join(100);
assertFalse(waiter.isAlive());
assertTrue(exception.get() instanceof IllegalStateException);
assertEquals(EXCEPTION, exception.get().getCause());
}
public void testThreadedServiceStartAndWaitStopAndWait() throws Throwable {
ThreadedService service = new ThreadedService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.awaitRunChecks();
service.stopAsync().awaitTerminated();
assertEquals(State.TERMINATED, service.state());
throwIfSet(thrownByExecutionThread);
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.STOPPING,
State.TERMINATED),
listener.getStateHistory());
}
public void testThreadedServiceStopIdempotence() throws Throwable {
ThreadedService service = new ThreadedService();
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.awaitRunChecks();
service.stopAsync();
service.stopAsync().awaitTerminated();
assertEquals(State.TERMINATED, service.state());
throwIfSet(thrownByExecutionThread);
}
public void testThreadedServiceStopIdempotenceAfterWait()
throws Throwable {
ThreadedService service = new ThreadedService();
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.awaitRunChecks();
service.stopAsync().awaitTerminated();
service.stopAsync();
assertEquals(State.TERMINATED, service.state());
executionThread.join();
throwIfSet(thrownByExecutionThread);
}
public void testThreadedServiceStopIdempotenceDoubleWait()
throws Throwable {
ThreadedService service = new ThreadedService();
service.startAsync().awaitRunning();
assertEquals(State.RUNNING, service.state());
service.awaitRunChecks();
service.stopAsync().awaitTerminated();
service.stopAsync().awaitTerminated();
assertEquals(State.TERMINATED, service.state());
throwIfSet(thrownByExecutionThread);
}
public void testManualServiceFailureIdempotence() {
ManualSwitchedService service = new ManualSwitchedService();
RecordingListener.record(service);
service.startAsync();
service.notifyFailed(new Exception("1"));
service.notifyFailed(new Exception("2"));
assertEquals("1", service.failureCause().getMessage());
try {
service.awaitRunning();
fail();
} catch (IllegalStateException e) {
assertEquals("1", e.getCause().getMessage());
}
}
private class ThreadedService extends AbstractService {
final CountDownLatch hasConfirmedIsRunning = new CountDownLatch(1);
/*
* The main test thread tries to stop() the service shortly after
* confirming that it is running. Meanwhile, the service itself is trying
* to confirm that it is running. If the main thread’s stop() call happens
* before it has the chance, the test will fail. To avoid this, the main
* thread calls this method, which waits until the service has performed
* its own "running" check.
*/
void awaitRunChecks() throws InterruptedException {
assertTrue("Service thread hasn’t finished its checks. "
+ "Exception status (possibly stale): " + thrownByExecutionThread,
hasConfirmedIsRunning.await(10, SECONDS));
}
@Override protected void doStart() {
assertEquals(State.STARTING, state());
invokeOnExecutionThreadForTest(new Runnable() {
@Override public void run() {
assertEquals(State.STARTING, state());
notifyStarted();
assertEquals(State.RUNNING, state());
hasConfirmedIsRunning.countDown();
}
});
}
@Override protected void doStop() {
assertEquals(State.STOPPING, state());
invokeOnExecutionThreadForTest(new Runnable() {
@Override public void run() {
assertEquals(State.STOPPING, state());
notifyStopped();
assertEquals(State.TERMINATED, state());
}
});
}
}
private void invokeOnExecutionThreadForTest(Runnable runnable) {
executionThread = new Thread(runnable);
executionThread.setUncaughtExceptionHandler(new UncaughtExceptionHandler() {
@Override
public void uncaughtException(Thread thread, Throwable e) {
thrownByExecutionThread = e;
}
});
executionThread.start();
}
private static void throwIfSet(Throwable t) throws Throwable {
if (t != null) {
throw t;
}
}
public void testStopUnstartedService() throws Exception {
NoOpService service = new NoOpService();
RecordingListener listener = RecordingListener.record(service);
service.stopAsync();
