/*
 * 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.channel;

import java.util.concurrent.ThreadFactory;

/**
 * Abstract base class for {@link EventLoop}'s that execute all its submitted tasks in a single thread.
 *
 */
public abstract class SingleThreadEventLoop extends SingleThreadEventExecutor implements EventLoop {

    /**
     *
     * @see SingleThreadEventExecutor#SingleThreadEventExecutor(EventExecutorGroup, ThreadFactory, ChannelTaskScheduler)
     */
    protected SingleThreadEventLoop(
            EventLoopGroup parent, ThreadFactory threadFactory, ChannelTaskScheduler scheduler) {
        super(parent, threadFactory, scheduler);
    }

    @Override
    public EventLoopGroup parent() {
        return (EventLoopGroup) super.parent();
    }

    @Override
    public EventLoop next() {
        return (EventLoop) super.next();
    }

    @Override
    public ChannelFuture register(Channel channel) {
        if (channel == null) {
            throw new NullPointerException("channel");
        }
        return register(channel, channel.newPromise());
    }

    @Override
    public ChannelFuture register(final Channel channel, final ChannelPromise promise) {
        if (isShutdown()) {
            channel.unsafe().closeForcibly();
            promise.setFailure(new EventLoopException("cannot register a channel to a shut down loop"));
            return promise;
        }

        if (inEventLoop()) {
            channel.unsafe().register(this, promise);
        } else {
            execute(new Runnable() {
                @Override
                public void run() {
                    channel.unsafe().register(SingleThreadEventLoop.this, promise);
                }
            });
        }

        return promise;
    }
}