io.grpc.stub.StreamObservers Maven / Gradle / Ivy
/*
* Copyright 2015, gRPC Authors All rights reserved.
*
* 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.stub;
import com.google.guava4pingcap.base.Preconditions;
import io.grpc.ExperimentalApi;
import java.util.Iterator;
/**
* Utility functions for working with {@link StreamObserver} and it's common subclasses like
* {@link CallStreamObserver}.
*/
@ExperimentalApi
public final class StreamObservers {
/**
* Copy the values of an {@link Iterator} to the target {@link CallStreamObserver} while properly
* accounting for outbound flow-control.
*
* For clients this method is safe to call inside {@link ClientResponseObserver#beforeStart},
* on servers it is safe to call inside the service method implementation.
*
*
* @param source of values expressed as an {@link Iterator}.
* @param target {@link CallStreamObserver} which accepts values from the source.
*/
public static void copyWithFlowControl(final Iterator source,
final CallStreamObserver target) {
Preconditions.checkNotNull(source, "source");
Preconditions.checkNotNull(target, "target");
final class FlowControllingOnReadyHandler implements Runnable {
@Override
public void run() {
while (target.isReady() && source.hasNext()) {
target.onNext(source.next());
}
if (!source.hasNext()) {
target.onCompleted();
}
}
}
target.setOnReadyHandler(new FlowControllingOnReadyHandler());
}
/**
* Copy the values of an {@link Iterable} to the target {@link CallStreamObserver} while properly
* accounting for outbound flow-control.
*
* For clients this method is safe to call inside {@link ClientResponseObserver#beforeStart},
* on servers it is safe to call inside the service method implementation.
*
*
* @param source of values expressed as an {@link Iterable}.
* @param target {@link CallStreamObserver} which accepts values from the source.
*/
public static void copyWithFlowControl(final Iterable source,
CallStreamObserver target) {
Preconditions.checkNotNull(source, "source");
copyWithFlowControl(source.iterator(), target);
}
}