#19310

Committed 25 Jun 2024 06:39PM CUT coverage: 88.417% (-0.04%) from 88.456%

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Start 1.64.2 development cycle (#11319)

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/../core/src/main/java/io/grpc/internal/DelayedClientTransport.java

/*
 * Copyright 2015 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.internal;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import io.grpc.CallOptions;
import io.grpc.ClientStreamTracer;
import io.grpc.Context;
import io.grpc.InternalChannelz.SocketStats;
import io.grpc.InternalLogId;
import io.grpc.LoadBalancer.PickResult;
import io.grpc.LoadBalancer.PickSubchannelArgs;
import io.grpc.LoadBalancer.SubchannelPicker;
import io.grpc.Metadata;
import io.grpc.MethodDescriptor;
import io.grpc.Status;
import io.grpc.SynchronizationContext;
import io.grpc.internal.ClientStreamListener.RpcProgress;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.concurrent.Executor;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.GuardedBy;

/**
 * A client transport that queues requests before a real transport is available. When {@link
 * #reprocess} is called, this class applies the provided {@link SubchannelPicker} to pick a
 * transport for each pending stream.
 *
 * <p>This transport owns every stream that it has created until a real transport has been picked
 * for that stream, at which point the ownership of the stream is transferred to the real transport,
 * thus the delayed transport stops owning the stream.
 */
final class DelayedClientTransport implements ManagedClientTransport {
  // lazily allocated, since it is infrequently used.
  private final InternalLogId logId =
      InternalLogId.allocate(DelayedClientTransport.class, /*details=*/ null);

  private final Object lock = new Object();

  private final Executor defaultAppExecutor;
  private final SynchronizationContext syncContext;

  private Runnable reportTransportInUse;
  private Runnable reportTransportNotInUse;
  private Runnable reportTransportTerminated;
  private Listener listener;

  @Nonnull
  @GuardedBy("lock")
  private Collection<PendingStream> pendingStreams = new LinkedHashSet<>();

  /**
   * When {@code shutdownStatus != null && !hasPendingStreams()}, then the transport is considered
   * terminated.
   */
  @GuardedBy("lock")
  private Status shutdownStatus;

  /**
   * The last picker that {@link #reprocess} has used. May be set to null when the channel has moved
   * to idle.
   */
  @GuardedBy("lock")
  @Nullable
  private SubchannelPicker lastPicker;

  @GuardedBy("lock")
  private long lastPickerVersion;

  /**
   * Creates a new delayed transport.
   *
   * @param defaultAppExecutor pending streams will create real streams and run bufferred operations
   *        in an application executor, which will be this executor, unless there is on provided in
   *        {@link CallOptions}.
   * @param syncContext all listener callbacks of the delayed transport will be run from this
   *        SynchronizationContext.
   */
  DelayedClientTransport(Executor defaultAppExecutor, SynchronizationContext syncContext) {
    this.defaultAppExecutor = defaultAppExecutor;
    this.syncContext = syncContext;
  }

  @Override
  public final Runnable start(final Listener listener) {
    this.listener = listener;
    reportTransportInUse = new Runnable() {
        @Override
        public void run() {
          listener.transportInUse(true);
        }
      };
    reportTransportNotInUse = new Runnable() {
        @Override
        public void run() {
          listener.transportInUse(false);
        }
      };
    reportTransportTerminated = new Runnable() {
        @Override
        public void run() {
          listener.transportTerminated();
        }
      };
    return null;
  }

