/*
 * Copyright 1999-2012 Alibaba Group.
 *  
 * 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.alibaba.cobar.net.handler;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.atomic.AtomicBoolean;

import com.alibaba.cobar.net.NIOHandler;

/**
 * @author xianmao.hexm 2012-7-13
 */
public abstract class BackendAsyncHandler implements NIOHandler {

    protected final BlockingQueue<byte[]> dataQueue = new LinkedBlockingQueue<byte[]>();
    protected final AtomicBoolean isHandling = new AtomicBoolean(false);

    protected void offerData(byte[] data, Executor executor) {
        if (dataQueue.offer(data)) {
            handleQueue(executor);
        } else {
            offerDataError();
        }
    }

    protected abstract void offerDataError();

    protected abstract void handleData(byte[] data);

    protected abstract void handleDataError(Throwable t);

    protected void handleQueue(final Executor executor) {
        if (isHandling.compareAndSet(false, true)) {
            // 异步处理后端数据
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    try {
                        byte[] data = null;
                        while ((data = dataQueue.poll()) != null) {
                            handleData(data);
                        }
                    } catch (Throwable t) {
                        handleDataError(t);
                    } finally {
                        isHandling.set(false);
                        if (dataQueue.size() > 0) {
                            handleQueue(executor);
                        }
                    }
                }
            });
        }
    }

}