assertEquals(State.TERMINATED, service.state());
try {
service.startAsync();
fail();
} catch (IllegalStateException expected) {}
assertEquals(State.TERMINATED, Iterables.getOnlyElement(listener.getStateHistory()));
}
public void testFailingServiceStartAndWait() throws Exception {
StartFailingService service = new StartFailingService();
RecordingListener listener = RecordingListener.record(service);
try {
service.startAsync().awaitRunning();
fail();
} catch (IllegalStateException e) {
assertEquals(EXCEPTION, service.failureCause());
assertEquals(EXCEPTION, e.getCause());
}
assertEquals(
ImmutableList.of(
State.STARTING,
State.FAILED),
listener.getStateHistory());
}
public void testFailingServiceStopAndWait_stopFailing() throws Exception {
StopFailingService service = new StopFailingService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync().awaitRunning();
try {
service.stopAsync().awaitTerminated();
fail();
} catch (IllegalStateException e) {
assertEquals(EXCEPTION, service.failureCause());
assertEquals(EXCEPTION, e.getCause());
}
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.STOPPING,
State.FAILED),
listener.getStateHistory());
}
public void testFailingServiceStopAndWait_runFailing() throws Exception {
RunFailingService service = new RunFailingService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync();
try {
service.awaitRunning();
fail();
} catch (IllegalStateException e) {
assertEquals(EXCEPTION, service.failureCause());
assertEquals(EXCEPTION, e.getCause());
}
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.FAILED),
listener.getStateHistory());
}
public void testThrowingServiceStartAndWait() throws Exception {
StartThrowingService service = new StartThrowingService();
RecordingListener listener = RecordingListener.record(service);
try {
service.startAsync().awaitRunning();
fail();
} catch (IllegalStateException e) {
assertEquals(service.exception, service.failureCause());
assertEquals(service.exception, e.getCause());
}
assertEquals(
ImmutableList.of(
State.STARTING,
State.FAILED),
listener.getStateHistory());
}
public void testThrowingServiceStopAndWait_stopThrowing() throws Exception {
StopThrowingService service = new StopThrowingService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync().awaitRunning();
try {
service.stopAsync().awaitTerminated();
fail();
} catch (IllegalStateException e) {
assertEquals(service.exception, service.failureCause());
assertEquals(service.exception, e.getCause());
}
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.STOPPING,
State.FAILED),
listener.getStateHistory());
}
public void testThrowingServiceStopAndWait_runThrowing() throws Exception {
RunThrowingService service = new RunThrowingService();
RecordingListener listener = RecordingListener.record(service);
service.startAsync();
try {
service.awaitTerminated();
fail();
} catch (IllegalStateException e) {
assertEquals(service.exception, service.failureCause());
assertEquals(service.exception, e.getCause());
}
assertEquals(
ImmutableList.of(
State.STARTING,
State.RUNNING,
State.FAILED),
listener.getStateHistory());
}
public void testFailureCause_throwsIfNotFailed() {
StopFailingService service = new StopFailingService();
try {
service.failureCause();
fail();
} catch (IllegalStateException e) {
// expected
}
service.startAsync().awaitRunning();
try {
service.failureCause();
fail();
} catch (IllegalStateException e) {
// expected
}
try {
service.stopAsync().awaitTerminated();
fail();
} catch (IllegalStateException e) {
assertEquals(EXCEPTION, service.failureCause());
assertEquals(EXCEPTION, e.getCause());
}
}
public void testAddListenerAfterFailureDoesntCauseDeadlock() throws InterruptedException {
final StartFailingService service = new StartFailingService();
service.startAsync();
assertEquals(State.FAILED, service.state());
service.addListener(new RecordingListener(service), MoreExecutors.sameThreadExecutor());
Thread thread = new Thread() {
@Override public void run() {
// Internally stopAsync() grabs a lock, this could be any such method on AbstractService.
