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grpc / grpc-java / #19431

21 Aug 2024 02:16PM CUT coverage: 84.49% (+0.01%) from 84.479%
#19431

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ejona86
core: In PF, remove extraneous index.reset()

The index was just reset by updateGroups().

33394 of 39524 relevant lines covered (84.49%)

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96.1
/../core/src/main/java/io/grpc/internal/DelayedClientTransport.java
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/*
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 * Copyright 2015 The gRPC Authors
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 *
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 * Licensed under the Apache License, Version 2.0 (the "License");
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 * you may not use this file except in compliance with the License.
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 * You may obtain a copy of the License at
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 *
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 *     http://www.apache.org/licenses/LICENSE-2.0
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 *
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 * Unless required by applicable law or agreed to in writing, software
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 * distributed under the License is distributed on an "AS IS" BASIS,
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 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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 * See the License for the specific language governing permissions and
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 * limitations under the License.
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 */
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package io.grpc.internal;
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import com.google.common.annotations.VisibleForTesting;
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import com.google.common.util.concurrent.ListenableFuture;
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import com.google.common.util.concurrent.SettableFuture;
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import io.grpc.CallOptions;
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import io.grpc.ClientStreamTracer;
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import io.grpc.Context;
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import io.grpc.InternalChannelz.SocketStats;
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import io.grpc.InternalLogId;
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import io.grpc.LoadBalancer.PickResult;
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import io.grpc.LoadBalancer.PickSubchannelArgs;
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import io.grpc.LoadBalancer.SubchannelPicker;
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import io.grpc.Metadata;
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import io.grpc.MethodDescriptor;
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import io.grpc.Status;
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import io.grpc.SynchronizationContext;
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import io.grpc.internal.ClientStreamListener.RpcProgress;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.LinkedHashSet;
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import java.util.concurrent.Executor;
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import javax.annotation.Nonnull;
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import javax.annotation.Nullable;
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import javax.annotation.concurrent.GuardedBy;
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/**
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 * A client transport that queues requests before a real transport is available. When {@link
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 * #reprocess} is called, this class applies the provided {@link SubchannelPicker} to pick a
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 * transport for each pending stream.
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 *
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 * <p>This transport owns every stream that it has created until a real transport has been picked
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 * for that stream, at which point the ownership of the stream is transferred to the real transport,
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 * thus the delayed transport stops owning the stream.
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 */
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final class DelayedClientTransport implements ManagedClientTransport {
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  // lazily allocated, since it is infrequently used.
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  private final InternalLogId logId =
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      InternalLogId.allocate(DelayedClientTransport.class, /*details=*/ null);
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  private final Object lock = new Object();
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  private final Executor defaultAppExecutor;
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  private final SynchronizationContext syncContext;
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  private Runnable reportTransportInUse;
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  private Runnable reportTransportNotInUse;
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  private Runnable reportTransportTerminated;
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  private Listener listener;
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  @Nonnull
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  @GuardedBy("lock")
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  private Collection<PendingStream> pendingStreams = new LinkedHashSet<>();
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  /** Immutable state needed for picking. 'lock' must be held for writing. */
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  private volatile PickerState pickerState = new PickerState(null, null);
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  /**
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   * Creates a new delayed transport.
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   *
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   * @param defaultAppExecutor pending streams will create real streams and run buffered operations
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   *        in an application executor, which will be this executor, unless there is on provided in
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   *        {@link CallOptions}.
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   * @param syncContext all listener callbacks of the delayed transport will be run from this
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   *        SynchronizationContext.
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   */
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  DelayedClientTransport(Executor defaultAppExecutor, SynchronizationContext syncContext) {
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    this.defaultAppExecutor = defaultAppExecutor;
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    this.syncContext = syncContext;
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  }
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  @Override
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  public final Runnable start(final Listener listener) {
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    this.listener = listener;
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    reportTransportInUse = new Runnable() {
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        @Override
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        public void run() {
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          listener.transportInUse(true);
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        }
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      };
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    reportTransportNotInUse = new Runnable() {
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        @Override
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        public void run() {
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          listener.transportInUse(false);
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        }
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      };
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    reportTransportTerminated = new Runnable() {
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        @Override
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        public void run() {
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          listener.transportTerminated();
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        }
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      };
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    return null;
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  }
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  /**
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   * If a {@link SubchannelPicker} is being, or has been provided via {@link #reprocess}, the last
