聊聊skywalking的spring-webflux-plugin

序

本文主要研究一下skywalking的spring-webflux-plugin

DispatcherHandlerInstrumentation

skywalking-6.6.0/apm-sniffer/optional-plugins/optional-spring-plugins/spring-webflux-5.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/spring/webflux/v5/define/DispatcherHandlerInstrumentation.java

public class DispatcherHandlerInstrumentation 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("handle");
                }

                @Override
                public String getMethodsInterceptor() {
                    return "org.apache.skywalking.apm.plugin.spring.webflux.v5.DispatcherHandlerHandleMethodInterceptor";
                }

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

    @Override
    protected ClassMatch enhanceClass() {
        return byName("org.springframework.web.reactive.DispatcherHandler");
    }
}

• DispatcherHandlerInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，其使用org.apache.skywalking.apm.plugin.spring.webflux.v5.DispatcherHandlerHandleMethodInterceptor增强org.springframework.web.reactive.DispatcherHandler的handle方法

DispatcherHandlerHandleMethodInterceptor

skywalking-6.6.0/apm-sniffer/optional-plugins/optional-spring-plugins/spring-webflux-5.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/spring/webflux/v5/DispatcherHandlerHandleMethodInterceptor.java

public class DispatcherHandlerHandleMethodInterceptor implements InstanceMethodsAroundInterceptor {
    private static final String DEFAULT_OPERATION_NAME = "WEBFLUX.handle";

    @Override
    public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class<?>[] argumentsTypes,
                             MethodInterceptResult result) throws Throwable {

    }

    @Override
    public Object afterMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class<?>[] argumentsTypes,
                              Object ret) throws Throwable {
        EnhancedInstance instance = getInstance(allArguments[0]);

        ServerWebExchange exchange = (ServerWebExchange) allArguments[0];

        ContextCarrier carrier = new ContextCarrier();
        CarrierItem next = carrier.items();
        HttpHeaders headers = exchange.getRequest().getHeaders();
        while (next.hasNext()) {
            next = next.next();
            List<String> header = headers.get(next.getHeadKey());
            if (header != null && header.size() > 0) {
                next.setHeadValue(header.get(0));
            }
        }

        AbstractSpan span = ContextManager.createEntrySpan(DEFAULT_OPERATION_NAME, carrier);
        span.setComponent(ComponentsDefine.SPRING_WEBFLUX);
        SpanLayer.asHttp(span);
        Tags.URL.set(span, exchange.getRequest().getURI().toString());
        HTTP.METHOD.set(span, exchange.getRequest().getMethodValue());
        instance.setSkyWalkingDynamicField(ContextManager.capture());
        span.prepareForAsync();
        ContextManager.stopSpan(span);

        return ((Mono) ret).doFinally(s -> {
            try {
                Object pathPattern = exchange.getAttribute(HandlerMapping.BEST_MATCHING_PATTERN_ATTRIBUTE);
                if (pathPattern != null) {
                    span.setOperationName(((PathPattern) pathPattern).getPatternString());
                }
                HttpStatus httpStatus = exchange.getResponse().getStatusCode();
                // fix webflux-2.0.0-2.1.0 version have bug. httpStatus is null. not support
                if (httpStatus != null) {
                    Tags.STATUS_CODE.set(span, Integer.toString(httpStatus.value()));
                    if (httpStatus.isError()) {
                        span.errorOccurred();
                    }
                }
            } finally {
                span.asyncFinish();
            }
        });

    }

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

    public static EnhancedInstance getInstance(Object o) {
        EnhancedInstance instance = null;
        if (o instanceof DefaultServerWebExchange) {
            instance = (EnhancedInstance) o;
        } else if (o instanceof ServerWebExchangeDecorator) {
            ServerWebExchange delegate = ((ServerWebExchangeDecorator) o).getDelegate();
            return getInstance(delegate);
        }
        return instance;
    }

}

• DispatcherHandlerHandleMethodInterceptor实现了InstanceMethodsAroundInterceptor接口，其afterMethod方法创建AbstractSpan，设置URL及METHOD的tag，执行span.prepareForAsync()，然后注册Mono的doFinally的Consumer，在里头设置span的operationName，statusCode，以及是否有异常，最后执行span.asyncFinish()

ServerWebExchangeInstrumentation

skywalking-6.6.0/apm-sniffer/optional-plugins/optional-spring-plugins/spring-webflux-5.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/spring/webflux/v5/define/ServerWebExchangeInstrumentation.java

public class ServerWebExchangeInstrumentation extends ClassInstanceMethodsEnhancePluginDefine {
    @Override
    public ConstructorInterceptPoint[] getConstructorsInterceptPoints() {
        return new ConstructorInterceptPoint[]{
            new ConstructorInterceptPoint() {
                @Override
                public ElementMatcher<MethodDescription> getConstructorMatcher() {
                    return any();
                }

                @Override
                public String getConstructorInterceptor() {
                    return "org.apache.skywalking.apm.plugin.spring.webflux.v5.ServerWebExchangeConstructorInterceptor";
                }
            }
        };
    }

    @Override
    public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
        return new InstanceMethodsInterceptPoint[0];
    }

    @Override
    protected ClassMatch enhanceClass() {
        return byName("org.springframework.web.server.adapter.DefaultServerWebExchange");
    }
}

• ServerWebExchangeInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，其使用org.apache.skywalking.apm.plugin.spring.webflux.v5.ServerWebExchangeConstructorInterceptor增强org.springframework.web.server.adapter.DefaultServerWebExchange的所有方法

ServerWebExchangeConstructorInterceptor

skywalking-6.6.0/apm-sniffer/optional-plugins/optional-spring-plugins/spring-webflux-5.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/spring/webflux/v5/ServerWebExchangeConstructorInterceptor.java

public class ServerWebExchangeConstructorInterceptor implements InstanceConstructorInterceptor {
    @Override
    public void onConstruct(EnhancedInstance objInst, Object[] allArguments) {
    }
}

• ServerWebExchangeConstructorInterceptor目前还是空实现

小结

DispatcherHandlerInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，其使用org.apache.skywalking.apm.plugin.spring.webflux.v5.DispatcherHandlerHandleMethodInterceptor增强org.springframework.web.reactive.DispatcherHandler的handle方法；ServerWebExchangeInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，其使用org.apache.skywalking.apm.plugin.spring.webflux.v5.ServerWebExchangeConstructorInterceptor增强org.springframework.web.server.adapter.DefaultServerWebExchange的所有方法

doc

• DispatcherHandlerInstrumentation
• ServerWebExchangeInstrumentation