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High-Performance Restful Client Library
package com.github.df.restypass.cb;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.Table;
import com.github.df.restypass.command.RestyCommand;
import com.github.df.restypass.enums.CircuitBreakerStatus;
import com.github.df.restypass.enums.RestyCommandStatus;
import com.github.df.restypass.exception.execute.RequestException;
import com.github.df.restypass.lb.server.ServerInstance;
import lombok.ToString;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.locks.ReentrantLock;
/**
* 默认断路器
* Created by darrenfu on 17-7-23.
*/
@SuppressWarnings({"FieldCanBeLocal", "WeakerAccess"})
@ToString(exclude = {"commandQueue", "halfOpenLock"})
@Slf4j
public class DefaultCircuitBreaker implements CircuitBreaker {
/**
* key:[RestyCommand#path, ServerInstance#instanceId, metricsKey]
*/
private static Table keyTable = HashBasedTable.create();
// TODO 熔断条件配置化
/**
* 短路条件：失败请求占总请求的比例
*/
private static Integer breakFailPercentage = 50;
/**
* 短路条件：失败请求最低数量
*/
private static Integer breakFailCount = 10;
/**
* 短路条件：连续失败次数
*/
private static Integer continuousFailCount = 10;
/**
* 断路器半开的时间间隔，Half_Open时，断路器会放行一个请求，如果成功->Open，如果失败->Break
*/
private static Long halfOpenMilliseconds = 1000 * 10L;
/**
* Event key的前缀
*/
private static final String KEY_PREFIX = "default-breaker-";
/**
* 注册事件使用Key
*/
private String eventKey;
/**
* 半开状态使用的锁，保证只有一个请求通过
*/
private ReentrantLock halfOpenLock;
/**
* 启动锁
*/
private ReentrantLock startLock;
/**
* 统计结果缓冲区 metricsKey->Metrics
*/
private ConcurrentHashMap segmentMap;
/**
* 记录短路状态 metricsKey->BreakerStatus
*/
private ConcurrentHashMap statusMap;
/**
* Command 阻塞队列
*/
private LinkedBlockingQueue commandQueue;
/**
* 损坏的server的InstanceId列表
*/
private Set brokenServerSet;
/**
* 断路器是否启动
*/
private boolean started;
/**
* Init Method
*/
public DefaultCircuitBreaker() {
this.started = false;
this.startLock = new ReentrantLock();
}
@Override
public String getEventKey() {
return this.eventKey;
}
@Override
public void start() {
if (!started) {
startLock.lock();
try {
if (!started) {
this.eventKey = KEY_PREFIX + UUID.randomUUID().toString().replace("-", "").toLowerCase();
this.segmentMap = new ConcurrentHashMap<>();
this.statusMap = new ConcurrentHashMap<>();
this.brokenServerSet = new CopyOnWriteArraySet<>();
this.commandQueue = new LinkedBlockingQueue<>();
this.halfOpenLock = new ReentrantLock();
this.registerEvent();
this.startTask();
started = true;
}
} finally {
startLock.unlock();
}
}
}
@Override
public void end() {
started = false;
}
@Override
public boolean shouldPass(RestyCommand restyCommand, ServerInstance serverInstance) {
// 未启动
if (!started) {
return true;
}
String metricsKey = getMetricsKey(restyCommand.getPath(), serverInstance.getInstanceId());
// 强制短路
if (restyCommand.getRestyCommandConfig().isForceBreakEnabled()) {
statusMap.put(metricsKey, CircuitBreakerStatus.FORCE_BREAK);
return false;
} else if (CircuitBreakerStatus.FORCE_BREAK == statusMap.get(metricsKey)) {
// 强制短路关闭后，OPEN
statusMap.put(metricsKey, CircuitBreakerStatus.OPEN);
}
// 断路器未启用
if (!restyCommand.getRestyCommandConfig().isCircuitBreakEnabled()) {
return true;
}
// 获取统计段
Metrics metrics = getCommandMetrics(metricsKey);
if (metrics == null) {
return true;
}
boolean shouldPass = true;
// 获取计数器
Metrics.SegmentMetrics segmentMetrics = metrics.getMetrics();
// 计数器中失败数量和比例超过阀值，则触发短路判断
if (segmentMetrics.getContinuousFailCount() >= continuousFailCount // 连续失败次数达到阀值
// 失败比例以及失败数量达到阀值
|| (segmentMetrics.failCount() >= breakFailCount && segmentMetrics.failPercentage() >= breakFailPercentage)) {
CircuitBreakerStatus breakerStatus = statusMap.get(metricsKey);
shouldPass = false;
if (breakerStatus == null || breakerStatus == CircuitBreakerStatus.OPEN) {
// 短路
statusMap.put(metricsKey, CircuitBreakerStatus.BREAK);
} else if (breakerStatus == CircuitBreakerStatus.HALF_OPEN) {
