hyracks/hyracks-control/hyracks-control-common/src/main/java/org/apache/hyracks/control/common/work/FutureValue.java

/*
 * 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.hyracks.control.common.work;

public class FutureValue<T> implements IResultCallback<T> {
    private boolean done;

    private T value;

    private Exception e;

    public FutureValue() {
        done = false;
        value = null;
        e = null;
    }

    @Override
    public synchronized void setValue(T value) {
        done = true;
        this.value = value;
        e = null;
        notifyAll();
    }

    @Override
    public synchronized void setException(Exception e) {
        done = true;
        this.e = e;
        value = null;
        notifyAll();
    }

    public synchronized void reset() {
        done = false;
        value = null;
        e = null;
        notifyAll();
    }

    public synchronized T get() throws Exception {
        while (!done) {
            wait();
        }
        if (e != null) {
            throw e;
        }
        return value;
    }
}