  /**
   * If a {@link SubchannelPicker} is being, or has been provided via {@link #reprocess}, the last
   * picker will be consulted.
   *
   * <p>Otherwise, if the delayed transport is not shutdown, then a {@link PendingStream} is
   * returned; if the transport is shutdown, then a {@link FailingClientStream} is returned.
   */
  @Override
  public final ClientStream newStream(
      MethodDescriptor<?, ?> method, Metadata headers, CallOptions callOptions,
      ClientStreamTracer[] tracers) {
    try {
      PickSubchannelArgs args = new PickSubchannelArgsImpl(
          method, headers, callOptions, new PickDetailsConsumerImpl(tracers));
      SubchannelPicker picker = null;
      long pickerVersion = -1;
      while (true) {
        synchronized (lock) {
          if (shutdownStatus != null) {
            return new FailingClientStream(shutdownStatus, tracers);
          }
          if (lastPicker == null) {
            return createPendingStream(args, tracers);
          }
          // Check for second time through the loop, and whether anything changed
          if (picker != null && pickerVersion == lastPickerVersion) {
            return createPendingStream(args, tracers);
          }
          picker = lastPicker;
          pickerVersion = lastPickerVersion;
        }
        PickResult pickResult = picker.pickSubchannel(args);
        ClientTransport transport = GrpcUtil.getTransportFromPickResult(pickResult,
            callOptions.isWaitForReady());
        if (transport != null) {
          return transport.newStream(
              args.getMethodDescriptor(), args.getHeaders(), args.getCallOptions(),
              tracers);
        }
        // This picker's conclusion is "buffer".  If there hasn't been a newer picker set (possible
        // race with reprocess()), we will buffer it.  Otherwise, will try with the new picker.
      }
    } finally {
      syncContext.drain();
    }
  }

  /**
   * Caller must call {@code syncContext.drain()} outside of lock because this method may
   * schedule tasks on syncContext.
   */
  @GuardedBy("lock")
  private PendingStream createPendingStream(
      PickSubchannelArgs args, ClientStreamTracer[] tracers) {
    PendingStream pendingStream = new PendingStream(args, tracers);
    pendingStreams.add(pendingStream);
    if (getPendingStreamsCount() == 1) {
      syncContext.executeLater(reportTransportInUse);
    }
    for (ClientStreamTracer streamTracer : tracers) {
      streamTracer.createPendingStream();
    }
    return pendingStream;
  }

  @Override
  public final void ping(final PingCallback callback, Executor executor) {
    throw new UnsupportedOperationException("This method is not expected to be called");
  }

  @Override
  public ListenableFuture<SocketStats> getStats() {
    SettableFuture<SocketStats> ret = SettableFuture.create();
    ret.set(null);
    return ret;
  }

  /**
   * Prevents creating any new streams.  Buffered streams are not failed and may still proceed
   * when {@link #reprocess} is called.  The delayed transport will be terminated when there is no
   * more buffered streams.
   */
  @Override
  public final void shutdown(final Status status) {
    synchronized (lock) {
      if (shutdownStatus != null) {
        return;
      }
      shutdownStatus = status;
      syncContext.executeLater(new Runnable() {
          @Override
          public void run() {
            listener.transportShutdown(status);
          }
        });
      if (!hasPendingStreams() && reportTransportTerminated != null) {
        syncContext.executeLater(reportTransportTerminated);
        reportTransportTerminated = null;
      }
    }
    syncContext.drain();
  }

  /**
   * Shuts down this transport and cancels all streams that it owns, hence immediately terminates
   * this transport.
   */
  @Override
  public final void shutdownNow(Status status) {
    shutdown(status);
    Collection<PendingStream> savedPendingStreams;
    Runnable savedReportTransportTerminated;
    synchronized (lock) {
      savedPendingStreams = pendingStreams;
      savedReportTransportTerminated = reportTransportTerminated;
      reportTransportTerminated = null;
      if (!pendingStreams.isEmpty()) {
        pendingStreams = Collections.emptyList();
      }
    }
    if (savedReportTransportTerminated != null) {
      for (PendingStream stream : savedPendingStreams) {
        Runnable runnable = stream.setStream(
            new FailingClientStream(status, RpcProgress.REFUSED, stream.tracers));
        if (runnable != null) {
          // Drain in-line instead of using an executor as failing stream just throws everything
          // away. This is essentially the same behavior as DelayedStream.cancel() but can be done
          // before stream.start().
          runnable.run();
        }
      }
      syncContext.execute(savedReportTransportTerminated);
    }
    // If savedReportTransportTerminated == null, transportTerminated() has already been called in
    // shutdown().
  }

  public final boolean hasPendingStreams() {
    synchronized (lock) {
      return !pendingStreams.isEmpty();
    }
  }

  @VisibleForTesting
  final int getPendingStreamsCount() {
    synchronized (lock) {
      return pendingStreams.size();
    }
  }