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   * picker will be consulted.
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   *
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   * <p>Otherwise, if the delayed transport is not shutdown, then a {@link PendingStream} is
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   * returned; if the transport is shutdown, then a {@link FailingClientStream} is returned.
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   */
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  @Override
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  public final ClientStream newStream(
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      MethodDescriptor<?, ?> method, Metadata headers, CallOptions callOptions,
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      ClientStreamTracer[] tracers) {
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    try {
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      PickSubchannelArgs args = new PickSubchannelArgsImpl(
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          method, headers, callOptions, new PickDetailsConsumerImpl(tracers));
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      PickerState state = pickerState;
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      while (true) {
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        if (state.shutdownStatus != null) {
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          return new FailingClientStream(state.shutdownStatus, tracers);
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        }
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        if (state.lastPicker != null) {
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          PickResult pickResult = state.lastPicker.pickSubchannel(args);
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          ClientTransport transport = GrpcUtil.getTransportFromPickResult(pickResult,
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              callOptions.isWaitForReady());
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          if (transport != null) {
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            return transport.newStream(
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                args.getMethodDescriptor(), args.getHeaders(), args.getCallOptions(),
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                tracers);
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          }
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        }
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        // This picker's conclusion is "buffer".  If there hasn't been a newer picker set (possible
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        // race with reprocess()), we will buffer the RPC.  Otherwise, will try with the new picker.
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        synchronized (lock) {
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          PickerState newerState = pickerState;
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          if (state == newerState) {
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            return createPendingStream(args, tracers);
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          }
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          state = newerState;
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        }
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      }
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    } finally {
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      syncContext.drain();
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    }
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  }
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  /**
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   * Caller must call {@code syncContext.drain()} outside of lock because this method may
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   * schedule tasks on syncContext.
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   */
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  @GuardedBy("lock")
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  private PendingStream createPendingStream(
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      PickSubchannelArgs args, ClientStreamTracer[] tracers) {
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    PendingStream pendingStream = new PendingStream(args, tracers);
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    pendingStreams.add(pendingStream);
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    if (getPendingStreamsCount() == 1) {
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      syncContext.executeLater(reportTransportInUse);
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    }
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    for (ClientStreamTracer streamTracer : tracers) {
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      streamTracer.createPendingStream();
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    }
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    return pendingStream;
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  }
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  @Override
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  public final void ping(final PingCallback callback, Executor executor) {
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    throw new UnsupportedOperationException("This method is not expected to be called");
×
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  }
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  @Override
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  public ListenableFuture<SocketStats> getStats() {
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    SettableFuture<SocketStats> ret = SettableFuture.create();
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    ret.set(null);
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    return ret;
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  }
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  /**
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   * Prevents creating any new streams.  Buffered streams are not failed and may still proceed
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   * when {@link #reprocess} is called.  The delayed transport will be terminated when there is no
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   * more buffered streams.
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   */
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  @Override
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  public final void shutdown(final Status status) {
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    synchronized (lock) {
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      if (pickerState.shutdownStatus != null) {
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        return;
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      }
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      pickerState = pickerState.withShutdownStatus(status);
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      syncContext.executeLater(new Runnable() {
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          @Override
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          public void run() {
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            listener.transportShutdown(status);
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          }
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        });
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      if (!hasPendingStreams() && reportTransportTerminated != null) {
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        syncContext.executeLater(reportTransportTerminated);
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        reportTransportTerminated = null;
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      }
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    }
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    syncContext.drain();
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  }
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  /**
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   * Shuts down this transport and cancels all streams that it owns, hence immediately terminates
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   * this transport.
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   */
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  @Override
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  public final void shutdownNow(Status status) {
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    shutdown(status);
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    Collection<PendingStream> savedPendingStreams;
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    Runnable savedReportTransportTerminated;
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    synchronized (lock) {
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      savedPendingStreams = pendingStreams;
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      savedReportTransportTerminated = reportTransportTerminated;
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      reportTransportTerminated = null;
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      if (!pendingStreams.isEmpty()) {
