序

本文主要研究一下skywalking的kafka-plugin

skywalking-plugin.def

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/resources/skywalking-plugin.def

kafka-0.11.x/1.x/2.x=org.apache.skywalking.apm.plugin.kafka.define.CallbackInstrumentation
kafka-0.11.x/1.x/2.x=org.apache.skywalking.apm.plugin.kafka.define.KafkaConsumerInstrumentation
kafka-0.11.x/1.x/2.x=org.apache.skywalking.apm.plugin.kafka.define.KafkaProducerInstrumentation
kafka-0.11.x/1.x/2.x=org.apache.skywalking.apm.plugin.kafka.define.KafkaProducerMapInstrumentation
kafka-0.11.x/1.x/2.x=org.apache.skywalking.apm.plugin.kafka.define.KafkaTemplateInstrumentation
kafka-0.11.x/1.x/2.x=org.apache.skywalking.apm.plugin.kafka.define.KafkaTemplateCallbackInstrumentation

• skywalking的kafka-plugin提供了CallbackInstrumentation、KafkaConsumerInstrumentation、KafkaProducerInstrumentation、KafkaProducerMapInstrumentation、KafkaTemplateInstrumentation、KafkaTemplateCallbackInstrumentation这几个增强

AbstractKafkaInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/define/AbstractKafkaInstrumentation.java

public abstract class AbstractKafkaInstrumentation extends ClassInstanceMethodsEnhancePluginDefine {

    @Override protected String[] witnessClasses() {
        return new String[]{"org.apache.kafka.clients.ApiVersions"};
    }
}

• AbstractKafkaInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，其witnessClasses为org.apache.kafka.clients.ApiVersions

AbstractKafkaTemplateInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/define/AbstractKafkaTemplateInstrumentation.java

public abstract class AbstractKafkaTemplateInstrumentation extends ClassInstanceMethodsEnhancePluginDefine {

    @Override protected String[] witnessClasses() {
        return new String[]{"org.springframework.kafka.core.KafkaTemplate"};
    }
}

• AbstractKafkaTemplateInstrumentation继承了ClassInstanceMethodsEnhancePluginDefine，其witnessClasses为org.springframework.kafka.core.KafkaTemplate

CallbackInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/define/CallbackInstrumentation.java

public class CallbackInstrumentation extends AbstractKafkaInstrumentation {

    public static final String ENHANCE_CLASS = "org.apache.kafka.clients.producer.Callback";
    public static final String ENHANCE_METHOD = "onCompletion";
    public static final String INTERCEPTOR_CLASS = "org.apache.skywalking.apm.plugin.kafka.CallbackInterceptor";

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

    @Override public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
        return new InstanceMethodsInterceptPoint[] {
            new InstanceMethodsInterceptPoint() {
                @Override public ElementMatcher<MethodDescription> getMethodsMatcher() {
                    return named(ENHANCE_METHOD);
                }

                @Override public String getMethodsInterceptor() {
                    return INTERCEPTOR_CLASS;
                }

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

    @Override protected ClassMatch enhanceClass() {
        return byHierarchyMatch(new String[] {ENHANCE_CLASS});
    }
}

• CallbackInstrumentation继承了AbstractKafkaInstrumentation，它使用org.apache.skywalking.apm.plugin.kafka.CallbackInterceptor增强实现了org.apache.kafka.clients.producer.Callback接口的类的onCompletion方法

CallbackInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/CallbackInterceptor.java

public class CallbackInterceptor implements InstanceMethodsAroundInterceptor {

    @Override
    public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class<?>[] argumentsTypes,
                             MethodInterceptResult result) throws Throwable {
        CallbackCache cache = (CallbackCache) objInst.getSkyWalkingDynamicField();
        if (null != cache) {
            ContextSnapshot snapshot = getSnapshot(cache);
            RecordMetadata metadata = (RecordMetadata) allArguments[0];
            AbstractSpan activeSpan = ContextManager.createLocalSpan("Kafka/Producer/Callback");
            activeSpan.setComponent(ComponentsDefine.KAFKA_PRODUCER);
            Tags.MQ_TOPIC.set(activeSpan, metadata.topic());
            ContextManager.continued(snapshot);
        }
    }

