Java tutorial
/* * Copyright 2018 The gRPC 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 io.grpc.testing; import static com.google.common.base.Preconditions.checkArgument; import static com.google.common.base.Preconditions.checkNotNull; import com.google.common.annotations.VisibleForTesting; import com.google.common.base.Stopwatch; import com.google.common.base.Ticker; import io.grpc.ExperimentalApi; import io.grpc.ManagedChannel; import io.grpc.Server; import java.util.ArrayList; import java.util.Arrays; import java.util.List; import java.util.concurrent.TimeUnit; import javax.annotation.Nonnull; import javax.annotation.concurrent.NotThreadSafe; import org.junit.rules.TestRule; import org.junit.runner.Description; import org.junit.runners.model.MultipleFailureException; import org.junit.runners.model.Statement; /** * A JUnit {@link TestRule} that can register gRPC resources and manages its automatic release at * the end of the test. If any of the resources registered to the rule can not be successfully * released, the test will fail. * * @since 1.13.0 */ @ExperimentalApi("https://github.com/grpc/grpc-java/issues/2488") @NotThreadSafe public final class GrpcCleanupRule implements TestRule { private final List<Resource> resources = new ArrayList<>(); private long timeoutNanos = TimeUnit.SECONDS.toNanos(10L); private Stopwatch stopwatch = Stopwatch.createUnstarted(); private Throwable firstException; /** * Sets a positive total time limit for the automatic resource cleanup. If any of the resources * registered to the rule fails to be released in time, the test will fail. * * <p>Note that the resource cleanup duration may or may not be counted as part of the JUnit * {@link org.junit.rules.Timeout Timeout} rule's test duration, depending on which rule is * applied first. * * @return this */ public GrpcCleanupRule setTimeout(long timeout, TimeUnit timeUnit) { checkArgument(timeout > 0, "timeout should be positive"); timeoutNanos = timeUnit.toNanos(timeout); return this; } /** * Sets a specified time source for monitoring cleanup timeout. * * @return this */ @SuppressWarnings("BetaApi") // Test only. @VisibleForTesting GrpcCleanupRule setTicker(Ticker ticker) { this.stopwatch = Stopwatch.createUnstarted(ticker); return this; } /** * Registers the given channel to the rule. Once registered, the channel will be automatically * shutdown at the end of the test. * * <p>This method need be properly synchronized if used in multiple threads. This method must * not be used during the test teardown. * * @return the input channel */ public <T extends ManagedChannel> T register(@Nonnull T channel) { checkNotNull(channel, "channel"); register(new ManagedChannelResource(channel)); return channel; } /** * Registers the given server to the rule. Once registered, the server will be automatically * shutdown at the end of the test. * * <p>This method need be properly synchronized if used in multiple threads. This method must * not be used during the test teardown. * * @return the input server */ public <T extends Server> T register(@Nonnull T server) { checkNotNull(server, "server"); register(new ServerResource(server)); return server; } @VisibleForTesting void register(Resource resource) { resources.add(resource); } @Override public Statement apply(final Statement base, Description description) { return new Statement() { @Override public void evaluate() throws Throwable { try { base.evaluate(); } catch (Throwable t) { firstException = t; try { teardown(); } catch (Throwable t2) { throw new MultipleFailureException(Arrays.asList(t, t2)); } throw t; } teardown(); if (firstException != null) { throw firstException; } } }; } /** * Releases all the registered resources. */ private void teardown() { stopwatch.start(); if (firstException == null) { for (int i = resources.size() - 1; i >= 0; i--) { resources.get(i).cleanUp(); } } for (int i = resources.size() - 1; i >= 0; i--) { if (firstException != null) { resources.get(i).forceCleanUp(); continue; } try { boolean released = resources.get(i).awaitReleased( timeoutNanos - stopwatch.elapsed(TimeUnit.NANOSECONDS), TimeUnit.NANOSECONDS); if (!released) { firstException = new AssertionError( "Resource " + resources.get(i) + " can not be released in time at the end of test"); } } catch (InterruptedException e) { Thread.currentThread().interrupt(); firstException = e; } if (firstException != null) { resources.get(i).forceCleanUp(); } } resources.clear(); } @VisibleForTesting interface Resource { void cleanUp(); /** * Error already happened, try the best to clean up. Never throws. */ void forceCleanUp(); /** * Returns true if the resource is released in time. */ boolean awaitReleased(long duration, TimeUnit timeUnit) throws InterruptedException; } private static final class ManagedChannelResource implements Resource { final ManagedChannel channel; ManagedChannelResource(ManagedChannel channel) { this.channel = channel; } @Override public void cleanUp() { channel.shutdown(); } @Override public void forceCleanUp() { channel.shutdownNow(); } @Override public boolean awaitReleased(long duration, TimeUnit timeUnit) throws InterruptedException { return channel.awaitTermination(duration, timeUnit); } @Override public String toString() { return channel.toString(); } } private static final class ServerResource implements Resource { final Server server; ServerResource(Server server) { this.server = server; } @Override public void cleanUp() { server.shutdown(); } @Override public void forceCleanUp() { server.shutdownNow(); } @Override public boolean awaitReleased(long duration, TimeUnit timeUnit) throws InterruptedException { return server.awaitTermination(duration, timeUnit); } @Override public String toString() { return server.toString(); } } }