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        pendingStreams = Collections.emptyList();
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      }
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    }
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    if (savedReportTransportTerminated != null) {
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      for (PendingStream stream : savedPendingStreams) {
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        Runnable runnable = stream.setStream(
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            new FailingClientStream(status, RpcProgress.REFUSED, stream.tracers));
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        if (runnable != null) {
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          // Drain in-line instead of using an executor as failing stream just throws everything
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          // away. This is essentially the same behavior as DelayedStream.cancel() but can be done
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          // before stream.start().
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          runnable.run();
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        }
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      }
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      syncContext.execute(savedReportTransportTerminated);
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    }
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    // If savedReportTransportTerminated == null, transportTerminated() has already been called in
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    // shutdown().
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  }
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  public final boolean hasPendingStreams() {
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    synchronized (lock) {
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      return !pendingStreams.isEmpty();
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    }
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  }
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  @VisibleForTesting
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  final int getPendingStreamsCount() {
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    synchronized (lock) {
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      return pendingStreams.size();
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    }
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  }
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  /**
261
   * Use the picker to try picking a transport for every pending stream, proceed the stream if the
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   * pick is successful, otherwise keep it pending.
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   *
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   * <p>This method may be called concurrently with {@code newStream()}, and it's safe.  All pending
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   * streams will be served by the latest picker (if a same picker is given more than once, they are
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   * considered different pickers) as soon as possible.
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   *
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   * <p>This method <strong>must not</strong> be called concurrently with itself.
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   */
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  final void reprocess(@Nullable SubchannelPicker picker) {
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    ArrayList<PendingStream> toProcess;
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    synchronized (lock) {
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      pickerState = pickerState.withPicker(picker);
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      if (picker == null || !hasPendingStreams()) {
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        return;
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      }
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      toProcess = new ArrayList<>(pendingStreams);
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    }
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    ArrayList<PendingStream> toRemove = new ArrayList<>();
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    for (final PendingStream stream : toProcess) {
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      PickResult pickResult = picker.pickSubchannel(stream.args);
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      CallOptions callOptions = stream.args.getCallOptions();
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      final ClientTransport transport = GrpcUtil.getTransportFromPickResult(pickResult,
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          callOptions.isWaitForReady());
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      if (transport != null) {
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        Executor executor = defaultAppExecutor;
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        // createRealStream may be expensive. It will start real streams on the transport. If
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        // there are pending requests, they will be serialized too, which may be expensive. Since
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        // we are now on transport thread, we need to offload the work to an executor.
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        if (callOptions.getExecutor() != null) {
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          executor = callOptions.getExecutor();
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        }
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        Runnable runnable = stream.createRealStream(transport);
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        if (runnable != null) {
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          executor.execute(runnable);
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        }
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        toRemove.add(stream);
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      }  // else: stay pending
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    }
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    synchronized (lock) {
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      // Between this synchronized and the previous one:
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      //   - Streams may have been cancelled, which may turn pendingStreams into emptiness.
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      //   - shutdown() may be called, which may turn pendingStreams into null.
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      if (!hasPendingStreams()) {
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        return;
×
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      }
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      pendingStreams.removeAll(toRemove);
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      // Because delayed transport is long-lived, we take this opportunity to down-size the
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      // hashmap.
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      if (pendingStreams.isEmpty()) {
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        pendingStreams = new LinkedHashSet<>();
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      }
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      if (!hasPendingStreams()) {
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        // There may be a brief gap between delayed transport clearing in-use state, and first real
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        // transport starting streams and setting in-use state.  During the gap the whole channel's
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        // in-use state may be false. However, it shouldn't cause spurious switching to idleness
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        // (which would shutdown the transports and LoadBalancer) because the gap should be shorter
320
        // than IDLE_MODE_DEFAULT_TIMEOUT_MILLIS (1 second).
321
        syncContext.executeLater(reportTransportNotInUse);
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        if (pickerState.shutdownStatus != null && reportTransportTerminated != null) {
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          syncContext.executeLater(reportTransportTerminated);
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          reportTransportTerminated = null;
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        }
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      }
327
    }
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    syncContext.drain();
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  }
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331
  @Override
332
  public InternalLogId getLogId() {
333
    return logId;
×
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  }
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336
  private class PendingStream extends DelayedStream {
337
    private final PickSubchannelArgs args;
338
    private final Context context = Context.current();
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    private final ClientStreamTracer[] tracers;
340

