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/*
* 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 static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.annotations.VisibleForTesting;
import io.grpc.Attributes;
import io.grpc.Compressor;
import io.grpc.Deadline;
import io.grpc.DecompressorRegistry;
import io.grpc.Metadata;
import io.grpc.Status;
import io.grpc.internal.ClientStreamListener.RpcProgress;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import javax.annotation.CheckReturnValue;
import javax.annotation.concurrent.GuardedBy;
/**
* A stream that queues requests before the transport is available, and delegates to a real stream
* implementation when the transport is available.
*
* {@code ClientStream} itself doesn't require thread-safety. However, the state of {@code
* DelayedStream} may be internally altered by different threads, thus internal synchronization is
* necessary.
*/
class DelayedStream implements ClientStream {
/** {@code true} once realStream is valid and all pending calls have been drained. */
private volatile boolean passThrough;
/**
* Non-{@code null} iff start has been called. Used to assert methods are called in appropriate
* order, but also used if an error occurrs before {@code realStream} is set.
*/
private ClientStreamListener listener;
/** Must hold {@code this} lock when setting. */
private ClientStream realStream;
@GuardedBy("this")
private Status error;
@GuardedBy("this")
private List pendingCalls = new ArrayList<>();
@GuardedBy("this")
private DelayedStreamListener delayedListener;
@GuardedBy("this")
private long startTimeNanos;
@GuardedBy("this")
private long streamSetTimeNanos;
// No need to synchronize; start() synchronization provides a happens-before
private List preStartPendingCalls = new ArrayList<>();
@Override
public void setMaxInboundMessageSize(final int maxSize) {
checkState(listener == null, "May only be called before start");
preStartPendingCalls.add(new Runnable() {
@Override
public void run() {
realStream.setMaxInboundMessageSize(maxSize);
}
});
}
@Override
public void setMaxOutboundMessageSize(final int maxSize) {
checkState(listener == null, "May only be called before start");
preStartPendingCalls.add(new Runnable() {
@Override
public void run() {
realStream.setMaxOutboundMessageSize(maxSize);
}
});
}
@Override
public void setDeadline(final Deadline deadline) {
checkState(listener == null, "May only be called before start");
preStartPendingCalls.add(new Runnable() {
@Override
public void run() {
realStream.setDeadline(deadline);
}
});
}
@Override
public void appendTimeoutInsight(InsightBuilder insight) {
synchronized (this) {
if (listener == null) {
return;
}
if (realStream != null) {
insight.appendKeyValue("buffered_nanos", streamSetTimeNanos - startTimeNanos);
realStream.appendTimeoutInsight(insight);
} else {
insight.appendKeyValue("buffered_nanos", System.nanoTime() - startTimeNanos);
insight.append("waiting_for_connection");
}
}
}
/**
* Transfers all pending and future requests and mutations to the given stream. Method will return
* quickly, but if the returned Runnable is non-null it must be called to complete the process.
* The Runnable may take a while to execute.
*
* No-op if either this method or {@link #cancel} have already been called.
*/
// When this method returns, start() has been called on realStream or passThrough is guaranteed to
// be true
@CheckReturnValue
final Runnable setStream(ClientStream stream) {
ClientStreamListener savedListener;
synchronized (this) {
// If realStream != null, then either setStream() or cancel() has been called.
if (realStream != null) {
return null;
}
setRealStream(checkNotNull(stream, "stream"));
savedListener = listener;
if (savedListener == null) {
assert pendingCalls.isEmpty();
pendingCalls = null;
passThrough = true;
}
}
if (savedListener == null) {
return null;
} else {
internalStart(savedListener);
return new Runnable() {
@Override
public void run() {
drainPendingCalls();
}
};
}
}
/**
* Called to transition {@code passThrough} to {@code true}. This method is not safe to be called
* multiple times; the caller must ensure it will only be called once, ever. {@code this} lock
* should not be held when calling this method.
