forked from DataDog/dd-trace-go
/
kafka.go
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/
kafka.go
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// Unless explicitly stated otherwise all files in this repository are licensed
// under the Apache License Version 2.0.
// This product includes software developed at Datadog (https://www.datadoghq.com/).
// Copyright 2016-2020 Datadog, Inc.
// Package kafka provides functions to trace the confluentinc/confluent-kafka-go package (https://github.com/confluentinc/confluent-kafka-go).
package kafka // import "gopkg.in/DataDog/dd-trace-go.v1/contrib/confluentinc/confluent-kafka-go/kafka"
import (
"math"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
"gopkg.in/confluentinc/confluent-kafka-go.v1/kafka"
)
// NewConsumer calls kafka.NewConsumer and wraps the resulting Consumer.
func NewConsumer(conf *kafka.ConfigMap, opts ...Option) (*Consumer, error) {
c, err := kafka.NewConsumer(conf)
if err != nil {
return nil, err
}
return WrapConsumer(c, opts...), nil
}
// NewProducer calls kafka.NewProducer and wraps the resulting Producer.
func NewProducer(conf *kafka.ConfigMap, opts ...Option) (*Producer, error) {
p, err := kafka.NewProducer(conf)
if err != nil {
return nil, err
}
return WrapProducer(p, opts...), nil
}
// A Consumer wraps a kafka.Consumer.
type Consumer struct {
*kafka.Consumer
cfg *config
events chan kafka.Event
prev ddtrace.Span
}
// WrapConsumer wraps a kafka.Consumer so that any consumed events are traced.
func WrapConsumer(c *kafka.Consumer, opts ...Option) *Consumer {
wrapped := &Consumer{
Consumer: c,
cfg: newConfig(opts...),
}
wrapped.events = wrapped.traceEventsChannel(c.Events())
return wrapped
}
func (c *Consumer) traceEventsChannel(in chan kafka.Event) chan kafka.Event {
// in will be nil when consuming via the events channel is not enabled
if in == nil {
return nil
}
out := make(chan kafka.Event, 1)
go func() {
defer close(out)
for evt := range in {
var next ddtrace.Span
// only trace messages
if msg, ok := evt.(*kafka.Message); ok {
next = c.startSpan(msg)
}
out <- evt
if c.prev != nil {
c.prev.Finish()
}
c.prev = next
}
// finish any remaining span
if c.prev != nil {
c.prev.Finish()
c.prev = nil
}
}()
return out
}
func (c *Consumer) startSpan(msg *kafka.Message) ddtrace.Span {
opts := []tracer.StartSpanOption{
tracer.ServiceName(c.cfg.consumerServiceName),
tracer.ResourceName("Consume Topic " + *msg.TopicPartition.Topic),
tracer.SpanType(ext.SpanTypeMessageConsumer),
tracer.Tag("partition", msg.TopicPartition.Partition),
tracer.Tag("offset", msg.TopicPartition.Offset),
tracer.Measured(),
}
if !math.IsNaN(c.cfg.analyticsRate) {
opts = append(opts, tracer.Tag(ext.EventSampleRate, c.cfg.analyticsRate))
}
// kafka supports headers, so try to extract a span context
carrier := NewMessageCarrier(msg)
if spanctx, err := tracer.Extract(carrier); err == nil {
opts = append(opts, tracer.ChildOf(spanctx))
}
span, _ := tracer.StartSpanFromContext(c.cfg.ctx, "kafka.consume", opts...)
// reinject the span context so consumers can pick it up
tracer.Inject(span.Context(), carrier)
return span
}
// Close calls the underlying Consumer.Close and if polling is enabled, finishes
// any remaining span.
func (c *Consumer) Close() error {
err := c.Consumer.Close()
// we only close the previous span if consuming via the events channel is
// not enabled, because otherwise there would be a data race from the
// consuming goroutine.
if c.events == nil && c.prev != nil {
c.prev.Finish()
c.prev = nil
}
return err
}
// Events returns the kafka Events channel (if enabled). Message events will be
// traced.
func (c *Consumer) Events() chan kafka.Event {
return c.events
}
// Poll polls the consumer for messages or events. Message events will be
// traced.
func (c *Consumer) Poll(timeoutMS int) (event kafka.Event) {
if c.prev != nil {
c.prev.Finish()
c.prev = nil
}
evt := c.Consumer.Poll(timeoutMS)
if msg, ok := evt.(*kafka.Message); ok {
c.prev = c.startSpan(msg)
}
return evt
}
// A Producer wraps a kafka.Producer.
type Producer struct {
*kafka.Producer
cfg *config
produceChannel chan *kafka.Message
}
// WrapProducer wraps a kafka.Producer so requests are traced.
func WrapProducer(p *kafka.Producer, opts ...Option) *Producer {
wrapped := &Producer{
Producer: p,
cfg: newConfig(opts...),
}
wrapped.produceChannel = wrapped.traceProduceChannel(p.ProduceChannel())
return wrapped
}
func (p *Producer) traceProduceChannel(out chan *kafka.Message) chan *kafka.Message {
if out == nil {
return out
}
in := make(chan *kafka.Message, 1)
go func() {
for msg := range in {
span := p.startSpan(msg)
out <- msg
span.Finish()
}
}()
return in
}
func (p *Producer) startSpan(msg *kafka.Message) ddtrace.Span {
opts := []tracer.StartSpanOption{
tracer.ServiceName(p.cfg.producerServiceName),
tracer.ResourceName("Produce Topic " + *msg.TopicPartition.Topic),
tracer.SpanType(ext.SpanTypeMessageProducer),
tracer.Tag("partition", msg.TopicPartition.Partition),
}
if !math.IsNaN(p.cfg.analyticsRate) {
opts = append(opts, tracer.Tag(ext.EventSampleRate, p.cfg.analyticsRate))
}
carrier := NewMessageCarrier(msg)
span, _ := tracer.StartSpanFromContext(p.cfg.ctx, "kafka.produce", opts...)
// inject the span context so consumers can pick it up
tracer.Inject(span.Context(), carrier)
return span
}
// Close calls the underlying Producer.Close and also closes the internal
// wrapping producer channel.
func (p *Producer) Close() {
close(p.produceChannel)
p.Producer.Close()
}
// Produce calls the underlying Producer.Produce and traces the request.
func (p *Producer) Produce(msg *kafka.Message, deliveryChan chan kafka.Event) error {
span := p.startSpan(msg)
// if the user has selected a delivery channel, we will wrap it and
// wait for the delivery event to finish the span
if deliveryChan != nil {
oldDeliveryChan := deliveryChan
deliveryChan = make(chan kafka.Event)
go func() {
var err error
evt := <-deliveryChan
if msg, ok := evt.(*kafka.Message); ok {
// delivery errors are returned via TopicPartition.Error
err = msg.TopicPartition.Error
}
span.Finish(tracer.WithError(err))
oldDeliveryChan <- evt
}()
}
err := p.Producer.Produce(msg, deliveryChan)
// with no delivery channel, finish immediately
if deliveryChan == nil {
span.Finish(tracer.WithError(err))
}
return err
}
// ProduceChannel returns a channel which can receive kafka Messages and will
// send them to the underlying producer channel.
func (p *Producer) ProduceChannel() chan *kafka.Message {
return p.produceChannel
}