DefaultTPSLimiter.java

/*
 * 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.dubbo.rpc.filter.tps;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

import com.alibaba.dubbo.common.Constants;
import com.alibaba.dubbo.common.URL;
import com.alibaba.dubbo.rpc.Invocation;

/**
 * @author <a href="mailto:gang.lvg@alibaba-inc.com">kimi</a>
 */
public class DefaultTPSLimiter implements TPSLimiter {

    private final ConcurrentMap<String, StatItem> stats
        = new ConcurrentHashMap<String, StatItem>();
    
    public boolean isAllowable(URL url, Invocation invocation) {
        int rate = url.getParameter(Constants.TPS_LIMIT_RATE_KEY, -1);
        long interval = url.getParameter(Constants.TPS_LIMIT_INTERVAL_KEY,
                                         Constants.DEFAULT_TPS_LIMIT_INTERVAL);
        String serviceKey = url.getServiceKey();
        if (rate > 0) {
            StatItem statItem = stats.get(serviceKey);
            if (statItem == null) {
                stats.putIfAbsent(serviceKey,
                                  new StatItem(serviceKey, rate, interval));
                statItem = stats.get(serviceKey);
            }
            return statItem.isAllowable(url, invocation);
        } else {
            StatItem statItem = stats.get(serviceKey);
            if (statItem != null) {
                stats.remove(serviceKey);
            }
        }

        return true;
    }

}