/*
 * 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 com.alipay.sofa.jraft.core;

import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;

/**
 *
 * @author jiachun.fjc
 */
public interface Scheduler {

    /**
     * Creates and executes a one-shot action that becomes enabled
     * after the given delay.
     *
     * @param command the task to execute
     * @param delay   the time from now to delay execution
     * @param unit    the time unit of the delay parameter
     * @return a ScheduledFuture representing pending completion of
     *         the task and whose {@code get()} method will return
     *         {@code null} upon completion
     *         scheduled for execution
     */
    ScheduledFuture<?> schedule(final Runnable command, final long delay, final TimeUnit unit);

    /**
     * Creates and executes a periodic action that becomes enabled first
     * after the given initial delay, and subsequently with the given
     * period; that is executions will commence after
     * {@code initialDelay} then {@code initialDelay+period}, then
     * {@code initialDelay + 2 * period}, and so on.
     * If any execution of the task
     * encounters an exception, subsequent executions are suppressed.
     * Otherwise, the task will only terminate via cancellation or
     * termination of the executor.  If any execution of this task
     * takes longer than its period, then subsequent executions
     * may start late, but will not concurrently execute.
     *
     * @param command      the task to execute
     * @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
     * @return a ScheduledFuture representing pending completion of
     *         the task, and whose {@code get()} method will throw an
     *         exception upon cancellation
     */
    ScheduledFuture<?> scheduleAtFixedRate(final Runnable command, final long initialDelay, final long period,
                                           final TimeUnit unit);

    /**
     * Creates and executes a periodic action that becomes enabled first
     * after the given initial delay, and subsequently with the
     * given delay between the termination of one execution and the
     * commencement of the next.  If any execution of the task
     * encounters an exception, subsequent executions are suppressed.
     * Otherwise, the task will only terminate via cancellation or
     * termination of the executor.
     *
     * @param command      the task to execute
     * @param initialDelay the time to delay first execution
     * @param delay        the delay between the termination of one
     *                     execution and the commencement of the next
     * @param unit         the time unit of the initialDelay and delay parameters
     * @return a ScheduledFuture representing pending completion of
     *         the task, and whose {@code get()} method will throw an
     *         exception upon cancellation
     */
    ScheduledFuture<?> scheduleWithFixedDelay(final Runnable command, final long initialDelay, final long delay,
                                              final TimeUnit unit);

    void shutdown();
}
