/** Add a listener that will be notified when the context becomes cancelled. */
public void addListener(
final CancellationListener cancellationListener, final Executor executor) {
Preconditions.checkNotNull(cancellationListener);
Preconditions.checkNotNull(executor);
if (canBeCancelled) {
ExecutableListener executableListener =
new ExecutableListener(executor, cancellationListener);
synchronized (this) {
if (isCancelled()) {
executableListener.deliver();
} else {
if (listeners == null) {
// Now that we have a listener we need to listen to our parent so
// we can cascade listener notification.
listeners = new ArrayList<ExecutableListener>();
listeners.add(executableListener);
parent.addListener(parentListener, MoreExecutors.directExecutor());
} else {
listeners.add(executableListener);
}
}
}
}
}
@Override
public void start(final Listener<RespT> observer, Metadata headers) {
checkState(stream == null, "Already started");
checkNotNull(observer, "observer");
checkNotNull(headers, "headers");
// Create the context
final Deadline effectiveDeadline = min(callOptions.getDeadline(), parentContext.getDeadline());
if (effectiveDeadline != parentContext.getDeadline()) {
context = parentContext.withDeadline(effectiveDeadline, deadlineCancellationExecutor);
} else {
context = parentContext.withCancellation();
}
if (context.isCancelled()) {
// Context is already cancelled so no need to create a real stream, just notify the observer
// of cancellation via callback on the executor
stream = NoopClientStream.INSTANCE;
callExecutor.execute(
new ContextRunnable(context) {
@Override
public void runInContext() {
observer.onClose(statusFromCancelled(context), new Metadata());
}
});
return;
}
final String compressorName = callOptions.getCompressor();
Compressor compressor = null;
if (compressorName != null) {
compressor = compressorRegistry.lookupCompressor(compressorName);
if (compressor == null) {
stream = NoopClientStream.INSTANCE;
callExecutor.execute(
new ContextRunnable(context) {
@Override
public void runInContext() {
observer.onClose(
Status.INTERNAL.withDescription(
String.format("Unable to find compressor by name %s", compressorName)),
new Metadata());
}
});
return;
}
} else {
compressor = Codec.Identity.NONE;
}
prepareHeaders(headers, callOptions, userAgent, decompressorRegistry, compressor);
final boolean deadlineExceeded = effectiveDeadline != null && effectiveDeadline.isExpired();
if (!deadlineExceeded) {
updateTimeoutHeaders(
effectiveDeadline, callOptions.getDeadline(), parentContext.getDeadline(), headers);
ClientTransport transport = clientTransportProvider.get(callOptions);
stream = transport.newStream(method, headers);
} else {
stream = new FailingClientStream(DEADLINE_EXCEEDED);
}
if (callOptions.getAuthority() != null) {
stream.setAuthority(callOptions.getAuthority());
}
stream.setCompressor(compressor);
stream.start(new ClientStreamListenerImpl(observer));
if (compressor != Codec.Identity.NONE) {
stream.setMessageCompression(true);
}
// Delay any sources of cancellation after start(), because most of the transports are broken if
// they receive cancel before start. Issue #1343 has more details
// Propagate later Context cancellation to the remote side.
context.addListener(this, directExecutor());
if (contextListenerShouldBeRemoved) {
// Race detected! ClientStreamListener.closed may have been called before
// deadlineCancellationFuture was set, thereby preventing the future from being cancelled.
// Go ahead and cancel again, just to be sure it was cancelled.
context.removeListener(this);
}
}
