浅谈skywalking的spring-webflux-plugin

本文参考原文-http://bjbsair.com/2020-03-22/tech-info/5100/
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

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

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

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

来源：51CTO

作者：朱柿子

链接：https://blog.51cto.com/14744108/2481183

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Spring

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