  /**
   * Use the picker to try picking a transport for every pending stream, proceed the stream if the
   * pick is successful, otherwise keep it pending.
   *
   * <p>This method may be called concurrently with {@code newStream()}, and it's safe.  All pending
   * streams will be served by the latest picker (if a same picker is given more than once, they are
   * considered different pickers) as soon as possible.
   *
   * <p>This method <strong>must not</strong> be called concurrently with itself.
   */
  final void reprocess(@Nullable SubchannelPicker picker) {
    ArrayList<PendingStream> toProcess;
    synchronized (lock) {
      lastPicker = picker;
      lastPickerVersion++;
      if (picker == null || !hasPendingStreams()) {
        return;
      }
      toProcess = new ArrayList<>(pendingStreams);
    }
    ArrayList<PendingStream> toRemove = new ArrayList<>();

    for (final PendingStream stream : toProcess) {
      PickResult pickResult = picker.pickSubchannel(stream.args);
      CallOptions callOptions = stream.args.getCallOptions();
      final ClientTransport transport = GrpcUtil.getTransportFromPickResult(pickResult,
          callOptions.isWaitForReady());
      if (transport != null) {
        Executor executor = defaultAppExecutor;
        // createRealStream may be expensive. It will start real streams on the transport. If
        // there are pending requests, they will be serialized too, which may be expensive. Since
        // we are now on transport thread, we need to offload the work to an executor.
        if (callOptions.getExecutor() != null) {
          executor = callOptions.getExecutor();
        }
        Runnable runnable = stream.createRealStream(transport);
        if (runnable != null) {
          executor.execute(runnable);
        }
        toRemove.add(stream);
      }  // else: stay pending
    }

    synchronized (lock) {
      // Between this synchronized and the previous one:
      //   - Streams may have been cancelled, which may turn pendingStreams into emptiness.
      //   - shutdown() may be called, which may turn pendingStreams into null.
      if (!hasPendingStreams()) {
        return;
      }
      pendingStreams.removeAll(toRemove);
      // Because delayed transport is long-lived, we take this opportunity to down-size the
      // hashmap.
      if (pendingStreams.isEmpty()) {
        pendingStreams = new LinkedHashSet<>();
      }
      if (!hasPendingStreams()) {
        // There may be a brief gap between delayed transport clearing in-use state, and first real
        // transport starting streams and setting in-use state.  During the gap the whole channel's
        // in-use state may be false. However, it shouldn't cause spurious switching to idleness
        // (which would shutdown the transports and LoadBalancer) because the gap should be shorter
        // than IDLE_MODE_DEFAULT_TIMEOUT_MILLIS (1 second).
        syncContext.executeLater(reportTransportNotInUse);
        if (shutdownStatus != null && reportTransportTerminated != null) {
          syncContext.executeLater(reportTransportTerminated);
          reportTransportTerminated = null;
        }
      }
    }
    syncContext.drain();
  }

  @Override
  public InternalLogId getLogId() {
    return logId;
  }

  private class PendingStream extends DelayedStream {
    private final PickSubchannelArgs args;
    private final Context context = Context.current();
    private final ClientStreamTracer[] tracers;

    private PendingStream(PickSubchannelArgs args, ClientStreamTracer[] tracers) {
      this.args = args;
      this.tracers = tracers;
    }

    /** Runnable may be null. */
    private Runnable createRealStream(ClientTransport transport) {
      ClientStream realStream;
      Context origContext = context.attach();
      try {
        realStream = transport.newStream(
            args.getMethodDescriptor(), args.getHeaders(), args.getCallOptions(),
            tracers);
      } finally {
        context.detach(origContext);
      }
      return setStream(realStream);
    }

    @Override
    public void cancel(Status reason) {
      super.cancel(reason);
      synchronized (lock) {
        if (reportTransportTerminated != null) {
          boolean justRemovedAnElement = pendingStreams.remove(this);
          if (!hasPendingStreams() && justRemovedAnElement) {
            syncContext.executeLater(reportTransportNotInUse);
            if (shutdownStatus != null) {
              syncContext.executeLater(reportTransportTerminated);
              reportTransportTerminated = null;
            }
          }
        }
      }
      syncContext.drain();
    }

