m-trieu commented on code in PR #32774: URL: https://github.com/apache/beam/pull/32774#discussion_r1837626505
########## runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/ResettableThrowingStreamObserver.java: ########## @@ -0,0 +1,158 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you 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.apache.beam.runners.dataflow.worker.windmill.client; + +import java.util.function.Supplier; +import javax.annotation.Nullable; +import javax.annotation.concurrent.GuardedBy; +import javax.annotation.concurrent.ThreadSafe; +import org.apache.beam.runners.dataflow.worker.windmill.client.grpc.observers.StreamObserverCancelledException; +import org.apache.beam.runners.dataflow.worker.windmill.client.grpc.observers.TerminatingStreamObserver; +import org.apache.beam.sdk.annotations.Internal; +import org.apache.beam.vendor.grpc.v1p60p1.io.grpc.stub.StreamObserver; +import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Preconditions; +import org.slf4j.Logger; + +/** + * Request observer that allows resetting its internal delegate using the given {@link + * #streamObserverFactory}. + * + * @implNote {@link StreamObserver}s generated by {@link #streamObserverFactory} are expected to be + * {@link ThreadSafe}. Has same methods declared in {@link StreamObserver}, but they throw + * {@link StreamClosedException} and {@link WindmillStreamShutdownException}, which much be + * handled by callers. + */ +@ThreadSafe +@Internal +final class ResettableThrowingStreamObserver<T> { + private final Supplier<TerminatingStreamObserver<T>> streamObserverFactory; + private final Logger logger; + + @GuardedBy("this") + private @Nullable TerminatingStreamObserver<T> delegateStreamObserver; + + @GuardedBy("this") + private boolean isPoisoned = false; + + /** + * Indicates that the current delegate is closed via {@link #poison() or {@link #onCompleted()}}. + * If not poisoned, a call to {@link #reset()} is required to perform future operations on the + * StreamObserver. + */ + @GuardedBy("this") + private boolean isCurrentStreamClosed = false; + + ResettableThrowingStreamObserver( + Supplier<TerminatingStreamObserver<T>> streamObserverFactory, Logger logger) { + this.streamObserverFactory = streamObserverFactory; + this.logger = logger; + this.delegateStreamObserver = null; + } + + private synchronized StreamObserver<T> delegate() + throws WindmillStreamShutdownException, StreamClosedException { + if (isPoisoned) { + throw new WindmillStreamShutdownException("Stream is already shutdown."); + } + + if (isCurrentStreamClosed) { + throw new StreamClosedException( + "Current stream is closed, requires reset for future stream operations."); + } + + return Preconditions.checkNotNull( + delegateStreamObserver, + "requestObserver cannot be null. Missing a call to startStream() to initialize."); + } + + /** Creates a new delegate to use for future {@link StreamObserver} methods. */ + synchronized void reset() throws WindmillStreamShutdownException { + if (isPoisoned) { + throw new WindmillStreamShutdownException("Stream is already shutdown."); + } + + delegateStreamObserver = streamObserverFactory.get(); + isCurrentStreamClosed = false; + } + + /** + * Indicates that the request observer should no longer be used. Attempts to perform operations on + * the request observer will throw an {@link WindmillStreamShutdownException}. + */ + synchronized void poison() { + if (!isPoisoned) { + isPoisoned = true; + if (delegateStreamObserver != null) { + delegateStreamObserver.terminate( + new WindmillStreamShutdownException("Explicit call to shutdown stream.")); + delegateStreamObserver = null; + isCurrentStreamClosed = true; + } + } + } + + public void onNext(T t) throws StreamClosedException, WindmillStreamShutdownException { + // Make sure onNext and onError below to be called on the same StreamObserver instance. + StreamObserver<T> delegate = delegate(); + try { + // Do NOT lock while sending message over the stream as this will block other StreamObserver + // operations. + delegate.onNext(t); + } catch (StreamObserverCancelledException e) { + synchronized (this) { + if (isPoisoned) { + logger.debug("Stream was shutdown during send.", e); + return; + } + } + + try { + delegate.onError(e); + } catch (RuntimeException ignored) { + // If the delegate above was already terminated via onError or onComplete from another + // thread. + logger.warn("StreamObserver was previously cancelled.", e); + } + } + } + + public void onError(Throwable throwable) + throws StreamClosedException, WindmillStreamShutdownException { + delegate().onError(throwable); + } + + public synchronized void onCompleted() Review Comment: done -- This is an automated message from the Apache Git Service. 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