com.hotels.styx.client.healthcheck.Schedule Maven / Gradle / Ivy

Go to download
/**
 * Copyright (C) 2013-2017 Expedia Inc.
 *
 * 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 com.hotels.styx.client.healthcheck;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import java.util.concurrent.TimeUnit;

/**
 * Represents a schedule for tasks that need to be executed at a fixed rate
 * (see {@link java.util.concurrent.ScheduledExecutorService#scheduleAtFixedRate(Runnable, long, long, TimeUnit)}.
 */
public class Schedule {
    private final long initialDelay;
    private final long period;
    private final TimeUnit unit;

    /**
     * Constructor. Constructs a Schedule with initialDelay=0.
     *
     * @param period       the period between successive executions
     * @param unit         the time unit of the initialDelay and period parameters
     */
    public Schedule(long period, TimeUnit unit) {
        this(0, period, unit);
    }

    /**
     * Constructor.
     *
     * @param initialDelay the time to delay first execution
     * @param period       the period between successive executions
     * @param unit         the time unit of the initialDelay and period parameters
     */
    public Schedule(long initialDelay, long period, TimeUnit unit) {
        this.initialDelay = atLeast(initialDelay, 0);
        this.period = atLeast(period, 1);
        this.unit = checkNotNull(unit);
    }

    private static long atLeast(long parameter, long atLeast) {
        checkArgument(parameter >= atLeast, parameter + " < " + atLeast);
        return parameter;
    }

    /**
     * Initial delay in the schedule's time unit.
     *
     * @return initial delay
     */
    public long initialDelay() {
        return initialDelay;
    }

    /**
     * Period in the schedule's time unit.
     *
     * @return period
     */
    public long period() {
        return period;
    }

    /**
     * Time unit of initial delay and period.
     *
     * @return time unit of initial delay and period.
     */
    public TimeUnit unit() {
        return unit;
    }
}