ren.hankai.cordwood.web.security.support.DefaultAccessLimiter.java Source code

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Here is the source code for ren.hankai.cordwood.web.security.support.DefaultAccessLimiter.java

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/*******************************************************************************
 * Copyright (C) 2018 hankai
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 ******************************************************************************/

package ren.hankai.cordwood.web.security.support;

import com.google.common.util.concurrent.RateLimiter;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpStatus;
import org.springframework.stereotype.Component;
import org.springframework.web.method.HandlerMethod;
import org.springframework.web.servlet.HandlerExecutionChain;
import ren.hankai.cordwood.web.security.AccessLimiter;
import ren.hankai.cordwood.web.security.annotation.Stabilized;

import java.util.HashMap;
import java.util.concurrent.TimeUnit;

import javax.servlet.http.HttpServletResponse;

/**
 * ? google guava ??
 *
 * @author hankai
 * @version 1.0.0
 * @since Oct 12, 2018 10:59:23 AM
 */
@Component
public class DefaultAccessLimiter implements AccessLimiter {

    private static final Logger logger = LoggerFactory.getLogger(DefaultAccessLimiter.class);

    /**
     * ???????
     */
    private final HashMap<HandlerMethod, RateLimitInfo> rateLimitMappings = new HashMap<>(64);

    /**
     * ???????
     *
     * @param stabilized ?
     * @return ???
     * @author hankai
     * @since Oct 12, 2018 11:46:00 AM
     */
    private String getStabilizationDescription(Stabilized stabilized) {
        return String.format("{ maxQps=%.2f, timeout=%d, warmupPeriod=%d, fusingInterval=%d, fusingThreshold=%d }",
                stabilized.maxQps(), stabilized.timeout(), stabilized.warmupPeriod(), stabilized.fusingInterval(),
                stabilized.fusingThreshold());
    }

    /**
     * ???
     *
     * @param handlerMethod ?
     * @return 
     * @author hankai
     * @since Oct 12, 2018 11:03:07 AM
     */
    private Stabilized getStabilizations(HandlerMethod handlerMethod) {
        // 
        Stabilized anno = handlerMethod.getMethodAnnotation(Stabilized.class);
        if (null == anno) {
            // ?
            final Class<?> beanType = handlerMethod.getBeanType();
            anno = beanType.getAnnotation(Stabilized.class);
        }
        if (anno != null) {
            logger.debug(
                    String.format("Access limit configuration: \n\n%s\n\n", getStabilizationDescription(anno)));
        }
        return anno;
    }

    @Override
    public boolean handleAccess(HandlerExecutionChain requestHandler, HttpServletResponse response) {
        final Object obj = requestHandler.getHandler();
        if (null != obj) {
            if (obj instanceof HandlerMethod) {
                final HandlerMethod hm = (HandlerMethod) obj;
                final Stabilized anno = getStabilizations(hm);
                // ??
                if (null != anno) {
                    // ????
                    RateLimitInfo limitInfo = rateLimitMappings.get(hm);
                    if (null == limitInfo) {
                        // ???
                        final RateLimiter limiter = RateLimiter.create(anno.maxQps(), anno.warmupPeriod(),
                                TimeUnit.SECONDS);
                        limitInfo = new RateLimitInfo(limiter);
                        rateLimitMappings.put(hm, limitInfo);
                    } else {
                        logger.debug(String.format(
                                "Access hit limit mapping, selected handler mapping was:\n\n %s\n", hm.toString()));
                    }
                    if (limitInfo.isFused(anno)) {
                        // 
                        logger.debug("Fused, service will be unavailable temporarily.");
                        response.setStatus(HttpStatus.SERVICE_UNAVAILABLE.value());
                        return false;
                    } else {
                        // ???
                        final boolean success = limitInfo.getLimiter().tryAcquire(1, anno.timeout(),
                                TimeUnit.MICROSECONDS);
                        if (success) {
                            limitInfo.resetFailures(); // ????
                            logger.debug("Token acquired, service is now available.");
                        } else {
                            logger.debug("Failed to acquire token, service will be unavailable temporarily.");
                            limitInfo.addFailures(); // ?
                            response.setStatus(HttpStatus.SERVICE_UNAVAILABLE.value());
                            return false;
                        }
                    }
                }
            }
        }
        return true;
    }

}