341
    private PendingStream(PickSubchannelArgs args, ClientStreamTracer[] tracers) {
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      this.args = args;
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      this.tracers = tracers;
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    }
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346
    /** Runnable may be null. */
347
    private Runnable createRealStream(ClientTransport transport) {
348
      ClientStream realStream;
349
      Context origContext = context.attach();
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      try {
351
        realStream = transport.newStream(
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            args.getMethodDescriptor(), args.getHeaders(), args.getCallOptions(),
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            tracers);
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      } finally {
355
        context.detach(origContext);
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      }
357
      return setStream(realStream);
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    }
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360
    @Override
361
    public void cancel(Status reason) {
362
      super.cancel(reason);
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      synchronized (lock) {
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        if (reportTransportTerminated != null) {
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          boolean justRemovedAnElement = pendingStreams.remove(this);
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          if (!hasPendingStreams() && justRemovedAnElement) {
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            syncContext.executeLater(reportTransportNotInUse);
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            if (pickerState.shutdownStatus != null) {
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              syncContext.executeLater(reportTransportTerminated);
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              reportTransportTerminated = null;
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            }
372
          }
373
        }
374
      }
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      syncContext.drain();
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    }
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378
    @Override
379
    protected void onEarlyCancellation(Status reason) {
380
      for (ClientStreamTracer tracer : tracers) {
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        tracer.streamClosed(reason);
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      }
383
    }
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385
    @Override
386
    public void appendTimeoutInsight(InsightBuilder insight) {
387
      if (args.getCallOptions().isWaitForReady()) {
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        insight.append("wait_for_ready");
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      }
390
      super.appendTimeoutInsight(insight);
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391
    }
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392
  }
393

394
  static final class PickerState {
395
    /**
396
     * The last picker that {@link #reprocess} has used. May be set to null when the channel has
397
     * moved to idle.
398
     */
399
    @Nullable
400
    final SubchannelPicker lastPicker;
401
    /**
402
     * When {@code shutdownStatus != null && !hasPendingStreams()}, then the transport is considered
403
     * terminated.
404
     */
405
    @Nullable
406
    final Status shutdownStatus;
407

408
    private PickerState(SubchannelPicker lastPicker, Status shutdownStatus) {
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409
      this.lastPicker = lastPicker;
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410
      this.shutdownStatus = shutdownStatus;
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411
    }
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413
    public PickerState withPicker(SubchannelPicker newPicker) {
414
      return new PickerState(newPicker, this.shutdownStatus);
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415
    }
416

417
    public PickerState withShutdownStatus(Status newShutdownStatus) {
418
      return new PickerState(this.lastPicker, newShutdownStatus);
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419
    }
420
  }
421
}
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