service.stopAsync();
}
};
thread.start();
thread.join(100);
assertFalse(thread + " is deadlocked", thread.isAlive());
}
public void testListenerDoesntDeadlockOnStartAndWaitFromRunning() throws Exception {
final NoOpThreadedService service = new NoOpThreadedService();
service.addListener(new Listener() {
@Override public void running() {
service.awaitRunning();
}
}, MoreExecutors.sameThreadExecutor());
service.startAsync().awaitRunning(10, TimeUnit.MILLISECONDS);
service.stopAsync();
}
public void testListenerDoesntDeadlockOnStopAndWaitFromTerminated() throws Exception {
final NoOpThreadedService service = new NoOpThreadedService();
service.addListener(new Listener() {
@Override public void terminated(State from) {
service.stopAsync().awaitTerminated();
}
}, MoreExecutors.sameThreadExecutor());
service.startAsync().awaitRunning();
Thread thread = new Thread() {
@Override public void run() {
service.stopAsync().awaitTerminated();
}
};
thread.start();
thread.join(100);
assertFalse(thread + " is deadlocked", thread.isAlive());
}
private static class NoOpThreadedService extends AbstractExecutionThreadService {
final CountDownLatch latch = new CountDownLatch(1);
@Override protected void run() throws Exception {
latch.await();
}
@Override protected void triggerShutdown() {
latch.countDown();
}
}
private static class StartFailingService extends AbstractService {
@Override protected void doStart() {
notifyFailed(EXCEPTION);
}
@Override protected void doStop() {
fail();
}
}
private static class RunFailingService extends AbstractService {
@Override protected void doStart() {
notifyStarted();
notifyFailed(EXCEPTION);
}
@Override protected void doStop() {
fail();
}
}
private static class StopFailingService extends AbstractService {
@Override protected void doStart() {
notifyStarted();
}
@Override protected void doStop() {
notifyFailed(EXCEPTION);
}
}
private static class StartThrowingService extends AbstractService {
final RuntimeException exception = new RuntimeException("deliberate");
@Override protected void doStart() {
throw exception;
}
@Override protected void doStop() {
fail();
}
}
private static class RunThrowingService extends AbstractService {
final RuntimeException exception = new RuntimeException("deliberate");
@Override protected void doStart() {
notifyStarted();
throw exception;
}
@Override protected void doStop() {
fail();
}
}
private static class StopThrowingService extends AbstractService {
final RuntimeException exception = new RuntimeException("deliberate");
@Override protected void doStart() {
notifyStarted();
}
@Override protected void doStop() {
throw exception;
}
}
private static class RecordingListener extends Listener {
static RecordingListener record(Service service) {
RecordingListener listener = new RecordingListener(service);
service.addListener(listener, MoreExecutors.sameThreadExecutor());
return listener;
}
final Service service;
RecordingListener(Service service) {
this.service = service;
}
@GuardedBy("this")
final List<State> stateHistory = Lists.newArrayList();
final CountDownLatch completionLatch = new CountDownLatch(1);
ImmutableList<State> getStateHistory() throws Exception {
completionLatch.await();
synchronized (this) {
return ImmutableList.copyOf(stateHistory);
}
}
@Override public synchronized void starting() {
assertTrue(stateHistory.isEmpty());
assertNotSame(State.NEW, service.state());
stateHistory.add(State.STARTING);
}
@Override public synchronized void running() {
assertEquals(State.STARTING, Iterables.getOnlyElement(stateHistory));
stateHistory.add(State.RUNNING);
service.awaitRunning();
assertNotSame(State.STARTING, service.state());
}
@Override public synchronized void stopping(State from) {
assertEquals(from, Iterables.getLast(stateHistory));
stateHistory.add(State.STOPPING);
if (from == State.STARTING) {
try {
service.awaitRunning();
fail();
} catch (IllegalStateException expected) {
assertNull(expected.getCause());
assertTrue(expected.getMessage().equals(
"Expected the service to be RUNNING, but was STOPPING"));
}
}
assertNotSame(from, service.state());
}
@Override public synchronized void terminated(State from) {
assertEquals(from, Iterables.getLast(stateHistory, State.NEW));
stateHistory.add(State.TERMINATED);
assertEquals(State.TERMINATED, service.state());
if (from == State.NEW) {
try {
service.awaitRunning();
fail();
} catch (IllegalStateException expected) {
assertNull(expected.getCause());
assertTrue(expected.getMessage().equals(
"Expected the service to be RUNNING, but was TERMINATED"));
}
}
completionLatch.countDown();
}
@Override public synchronized void failed(State from, Throwable failure) {
assertEquals(from, Iterables.getLast(stateHistory));
stateHistory.add(State.FAILED);
assertEquals(State.FAILED, service.state());
assertEquals(failure, service.failureCause());
if (from == State.STARTING) {
try {