    @Override
    public Object afterMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class<?>[] argumentsTypes,
                              Object ret) throws Throwable {
        CallbackCache cache = (CallbackCache) objInst.getSkyWalkingDynamicField();
        if (null != cache) {
            ContextSnapshot snapshot = getSnapshot(cache);
            if (null != snapshot) {
                Exception exceptions = (Exception) allArguments[1];
                if (exceptions != null) {
                    ContextManager.activeSpan().errorOccurred().log(exceptions);
                }
                ContextManager.stopSpan();
            }
        }
        return ret;
    }

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

    private ContextSnapshot getSnapshot(CallbackCache cache) {
        ContextSnapshot snapshot = cache.getSnapshot();
        if (snapshot == null) {
            snapshot = ((CallbackCache) ((EnhancedInstance) cache.getCallback()).getSkyWalkingDynamicField()).getSnapshot();
        }
        return snapshot;
    }
}

• CallbackInterceptor实现了InstanceMethodsAroundInterceptor接口，其beforeMethod方法设置Tags.MQ_TOPIC；其afterMethod方法有异常时执行ContextManager.activeSpan().errorOccurred().log(exceptions)，然后执行ContextManager.stopSpan()；其handleMethodException方法执行ContextManager.activeSpan().errorOccurred().log(t)

KafkaConsumerInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/define/KafkaConsumerInstrumentation.java

public class KafkaConsumerInstrumentation extends AbstractKafkaInstrumentation {

    public static final String CONSTRUCTOR_INTERCEPT_TYPE = "org.apache.kafka.clients.consumer.ConsumerConfig";
    public static final String CONSTRUCTOR_INTERCEPTOR_CLASS = "org.apache.skywalking.apm.plugin.kafka.ConsumerConstructorInterceptor";
    public static final String INTERCEPTOR_CLASS = "org.apache.skywalking.apm.plugin.kafka.KafkaConsumerInterceptor";
    public static final String ENHANCE_METHOD = "pollOnce";
    public static final String ENHANCE_COMPATIBLE_METHOD = "pollForFetches";
    public static final String ENHANCE_CLASS = "org.apache.kafka.clients.consumer.KafkaConsumer";
    public static final String SUBSCRIBE_METHOD = "subscribe";
    public static final String SUBSCRIBE_INTERCEPT_TYPE = "org.apache.kafka.clients.consumer.ConsumerRebalanceListener";
    public static final String SUBSCRIBE_INTERCEPT_CLASS = "org.apache.skywalking.apm.plugin.kafka.SubscribeMethodInterceptor";

    @Override public ConstructorInterceptPoint[] getConstructorsInterceptPoints() {
        return new ConstructorInterceptPoint[] {
            new ConstructorInterceptPoint() {
                @Override public ElementMatcher<MethodDescription> getConstructorMatcher() {
                    return takesArgumentWithType(0, CONSTRUCTOR_INTERCEPT_TYPE);
                }

                @Override public String getConstructorInterceptor() {
                    return CONSTRUCTOR_INTERCEPTOR_CLASS;
                }
            }
        };
    }

    @Override public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
        return new InstanceMethodsInterceptPoint[] {
            new InstanceMethodsInterceptPoint() {
                @Override public ElementMatcher<MethodDescription> getMethodsMatcher() {
                    return named(ENHANCE_METHOD).or(named(ENHANCE_COMPATIBLE_METHOD));
                }

                @Override public String getMethodsInterceptor() {
                    return INTERCEPTOR_CLASS;
                }

                @Override public boolean isOverrideArgs() {
                    return false;
                }
            },
            new InstanceMethodsInterceptPoint() {
                @Override public ElementMatcher<MethodDescription> getMethodsMatcher() {
                    return named(SUBSCRIBE_METHOD).and(takesArgumentWithType(1, SUBSCRIBE_INTERCEPT_TYPE));
                }

                @Override public String getMethodsInterceptor() {
                    return SUBSCRIBE_INTERCEPT_CLASS;
                }

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

    @Override protected ClassMatch enhanceClass() {
        return byName(ENHANCE_CLASS);
    }
}

• KafkaConsumerInstrumentation继承了AbstractKafkaInstrumentation，它增强的是org.apache.kafka.clients.consumer.KafkaConsumer类；它使用org.apache.skywalking.apm.plugin.kafka.ConsumerConstructorInterceptor增强其参数为org.apache.kafka.clients.consumer.ConsumerConfig的构造器；它使用org.apache.skywalking.apm.plugin.kafka.KafkaConsumerInterceptor增强pollOnce、pollForFetches方法；它使用org.apache.skywalking.apm.plugin.kafka.SubscribeMethodInterceptor增强第二个参数为org.apache.kafka.clients.consumer.ConsumerRebalanceListener的subscribe方法

ConsumerConstructorInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/ConsumerConstructorInterceptor.java

public class ConsumerConstructorInterceptor implements InstanceConstructorInterceptor {

    @Override public void onConstruct(EnhancedInstance objInst, Object[] allArguments) {
        ConsumerConfig config = (ConsumerConfig)allArguments[0];
        // set the bootstrap server address
        ConsumerEnhanceRequiredInfo requiredInfo = new ConsumerEnhanceRequiredInfo();
        requiredInfo.setBrokerServers(config.getList("bootstrap.servers"));
        requiredInfo.setGroupId(config.getString("group.id"));
        objInst.setSkyWalkingDynamicField(requiredInfo);
    }
}

• ConsumerConstructorInterceptor实现了InstanceConstructorInterceptor接口，其onConstruct方法创建ConsumerEnhanceRequiredInfo并设置到objInst的skyWalkingDynamicField

KafkaConsumerInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/KafkaConsumerInterceptor.java

public class KafkaConsumerInterceptor implements InstanceMethodsAroundInterceptor {

    public static final String OPERATE_NAME_PREFIX = "Kafka/";
    public static final String CONSUMER_OPERATE_NAME = "/Consumer/";

    @Override
    public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class<?>[] argumentsTypes,
        MethodInterceptResult result) throws Throwable {
        ConsumerEnhanceRequiredInfo requiredInfo = (ConsumerEnhanceRequiredInfo)objInst.getSkyWalkingDynamicField();
        requiredInfo.setStartTime(System.currentTimeMillis());
    }

    @Override
    public Object afterMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class<?>[] argumentsTypes,
        Object ret) throws Throwable {
        Map<TopicPartition, List<ConsumerRecord<?, ?>>> records = (Map<TopicPartition, List<ConsumerRecord<?, ?>>>)ret;
        //
        // The entry span will only be created when the consumer received at least one message.
        //
        if (records.size() > 0) {
            ConsumerEnhanceRequiredInfo requiredInfo = (ConsumerEnhanceRequiredInfo)objInst.getSkyWalkingDynamicField();
            AbstractSpan activeSpan = ContextManager.createEntrySpan(OPERATE_NAME_PREFIX + requiredInfo.getTopics() + CONSUMER_OPERATE_NAME + requiredInfo.getGroupId(), null).start(requiredInfo.getStartTime());

            activeSpan.setComponent(ComponentsDefine.KAFKA_CONSUMER);
            SpanLayer.asMQ(activeSpan);
            Tags.MQ_BROKER.set(activeSpan, requiredInfo.getBrokerServers());
            Tags.MQ_TOPIC.set(activeSpan, requiredInfo.getTopics());

            for (List<ConsumerRecord<?, ?>> consumerRecords : records.values()) {
                for (ConsumerRecord<?, ?> record : consumerRecords) {
                    ContextCarrier contextCarrier = new ContextCarrier();

                    CarrierItem next = contextCarrier.items();
                    while (next.hasNext()) {
                        next = next.next();
                        Iterator<Header> iterator = record.headers().headers(next.getHeadKey()).iterator();
                        if (iterator.hasNext()) {
                            next.setHeadValue(new String(iterator.next().value()));
                        }
                    }
                    ContextManager.extract(contextCarrier);
                }
            }
            ContextManager.stopSpan();
        }
        return ret;
    }

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

• KafkaConsumerInterceptor实现了InstanceMethodsAroundInterceptor接口，其beforeMethod方法获取ConsumerEnhanceRequiredInfo并设置其startTime；其afterMethod方法在records.size()大于0的时候设置Tags.MQ_BROKER、Tags.MQ_TOPIC，然后从ConsumerRecord提取contextCarrier.items()指定的header，然后执行ContextManager.extract(contextCarrier)，最后执行ContextManager.stopSpan()；其handleMethodException方法执行ContextManager.activeSpan().errorOccurred().log(t)

SubscribeMethodInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/SubscribeMethodInterceptor.java

public class SubscribeMethodInterceptor implements InstanceMethodsAroundInterceptor {
    @Override
    public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments, Class<?>[] argumentsTypes,
        MethodInterceptResult result) throws Throwable {
        ConsumerEnhanceRequiredInfo requiredInfo = (ConsumerEnhanceRequiredInfo)objInst.getSkyWalkingDynamicField();
        requiredInfo.setTopics((Collection<String>)allArguments[0]);

        objInst.setSkyWalkingDynamicField(requiredInfo);
    }

    @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) {
        ContextManager.activeSpan().errorOccurred().log(t);
    }
}

• SubscribeMethodInterceptor实现了InstanceMethodsAroundInterceptor接口，其beforeMethod方法创建ConsumerEnhanceRequiredInfo并设置到objInst的skyWalkingDynamicField；其handleMethodException执行ContextManager.activeSpan().errorOccurred().log(t)

KafkaProducerInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/define/KafkaProducerInstrumentation.java

public class KafkaProducerInstrumentation extends AbstractKafkaInstrumentation {

    public static final String INTERCEPTOR_CLASS = "org.apache.skywalking.apm.plugin.kafka.KafkaProducerInterceptor";
    public static final String ENHANCE_CLASS = "org.apache.kafka.clients.producer.KafkaProducer";
    public static final String ENHANCE_METHOD = "doSend";
    public static final String CONSTRUCTOR_INTERCEPTOR_CLASS = "org.apache.skywalking.apm.plugin.kafka.ProducerConstructorInterceptor";
    public static final String CONSTRUCTOR_INTERCEPTOR_FLAG = "org.apache.kafka.clients.producer.ProducerConfig";

    @Override
    public ConstructorInterceptPoint[] getConstructorsInterceptPoints() {
        return new ConstructorInterceptPoint[]{
            new ConstructorInterceptPoint() {
                @Override
                public ElementMatcher<MethodDescription> getConstructorMatcher() {
                    return takesArgumentWithType(0, CONSTRUCTOR_INTERCEPTOR_FLAG);
                }

                @Override
                public String getConstructorInterceptor() {
                    return CONSTRUCTOR_INTERCEPTOR_CLASS;
                }
            }
        };
    }

    @Override
    public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
        return new InstanceMethodsInterceptPoint[]{
            new InstanceMethodsInterceptPoint() {
                @Override
                public ElementMatcher<MethodDescription> getMethodsMatcher() {
                    return named(ENHANCE_METHOD);
                }

                @Override
                public String getMethodsInterceptor() {
                    return INTERCEPTOR_CLASS;
                }

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

    @Override
    protected ClassMatch enhanceClass() {
        return byName(ENHANCE_CLASS);
    }
}

• KafkaProducerInstrumentation继承了AbstractKafkaInstrumentation，它增强的是org.apache.kafka.clients.producer.KafkaProducer类；它使用org.apache.skywalking.apm.plugin.kafka.ProducerConstructorInterceptor增强了其参数为org.apache.kafka.clients.producer.ProducerConfig的构造器；它使用org.apache.skywalking.apm.plugin.kafka.KafkaProducerInterceptor增强其doSend方法

ProducerConstructorInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/ProducerConstructorInterceptor.java

public class ProducerConstructorInterceptor implements InstanceConstructorInterceptor {

    @Override
    public void onConstruct(EnhancedInstance objInst, Object[] allArguments) {
        ProducerConfig config = (ProducerConfig) allArguments[0];
        objInst.setSkyWalkingDynamicField(StringUtil.join(';', config.getList("bootstrap.servers").toArray(new String[0])));
    }
}

• ProducerConstructorInterceptor实现了InstanceConstructorInterceptor接口，其onConstruct将bootstrap.servers信息设置到objInst的skyWalkingDynamicField

KafkaProducerInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/KafkaProducerInterceptor.java

public class KafkaProducerInterceptor implements InstanceMethodsAroundInterceptor {

    public static final String OPERATE_NAME_PREFIX = "Kafka/";
    public static final String PRODUCER_OPERATE_NAME_SUFFIX = "/Producer";

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

        ContextCarrier contextCarrier = new ContextCarrier();

        ProducerRecord record = (ProducerRecord) allArguments[0];
        String topicName = record.topic();
        AbstractSpan activeSpan = ContextManager.createExitSpan(OPERATE_NAME_PREFIX + topicName + PRODUCER_OPERATE_NAME_SUFFIX, contextCarrier, (String) objInst.getSkyWalkingDynamicField());

