An Spring AOP annotation CircuitBreaker using the NetFlix Hystrix circuit breaker (https://github.com/Netflix/Hystrix)
Based on http://blog.mirkosertic.de/architecturedesign/springhystrix
@Override
@CircuitBreaker
public String methodName() throws MyException {
}This will use a Hytrix command to execute the method methodName. The name used for the Hystrix command will be the signature of the method.
You must also include Spring's AOP configuration see below
There are five options
- name - Name of the command used to collect statistics and for display when used with the Hystrix dashboard
- value - Name of the command if no name is specified
- timeoutMilliseconds - Execution timeout in milliseconds. Default is 1000 ms.
- useThreads - If true then a thread pool is used to handle the command execution. Otherwise the command runs in the current thread and semaphores are used to control the number of concurrent executions.
- fallback - Method name for the fallback method (i.e. method executed if an exception is thrown. If a fallback is not specified then the exception is thrown for the calling application to handle.
Create a Circuit Breaker with name "getValue". The timeout will be 5,000 ms and it will use thread pools.
@CircuitBreaker("getValue")Create a Circuit Breaker with name "getValue". The timeout will be 10 sec and it will use semaphore to control access, not thread pools.
@CircuitBreaker(name="getValue", timeoutMilliseconds=10000, useThreads=false)The fallback method should have the same signature as the method that was annotated. For instance
@CircuitBreaker(fallback="fallback")
public String exceptionWithFallback(String s) {
throw new MyRuntimeException();
}
public String fallback(String s) {
return s;
}The fallback can also add a Throwable argument to the end of the parameter list to
get the exception that caused the fallback to be executed.
@CircuitBreaker(fallback="fallback")
public String exceptionWithFallback(String s) {
throw new MyRuntimeException();
}
public String fallback(String s, Throwable t) {
t.printStackTrace();
return s;
}<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<aop:aspectj-autoproxy/>
<context:component-scan base-package="com.marblesit.circuitbreaker"/>
</beans>