    @Override
    protected void onEarlyCancellation(Status reason) {
      for (ClientStreamTracer tracer : tracers) {
        tracer.streamClosed(reason);
      }
    }

    @Override
    public void appendTimeoutInsight(InsightBuilder insight) {
      if (args.getCallOptions().isWaitForReady()) {
        insight.append("wait_for_ready");
      }
      super.appendTimeoutInsight(insight);
    }
  }
}

1	/*
2	* Copyright 2015 The gRPC Authors
3	*
4	* Licensed under the Apache License, Version 2.0 (the "License");
5	* you may not use this file except in compliance with the License.
6	* You may obtain a copy of the License at
7	*
8	* http://www.apache.org/licenses/LICENSE-2.0
9	*
10	* Unless required by applicable law or agreed to in writing, software
11	* distributed under the License is distributed on an "AS IS" BASIS,
12	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13	* See the License for the specific language governing permissions and
14	* limitations under the License.
15	*/
16
17	package io.grpc.internal;
18
19	import com.google.common.annotations.VisibleForTesting;
20	import com.google.common.util.concurrent.ListenableFuture;
21	import com.google.common.util.concurrent.SettableFuture;
22	import io.grpc.CallOptions;
23	import io.grpc.ClientStreamTracer;
24	import io.grpc.Context;
25	import io.grpc.InternalChannelz.SocketStats;
26	import io.grpc.InternalLogId;
27	import io.grpc.LoadBalancer.PickResult;
28	import io.grpc.LoadBalancer.PickSubchannelArgs;
29	import io.grpc.LoadBalancer.SubchannelPicker;
30	import io.grpc.Metadata;
31	import io.grpc.MethodDescriptor;
32	import io.grpc.Status;
33	import io.grpc.SynchronizationContext;
34	import io.grpc.internal.ClientStreamListener.RpcProgress;
35	import java.util.ArrayList;
36	import java.util.Collection;
37	import java.util.Collections;
38	import java.util.LinkedHashSet;
39	import java.util.concurrent.Executor;
40	import javax.annotation.Nonnull;
41	import javax.annotation.Nullable;
42	import javax.annotation.concurrent.GuardedBy;
43
44	/**
45	* A client transport that queues requests before a real transport is available. When {@link
46	* #reprocess} is called, this class applies the provided {@link SubchannelPicker} to pick a
47	* transport for each pending stream.
48	*
49	* <p>This transport owns every stream that it has created until a real transport has been picked
50	* for that stream, at which point the ownership of the stream is transferred to the real transport,
51	* thus the delayed transport stops owning the stream.
52	*/
53	final class DelayedClientTransport implements ManagedClientTransport {
54	// lazily allocated, since it is infrequently used.
55	private final InternalLogId logId =	1✔
56	InternalLogId.allocate(DelayedClientTransport.class, /details=/ null);	1✔
57
58	private final Object lock = new Object();	1✔
59
60	private final Executor defaultAppExecutor;
61	private final SynchronizationContext syncContext;
62
63	private Runnable reportTransportInUse;
64	private Runnable reportTransportNotInUse;
65	private Runnable reportTransportTerminated;
66	private Listener listener;
67
68	@Nonnull	1✔
69	@GuardedBy("lock")
70	private Collection<PendingStream> pendingStreams = new LinkedHashSet<>();
71
72	/**
73	* When {@code shutdownStatus != null && !hasPendingStreams()}, then the transport is considered
74	* terminated.
75	*/
76	@GuardedBy("lock")
77	private Status shutdownStatus;
78
79	/**
80	* The last picker that {@link #reprocess} has used. May be set to null when the channel has moved
81	* to idle.
82	*/
83	@GuardedBy("lock")
84	@Nullable
85	private SubchannelPicker lastPicker;
86
87	@GuardedBy("lock")
88	private long lastPickerVersion;
89
90	/**
91	* Creates a new delayed transport.
92	*
93	* @param defaultAppExecutor pending streams will create real streams and run bufferred operations
