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/*
* Copyright 2021 the original author or 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 org.gradle.util.internal;
import groovy.lang.Closure;
import junit.framework.AssertionFailedError;
import org.codehaus.groovy.runtime.InvokerInvocationException;
import org.gradle.internal.UncheckedException;
import org.gradle.internal.concurrent.DefaultExecutorFactory;
import org.gradle.internal.concurrent.ExecutorFactory;
import org.hamcrest.Matcher;
import org.junit.After;
import org.junit.rules.ExternalResource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Date;
import java.util.EnumSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.AbstractExecutorService;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
/**
* A rule for testing concurrent code.
*
* Provides several ways to start and manage threads. You can use the {@link #start(groovy.lang.Closure)} or {@link
* #run(groovy.lang.Closure)} methods to execute test code in other threads. You can use {@link #waitForAll()} to wait
* for all test threads to complete. In addition, the test tear-down method blocks until all test threads have stopped
* and ensures that no exceptions were thrown in any test threads.
*
* Provides an {@link java.util.concurrent.Executor} implementation, which uses test threads to execute any tasks
* submitted to it.
*
* You can use {@link #syncAt(int)} and {@link #expectBlocksUntil(int, groovy.lang.Closure)} to synchronise between
* test threads.
*/
public class MultithreadedTestRule extends ExternalResource {
private static final Logger LOGGER = LoggerFactory.getLogger(MultithreadedTestRule.class);
private static final int MAX_WAIT_TIME = 5000;
private ExecutorImpl executor;
private final Lock lock = new ReentrantLock();
private final Condition condition = lock.newCondition();
private final Set active = new HashSet();
private final Set synching = new HashSet();
private final List failures = new ArrayList();
private final Map ticks = new HashMap();
private ClockTickImpl currentTick = getTick(0);
private boolean stopped;
private final ThreadLocal> expectedFailure
= new ThreadLocal>();
private final SyncPoint syncPoint = new SyncPoint();
/**
* Creates an Executor which the test can control.
*/
protected ExecutorService getExecutor() {
if (executor == null) {
executor = new ExecutorImpl();
}
return executor;
}
/**
* Creates an ExecutorFactory for the test to use.
*/
protected ExecutorFactory getExecutorFactory() {
return new DefaultExecutorFactory() {
@Override
protected ExecutorService createExecutor(String displayName) {
return new ExecutorImpl();
}
};
}
/**
* Executes the given closure in a test thread.
*/
protected ThreadHandle start(final Closure closure) {
Runnable task = new Runnable() {
@Override
public void run() {
closure.call();
}
};
return start(task);
}
/**
* Executes the given closure in a test thread and waits for it to complete.
*/
protected ThreadHandle run(final Closure closure) {
Runnable task = new Runnable() {
@Override
public void run() {
closure.call();
}
};
return start(task).waitFor();
}
public ThreadHandle expectTimesOut(int value, TimeUnit units, Closure closure) {
Date start = new Date();
ThreadHandle threadHandle = start(closure);
threadHandle.waitFor();
Date end = new Date();
long actual = end.getTime() - start.getTime();
long expected = units.toMillis(value);
if (actual < expected - 200) {
throw new RuntimeException(String.format(
"Action did not block for expected time. Expected ~ %d ms, was %d ms.", expected, actual));
}
if (actual > expected + 1200) {
throw new RuntimeException(String.format(
"Action did not complete within expected time. Expected ~ %d ms, was %d ms.", expected, actual));
}
return threadHandle;
}
/**
* Executes the given runnable in a test thread.
