com.couchbase.client.core.deps.io.grpc.stub.ServerCallStreamObserver Maven / Gradle / Ivy
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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 com.couchbase.client.core.deps.io.grpc.stub;
import com.couchbase.client.core.deps.io.grpc.ExperimentalApi;
/**
* A refinement of {@link CallStreamObserver} to allows for interaction with call
* cancellation events on the server side. An instance of this class is obtained by casting the
* {@code StreamObserver} passed as an argument to service implementations.
*
* Like {@code StreamObserver}, implementations are not required to be thread-safe; if multiple
* threads will be writing to an instance concurrently, the application must synchronize its calls.
*
*
DO NOT MOCK: The API is too complex to reliably mock. Use InProcessChannelBuilder to create
* "real" RPCs suitable for testing and interact with the server using a normal client stub.
*/
public abstract class ServerCallStreamObserver extends CallStreamObserver {
/**
* Returns {@code true} when the call is cancelled and the server is encouraged to abort
* processing to save resources, since the client will not be processing any further methods.
* Cancellations can be caused by timeouts, explicit cancellation by client, network errors, and
* similar.
*
* This method may safely be called concurrently from multiple threads.
*/
public abstract boolean isCancelled();
/**
* Sets a {@link Runnable} to be called if the call is cancelled and the server is encouraged to
* abort processing to save resources, since the client will not process any further messages.
* Cancellations can be caused by timeouts, explicit cancellation by the client, network errors,
* etc.
*
*
It is guaranteed that execution of the {@link Runnable} is serialized with calls to the
* 'inbound' {@link StreamObserver}. That also means that the callback will be delayed if other
* callbacks are running; if one of those other callbacks runs for a significant amount of time
* it can poll {@link #isCancelled()}, which is not delayed.
*
*
This method may only be called during the initial call to the application, before the
* service returns its {@code StreamObserver}.
*
*
Setting the onCancelHandler will suppress the on-cancel exception thrown by
* {@link #onNext}. If the caller is already handling cancellation via polling or cannot
* substantially benefit from observing cancellation, using a no-op {@code onCancelHandler} is
* useful just to suppress the {@code onNext()} exception.
*
* @param onCancelHandler to call when client has cancelled the call.
*/
public abstract void setOnCancelHandler(Runnable onCancelHandler);
/**
* Sets the compression algorithm to use for the call. May only be called before sending any
* messages. Default gRPC servers support the "gzip" compressor.
*
*
It is safe to call this even if the client does not support the compression format chosen.
* The implementation will handle negotiation with the client and may fall back to no compression.
*
* @param compression the compression algorithm to use.
* @throws IllegalArgumentException if the compressor name can not be found.
*/
public abstract void setCompression(String compression);
/**
* Swaps to manual flow control where no message will be delivered to {@link
* StreamObserver#onNext(Object)} unless it is {@link #request request()}ed.
*
*
It may only be called during the initial call to the application, before the service returns
* its {@code StreamObserver}.
*
*
Note that for cases where the message is received before the service handler is invoked,
* this method will have no effect. This is true for:
*
*
* - {@link com.couchbase.client.core.deps.io.grpc.MethodDescriptor.MethodType#UNARY} operations.
* - {@link com.couchbase.client.core.deps.io.grpc.MethodDescriptor.MethodType#SERVER_STREAMING} operations.
*
*
*/
public void disableAutoRequest() {
throw new UnsupportedOperationException();
}
/**
* If {@code true}, indicates that the observer is capable of sending additional messages
* without requiring excessive buffering internally. This value is just a suggestion and the
* application is free to ignore it, however doing so may result in excessive buffering within the
* observer.
*
* If {@code false}, the runnable passed to {@link #setOnReadyHandler} will be called after
* {@code isReady()} transitions to {@code true}.
*/
@Override
public abstract boolean isReady();
/**
* Set a {@link Runnable} that will be executed every time the stream {@link #isReady()} state
* changes from {@code false} to {@code true}. While it is not guaranteed that the same
* thread will always be used to execute the {@link Runnable}, it is guaranteed that executions
* are serialized with calls to the 'inbound' {@link StreamObserver}.
*
*
May only be called during the initial call to the application, before the service returns
* its {@code StreamObserver}.
*
*
Because there is a processing delay to deliver this notification, it is possible for
* concurrent writes to cause {@code isReady() == false} within this callback. Handle "spurious"
* notifications by checking {@code isReady()}'s current value instead of assuming it is now
* {@code true}. If {@code isReady() == false} the normal expectations apply, so there would be
* another {@code onReadyHandler} callback.
*
* @param onReadyHandler to call when peer is ready to receive more messages.
*/
@Override
public abstract void setOnReadyHandler(Runnable onReadyHandler);
/**
* Requests the peer to produce {@code count} more messages to be delivered to the 'inbound'
* {@link StreamObserver}.
*
*
This method is safe to call from multiple threads without external synchronization.
*
* @param count more messages
*/
@Override
public abstract void request(int count);
/**
* Sets message compression for subsequent calls to {@link #onNext}.
*
* @param enable whether to enable compression.
*/
@Override
public abstract void setMessageCompression(boolean enable);
/**
* Sets a {@link Runnable} to be executed when the call is closed cleanly from the server's
* point of view: either {@link #onCompleted()} or {@link #onError(Throwable)} has been called,
* all the messages and trailing metadata have been sent and the stream has been closed. Note
* however that the client still may have not received all the messages due to network delay,
* client crashes, and cancellation races.
*
*
Exactly one of {@code onCloseHandler} and {@code onCancelHandler} is guaranteed to be called
* when the RPC terminates.
*
* It is guaranteed that execution of {@code onCloseHandler} is serialized with calls to
* the 'inbound' {@link StreamObserver}. That also means that the callback will be delayed if
* other callbacks are running.
*
* This method may only be called during the initial call to the application, before the
* service returns its {@link StreamObserver request observer}.
*
* @param onCloseHandler to execute when the call has been closed cleanly.
*/
@ExperimentalApi("https://github.com/grpc/grpc-java/issues/8467")
public void setOnCloseHandler(Runnable onCloseHandler) {
throw new UnsupportedOperationException();
}
}