        Tags.MQ_BROKER.set(activeSpan, (String) objInst.getSkyWalkingDynamicField());
        Tags.MQ_TOPIC.set(activeSpan, topicName);
        SpanLayer.asMQ(activeSpan);
        activeSpan.setComponent(ComponentsDefine.KAFKA_PRODUCER);

        CarrierItem next = contextCarrier.items();
        while (next.hasNext()) {
            next = next.next();
            record.headers().add(next.getHeadKey(), next.getHeadValue().getBytes());
        }
        EnhancedInstance callbackInstance = (EnhancedInstance) allArguments[1];
        if (null != callbackInstance) {
            ContextSnapshot snapshot = ContextManager.capture();
            if (null != snapshot) {
                CallbackCache cache = new CallbackCache();
                cache.setSnapshot(snapshot);
                callbackInstance.setSkyWalkingDynamicField(cache);
            }
        }
    }

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

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

    }
}

• KafkaProducerInterceptor实现了InstanceMethodsAroundInterceptor接口，其beforeMethod方法设置Tags.MQ_BROKER、Tags.MQ_TOPIC，然后将contextCarrier.items()的信息设置到ProducerRecord的header中，另外若ContextSnapshot不为null则执行callbackInstance.setSkyWalkingDynamicField(cache)；其afterMethod方法执行ContextManager.stopSpan()

KafkaProducerMapInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/define/KafkaProducerMapInstrumentation.java

public class KafkaProducerMapInstrumentation extends AbstractKafkaInstrumentation {

    public static final String ENHANCE_CLASS = "org.apache.kafka.clients.producer.KafkaProducer";
    public static final String CONSTRUCTOR_INTERCEPTOR_CLASS = "org.apache.skywalking.apm.plugin.kafka.ProducerConstructorMapInterceptor";
    public static final String CONSTRUCTOR_INTERCEPTOR_FLAG = "java.util.Map";

    @Override
    public ConstructorInterceptPoint[] getConstructorsInterceptPoints() {
        return new ConstructorInterceptPoint[]{
            new ConstructorInterceptPoint() {
                @Override
                public ElementMatcher<MethodDescription> getConstructorMatcher() {
                    return takesArgumentWithType(0, CONSTRUCTOR_INTERCEPTOR_FLAG);
                }

                @Override
                public String getConstructorInterceptor() {
                    return CONSTRUCTOR_INTERCEPTOR_CLASS;
                }
            }
        };
    }

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

    @Override
    protected ClassMatch enhanceClass() {
        return byName(ENHANCE_CLASS);
    }
}

• KafkaProducerMapInstrumentation继承了AbstractKafkaInstrumentation，它使用org.apache.skywalking.apm.plugin.kafka.ProducerConstructorMapInterceptor增强了org.apache.kafka.clients.producer.KafkaProducer参数为java.util.Map的构造器

ProducerConstructorMapInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/ProducerConstructorMapInterceptor.java

public class ProducerConstructorMapInterceptor implements InstanceConstructorInterceptor {

    @Override
    public void onConstruct(EnhancedInstance objInst, Object[] allArguments) {
        Map<String, Object> config = (Map<String, Object>) allArguments[0];
        // prevent errors caused by secondary interception in kafkaTemplate
        if (objInst.getSkyWalkingDynamicField() == null) {
            objInst.setSkyWalkingDynamicField(StringUtil.join(';', ((String) config.get("bootstrap.servers")).split(",")));
        }
    }
}

• ProducerConstructorMapInterceptor实现了InstanceConstructorInterceptor接口，其onConstruct方法将bootstrap.servers信息设置到objInst的skyWalkingDynamicField

KafkaTemplateInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/define/KafkaTemplateInstrumentation.java

public class KafkaTemplateInstrumentation extends AbstractKafkaTemplateInstrumentation {

    private static final String ENHANCE_CLASS = "org.springframework.kafka.core.KafkaTemplate";
    private static final String ENHANCE_METHOD = "buildCallback";
    private static final String INTERCEPTOR_CLASS = "org.apache.skywalking.apm.plugin.kafka.KafkaTemplateCallbackInterceptor";


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

    @Override
    public InstanceMethodsInterceptPoint[] getInstanceMethodsInterceptPoints() {
        return new InstanceMethodsInterceptPoint[]{
            new InstanceMethodsInterceptPoint() {
                @Override
                public ElementMatcher<MethodDescription> getMethodsMatcher() {
                    return named(ENHANCE_METHOD);
                }