*/
protected ThreadHandle start(final Runnable task) {
final Thread thread = new Thread() {
@Override
public String toString() {
return "test thread " + getId();
}
@Override
public void run() {
Throwable failure = null;
try {
try {
task.run();
} catch (InvokerInvocationException e) {
failure = e.getCause();
} catch (Throwable throwable) {
failure = throwable;
}
} finally {
testThreadFinished(this, failure);
}
}
};
testThreadStarted(thread);
thread.start();
return new ThreadHandleImpl(thread);
}
private void testThreadStarted(Thread thread) {
lock.lock();
try {
if (stopped) {
throw new IllegalStateException("Cannot start new threads, as this test case has been stopped.");
}
LOGGER.debug("Started {}", thread);
active.add(thread);
condition.signalAll();
} finally {
lock.unlock();
}
}
private void testThreadFinished(Thread thread, Throwable failure) {
lock.lock();
try {
active.remove(thread);
Matcher matcher = expectedFailure.get();
if (failure != null) {
if (matcher != null && matcher.matches(failure)) {
LOGGER.debug("Finished {} with expected failure.", thread);
} else {
LOGGER.error(String.format("Failure in %s", thread), failure);
failures.add(failure);
}
} else {
if (matcher != null) {
String message = String.format("Did not get expected failure in %s", thread);
LOGGER.error(message);
failures.add(new AssertionFailedError(message));
} else {
LOGGER.debug("Finished {}", thread);
}
}
condition.signalAll();
} finally {
lock.unlock();
}
}
/**
* Waits for all asynchronous activity to complete. Applies a timeout, and re-throws any exceptions which occurred.
*/
public void waitForAll() {
Date expiry = new Date(System.currentTimeMillis() + 2 * MAX_WAIT_TIME);
lock.lock();
try {
LOGGER.debug("Waiting for test threads complete.");
if (active.contains(Thread.currentThread())) {
throw new RuntimeException("A test thread cannot wait for test threads to complete.");
}
try {
while (!active.isEmpty()) {
boolean signaled = condition.awaitUntil(expiry);
if (!signaled) {
failures.add(new RuntimeException("Timeout waiting for threads to finish."));
break;
}
}
} catch (InterruptedException e) {
throw UncheckedException.throwAsUncheckedException(e);
}
LOGGER.debug("All test threads complete.");
if (!failures.isEmpty()) {
Throwable failure = failures.get(0);
failures.clear();
if (failure instanceof RuntimeException) {
throw (RuntimeException) failure;
}
if (failure instanceof Error) {
throw (Error) failure;
}
throw new RuntimeException("An unexpected exception occurred in a test thread.", failure);
}
} finally {
lock.unlock();
}
}
@After
public void waitForStop() {
lock.lock();
try {
stopped = true;
} finally {
lock.unlock();
}
waitForAll();
}
@Override
protected void after() {
waitForStop();
}
/**
* Returns the meta-info for the given clock tick.
*/
public ClockTick clockTick(int tick) {
lock.lock();
try {
return getTick(tick);
} finally {
lock.unlock();
}
}
private ClockTickImpl getTick(int tick) {
ClockTickImpl clockTick = ticks.get(tick);
if (clockTick == null) {
clockTick = new ClockTickImpl(tick);
ticks.put(tick, clockTick);
}
return clockTick;
}
/**
* Blocks until the clock has reached the given tick. The clock advances to the given tick when all test threads
* have called {@link #syncAt(int)} or {@link #expectBlocksUntil(int, groovy.lang.Closure)} with the given tick, and
* there are least 2 test threads.
*
* @param tick The expected clock tick
*/
public void syncAt(int tick) {
LOGGER.debug("Thread {} synching at tick {}", Thread.currentThread(), tick);
lock.lock();
try {
ClockTickImpl clockTick = getTick(tick);
if (!clockTick.isImmediatelyAfter(currentTick)) {
throw new RuntimeException(String.format("Cannot wait for %s, as clock is currently at %s.", clockTick,
currentTick));
}
if (!active.contains(Thread.currentThread())) {
throw new RuntimeException("Cannot wait for clock tick from a thread which is not a test thread.");
}
Date expiry = new Date(System.currentTimeMillis() + MAX_WAIT_TIME);
synching.add(Thread.currentThread());
condition.signalAll();
while (failures.isEmpty() && currentTick != clockTick && !clockTick.allThreadsSynced(synching, active)) {
try {
boolean signalled = condition.awaitUntil(expiry);
if (!signalled) {
throw new RuntimeException(String.format(
"Timeout waiting for all threads to reach %s. Currently at %s.", clockTick,
currentTick));
}
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
if (!failures.isEmpty()) {
throw new RuntimeException(String.format(
"Could not wait for all threads to reach %s, as a failure has occurred in another test thread.",
clockTick));
}
if (clockTick.isImmediatelyAfter(currentTick)) {
currentTick = clockTick;
synching.clear();
}
} finally {
lock.unlock();
}
LOGGER.debug("Thread {} sync done", Thread.currentThread());
}
/**
* Expects that the given tick will be reached at some point in the future. Does not block until the tick has been
* reached.