94	* in an application executor, which will be this executor, unless there is on provided in
95	* {@link CallOptions}.
96	* @param syncContext all listener callbacks of the delayed transport will be run from this
97	* SynchronizationContext.
98	*/
99	DelayedClientTransport(Executor defaultAppExecutor, SynchronizationContext syncContext) {	1✔
100	this.defaultAppExecutor = defaultAppExecutor;	1✔
101	this.syncContext = syncContext;	1✔
102	}	1✔
103
104	@Override
105	public final Runnable start(final Listener listener) {
106	this.listener = listener;	1✔
107	reportTransportInUse = new Runnable() {	1✔
108	@Override
109	public void run() {
110	listener.transportInUse(true);	1✔
111	}	1✔
112	};
113	reportTransportNotInUse = new Runnable() {	1✔
114	@Override
115	public void run() {
116	listener.transportInUse(false);	1✔
117	}	1✔
118	};
119	reportTransportTerminated = new Runnable() {	1✔
120	@Override
121	public void run() {
122	listener.transportTerminated();	1✔
123	}	1✔
124	};
125	return null;	1✔
126	}
127
128	/**
129	* If a {@link SubchannelPicker} is being, or has been provided via {@link #reprocess}, the last
130	* picker will be consulted.
131	*
132	* <p>Otherwise, if the delayed transport is not shutdown, then a {@link PendingStream} is
133	* returned; if the transport is shutdown, then a {@link FailingClientStream} is returned.
134	*/
135	@Override
136	public final ClientStream newStream(
137	MethodDescriptor<?, ?> method, Metadata headers, CallOptions callOptions,
138	ClientStreamTracer[] tracers) {
139	try {
140	PickSubchannelArgs args = new PickSubchannelArgsImpl(	1✔
141	method, headers, callOptions, new PickDetailsConsumerImpl(tracers));
142	SubchannelPicker picker = null;	1✔
143	long pickerVersion = -1;	1✔
144	while (true) {
145	synchronized (lock) {	1✔
146	if (shutdownStatus != null) {	1✔
147	return new FailingClientStream(shutdownStatus, tracers);	1✔
148	}
149	if (lastPicker == null) {	1✔
150	return createPendingStream(args, tracers);	1✔
151	}
152	// Check for second time through the loop, and whether anything changed
153	if (picker != null && pickerVersion == lastPickerVersion) {	1✔
154	return createPendingStream(args, tracers);	1✔
155	}
156	picker = lastPicker;	1✔
157	pickerVersion = lastPickerVersion;	1✔
158	}	1✔
159	PickResult pickResult = picker.pickSubchannel(args);	1✔
160	ClientTransport transport = GrpcUtil.getTransportFromPickResult(pickResult,	1✔
161	callOptions.isWaitForReady());	1✔
162	if (transport != null) {	1✔
163	return transport.newStream(	1✔
164	args.getMethodDescriptor(), args.getHeaders(), args.getCallOptions(),	1✔
165	tracers);
166	}
167	// This picker's conclusion is "buffer". If there hasn't been a newer picker set (possible
168	// race with reprocess()), we will buffer it. Otherwise, will try with the new picker.
169	}	1✔
170	} finally {
171	syncContext.drain();	1✔
172	}
173	}
174
175	/**
176	* Caller must call {@code syncContext.drain()} outside of lock because this method may
177	* schedule tasks on syncContext.
178	*/
179	@GuardedBy("lock")
180	private PendingStream createPendingStream(
181	PickSubchannelArgs args, ClientStreamTracer[] tracers) {
182	PendingStream pendingStream = new PendingStream(args, tracers);	1✔
183	pendingStreams.add(pendingStream);	1✔
184	if (getPendingStreamsCount() == 1) {	1✔
185	syncContext.executeLater(reportTransportInUse);	1✔
186	}
187	for (ClientStreamTracer streamTracer : tracers) {	1✔
188	streamTracer.createPendingStream();	1✔
189	}
190	return pendingStream;	1✔
191	}
192
193	@Override
194	public final void ping(final PingCallback callback, Executor executor) {
195	throw new UnsupportedOperationException("This method is not expected to be called");	×
196	}
197
198	@Override
199	public ListenableFuture<SocketStats> getStats() {
