/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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 io.netty.util.concurrent;

import java.util.Iterator;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;

The EventExecutorGroup is responsible for providing the EventExecutor's to use via its next() method. Besides this, it is also responsible for handling their life-cycle and allows shutting them down in a global fashion. /**
 * The {@link EventExecutorGroup} is responsible for providing the {@link EventExecutor}'s to use
 * via its {@link #next()} method. Besides this, it is also responsible for handling their
 * life-cycle and allows shutting them down in a global fashion.
 *
 */
public interface EventExecutorGroup extends ScheduledExecutorService, Iterable<EventExecutor> {

    
Returns true if and only if all EventExecutors managed by this EventExecutorGroup are being shut down gracefully or was shut down. /**
     * Returns {@code true} if and only if all {@link EventExecutor}s managed by this {@link EventExecutorGroup}
     * are being {@linkplain #shutdownGracefully() shut down gracefully} or was {@linkplain #isShutdown() shut down}.
     */
    boolean isShuttingDown();

    
Shortcut method for shutdownGracefully(long, long, TimeUnit) with sensible default values. 
Returns:
the terminationFuture()/**
     * Shortcut method for {@link #shutdownGracefully(long, long, TimeUnit)} with sensible default values.
     *
     * @return the {@link #terminationFuture()}
     */
    Future<?> shutdownGracefully();

    
Signals this executor that the caller wants the executor to be shut down. Once this method is called, isShuttingDown() starts to return true, and the executor prepares to shut itself down. Unlike shutdown(), graceful shutdown ensures that no tasks are submitted for 'the quiet period'
(usually a couple seconds) before it shuts itself down.  If a task is submitted during the quiet period,
it is guaranteed to be accepted and the quiet period will start over.
Params:
quietPeriod – the quiet period as described in the documentation
timeout –  the maximum amount of time to wait until the executor is shutdown() regardless if a task was submitted during the quiet period
unit –  the unit of quietPeriod and timeout
Returns:
the terminationFuture()/**
     * Signals this executor that the caller wants the executor to be shut down.  Once this method is called,
     * {@link #isShuttingDown()} starts to return {@code true}, and the executor prepares to shut itself down.
     * Unlike {@link #shutdown()}, graceful shutdown ensures that no tasks are submitted for <i>'the quiet period'</i>
     * (usually a couple seconds) before it shuts itself down.  If a task is submitted during the quiet period,
     * it is guaranteed to be accepted and the quiet period will start over.
     *
     * @param quietPeriod the quiet period as described in the documentation
     * @param timeout     the maximum amount of time to wait until the executor is {@linkplain #shutdown()}
     *                    regardless if a task was submitted during the quiet period
     * @param unit        the unit of {@code quietPeriod} and {@code timeout}
     *
     * @return the {@link #terminationFuture()}
     */
    Future<?> shutdownGracefully(long quietPeriod, long timeout, TimeUnit unit);

    
Returns the Future which is notified when all EventExecutors managed by this EventExecutorGroup have been terminated. /**
     * Returns the {@link Future} which is notified when all {@link EventExecutor}s managed by this
     * {@link EventExecutorGroup} have been terminated.
     */
    Future<?> terminationFuture();

    
Deprecated:
shutdownGracefully(long, long, TimeUnit) or shutdownGracefully() instead./**
     * @deprecated {@link #shutdownGracefully(long, long, TimeUnit)} or {@link #shutdownGracefully()} instead.
     */
    @Override
    @Deprecated
    void shutdown();

    
Deprecated:
shutdownGracefully(long, long, TimeUnit) or shutdownGracefully() instead./**
     * @deprecated {@link #shutdownGracefully(long, long, TimeUnit)} or {@link #shutdownGracefully()} instead.
     */
    @Override
    @Deprecated
    List<Runnable> shutdownNow();

    
Returns one of the EventExecutors managed by this EventExecutorGroup. /**
     * Returns one of the {@link EventExecutor}s managed by this {@link EventExecutorGroup}.
     */
    EventExecutor next();

    @Override
    Iterator<EventExecutor> iterator();

    @Override
    Future<?> submit(Runnable task);

    @Override
    <T> Future<T> submit(Runnable task, T result);

    @Override
    <T> Future<T> submit(Callable<T> task);

    @Override
    ScheduledFuture<?> schedule(Runnable command, long delay, TimeUnit unit);

    @Override
    <V> ScheduledFuture<V> schedule(Callable<V> callable, long delay, TimeUnit unit);

    @Override
    ScheduledFuture<?> scheduleAtFixedRate(Runnable command, long initialDelay, long period, TimeUnit unit);

    @Override
    ScheduledFuture<?> scheduleWithFixedDelay(Runnable command, long initialDelay, long delay, TimeUnit unit);
}