service.awaitRunning();
fail();
} catch (IllegalStateException e) {
assertEquals(failure, e.getCause());
}
}
try {
service.awaitTerminated();
fail();
} catch (IllegalStateException e) {
assertEquals(failure, e.getCause());
}
completionLatch.countDown();
}
}
public void testNotifyStartedWhenNotStarting() {
AbstractService service = new DefaultService();
try {
service.notifyStarted();
fail();
} catch (IllegalStateException expected) {}
}
public void testNotifyStoppedWhenNotRunning() {
AbstractService service = new DefaultService();
try {
service.notifyStopped();
fail();
} catch (IllegalStateException expected) {}
}
public void testNotifyFailedWhenNotStarted() {
AbstractService service = new DefaultService();
try {
service.notifyFailed(new Exception());
fail();
} catch (IllegalStateException expected) {}
}
public void testNotifyFailedWhenTerminated() {
NoOpService service = new NoOpService();
service.startAsync().awaitRunning();
service.stopAsync().awaitTerminated();
try {
service.notifyFailed(new Exception());
fail();
} catch (IllegalStateException expected) {}
}
private static class DefaultService extends AbstractService {
@Override protected void doStart() {}
@Override protected void doStop() {}
}
private static final Exception EXCEPTION = new Exception();
}
<pre>[/code]
ServiceManagerTest
[code lang=”java”]</pre>
/*
* 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 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.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 NoOpDelayedSerivce extends NoOpService {
private long delay;
public NoOpDelayedSerivce(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("failed"));
}
}
private static class FailRunService extends NoOpService {
@Override protected void doStart() {
super.doStart();
notifyFailed(new IllegalStateException("failed"));
}
}
private static class FailStopService extends NoOpService {
@Override protected void doStop() {
notifyFailed(new IllegalStateException("failed"));
}
}
public void testServiceStartupTimes() {
Service a = new NoOpDelayedSerivce(150);
Service b = new NoOpDelayedSerivce(353);
ServiceManager serviceManager = new ServiceManager(asList(a, b));
serviceManager.startAsync().awaitHealthy();
ImmutableMap<Service, Long> startupTimes = serviceManager.startupTimes();
assertEquals(2, startupTimes.size());
assertTrue(startupTimes.get(a) >= 150);
assertTrue(startupTimes.get(b) >= 353);
}
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();
assertTrue(toString.contains("NoOpService"));
assertTrue(toString.contains("FailStartService"));
}
public void testTimeouts() throws Exception {
Service a = new NoOpDelayedSerivce(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, MoreExecutors.sameThreadExecutor());
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()) {
assertFalse(logFormatter.format(record).contains("NoOpService"));
}
}
/**
* This is for a case where a long running Listener using the sameThreadListener could deadlock
* another thread calling stopAsync().
*/
public void testListenerDeadlock() throws InterruptedException {
final CountDownLatch failEnter = new CountDownLatch(1);
Service failRunService = new AbstractService() {
@Override protected void doStart() {
new Thread() {
@Override public void run() {
notifyStarted();
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 forever!
Uninterruptibles.awaitUninterruptibly(new CountDownLatch(1));
}
}, MoreExecutors.sameThreadExecutor());
// 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.
manager.startAsync();
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());
}
/**
* 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 ListenableFuture<State> start() {
return delegate.start();
}
@Override public final ListenableFuture<State> stop() {
return delegate.stop();
}
@Override public State startAndWait() {
return delegate.startAndWait();
}
@Override public State stopAndWait() {
return delegate.stopAndWait();
}
@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) {
assertTrue(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);
}
}
}
<pre>[/code]
原创文章，转载请注明： 转载自并发编程网 – ifeve.com本文链接地址: Google-Guava Concurrent包里的Service框架浅析
(13 votes, average: 4.69 out of 5)
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这个东西不晓得用在什么场景比较合适呢？有无DEMO参考一下，这样看起来有点抽象。
文中提到适用于 web服务器，RPC服务器、计时器等可以实现这个接口。想研究的话最好还是动手试试。
guava的Service框架本身是一个抽象封装、适应于并发环境下基于状态机的服务实现；大到Web服务器实现、小到应用中具有生命周期且能包装成服务的业务场景（如Web服务、有状态转换的定时任务等）都可以利用这个基础包
附上了单元测试TestCase、可以作为Demo参考
“一般情况下，你可以使用已提供的3个schedules方法：AbstractScheduledService.Scheduler, newFixedRateSchedule(initialDelay, delay, TimeUnit) 和newFixedDelaySchedule(initialDelay, delay, TimeUnit)”
原文意思是说AbstractScheduledService.Scheduler类提供的调度器（provided schedules from AbstractScheduledService.Scheduler），所以是两个方法，也和JDK的两种调度对应。
多谢指正、已修改
Hadoop Yarn源代码里面就大量用到了这种Service状态驱动模式
代码的堆砌很成问题
这代码贴的我也是醉了…推荐能用个有滚动条的方框框起来；还有个悬停的导航栏