                @Override
                public String getMethodsInterceptor() {
                    return INTERCEPTOR_CLASS;
                }

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

    @Override
    protected ClassMatch enhanceClass() {
        return byName(ENHANCE_CLASS);
    }
}

• KafkaTemplateInstrumentation继承了AbstractKafkaTemplateInstrumentation；它使用org.apache.skywalking.apm.plugin.kafka.KafkaTemplateCallbackInterceptor增强了org.springframework.kafka.core.KafkaTemplate的buildCallback方法

KafkaTemplateCallbackInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/KafkaTemplateCallbackInterceptor.java

public class KafkaTemplateCallbackInterceptor implements InstanceMethodsAroundInterceptor {
    @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 {
        return new CallbackAdapter((org.apache.kafka.clients.producer.Callback) ret, objInst);
    }

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

    }
}

• KafkaTemplateCallbackInterceptor实现了InstanceMethodsAroundInterceptor接口，其afterMethod方法将org.apache.kafka.clients.producer.Callback包装为CallbackAdapter返回

KafkaTemplateCallbackInstrumentation

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/define/KafkaTemplateCallbackInstrumentation.java

public class KafkaTemplateCallbackInstrumentation extends AbstractKafkaTemplateInstrumentation {

    private static final String ENHANCE_CLASS = "org.apache.kafka.clients.producer.KafkaProducer$InterceptorCallback";
    private static final String CONSTRUCTOR_INTERCEPT_TYPE = "org.apache.kafka.clients.producer.Callback";
    private static final String CONSTRUCTOR_INTERCEPTOR_CLASS = "org.apache.skywalking.apm.plugin.kafka.CallbackConstructorInterceptor";

    @Override
    public ConstructorInterceptPoint[] getConstructorsInterceptPoints() {
        return new ConstructorInterceptPoint[]{
            new ConstructorInterceptPoint() {
                @Override
                public ElementMatcher<MethodDescription> getConstructorMatcher() {
                    return takesArgumentWithType(0, CONSTRUCTOR_INTERCEPT_TYPE);
                }

                @Override
                public String getConstructorInterceptor() {
                    return CONSTRUCTOR_INTERCEPTOR_CLASS;
                }
            }
        };
    }

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

    @Override
    protected ClassMatch enhanceClass() {
        return byName(ENHANCE_CLASS);
    }
}

• KafkaTemplateCallbackInstrumentation继承了AbstractKafkaTemplateInstrumentation；它使用org.apache.skywalking.apm.plugin.kafka.CallbackConstructorInterceptor增强了org.apache.kafka.clients.producer.KafkaProducer$InterceptorCallback的参数为org.apache.kafka.clients.producer.Callback的构造器

CallbackConstructorInterceptor

skywalking-6.6.0/apm-sniffer/apm-sdk-plugin/kafka-plugin/src/main/java/org/apache/skywalking/apm/plugin/kafka/CallbackConstructorInterceptor.java

public class CallbackConstructorInterceptor implements InstanceConstructorInterceptor {

    @Override
    public void onConstruct(EnhancedInstance objInst, Object[] allArguments) {
        Callback callback = (Callback) allArguments[0];
        CallbackCache cache;
        if (null != objInst.getSkyWalkingDynamicField()) {
            cache = (CallbackCache) objInst.getSkyWalkingDynamicField();
        } else {
            cache = new CallbackCache();
        }
        cache.setCallback(callback);
        objInst.setSkyWalkingDynamicField(cache);
    }
}

• CallbackConstructorInterceptor实现了InstanceConstructorInterceptor接口，其onConstruct方法将CallbackCache设置到objInst的skyWalkingDynamicField

小结

skywalking的kafka-plugin提供了CallbackInstrumentation、KafkaConsumerInstrumentation、KafkaProducerInstrumentation、KafkaProducerMapInstrumentation、KafkaTemplateInstrumentation、KafkaTemplateCallbackInstrumentation这几个增强

doc

• AbstractKafkaInstrumentation
• AbstractKafkaTemplateInstrumentation
• CallbackInstrumentation
• KafkaConsumerInstrumentation
• KafkaProducerInstrumentation
• KafkaProducerMapInstrumentation
• KafkaTemplateInstrumentation
• KafkaTemplateCallbackInstrumentation