/
library.go
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/
library.go
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// MIT License
//
// (C) Copyright [2020-2022] Hewlett Packard Enterprise Development LP
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
// THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
// OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
// OTHER DEALINGS IN THE SOFTWARE.
package trs_kafka
import (
"context"
"fmt"
"math/rand"
"sort"
"sync"
"time"
"github.com/confluentinc/confluent-kafka-go/kafka"
"github.com/sirupsen/logrus"
)
type TRSKafkaConsumer struct {
Errors chan error
Responses chan *kafka.Message
Logger *logrus.Logger
}
type TRSKafkaClient struct {
Producer *kafka.Producer
Consumer *TRSKafkaConsumer
Logger *logrus.Logger
}
type TRSKafka struct {
Client *TRSKafkaClient
ConsumerShutdown chan int
RcvTopicNames []string
Mux sync.Mutex
Logger *logrus.Logger
}
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// TRS Kafka API Functions
/////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////
// This function sets up a kafka interface capable of publishing tasks to
// a topic and consuming data from a TRS worker.
//
// ctx: Cancel-able global context that everything runs under.
// appName: Application name, used for constructing topics.
// workerClass: TRS worker class. Currently REST.
// consumerGroup: Kafka response consumer group. nil == random.
// Random will cause all instances of your app to receive
// all responses from TRS workers.
// brokerSpec: Kafka broker to use (e.g. 10.2.3.4:9092)
// tasksChan: Channel through which TRS responses are consumed. "" == N/A.
func (trsKafka *TRSKafka) Init(ctx context.Context,
initialReceiveTopics []string,
consumerGroup string,
brokerSpec string,
tasksChan chan *kafka.Message, logger *logrus.Logger) (err error) {
if logger != nil {
trsKafka.Logger = logger
} else {
trsKafka.Logger = logrus.New()
}
var consumerGroupName string
if len(initialReceiveTopics) == 0 {
err = fmt.Errorf("Invalid empty initial receiver topic.")
return
}
if ctx == nil {
err = fmt.Errorf("Non-nil context required.")
return
}
if brokerSpec == "" {
err = fmt.Errorf("Non-nil broker specification is required.")
return
}
trsKafka.Mux.Lock()
trsKafka.RcvTopicNames = initialReceiveTopics
trsKafka.Mux.Unlock()
//Consumer group is only for responses. nil == use a random one.
if consumerGroup == "" {
s1 := rand.NewSource(time.Now().UnixNano())
r1 := rand.New(s1)
consumerGroupName = fmt.Sprintf("%d", r1.Int31())
} else {
consumerGroupName = consumerGroup
}
connected := false
// Spin up Kafka Producer
var kafkaProducer *kafka.Producer
var kafkaConnectErr error
for !connected {
kafkaProducer, kafkaConnectErr = kafka.NewProducer(&kafka.ConfigMap{
"bootstrap.servers": brokerSpec})
if kafkaConnectErr != nil {
trsKafka.Logger.Errorf("BrokerAddress: %s -- Unable to connect to Kafka! Trying again in 1 second... err: %s",
brokerSpec, kafkaConnectErr)
time.Sleep(1 * time.Second)
} else {
connected = true
}
}
trsKafka.Logger.Infof("Broker: %s -- Connected to Kafka server.",
brokerSpec)
// Now, setup a consumer on the response channel. The client might
// not care about responses, but we're going to listen for them anyway.
kafkaConsumer, kafkaConsumerErr := kafka.NewConsumer(&kafka.ConfigMap{
"bootstrap.servers": brokerSpec,
"broker.address.family": "v4",
"group.id": consumerGroupName,
"session.timeout.ms": 10000,
"auto.offset.reset": "latest"})
if kafkaConsumerErr != nil {
err = fmt.Errorf("unable to setup consumer: %s", kafkaConsumerErr)
return
}
trsKafka.Logger.Tracef("NewConsumer() succeeded.")
consumer := &TRSKafkaConsumer{
Errors: make(chan error),
Responses: tasksChan,
}
consumer.Logger = trsKafka.Logger
//Subscribe to initial topics.
subErr := kafkaConsumer.SubscribeTopics(trsKafka.RcvTopicNames,nil)
if (subErr != nil) {
err = fmt.Errorf("Error subscribing to topics: '%v': %v",
trsKafka.RcvTopicNames,subErr)
return
}
//Consumer thread, reads messages and handles error messages.
go func() {
topix := trsKafka.RcvTopicNames
for {
ev := kafkaConsumer.Poll(500) //Block no more than .5 sec
switch e := ev.(type) {
case *kafka.Message:
consumer.Responses <-e
case *kafka.Error:
err = fmt.Errorf(e.Error())
consumer.Errors <-err
//TODO: really kill the loop on consume error?
return
default:
trsKafka.Logger.Tracef("Kafka poll() info: %v",e)
}
// Check if context was cancelled, signaling that the consumer
// should stop.
if ctx.Err() != nil {
consumer.Errors <- ctx.Err()
err = ctx.Err()
return
}
//Check for topic changes. If there are changes, apply them.
if (newTopics(topix,trsKafka.RcvTopicNames)) {
topix = trsKafka.RcvTopicNames
subErr := kafkaConsumer.SubscribeTopics(trsKafka.RcvTopicNames,nil)
if (subErr != nil) {
trsKafka.Logger.Errorf("Changing consumer topics to '%v' failed...")
