/*******************************************************************************
* Copyright (c) 2005, 2014 springside.github.io
*
* Licensed under the Apache License, Version 2.0 (the "License");
*******************************************************************************/
package org.springside.examples.showcase.demos.hystrix.service;
import java.util.HashMap;
import javax.annotation.PostConstruct;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestTemplate;
import org.springside.examples.showcase.webservice.rest.UserDTO;
import com.netflix.hystrix.HystrixCircuitBreaker;
import com.netflix.hystrix.HystrixCommand.Setter;
import com.netflix.hystrix.HystrixCommandGroupKey;
import com.netflix.hystrix.HystrixCommandKey;
import com.netflix.hystrix.HystrixCommandMetrics;
import com.netflix.hystrix.HystrixCommandMetrics.HealthCounts;
import com.netflix.hystrix.HystrixCommandProperties;
import com.netflix.hystrix.HystrixCommandProperties.ExecutionIsolationStrategy;
import com.netflix.hystrix.HystrixThreadPoolProperties;
import com.netflix.hystrix.util.HystrixRollingNumberEvent;
/**
* 使用Hystrix 封装的Service。原来直接调用restTemplate改为调用Hystrix Command的封装.
*
* @author calvin
*/
@Service
public class UserService {
private boolean isolateThreadPool = true;
private Setter commandConfig;
private RestTemplate restTemplate;
/**
* 创建并调用command, 不处理Hystrix Error，直接透传到Web层.
*/
public UserDTO getUser(Long id) throws Exception {
GetUserCommand command = new GetUserCommand(commandConfig, restTemplate, id);
return command.execute();
}
/**
* 演示获取Hystrix的Metrics.
*/
public MetricsMap getHystrixMetrics() {
MetricsMap metricsMap = new MetricsMap();
HystrixCommandKey key = HystrixCommandKey.Factory.asKey("GetUserCommand");
HystrixCommandMetrics metrics = HystrixCommandMetrics.getInstance(key);
if (metrics != null) {
HealthCounts counts = metrics.getHealthCounts();
HystrixCircuitBreaker circuitBreaker = HystrixCircuitBreaker.Factory.getInstance(key);
metricsMap.put("circuitOpen", circuitBreaker.isOpen());
metricsMap.put("totalRequest", counts.getTotalRequests());
metricsMap.put("errorPercentage", counts.getErrorPercentage());
metricsMap.put("success", metrics.getRollingCount(HystrixRollingNumberEvent.SUCCESS));
metricsMap.put("timeout", metrics.getRollingCount(HystrixRollingNumberEvent.TIMEOUT));
metricsMap.put("failure", metrics.getRollingCount(HystrixRollingNumberEvent.FAILURE));
metricsMap.put("shortCircuited", metrics.getRollingCount(HystrixRollingNumberEvent.SHORT_CIRCUITED));
metricsMap.put("threadPoolRejected",
metrics.getRollingCount(HystrixRollingNumberEvent.THREAD_POOL_REJECTED));
metricsMap.put("semaphoreRejected", metrics.getRollingCount(HystrixRollingNumberEvent.SEMAPHORE_REJECTED));
metricsMap.put("latency50", metrics.getTotalTimePercentile(50));
metricsMap.put("latency90", metrics.getTotalTimePercentile(90));
metricsMap.put("latency100", metrics.getTotalTimePercentile(100));
}
return metricsMap;
}
/**
* 演示Hystrix Command的各种配置项, 并构造Thread-Safed的RestTemplate.
*/
@PostConstruct
public void init() {
// 初始化RestTemplate
restTemplate = new RestTemplate();
// 设置Command名称 //
commandConfig = Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("ExampleGroup")).andCommandKey(
HystrixCommandKey.Factory.asKey("GetUserCommand"));
HystrixCommandProperties.Setter commandProperties = HystrixCommandProperties.Setter();
commandConfig.andCommandPropertiesDefaults(commandProperties);
// 设置短路规则 //
// 设置短路后的保护时间 ，默认为5秒，改为20秒方便演示
commandProperties.withCircuitBreakerSleepWindowInMilliseconds(20000)
// 多少百分比的失败在rolling windows内发生，计算为短路。默认为50%，无改变.
.withCircuitBreakerErrorThresholdPercentage(50)
// 至少多少请求在rolling window内发生，才开始触发短路的计算，默认为20, 设为3方便演示.
.withCircuitBreakerRequestVolumeThreshold(3)
// rolling windows 长度，默认为20秒，改为120秒方便演示。同时相应改变桶的数量.
.withMetricsRollingStatisticalWindowInMilliseconds(120000)
.withMetricsRollingStatisticalWindowBuckets(120);
// 设置超时与并发控制 //
if (isolateThreadPool) { // 使用隔离的Hystrix线程池
// 线程超时，默认为1秒，设为3秒方便演示.
commandProperties.withExecutionIsolationThreadTimeoutInMilliseconds(3000);
// 线程池属性， 线程池大小，默认为10，无改变。待执行队列的大小，默认为5，无改变.
commandConfig.andThreadPoolPropertiesDefaults(HystrixThreadPoolProperties.Setter().withCoreSize(10)
.withQueueSizeRejectionThreshold(5));
} else { // 使用原有的调用者线程
// 依靠RestTemplate本身的超时机制，设为10秒。
((SimpleClientHttpRequestFactory) restTemplate.getRequestFactory()).setReadTimeout(10000);
// 设置使用原有的调用者线程，设置并发，默认为10，无改变.
commandProperties.withExecutionIsolationStrategy(ExecutionIsolationStrategy.SEMAPHORE)
.withExecutionIsolationSemaphoreMaxConcurrentRequests(10);
}
}
public void setIsolateThreadPool(boolean isolateThreadPool) {
this.isolateThreadPool = isolateThreadPool;
}
/**
* 简易Map，对不存在的统计项返回0.
*/
public static class MetricsMap extends HashMap {
@Override
public Object get(Object key) {
Object result = super.get(key);
return result != null ? result : "0";
}
}
}