io.grpc.internal.ManagedClientTransport Maven / Gradle / Ivy
/*
* Copyright 2016 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 io.grpc.Attributes;
import io.grpc.Status;
import javax.annotation.CheckReturnValue;
import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;
/**
* A {@link ClientTransport} that has life-cycle management.
*
* {@link #start} must be the first method call to this interface and return before calling other
* methods.
*
*
Typically the transport owns the streams it creates through {@link #newStream}, while some
* implementations may transfer the streams to somewhere else. Either way they must conform to the
* contract defined by {@link #shutdown}, {@link Listener#transportShutdown} and
* {@link Listener#transportTerminated}.
*/
@ThreadSafe
public interface ManagedClientTransport extends ClientTransport {
/**
* Starts transport. This method may only be called once.
*
*
Implementations must not call {@code listener} from within {@link #start}; implementations
* are expected to notify listener on a separate thread or when the returned {@link Runnable} is
* run. This method and the returned {@code Runnable} should not throw any exceptions.
*
* @param listener non-{@code null} listener of transport events
* @return a {@link Runnable} that is executed after-the-fact by the original caller, typically
* after locks are released
*/
@CheckReturnValue
@Nullable
Runnable start(Listener listener);
/**
* Initiates an orderly shutdown of the transport. Existing streams continue, but the transport
* will not own any new streams. New streams will either fail (once
* {@link Listener#transportShutdown} callback called), or be transferred off this transport (in
* which case they may succeed). This method may only be called once.
*/
void shutdown(Status reason);
/**
* Initiates a forceful shutdown in which preexisting and new calls are closed. Existing calls
* should be closed with the provided {@code reason}.
*/
void shutdownNow(Status reason);
/**
* Receives notifications for the transport life-cycle events. Implementation does not need to be
* thread-safe, so notifications must be properly synchronized externally.
*/
interface Listener {
/**
* The transport is shutting down. This transport will stop owning new streams, but existing
* streams may continue, and the transport may still be able to process {@link #newStream} as
* long as it doesn't own the new streams. Shutdown could have been caused by an error or normal
* operation. It is possible that this method is called without {@link #shutdown} being called.
*
*
This is called exactly once, and must be called prior to {@link #transportTerminated}.
*
* @param s the reason for the shutdown.
*/
void transportShutdown(Status s);
/**
* The transport completed shutting down. All resources have been released. All streams have
* either been closed or transferred off this transport. This transport may still be able to
* process {@link #newStream} as long as it doesn't own the new streams.
*
*
This is called exactly once, and must be called after {@link #transportShutdown} has been
* called.
*/
void transportTerminated();
/**
* The transport is ready to accept traffic, because the connection is established. This is
* called at most once.
*
*
Streams created before this milestone are not guaranteed to function.
*/
void transportReady();
/**
* Called whenever the transport's in-use state has changed. A transport is in-use when it has
* at least one stream.
*/
void transportInUse(boolean inUse);
/**
* Called just before {@link #transportReady} to allow direct modification of transport
* Attributes.
*/
default Attributes filterTransport(Attributes attributes) {
return attributes;
}
}
}