sentinel/sentinel-extension/sentinel-annotation-aspectj

Sentinel Annotation AspectJ

This extension is an AOP implementation using AspectJ for Sentinel annotations. Currently only runtime weaving is supported.

Annotation

The @SentinelResource annotation indicates a resource definition, including:

• value: Resource name, required (cannot be empty)
• entryType: Resource entry type (inbound or outbound), EntryType.OUT by default
• fallback (refactored since 1.6.0): Fallback method when exceptions caught (including BlockException, but except the exceptions defined in exceptionsToIgnore). The fallback method should be located in the same class with original method by default. If you want to use method in other classes, you can set the fallbackClass with corresponding Class (Note the method in other classes must be static). The method signature requirement:
  • The return type should match the origin method;
  • The parameter list should match the origin method, and an additional Throwable parameter can be provided to get the actual exception.
• defaultFallback (since 1.6.0): The default fallback method when exceptions caught (including BlockException, but except the exceptions defined in exceptionsToIgnore). Its intended to be a universal common fallback method. The method should be located in the same class with original method by default. If you want to use method in other classes, you can set the fallbackClass with corresponding Class (Note the method in other classes must be static). The default fallback method signature requirement:
  • The return type should match the origin method;
  • parameter list should be empty, and an additional Throwable parameter can be provided to get the actual exception.
• blockHandler: Handler method that handles BlockException when blocked. The parameter list of the method should match original method, with the last additional parameter type BlockException. The return type should be same as the original method. The blockHandler method should be located in the same class with original method by default. If you want to use method in other classes, you can set the blockHandlerClass with corresponding Class (Note the method in other classes must be static).
• exceptionsToIgnore (since 1.6.0): List of business exception classes that should not be traced and caught in fallback.
• exceptionsToTrace (since 1.5.1): List of business exception classes to trace and record. In most cases, using exceptionsToIgnore is better. If both exceptionsToTrace and exceptionsToIgnore are present, only exceptionsToIgnore will be activated.

For example:

@SentinelResource(value = "abc", fallback = "doFallback")
public String doSomething(long i) {
    return "Hello " + i;
}

public String doFallback(long i, Throwable t) {
    // Return fallback value.
    return "fallback";
}

public String defaultFallback(Throwable t) {
    return "default_fallback";
}

Configuration

AspectJ

If you are using AspectJ directly, you can add the Sentinel annotation aspect to your aop.xml:

<aspects>
    <aspect name="com.alibaba.csp.sentinel.annotation.aspectj.SentinelResourceAspect"/>
</aspects>

Spring AOP

If you are using Spring AOP, you should add a configuration to register the aspect as a Spring bean:

@Configuration
public class SentinelAspectConfiguration {

    @Bean
    public SentinelResourceAspect sentinelResourceAspect() {
        return new SentinelResourceAspect();
    }
}

An example for using Sentinel Annotation AspectJ with Spring Boot can be found here.