聊聊skywalking的async-annotation-plugin

序

本文主要研究一下skywalking的async-annotation-plugin

AsyncExecutionInterceptorInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/spring-plugins/async-annotation-plugin/src/main/java/org/apache/skywalking/apm/plugin/spring/async/define/AsyncExecutionInterceptorInstrumentation.java

public class AsyncExecutionInterceptorInstrumentation extends ClassInstanceMethodsEnhancePluginDefine {

    @Override
    public ConstructorInterceptPoint[] getConstructorsInterceptPoints() {
        return new ConstructorInterceptPoint[0];
    }

    @Override
    public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
        return new InstanceMethodsInterceptPoint[]{
            new InstanceMethodsInterceptPoint() {
                @Override
                public ElementMatcher getMethodsMatcher() {
                    return named("doSubmit").and(takesArgumentWithType(0, "java.util.concurrent.Callable"));
                }

                @Override
                public String getMethodsInterceptor() {
                    return "org.apache.skywalking.apm.plugin.spring.async.DoSubmitMethodInterceptor";
                }

                @Override
                public boolean isOverrideArgs() {
                    return true;
                }
            }
        };
    }

    @Override
    public ClassMatch enhanceClass() {
        return byName("org.springframework.aop.interceptor.AsyncExecutionAspectSupport");
    }
}

• AsyncExecutionInterceptorInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，它使用org.apache.skywalking.apm.plugin.spring.async.DoSubmitMethodInterceptor拦截org.springframework.aop.interceptor.AsyncExecutionAspectSupport的第一个参数类型为java.util.concurrent.Callable的doSubmit方法

DoSubmitMethodInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/spring-plugins/async-annotation-plugin/src/main/java/org/apache/skywalking/apm/plugin/spring/async/DoSubmitMethodInterceptor.java

public class DoSubmitMethodInterceptor implements InstanceMethodsAroundInterceptor {

    @Override
    public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class[] argumentsTypes,
                             MethodInterceptResult result) throws Throwable {
        if (ContextManager.isActive()) {
            allArguments[0] = new SWCallable((Callable) allArguments[0], ContextManager.capture());
        }
    }

    @Override
    public Object afterMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
                              Class[] argumentsTypes, Object ret) throws Throwable {
        return ret;
    }


    @Override
    public void handleMethodException(EnhancedInstance objInst, Method method, Object[] allArguments,
                                      Class[] argumentsTypes, Throwable t) {
    }
}

• DoSubmitMethodInterceptor实现了InstanceMethodsAroundInterceptor接口，其beforeMethod方法将allArguments[0]包装为SWCallable

SWCallable

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/spring-plugins/async-annotation-plugin/src/main/java/org/apache/skywalking/apm/plugin/spring/async/SWCallable.java

public class SWCallable implements Callable {

    private static final String OPERATION_NAME = "SpringAsync";

    private Callable callable;

    private ContextSnapshot snapshot;

    SWCallable(Callable callable, ContextSnapshot snapshot) {
        this.callable = callable;
        this.snapshot = snapshot;
    }

    @Override
    public V call() throws Exception {
        AbstractSpan span = ContextManager.createLocalSpan(SWCallable.OPERATION_NAME);
        span.setComponent(ComponentsDefine.SPRING_ASYNC);
        try {
            ContextManager.continued(snapshot);
            return callable.call();
        } catch (Exception e) {
            ContextManager.activeSpan().errorOccurred().log(e);
            throw e;
        } finally {
            ContextManager.stopSpan();
        }
    }
}

• SWCallable实现了Callable接口，其call方法在执行callable.call()之前先ContextManager.createLocalSpan，然后执行ContextManager.continued(snapshot)，之后在catch异常里头执行ContextManager.activeSpan().errorOccurred().log(e)，最后在finally里头执行ContextManager.stopSpan()

小结

AsyncExecutionInterceptorInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，它使用org.apache.skywalking.apm.plugin.spring.async.DoSubmitMethodInterceptor拦截org.springframework.aop.interceptor.AsyncExecutionAspectSupport的第一个参数类型为java.util.concurrent.Callable的doSubmit方法

doc

• AsyncExecutionInterceptorInstrumentation