| /** |
| * 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.avro.ipc; |
| |
| import java.util.concurrent.CountDownLatch; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.Future; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.TimeoutException; |
| |
| /** |
| * A Future implementation for RPCs. |
| */ |
| public class CallFuture<T> implements Future<T>, Callback<T> { |
| private final CountDownLatch latch = new CountDownLatch(1); |
| private final Callback<T> chainedCallback; |
| private T result = null; |
| private Throwable error = null; |
| |
| /** |
| * Creates a CallFuture. |
| */ |
| public CallFuture() { |
| this(null); |
| } |
| |
| /** |
| * Creates a CallFuture with a chained Callback which will be invoked |
| * when this CallFuture's Callback methods are invoked. |
| * @param chainedCallback the chained Callback to set. |
| */ |
| public CallFuture(Callback<T> chainedCallback) { |
| this.chainedCallback = chainedCallback; |
| } |
| |
| /** |
| * Sets the RPC response, and unblocks all threads waiting on {@link #get()} |
| * or {@link #get(long, TimeUnit)}. |
| * @param result the RPC result to set. |
| */ |
| @Override |
| public void handleResult(T result) { |
| this.result = result; |
| latch.countDown(); |
| if (chainedCallback != null) { |
| chainedCallback.handleResult(result); |
| } |
| } |
| |
| /** |
| * Sets an error thrown during RPC execution, and unblocks all threads waiting |
| * on {@link #get()} or {@link #get(long, TimeUnit)}. |
| * @param error the RPC error to set. |
| */ |
| @Override |
| public void handleError(Throwable error) { |
| this.error = error; |
| latch.countDown(); |
| if (chainedCallback != null) { |
| chainedCallback.handleError(error); |
| } |
| } |
| |
| /** |
| * Gets the value of the RPC result without blocking. |
| * Using {@link #get()} or {@link #get(long, TimeUnit)} is usually |
| * preferred because these methods block until the result is available or |
| * an error occurs. |
| * @return the value of the response, or null if no result was returned or |
| * the RPC has not yet completed. |
| */ |
| public T getResult() { |
| return result; |
| } |
| |
| /** |
| * Gets the error that was thrown during RPC execution. Does not block. |
| * Either {@link #get()} or {@link #get(long, TimeUnit)} should be called |
| * first because these methods block until the RPC has completed. |
| * @return the RPC error that was thrown, or null if no error has occurred or |
| * if the RPC has not yet completed. |
| */ |
| public Throwable getError() { |
| return error; |
| } |
| |
| @Override |
| public boolean cancel(boolean mayInterruptIfRunning) { |
| return false; |
| } |
| |
| @Override |
| public boolean isCancelled() { |
| return false; |
| } |
| |
| @Override |
| public T get() throws InterruptedException, |
| ExecutionException { |
| latch.await(); |
| if (error != null) { |
| throw new ExecutionException(error); |
| } |
| return result; |
| } |
| |
| @Override |
| public T get(long timeout, TimeUnit unit) |
| throws InterruptedException, ExecutionException, TimeoutException { |
| if (latch.await(timeout, unit)) { |
| if (error != null) { |
| throw new ExecutionException(error); |
| } |
| return result; |
| } else { |
| throw new TimeoutException(); |
| } |
| } |
| |
| /** |
| * Waits for the CallFuture to complete without returning the result. |
| * @throws InterruptedException if interrupted. |
| */ |
| public void await() throws InterruptedException { |
| latch.await(); |
| } |
| |
| /** |
| * Waits for the CallFuture to complete without returning the result. |
| * @param timeout the maximum time to wait. |
| * @param unit the time unit of the timeout argument. |
| * @throws InterruptedException if interrupted. |
| * @throws TimeoutException if the wait timed out. |
| */ |
| public void await(long timeout, TimeUnit unit) |
| throws InterruptedException, TimeoutException { |
| if (!latch.await(timeout, unit)) { |
| throw new TimeoutException(); |
| } |
| } |
| |
| @Override |
| public boolean isDone() { |
| return latch.getCount() <= 0; |
| } |
| } |