/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 org.apache.hadoop.hbase.ipc;
import com.google.protobuf.RpcCallback;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import java.io.IOException;
import java.io.InterruptedIOException;
/**
* Simple {@link RpcCallback} implementation providing a
* {@link java.util.concurrent.Future}-like {@link BlockingRpcCallback#get()} method, which
* will block util the instance's {@link BlockingRpcCallback#run(Object)} method has been called.
* {@code R} is the RPC response type that will be passed to the {@link #run(Object)} method.
*/
@InterfaceAudience.Public
@InterfaceStability.Evolving
public class BlockingRpcCallback<R> implements RpcCallback<R> {
private R result;
private boolean resultSet = false;
/**
* Called on completion of the RPC call with the response object, or {@code null} in the case of
* an error.
* @param parameter the response object or {@code null} if an error occurred
*/
@Override
public void run(R parameter) {
synchronized (this) {
result = parameter;
resultSet = true;
this.notify();
}
}
/**
* Returns the parameter passed to {@link #run(Object)} or {@code null} if a null value was
* passed. When used asynchronously, this method will block until the {@link #run(Object)}
* method has been called.
* @return the response object or {@code null} if no response was passed
*/
public synchronized R get() throws IOException {
while (!resultSet) {
try {
this.wait();
} catch (InterruptedException ie) {
Thread.currentThread().interrupt();
InterruptedIOException exception = new InterruptedIOException(ie.getMessage());
exception.initCause(ie);
throw exception;
}
}
return result;
}
}