private void caughtException(Invoker<?> invoker, Invocation invocation, Exception e) {
String interfaceName = invoker.getUrl().getParameter(Constants.INTERFACE_KEY);
String method = invocation.getMethodName();
StringBuffer interfaceConfig = new StringBuffer(Config.DUBBO_REFERENCE_PREFIX);
interfaceConfig.append(interfaceName);
StringBuffer methodConfig = new StringBuffer(interfaceConfig.toString());
methodConfig.append(".").append(method);
String methodKey = methodConfig.toString();
int timeout =
invoker
.getUrl()
.getMethodParameter(
invocation.getMethodName(), Constants.TIMEOUT_KEY, Constants.DEFAULT_TIMEOUT);
int limit = Config.getBreakLimit(invoker, invocation);
// 一个异常的有效期，是通过连续出现异常数量乘以每个调用的超时时间，比如你配置连续出现10次异常之后进行服务降级，并且每次服务调用的超时时间是2000ms的话，同时
// 每个服务重试次数是为2次，那么就是在(2+1)*2000*10
ExceptionMarker breakMarker =
new ExceptionMarker(System.currentTimeMillis(), limit * timeout, e);
if (!breakCounterMap.containsKey(methodKey)) {
BreakCounter oldValue = breakCounterMap.putIfAbsent(methodKey, new BreakCounter(methodKey));
// 返回的oldValue为空，表示之前没有创建了赌赢的异常计数器,则需要对它分配一个loop
if (oldValue == null) {
nextLoop().register(breakCounterMap.get(methodKey));
}
}
BreakCounter counter = breakCounterMap.get(methodKey);
counter.addExceptionMarker(breakMarker);
logger.info(
"[{}] caught exception for rpc invoke [{}.{}],current exception count [{}]",
localHost,
interfaceName,
method,
counter.getCurrentExceptionCount());
}
/**
* 这里会判断当前调用服务的状态，分析判断是否需要进入降级状态 如果服务在指定的时间区间内累积的错误，达到了配置的次数，则进入服务降级
* 如果满足上面条件，并且满足重试机制，则也不会进入降级流程，而是触发远程服务调用
*
* @param invoker
* @param invocation
* @return
*/
private boolean checkNeedCircuitBreak(Invoker<?> invoker, Invocation invocation) {
String interfaceName = invoker.getUrl().getParameter(Constants.INTERFACE_KEY);
String method = invocation.getMethodName();
String methodKey = Config.getMethodPropertyName(invoker, invocation).toString();
int limit = Config.getBreakLimit(invoker, invocation);
BreakCounter breakCounter = breakCounterMap.get(methodKey);
if (breakCounter != null && breakCounter.isEnable()) {
long currentExceptionCount = breakCounter.getCurrentExceptionCount();
long currentBreakCount = breakCounter.getCurrentBreakCount();
logger.info(
"[{}] check invoke [{}.{}] circuit break,current exception count [{}] limit [{}]",
localHost,
interfaceName,
method,
currentExceptionCount,
limit);
if (limit <= currentExceptionCount) {
if (currentBreakCount > 0 && needRetry(invoker, invocation, currentBreakCount)) {
logger.info(
"[{}] retry invoke [{}.{}] current break count [{}]",
localHost,
interfaceName,
method,
currentBreakCount);
breakCounter.incrementRetryTimes();
return false;
}
return true;
}
}
return false;
}
private void incrementBreakCount(Invoker<?> invoker, Invocation invocation) {
String interfaceName = invoker.getUrl().getParameter(Constants.INTERFACE_KEY);
String method = invocation.getMethodName();
StringBuffer interfaceConfig = new StringBuffer(Config.DUBBO_REFERENCE_PREFIX);
interfaceConfig.append(interfaceName);
StringBuffer methodConfig = new StringBuffer(interfaceConfig.toString());
methodConfig.append(".").append(method);
String methodKey = methodConfig.toString();
BreakCounter counter = breakCounterMap.get(methodKey);
counter.incrementBreakCount();
}
/**
* 将服务恢复正常
*
* @param invoker
* @param invocation
*/
private void toBeNormal(Invoker<?> invoker, Invocation invocation) {
String interfaceName = invoker.getUrl().getParameter(Constants.INTERFACE_KEY);
String method = invocation.getMethodName();
StringBuffer methodConfig = new StringBuffer(Config.DUBBO_REFERENCE_PREFIX);
methodConfig.append(interfaceName).append(".").append(method);
String methodKey = methodConfig.toString();
// 从其中删除对应的异常计数器
BreakCounter counter = breakCounterMap.remove(methodKey);
if (counter != null) {
logger.info("[{}] [{}.{}] to be normal", localHost, interfaceName, methodKey);
// 将这个counter设置为失效
counter.disable();
}
}