/*
 * 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.handler.traffic;

import io.netty.channel.ChannelHandlerContext;

/**
 * This implementation of the {@link AbstractTrafficShapingHandler} is for channel
 * traffic shaping, that is to say a per channel limitation of the bandwidth.<br><br>
 *
 * The general use should be as follow:<br>
 * <ul>
 * <li>Add in your pipeline a new ChannelTrafficShapingHandler.<br>
 * <tt>ChannelTrafficShapingHandler myHandler = new ChannelTrafficShapingHandler();</tt><br>
 * <tt>pipeline.addLast(myHandler);</tt><br><br>
 *
 * <b>Note that this handler has a Pipeline Coverage of "one" which means a new handler must be created
 * for each new channel as the counter cannot be shared among all channels.</b>.<br><br>
 *
 * Other arguments can be passed like write or read limitation (in bytes/s where 0 means no limitation)
 * or the check interval (in millisecond) that represents the delay between two computations of the
 * bandwidth and so the call back of the doAccounting method (0 means no accounting at all).<br><br>
 *
 * A value of 0 means no accounting for checkInterval. If you need traffic shaping but no such accounting,
 * it is recommended to set a positive value, even if it is high since the precision of the
 * Traffic Shaping depends on the period where the traffic is computed. The highest the interval,
 * the less precise the traffic shaping will be. It is suggested as higher value something close
 * to 5 or 10 minutes.<br>
 * </li>
 * </ul><br>
 */
public class ChannelTrafficShapingHandler extends AbstractTrafficShapingHandler {

    /**
     * Create a new instance
     *
     * @param writeLimit
     *          0 or a limit in bytes/s
     * @param readLimit
     *          0 or a limit in bytes/s
     * @param checkInterval
     *          The delay between two computations of performances for
     *            channels or 0 if no stats are to be computed
     */
    public ChannelTrafficShapingHandler(long writeLimit,
            long readLimit, long checkInterval) {
        super(writeLimit, readLimit, checkInterval);
    }

    /**
     * Create a new instance
     *
     * @param writeLimit
     *          0 or a limit in bytes/s
     * @param readLimit
     *          0 or a limit in bytes/s
     */
    public ChannelTrafficShapingHandler(long writeLimit,
            long readLimit) {
        super(writeLimit, readLimit);
    }

    /**
     * Create a new instance
     *
     * @param checkInterval
     *          The delay between two computations of performances for
     *            channels or 0 if no stats are to be computed
     */
    public ChannelTrafficShapingHandler(long checkInterval) {
        super(checkInterval);
    }

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
        TrafficCounter trafficCounter = new TrafficCounter(this, ctx.executor(), "ChannelTC" +
                ctx.channel().hashCode(), checkInterval);
        setTrafficCounter(trafficCounter);
        trafficCounter.start();
    }

    @Override
    public void handlerRemoved(ChannelHandlerContext ctx) throws Exception {
        if (trafficCounter != null) {
            trafficCounter.stop();
        }
    }
}