WaitForResult.java

/*
 * Copyright (c) 2002 Cunningham & Cunningham, Inc.
 * Copyright (c) 2009-2015 by Jochen Wierum & Cologne Intelligence
 *
 * This file is part of FitGoodies.
 *
 * FitGoodies is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * FitGoodies is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with FitGoodies.  If not, see <http://www.gnu.org/licenses/>.
 */

package de.cologneintelligence.fitgoodies.util;

import java.lang.reflect.Method;


/**
 * With this class is it possible to invoke a given method of a given class
 * by reflection until the method returns true or a given maxTime is reached.
 * <p>
 * The method must have the signature {@code boolean method()}.
 *
 * @author kmussawisade
 */
public class WaitForResult {
    private final SystemTime systemTime;

    private long lastElapsedTime;
    private boolean lastCallWasSuccessful;

    /**
     * Initializes a new object.
     *
     * @param systemTime SystemTime implementation to use
     */
    public WaitForResult(final SystemTime systemTime) {
        this.systemTime = systemTime;
    }

    /**
     * Initializes a new object. The object will use {@link SystemTime}.
     */
    public WaitForResult() {
        this(new SystemTime());
    }

    private boolean invokeMethod(Object target, Method method) {
        try {
            return (boolean) method.invoke(target);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Invokes the method multiple times, either until it returns true, or
     * until maxtime is over. After each invoke, the class waits
     * {@code sleepTime} milliseconds.
     *
     * @param target    Object which receives the call.
     * @param method    Method to invoke on {@code target}.
     * @param maxTime   Maximum time to wait before causing a failure.
     * @param sleepTime Time to sleep between method calls.
     */
    public void wait(Object target, Method method, long maxTime, long sleepTime) {
        long remaining = maxTime;

        lastCallWasSuccessful = invokeMethod(target, method);
        while (!lastCallWasSuccessful && remaining > 0) {
            systemTime.sleep(sleepTime);
            remaining -= sleepTime;
            lastCallWasSuccessful = invokeMethod(target, method);
        }

        lastElapsedTime = maxTime - remaining;
    }

    /**
     * Gets the elapsed time of the last call to {@link #wait(Object, Method, long, long)}.
     *
     * @return the elapsed time in milliseconds
     */
    public long getLastElapsedTime() {
        return lastElapsedTime;
    }

    public boolean lastCallWasSuccessful() {
        return lastCallWasSuccessful;
    }
}