*
* @param tick The expected clock tick.
*/
public void expectLater(final int tick) {
final Thread targetThread = Thread.currentThread();
LOGGER.debug("Thread {} expecting tick {}", targetThread, tick);
start(new Runnable() {
@Override
public void run() {
try {
Thread.sleep(500L);
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
lock.lock();
try {
ClockTickImpl clockTick = getTick(tick);
if (!clockTick.isImmediatelyAfter(currentTick)) {
throw new RuntimeException(String.format("Cannot wait for %s, as clock is currently at %s.",
clockTick, currentTick));
}
if (!active.contains(targetThread)) {
throw new RuntimeException(
"Cannot wait for clock tick from a thread which is not a test thread.");
}
synching.add(targetThread);
condition.signalAll();
} finally {
lock.unlock();
}
}
});
}
/**
* Asserts that the given closure blocks until the given clock tick is reached.
*
* @param tick The expected clock tick when the closure completes.
* @param closure The closure to execute.
*/
public void expectBlocksUntil(int tick, Closure closure) {
expectLater(tick);
closure.call();
shouldBeAt(tick);
}
/**
* Asserts that the clock is at the given tick.
*
* @param tick The expected clock tick.
*/
public void shouldBeAt(int tick) {
lock.lock();
try {
if (currentTick != getTick(tick)) {
throw new RuntimeException(String.format("Expected clock to be at %s, but is at %s.", tick,
currentTick));
}
} finally {
lock.unlock();
}
}
/**
* Indicates that the current test thread will fail with an exception that matches the given criteria.
*/
public void willFailWith(Matcher matcher) {
expectedFailure.set(matcher);
}
/**
* Executes the given action in another thread, and asserts that the action blocks until all actions provided to
* {@link #expectUnblocks(groovy.lang.Closure)} have been executed.
*
* @param action The action to execute.
*/
public void expectBlocks(Closure action) {
syncPoint.expectBlocks(action);
}
/**
* Executes the given action, asserting that it unblocks all actions provided to {@link
* #expectBlocks(groovy.lang.Closure)}
*
* @param action The action to execute.
*/
public void expectUnblocks(Closure action) {
syncPoint.expectUnblocks(action);
}
private class ExecutorImpl extends AbstractExecutorService {
private final Set threads = new CopyOnWriteArraySet();
@Override
public void execute(Runnable command) {
threads.add(start(command));
}
@Override
public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException {
Date expiry = new Date(System.currentTimeMillis() + unit.toMillis(timeout));
for (ThreadHandle thread : threads) {
if (!thread.waitUntil(expiry)) {
return false;
}
}
return true;
}
@Override
public void shutdown() {
}
@Override
public List shutdownNow() {
return new ArrayList();
}
@Override
public boolean isShutdown() {
throw new UnsupportedOperationException();
}
@Override
public boolean isTerminated() {
throw new UnsupportedOperationException();
}
}
public interface ThreadHandle {
ThreadHandle waitFor();
boolean waitUntil(Date expiry);
boolean isCurrentThread();
void waitUntilBlocked();
}
public interface ClockTick {
ClockTick hasParticipants(int count);
}
private static class ClockTickImpl implements ClockTick {
private final int number;
private int participants;
private ClockTickImpl(int number) {
this.number = number;
}
@Override
public String toString() {
return String.format("tick %d", number);
}
@Override
public ClockTick hasParticipants(int count) {
participants = count;
return this;
}
public boolean allThreadsSynced(Set synching, Set active) {
if (participants > 0) {
return synching.size() == participants;
}
return synching.equals(active) && synching.size() > 1;
}
public boolean isImmediatelyAfter(ClockTickImpl other) {
return number == other.number + 1;
}
}
private enum State {
Idle, Blocking, Blocked, Unblocking, Unblocked, Failed