*/
private void drainPendingCalls() {
assert realStream != null;
assert !passThrough;
List toRun = new ArrayList<>();
DelayedStreamListener delayedListener = null;
while (true) {
synchronized (this) {
if (pendingCalls.isEmpty()) {
pendingCalls = null;
passThrough = true;
delayedListener = this.delayedListener;
break;
}
// Since there were pendingCalls, we need to process them. To maintain ordering we can't set
// passThrough=true until we run all pendingCalls, but new Runnables may be added after we
// drop the lock. So we will have to re-check pendingCalls.
List tmp = toRun;
toRun = pendingCalls;
pendingCalls = tmp;
}
for (Runnable runnable : toRun) {
// Must not call transport while lock is held to prevent deadlocks.
// TODO(ejona): exception handling
runnable.run();
}
toRun.clear();
}
if (delayedListener != null) {
delayedListener.drainPendingCallbacks();
}
}
/**
* Enqueue the runnable or execute it now. Call sites that may be called many times may want avoid
* this method if {@code passThrough == true}.
*
* Note that this method is no more thread-safe than {@code runnable}. It is thread-safe if and
* only if {@code runnable} is thread-safe.
*/
private void delayOrExecute(Runnable runnable) {
checkState(listener != null, "May only be called after start");
synchronized (this) {
if (!passThrough) {
pendingCalls.add(runnable);
return;
}
}
runnable.run();
}
@Override
public void setAuthority(final String authority) {
checkState(listener == null, "May only be called before start");
checkNotNull(authority, "authority");
preStartPendingCalls.add(new Runnable() {
@Override
public void run() {
realStream.setAuthority(authority);
}
});
}
@Override
public void start(ClientStreamListener listener) {
checkNotNull(listener, "listener");
checkState(this.listener == null, "already started");
Status savedError;
boolean savedPassThrough;
synchronized (this) {
// If error != null, then cancel() has been called and was unable to close the listener
savedError = error;
savedPassThrough = passThrough;
if (!savedPassThrough) {
listener = delayedListener = new DelayedStreamListener(listener);
}
this.listener = listener;
startTimeNanos = System.nanoTime();
}
if (savedError != null) {
listener.closed(savedError, RpcProgress.PROCESSED, new Metadata());
return;
}
if (savedPassThrough) {
internalStart(listener);
} // else internalStart() will be called by setStream
}
/**
* Starts stream without synchronization. {@code listener} should be same instance as {@link
* #listener}.
*/
private void internalStart(ClientStreamListener listener) {
for (Runnable runnable : preStartPendingCalls) {
runnable.run();
}
preStartPendingCalls = null;
realStream.start(listener);
}
@Override
public Attributes getAttributes() {
ClientStream savedRealStream;
synchronized (this) {
savedRealStream = realStream;
}
if (savedRealStream != null) {
return savedRealStream.getAttributes();
} else {
return Attributes.EMPTY;
}
}
@Override
public void writeMessage(final InputStream message) {
checkState(listener != null, "May only be called after start");
checkNotNull(message, "message");
if (passThrough) {
realStream.writeMessage(message);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realStream.writeMessage(message);
}
});
}
}
@Override
public void flush() {
checkState(listener != null, "May only be called after start");
if (passThrough) {
realStream.flush();
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realStream.flush();
}
});
}
}
// When this method returns, passThrough is guaranteed to be true
@Override
public void cancel(final Status reason) {
checkState(listener != null, "May only be called after start");
checkNotNull(reason, "reason");
boolean delegateToRealStream = true;
synchronized (this) {
// If realStream != null, then either setStream() or cancel() has been called
if (realStream == null) {
setRealStream(NoopClientStream.INSTANCE);
delegateToRealStream = false;
error = reason;
}
}
if (delegateToRealStream) {
delayOrExecute(new Runnable() {
@Override
public void run() {
realStream.cancel(reason);
}
});
} else {
drainPendingCalls();
onEarlyCancellation(reason);
// Note that listener is a DelayedStreamListener
listener.closed(reason, RpcProgress.PROCESSED, new Metadata());
}
}
protected void onEarlyCancellation(Status reason) {
}
@GuardedBy("this")
private void setRealStream(ClientStream realStream) {