200	SettableFuture<SocketStats> ret = SettableFuture.create();	×
201	ret.set(null);	×
202	return ret;	×
203	}
204
205	/**
206	* Prevents creating any new streams. Buffered streams are not failed and may still proceed
207	* when {@link #reprocess} is called. The delayed transport will be terminated when there is no
208	* more buffered streams.
209	*/
210	@Override
211	public final void shutdown(final Status status) {
212	synchronized (lock) {	1✔
213	if (shutdownStatus != null) {	1✔
214	return;	1✔
215	}
216	shutdownStatus = status;	1✔
217	syncContext.executeLater(new Runnable() {	1✔
218	@Override
219	public void run() {
220	listener.transportShutdown(status);	1✔
221	}	1✔
222	});
223	if (!hasPendingStreams() && reportTransportTerminated != null) {	1✔
224	syncContext.executeLater(reportTransportTerminated);	1✔
225	reportTransportTerminated = null;	1✔
226	}
227	}	1✔
228	syncContext.drain();	1✔
229	}	1✔
230
231	/**
232	* Shuts down this transport and cancels all streams that it owns, hence immediately terminates
233	* this transport.
234	*/
235	@Override
236	public final void shutdownNow(Status status) {
237	shutdown(status);	1✔
238	Collection<PendingStream> savedPendingStreams;
239	Runnable savedReportTransportTerminated;
240	synchronized (lock) {	1✔
241	savedPendingStreams = pendingStreams;	1✔
242	savedReportTransportTerminated = reportTransportTerminated;	1✔
243	reportTransportTerminated = null;	1✔
244	if (!pendingStreams.isEmpty()) {	1✔
245	pendingStreams = Collections.emptyList();	1✔
246	}
247	}	1✔
248	if (savedReportTransportTerminated != null) {	1✔
249	for (PendingStream stream : savedPendingStreams) {	1✔
250	Runnable runnable = stream.setStream(	1✔
251	new FailingClientStream(status, RpcProgress.REFUSED, stream.tracers));	1✔
252	if (runnable != null) {	1✔
253	// Drain in-line instead of using an executor as failing stream just throws everything
254	// away. This is essentially the same behavior as DelayedStream.cancel() but can be done
255	// before stream.start().
256	runnable.run();	1✔
257	}
258	}	1✔
259	syncContext.execute(savedReportTransportTerminated);	1✔
260	}
261	// If savedReportTransportTerminated == null, transportTerminated() has already been called in
262	// shutdown().
263	}	1✔
264
265	public final boolean hasPendingStreams() {
266	synchronized (lock) {	1✔
267	return !pendingStreams.isEmpty();	1✔
268	}
269	}
270
271	@VisibleForTesting
272	final int getPendingStreamsCount() {
273	synchronized (lock) {	1✔
274	return pendingStreams.size();	1✔
275	}
276	}
277
278	/**
279	* Use the picker to try picking a transport for every pending stream, proceed the stream if the
280	* pick is successful, otherwise keep it pending.
281	*
282	* <p>This method may be called concurrently with {@code newStream()}, and it's safe. All pending
283	* streams will be served by the latest picker (if a same picker is given more than once, they are
284	* considered different pickers) as soon as possible.
285	*
286	* <p>This method <strong>must not</strong> be called concurrently with itself.
287	*/
288	final void reprocess(@Nullable SubchannelPicker picker) {
289	ArrayList<PendingStream> toProcess;
290	synchronized (lock) {	1✔
291	lastPicker = picker;	1✔
292	lastPickerVersion++;	1✔
293	if (picker == null \|\| !hasPendingStreams()) {	1✔
294	return;	1✔
295	}
296	toProcess = new ArrayList<>(pendingStreams);	1✔
297	}	1✔
298	ArrayList<PendingStream> toRemove = new ArrayList<>();	1✔
299
300	for (final PendingStream stream : toProcess) {	1✔
301	PickResult pickResult = picker.pickSubchannel(stream.args);	1✔
302	CallOptions callOptions = stream.args.getCallOptions();	1✔
303	final ClientTransport transport = GrpcUtil.getTransportFromPickResult(pickResult,	1✔
304	callOptions.isWaitForReady());	1✔
305	if (transport != null) {	1✔
306	Executor executor = defaultAppExecutor;	1✔
