/
listener.go
133 lines (116 loc) · 3.16 KB
/
listener.go
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package sqs
import (
"fmt"
"github.com/aws/aws-sdk-go/aws"
"github.com/aws/aws-sdk-go/aws/awserr"
"github.com/aws/aws-sdk-go/aws/session"
"github.com/aws/aws-sdk-go/service/sqs"
"github.com/bogdanrat/web-server/service/queue"
"log"
"strings"
)
type sqsEventListener struct {
svc *sqs.SQS
queueUrl *string
mapper queue.EventMapper
config Config
}
func NewEventListener(sess *session.Session, config Config) (queue.EventListener, error) {
if sess == nil {
return nil, fmt.Errorf("aws session is nil")
}
svc := sqs.New(sess)
mapper, err := queue.NewEventMapper(queue.StaticMapper)
if err != nil {
return nil, err
}
listener := &sqsEventListener{
svc: svc,
mapper: mapper,
config: config,
}
if err := listener.setup(config); err != nil {
return nil, err
}
return listener, nil
}
func (l *sqsEventListener) setup(config Config) error {
output, err := l.svc.GetQueueUrl(&sqs.GetQueueUrlInput{
QueueName: aws.String(config.QueueName),
})
if err != nil {
if aerr, ok := err.(awserr.Error); ok {
code := aerr.Code()
switch code {
case sqs.ErrCodeQueueDoesNotExist, "NotFound":
log.Printf("SQS Queue not found: %s\n", config.QueueName)
return err
}
}
return err
}
l.queueUrl = output.QueueUrl
return nil
}
func (l *sqsEventListener) Listen(eventNames ...string) (<-chan queue.Event, <-chan error, error) {
events := make(chan queue.Event)
errors := make(chan error)
go func() {
for {
l.receiveMessage(events, errors, eventNames...)
}
}()
return events, errors, nil
}
func (l *sqsEventListener) receiveMessage(events chan queue.Event, errors chan error, eventNames ...string) {
output, err := l.svc.ReceiveMessage(&sqs.ReceiveMessageInput{
QueueUrl: l.queueUrl,
MaxNumberOfMessages: aws.Int64(l.config.MaxNumberOfMessages),
VisibilityTimeout: aws.Int64(l.config.VisibilityTimeout),
WaitTimeSeconds: aws.Int64(l.config.WaitTimeSeconds),
AttributeNames: aws.StringSlice([]string{sqs.MessageSystemAttributeNameMessageGroupId}),
MessageAttributeNames: aws.StringSlice([]string{sqs.QueueAttributeNameAll}),
})
if err != nil {
errors <- err
return
}
foundEvent := false
for _, message := range output.Messages {
attributeValue, ok := message.MessageAttributes[queue.EventNameHeader]
if !ok {
continue
}
messageGroupID, ok := message.Attributes[sqs.MessageSystemAttributeNameMessageGroupId]
if ok && strings.EqualFold(*messageGroupID, MessageGroupIDAuth) {
// have a fan-out based on message group id, for example
}
eventName := aws.StringValue(attributeValue.StringValue)
for _, event := range eventNames {
if strings.EqualFold(eventName, event) {
foundEvent = true
break
}
}
if !foundEvent {
continue
}
messageBody := aws.StringValue(message.Body)
event, err := l.mapper.MapEvent(eventName, []byte(messageBody))
if err != nil {
errors <- err
continue
}
events <- event
_, err = l.svc.DeleteMessage(&sqs.DeleteMessageInput{
QueueUrl: l.queueUrl,
ReceiptHandle: message.ReceiptHandle,
})
if err != nil {
errors <- err
}
}
}
func (l *sqsEventListener) EventMapper() queue.EventMapper {
return l.mapper
}