聊聊skywalking的async-annotation-plugin

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<MethodDescription> getMethodsMatcher() {
                    return named("doSubmit").and(takesArgumentWithType(0, "java.util.concurrent.Callable"));
                }
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                @Override
                public String getMethodsInterceptor() {
                    return "org.apache.skywalking.apm.plugin.spring.async.DoSubmitMethodInterceptor";
                }
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                @Override
                public boolean isOverrideArgs() {
                    return true;
                }
            }
        };
    }
​
    @Override
    public ClassMatch enhanceClass() {
        return byName("org.springframework.aop.interceptor.AsyncExecutionAspectSupport");
    }
}

public class DoSubmitMethodInterceptor implements InstanceMethodsAroundInterceptor {
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    @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) {
    }
}

public class SWCallable<V> implements Callable<V> {
​
    private static final String OPERATION_NAME = "SpringAsync";
​
    private Callable<V> callable;
​
    private ContextSnapshot snapshot;
​
    SWCallable(Callable<V> 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();
        }
    }
}