307	// createRealStream may be expensive. It will start real streams on the transport. If
308	// there are pending requests, they will be serialized too, which may be expensive. Since
309	// we are now on transport thread, we need to offload the work to an executor.
310	if (callOptions.getExecutor() != null) {	1✔
311	executor = callOptions.getExecutor();	1✔
312	}
313	Runnable runnable = stream.createRealStream(transport);	1✔
314	if (runnable != null) {	1✔
315	executor.execute(runnable);	1✔
316	}
317	toRemove.add(stream);	1✔
318	} // else: stay pending
319	}	1✔
320
321	synchronized (lock) {	1✔
322	// Between this synchronized and the previous one:
323	// - Streams may have been cancelled, which may turn pendingStreams into emptiness.
324	// - shutdown() may be called, which may turn pendingStreams into null.
325	if (!hasPendingStreams()) {	1✔
326	return;	×
327	}
328	pendingStreams.removeAll(toRemove);	1✔
329	// Because delayed transport is long-lived, we take this opportunity to down-size the
330	// hashmap.
331	if (pendingStreams.isEmpty()) {	1✔
332	pendingStreams = new LinkedHashSet<>();	1✔
333	}
334	if (!hasPendingStreams()) {	1✔
335	// There may be a brief gap between delayed transport clearing in-use state, and first real
336	// transport starting streams and setting in-use state. During the gap the whole channel's
337	// in-use state may be false. However, it shouldn't cause spurious switching to idleness
338	// (which would shutdown the transports and LoadBalancer) because the gap should be shorter
339	// than IDLE_MODE_DEFAULT_TIMEOUT_MILLIS (1 second).
340	syncContext.executeLater(reportTransportNotInUse);	1✔
341	if (shutdownStatus != null && reportTransportTerminated != null) {	1✔
342	syncContext.executeLater(reportTransportTerminated);	1✔
343	reportTransportTerminated = null;	1✔
344	}
345	}
346	}	1✔
347	syncContext.drain();	1✔
348	}	1✔
349
350	@Override
351	public InternalLogId getLogId() {
352	return logId;	×
353	}
354
355	private class PendingStream extends DelayedStream {
356	private final PickSubchannelArgs args;
357	private final Context context = Context.current();	1✔
358	private final ClientStreamTracer[] tracers;
359
360	private PendingStream(PickSubchannelArgs args, ClientStreamTracer[] tracers) {	1✔
361	this.args = args;	1✔
362	this.tracers = tracers;	1✔
363	}	1✔
364
365	/** Runnable may be null. */
366	private Runnable createRealStream(ClientTransport transport) {
367	ClientStream realStream;
368	Context origContext = context.attach();	1✔
369	try {
370	realStream = transport.newStream(	1✔
371	args.getMethodDescriptor(), args.getHeaders(), args.getCallOptions(),	1✔
372	tracers);
373	} finally {
374	context.detach(origContext);	1✔
375	}
376	return setStream(realStream);	1✔
377	}
378
379	@Override
380	public void cancel(Status reason) {
381	super.cancel(reason);	1✔
382	synchronized (lock) {	1✔
383	if (reportTransportTerminated != null) {	1✔
384	boolean justRemovedAnElement = pendingStreams.remove(this);	1✔
385	if (!hasPendingStreams() && justRemovedAnElement) {	1✔
386	syncContext.executeLater(reportTransportNotInUse);	1✔
387	if (shutdownStatus != null) {	1✔
388	syncContext.executeLater(reportTransportTerminated);	1✔
389	reportTransportTerminated = null;	1✔
390	}
391	}
392	}
393	}	1✔
394	syncContext.drain();	1✔
395	}	1✔
396
397	@Override
398	protected void onEarlyCancellation(Status reason) {
399	for (ClientStreamTracer tracer : tracers) {	1✔
400	tracer.streamClosed(reason);	1✔
401	}
402	}	1✔
403
404	@Override
405	public void appendTimeoutInsight(InsightBuilder insight) {
406	if (args.getCallOptions().isWaitForReady()) {	1✔
407	insight.append("wait_for_ready");	1✔
408	}
409	super.appendTimeoutInsight(insight);	1✔
410	}	1✔
411	}
412	}

grpc / grpc-java / #19310

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