checkState(this.realStream == null, "realStream already set to %s", this.realStream);
this.realStream = realStream;
streamSetTimeNanos = System.nanoTime();
}
@Override
public void halfClose() {
checkState(listener != null, "May only be called after start");
delayOrExecute(new Runnable() {
@Override
public void run() {
realStream.halfClose();
}
});
}
@Override
public void request(final int numMessages) {
checkState(listener != null, "May only be called after start");
if (passThrough) {
realStream.request(numMessages);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realStream.request(numMessages);
}
});
}
}
@Override
public void optimizeForDirectExecutor() {
checkState(listener == null, "May only be called before start");
preStartPendingCalls.add(new Runnable() {
@Override
public void run() {
realStream.optimizeForDirectExecutor();
}
});
}
@Override
public void setCompressor(final Compressor compressor) {
checkState(listener == null, "May only be called before start");
checkNotNull(compressor, "compressor");
preStartPendingCalls.add(new Runnable() {
@Override
public void run() {
realStream.setCompressor(compressor);
}
});
}
@Override
public void setFullStreamDecompression(final boolean fullStreamDecompression) {
checkState(listener == null, "May only be called before start");
preStartPendingCalls.add(
new Runnable() {
@Override
public void run() {
realStream.setFullStreamDecompression(fullStreamDecompression);
}
});
}
@Override
public void setDecompressorRegistry(final DecompressorRegistry decompressorRegistry) {
checkState(listener == null, "May only be called before start");
checkNotNull(decompressorRegistry, "decompressorRegistry");
preStartPendingCalls.add(new Runnable() {
@Override
public void run() {
realStream.setDecompressorRegistry(decompressorRegistry);
}
});
}
@Override
public boolean isReady() {
if (passThrough) {
return realStream.isReady();
} else {
return false;
}
}
@Override
public void setMessageCompression(final boolean enable) {
checkState(listener != null, "May only be called after start");
if (passThrough) {
realStream.setMessageCompression(enable);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realStream.setMessageCompression(enable);
}
});
}
}
@VisibleForTesting
ClientStream getRealStream() {
return realStream;
}
private static class DelayedStreamListener implements ClientStreamListener {
private final ClientStreamListener realListener;
private volatile boolean passThrough;
@GuardedBy("this")
private List pendingCallbacks = new ArrayList<>();
public DelayedStreamListener(ClientStreamListener listener) {
this.realListener = listener;
}
private void delayOrExecute(Runnable runnable) {
synchronized (this) {
if (!passThrough) {
pendingCallbacks.add(runnable);
return;
}
}
runnable.run();
}
@Override
public void messagesAvailable(final MessageProducer producer) {
if (passThrough) {
realListener.messagesAvailable(producer);
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realListener.messagesAvailable(producer);
}
});
}
}
@Override
public void onReady() {
if (passThrough) {
realListener.onReady();
} else {
delayOrExecute(new Runnable() {
@Override
public void run() {
realListener.onReady();
}
});
}
}
@Override
public void headersRead(final Metadata headers) {
delayOrExecute(new Runnable() {
@Override
public void run() {
realListener.headersRead(headers);
}
});
}
@Override
public void closed(
final Status status, final RpcProgress rpcProgress,
final Metadata trailers) {
delayOrExecute(new Runnable() {
@Override
public void run() {
realListener.closed(status, rpcProgress, trailers);
}
});
}
public void drainPendingCallbacks() {
assert !passThrough;
List toRun = new ArrayList<>();
while (true) {
synchronized (this) {
if (pendingCallbacks.isEmpty()) {
pendingCallbacks = null;
passThrough = true;
break;
}
// Since there were pendingCallbacks, we need to process them. To maintain ordering we
// can't set passThrough=true until we run all pendingCallbacks, but new Runnables may be
// added after we drop the lock. So we will have to re-check pendingCallbacks.
List tmp = toRun;
toRun = pendingCallbacks;
pendingCallbacks = tmp;
}
for (Runnable runnable : toRun) {
// Avoid calling listener while lock is held to prevent deadlocks.
// TODO(ejona): exception handling
runnable.run();
}
toRun.clear();
}
}
}
}