plugins/segmentio-kafka/reader_interceptor.go

// Licensed to Apache Software Foundation (ASF) under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Apache Software Foundation (ASF) licenses this file to you under
// the Apache License, Version 2.0 (the "License"); you may
// not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package segmentiokafka

import (
	"strings"

	"github.com/segmentio/kafka-go"

	"github.com/apache/skywalking-go/plugins/core/operator"
	"github.com/apache/skywalking-go/plugins/core/tracing"
)

const (
	kafkaReaderPrefix      = "Kafka/"
	kafkaReaderSuffix      = "/Consumer"
	kafkaReaderComponentID = 41
	semicolon              = ";"
)

type ReaderInterceptor struct {
}

func (r *ReaderInterceptor) BeforeInvoke(invocation operator.Invocation) error {
	return nil
}

func (r *ReaderInterceptor) AfterInvoke(invocation operator.Invocation, result ...interface{}) error {
	reader := invocation.CallerInstance().(*kafka.Reader)
	brokers := strings.Join(reader.Config().Brokers, semicolon)
	message := result[0].(kafka.Message)
	topic := message.Topic
	operationName := kafkaReaderPrefix + topic + kafkaReaderSuffix

	span, err := tracing.CreateEntrySpan(operationName, func(headerKey string) (string, error) {
		for _, header := range message.Headers {
			if header.Key == headerKey {
				return string(header.Value), nil
			}
		}
		return "", nil
	},
		tracing.WithLayer(tracing.SpanLayerMQ),
		tracing.WithComponent(kafkaReaderComponentID),
		tracing.WithTag(tracing.TagMQBroker, brokers),
		tracing.WithTag(tracing.TagMQTopic, topic),
	)
	if err != nil {
		return err
	}

	if err, ok := result[1].(error); ok {
		span.Tag(tracing.TagMQStatus, err.Error())
		span.Error(err.Error())
	}
	span.SetPeer(brokers)
	span.End()
	return nil
}