}
}
}
}()
//Producer thread. Drains error messages only.
go func() {
evChan := kafkaProducer.Events()
for {
e,isOpen := <-evChan
if (!isOpen) {
trsKafka.Logger.Tracef("Closing kafka producer thread, producer is gone.")
return
}
switch ev := e.(type) {
case *kafka.Message:
m := ev
if m.TopicPartition.Error != nil {
logger.Errorf("Kafka message delivery failed: key: '%s', topic: '%s', partition: %d, error: %v",
string(m.Key),
*m.TopicPartition.Topic,
m.TopicPartition.Partition,
m.TopicPartition.Error)
} else {
logger.Tracef("Kafka delivered message to topic %s [%d] at offset %v",
*m.TopicPartition.Topic, m.TopicPartition.Partition,
m.TopicPartition.Offset)
}
default:
logger.Tracef("Kafka producer: Ignored event: %s", ev)
}
}
}()
trsKafka.Client = &TRSKafkaClient{
Producer: kafkaProducer,
Consumer: consumer,
}
trsKafka.Client.Logger = trsKafka.Logger
trsKafka.ConsumerShutdown = make(chan int)
// Now that we know the client is up and running, spin up a goroutine
// to monitor the context and when it cancels cleanup the client.
go func() {
select {
case <-trsKafka.ConsumerShutdown:
case <-ctx.Done():
// Best attempt, no point in complaining, we're ending anyway.
_ = kafkaConsumer.Close()
}
}()
return
}
// Convenience function to create topic names for a service. Given the
// app name, worker class, and consumer group names, returns the "cooked"
// send, receive topic and the consumer group.
//
// appName: Name of this application.
// workerClass: Application class (e.g. "REST")
// consumerGroup: If empty, a random consumer group will be generated.
// Otherwise a predictable consumer group name is generated.
// Return: Formatted send and receive topics, and consumer group name.
func GenerateSendReceiveConsumerGroupName(appName, workerClass, consumerGroup string) (sendTopic string, rcvTopic string, cgroupName string) {
cgroupName = ""
if consumerGroup == "" {
s1 := rand.NewSource(time.Now().UnixNano())
r1 := rand.New(s1)
cgroupName = fmt.Sprintf("%s-%s-%d", appName, workerClass, r1.Int31())
} else {
cgroupName = fmt.Sprintf("%s-%s-%s", appName, workerClass, consumerGroup)
}
sendTopic = fmt.Sprintf("trs-%s-%s-send", appName, workerClass)
rcvTopic = fmt.Sprintf("trs-%s-%s-rcv", appName, workerClass)
return
}
// This function will cause the given payload to be written using the
// topic specified when opening the connection.
func (trsKafka *TRSKafka) Write(topic string, payload []byte) {
msg := &kafka.Message{TopicPartition: kafka.TopicPartition{Topic: &topic, Partition: kafka.PartitionAny}, Value: payload}
(*trsKafka.Client.Producer).ProduceChannel() <- msg
trsKafka.Logger.Tracef("Sent message; topic: %s, msg.Value: %s",
topic, string(payload))
}
func (trsKafka *TRSKafka) SetTopics(topics []string) (err error) {
if len(topics) == 0 {
err = fmt.Errorf("Invalid receiver topics")
return
}
trsKafka.Logger.Tracef("Current topics: %s", trsKafka.RcvTopicNames)
trsKafka.Mux.Lock()
trsKafka.RcvTopicNames = topics
trsKafka.Mux.Unlock()
trsKafka.Logger.Tracef("New topics: %s", trsKafka.RcvTopicNames)
return
}
// Shut down a Kafka client connection
func (trsKafka *TRSKafka) Shutdown() {
if trsKafka.Client != nil {
trsKafka.ConsumerShutdown <- 1
if trsKafka.Client.Producer != nil {
(*trsKafka.Client.Producer).Close()
}
}
}
// Convenience function, checks topic list to see if it has changed.
func newTopics(currTopics []string, newTopics []string) bool {
isNew := false
if (len(currTopics) != len(newTopics)) {
isNew = true
} else {
//Pain, should sort to be sure someone didn't just re-do
//the same topics but in a different order.
tSorted := currTopics
sort.Strings(tSorted)
rtnSorted := newTopics
sort.Strings(rtnSorted)
for ix := 0; ix < len(tSorted); ix ++ {
if (tSorted[ix] != rtnSorted[ix]) {
isNew = true
break
}
}
}
return isNew
}