}
private class SyncPoint {
private final Lock lock = new ReentrantLock();
private final Condition condition = lock.newCondition();
private State state = State.Idle;
private ThreadHandle blockingThread;
public void expectBlocks(Closure action) {
try {
setState(State.Idle, State.Blocking);
setBlockingThread(start(action));
setState(State.Blocking, State.Blocked);
waitForState(State.Unblocked, State.Failed);
} catch (InterruptedException e) {
throw UncheckedException.throwAsUncheckedException(e);
}
}
public void expectUnblocks(Closure action) {
try {
waitForState(State.Blocked);
ThreadHandle thread = getBlockingThread();
if (thread.isCurrentThread()) {
throw new IllegalStateException("The blocking thread cannot unblock itself.");
}
setState(State.Blocked, State.Unblocking);
try {
thread.waitUntilBlocked();
action.call();
boolean completed = thread.waitUntil(new Date(System.currentTimeMillis() + 500L));
if (!completed) {
throw new IllegalStateException("Expected blocking action to unblock, but it did not.");
}
setState(State.Unblocking, State.Unblocked);
} catch (Throwable e) {
setState(State.Unblocking, State.Failed);
throw UncheckedException.throwAsUncheckedException(e);
} finally {
setBlockingThread(null);
}
} catch (InterruptedException e) {
throw UncheckedException.throwAsUncheckedException(e);
}
}
private ThreadHandle getBlockingThread() {
lock.lock();
try {
return blockingThread;
} finally {
lock.unlock();
}
}
private void setBlockingThread(ThreadHandle thread) {
lock.lock();
try {
blockingThread = thread;
} finally {
lock.unlock();
}
}
private State waitForState(State... states) throws InterruptedException {
Date expiry = new Date(System.currentTimeMillis() + 4000L);
Collection expectedStates = Arrays.asList(states);
lock.lock();
try {
while (!expectedStates.contains(state)) {
if (!condition.awaitUntil(expiry)) {
throw new IllegalStateException(String.format("Timeout waiting for one of: %s",
expectedStates));
}
}
return state;
} finally {
lock.unlock();
}
}
private void setState(State expected, State newState) {
lock.lock();
try {
if (state != expected) {
throw new IllegalStateException(String.format("In unexpected state. Expected %s, actual %s",
expected, state));
}
state = newState;
condition.signalAll();
} finally {
lock.unlock();
}
}
}
private class ThreadHandleImpl implements ThreadHandle {
private final Thread thread;
private final Set blockedStates = EnumSet.of(Thread.State.BLOCKED, Thread.State.TIMED_WAITING,
Thread.State.WAITING);
public ThreadHandleImpl(Thread thread) {
this.thread = thread;
}
@Override
public ThreadHandle waitFor() {
Date expiry = new Date(System.currentTimeMillis() + 2 * MAX_WAIT_TIME);
if (!waitUntil(expiry)) {
throw new RuntimeException("timeout waiting for test thread to stop.");
}
return this;
}
@Override
public boolean waitUntil(Date expiry) {
if (isCurrentThread()) {
throw new RuntimeException("A test thread cannot wait for itself to complete.");
}
lock.lock();
try {
while (active.contains(thread)) {
try {
boolean signalled = condition.awaitUntil(expiry);
if (!signalled) {
return false;
}
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
}
} finally {
lock.unlock();
}
return true;
}
@Override
public boolean isCurrentThread() {
return Thread.currentThread() == thread;
}
public boolean isBlocked() {
return blockedStates.contains(thread.getState());
}
@Override
public void waitUntilBlocked() {
long expiry = System.currentTimeMillis() + 2000L;
while (!isBlocked()) {
if (System.currentTimeMillis() > expiry) {
throw new IllegalStateException("Timeout waiting for thread to block.");
}
try {
Thread.sleep(200L);
} catch (InterruptedException e) {
throw UncheckedException.throwAsUncheckedException(e);
}
}
}
}
}
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