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/*
* 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.CallOptions;
import io.grpc.Instrumented;
import io.grpc.InternalChannelz.SocketStats;
import io.grpc.Metadata;
import io.grpc.MethodDescriptor;
import java.util.concurrent.Executor;
import javax.annotation.concurrent.ThreadSafe;
/**
* The client-side transport typically encapsulating a single connection to a remote
* server. However, streams created before the client has discovered any server address may
* eventually be issued on different connections. All methods on the transport and its callbacks
* are expected to execute quickly.
*/
@ThreadSafe
public interface ClientTransport extends Instrumented<SocketStats> {
/**
* Creates a new stream for sending messages to a remote end-point.
*
* <p>This method returns immediately and does not wait for any validation of the request. If
* creation fails for any reason, {@link ClientStreamListener#closed} will be called to provide
* the error information. Any sent messages for this stream will be buffered until creation has
* completed (either successfully or unsuccessfully).
*
* <p>This method is called under the {@link io.grpc.Context} of the {@link io.grpc.ClientCall}.
*
* @param method the descriptor of the remote method to be called for this stream.
* @param headers to send at the beginning of the call
* @param callOptions runtime options of the call
* @return the newly created stream.
*/
// TODO(nmittler): Consider also throwing for stopping.
ClientStream newStream(MethodDescriptor<?, ?> method, Metadata headers, CallOptions callOptions);
/**
* Pings a remote endpoint. When an acknowledgement is received, the given callback will be
* invoked using the given executor.
*
* <p>Pings are not necessarily sent to the same endpont, thus a successful ping only means at
* least one endpoint responded, but doesn't imply the availability of other endpoints (if there
* is any).
*
* <p>This is an optional method. Transports that do not have any mechanism by which to ping the
* remote endpoint may throw {@link UnsupportedOperationException}.
*/
void ping(PingCallback callback, Executor executor);
/**
* A callback that is invoked when the acknowledgement to a {@link #ping} is received. Exactly one
* of the two methods should be called per {@link #ping}.
*/
interface PingCallback {
/**
* Invoked when a ping is acknowledged. The given argument is the round-trip time of the ping,
* in nanoseconds.
*
* @param roundTripTimeNanos the round-trip duration between the ping being sent and the
* acknowledgement received
*/
void onSuccess(long roundTripTimeNanos);
/**
* Invoked when a ping fails. The given argument is the cause of the failure.
*
* @param cause the cause of the ping failure
*/
void onFailure(Throwable cause);
}
}
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