// noop
} else {
// 如果上次的请求距离现在超过阀值，则允许一次试探请求
long now = System.currentTimeMillis();
if (segmentMetrics.last() != null && (now - segmentMetrics.last() > halfOpenMilliseconds)) {
final ReentrantLock lock = this.halfOpenLock;
lock.lock();
try {
// 判断当前短路状态 确保只有一个请求通过
if (statusMap.get(metricsKey) == CircuitBreakerStatus.BREAK) {
statusMap.put(metricsKey, CircuitBreakerStatus.HALF_OPEN);
shouldPass = true;
}
} finally {
lock.unlock();
}
}
}
if (shouldPass) {
if (log.isDebugEnabled()) {
log.debug("尝试恢复短路服务:{}:{},metrics:{}", restyCommand.getServiceName(), restyCommand.getPath(), metrics);
}
} else if (log.isDebugEnabled()) {
log.debug("熔断服务:{}:{},metrics:{}", restyCommand.getServiceName(), restyCommand.getPath(), metrics);
}
}
return shouldPass;
}
@Override
public Set getBrokenServer() {
return Collections.EMPTY_SET;
}
@Override
public void setStatus(RestyCommand restyCommand, CircuitBreakerStatus status) {
}
/**
* 注册事件以及消费函数
*/
private void registerEvent() {
this.on(this.eventKey, (command) -> {
if (command instanceof RestyCommand) {
if (isQueueAvailable()) {
boolean offer = commandQueue.offer((RestyCommand) command);
if (!offer) {
throw new RuntimeException("Failed to add command into queue");
}
}
}
});
}
/**
* command阻塞队列是否可用
*
* @return 可用 true，不可用 false
*/
private boolean isQueueAvailable() {
return commandQueue != null && commandQueue.size() < 20000;
}
/**
* 消费队列 统计已完成的command信息，更新 segment
*/
private void startTask() {
Executors.newSingleThreadExecutor().submit(() -> {
log.info("启动RestyCommand统计线程:" + this.eventKey);
while (true) {
try {
// 阻塞
RestyCommand firstCommand = commandQueue.take();
// 取出queue中所有的数据
List commandList = new LinkedList<>();
commandList.add(firstCommand);
commandQueue.drainTo(commandList);
for (RestyCommand restyCommand : commandList) {
String key = getMetricsKey(restyCommand.getPath(), restyCommand.getInstanceId());
// 获取 计数器
Metrics metrics = getCommandMetrics(key);
boolean isSuccess = isCommandSuccessExecuted(restyCommand);
boolean forceUseNewMetrics = false;
// 如果当前处在短路或半短路状态
CircuitBreakerStatus breakerStatus = statusMap.get(key);
if ((breakerStatus == CircuitBreakerStatus.BREAK || breakerStatus == CircuitBreakerStatus.HALF_OPEN)) {
// 结果成功 则不再短路，打开断路器
if (isSuccess) {
// 并使用一个新的计数器
forceUseNewMetrics = true;
statusMap.put(key, CircuitBreakerStatus.OPEN);
} else {
// 否则恢复到短路状态
statusMap.put(key, CircuitBreakerStatus.BREAK);
}
}
metrics.store(isSuccess, forceUseNewMetrics);
}
if (log.isTraceEnabled()) {
log.trace("处理完成, 处理个数:{}，剩余:{}个", commandList.size(), commandQueue.size());
}
} catch (Exception ex) {
log.error("断路器RestyCommand处理失败:{}", ex);
}
}
});
}
/**
* command是否成功执行
*
* @param restyCommand Resty请求
* @return 请求是否成功
*/
private boolean isCommandSuccessExecuted(RestyCommand restyCommand) {
if (restyCommand.getStatus() == RestyCommandStatus.FAILED) {
// 请求错误是客户端错误，此处认为请求已被成功执行
return restyCommand.getFailException() instanceof RequestException;
} else if (restyCommand.getStatus() == RestyCommandStatus.SUCCESS) {
return true;
}
return false;
}
/**
* 返回MetricsKey
*
* @param commandPath 请求 path
* @param instanceId server实例ID
* @return key
*/
private String getMetricsKey(String commandPath, String instanceId) {
String metricsKey = keyTable.get(commandPath, instanceId);
if (StringUtils.isEmpty(metricsKey)) {
metricsKey = commandPath + instanceId;
keyTable.put(commandPath, instanceId, metricsKey);
}
return metricsKey;
}
/**
* 获取 segmentDeque
*
* @param metricsKey key
* @return 计数器
*/
private Metrics getCommandMetrics(String metricsKey) {
if (segmentMap == null) {
System.out.println("NULL le ");
}
Metrics metrics = segmentMap.get(metricsKey);
if (metrics == null) {
Metrics newMetrics = new Metrics();
// putIfAbsent
segmentMap.putIfAbsent(metricsKey, newMetrics);
metrics = segmentMap.get(metricsKey);
}
return metrics;
}
}
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