/
consumer.go
98 lines (83 loc) · 2.56 KB
/
consumer.go
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package delayd2
import (
"errors"
"log"
"strconv"
"github.com/aws/aws-sdk-go/service/sqs"
"github.com/nabeken/aws-go-sqs/queue"
"github.com/nabeken/aws-go-sqs/queue/option"
)
var ErrInvalidAttributes = errors.New("delayd2: invalid attributes")
const (
sqsMessageDurationKey = "delayd2-delay"
sqsMessageRelayToKey = "delayd2-relay-to"
)
// Consumer represents a SQS message consumer.
type Consumer struct {
workerID string
driver Driver
queue *queue.Queue
}
func NewConsumer(workerID string, driver Driver, queue *queue.Queue) *Consumer {
return &Consumer{
workerID: workerID,
driver: driver,
queue: queue,
}
}
// ConsumeMessages consumes messages in SQS queue.
// It returns the number of consumed message in success.
func (c *Consumer) ConsumeMessages() (int64, error) {
messages, err := c.queue.ReceiveMessage(
option.MaxNumberOfMessages(10),
option.UseAllAttribute(),
)
if err != nil {
return 0, err
}
var n int64
succeededReceiptHandles := make([]*string, 0, len(messages))
for _, m := range messages {
duration, relayTo, err := extractDelayd2MessageAttributes(m)
if err != nil {
log.Printf("consumer: %s: unable to extract attributes. skipping.", *m.MessageId)
continue
}
err = c.driver.Enqueue(*m.MessageId, duration, relayTo, *m.Body)
if err != nil && err != ErrMessageDuplicated {
log.Printf("consumer: %s: %s: unable to enqueue this message. skipping", *m.MessageId, err)
continue
}
if err == ErrMessageDuplicated {
// delete immediately if duplicated
log.Printf("consumer: %s: %s", *m.MessageId, err)
}
succeededReceiptHandles = append(succeededReceiptHandles, m.ReceiptHandle)
n++
}
if len(succeededReceiptHandles) > 0 {
if err := c.queue.DeleteMessageBatch(succeededReceiptHandles...); err != nil {
log.Printf("consumer: unable to delete messages in batch but continuing since messages will appear again: %s", err)
}
}
return n, nil
}
func extractDelayd2MessageAttributes(message *sqs.Message) (int64, string, error) {
var duration int64
var relayTo string
var err error
durationAttr, found := message.MessageAttributes[sqsMessageDurationKey]
if !found || *durationAttr.DataType != option.DataTypeNumber {
return 0, "", ErrInvalidAttributes
}
duration, err = strconv.ParseInt(*durationAttr.StringValue, 10, 64)
if err != nil {
return 0, "", err
}
relayToAttr, found := message.MessageAttributes[sqsMessageRelayToKey]
if !found || *relayToAttr.DataType != option.DataTypeString {
return 0, "", ErrInvalidAttributes
}
relayTo = *relayToAttr.StringValue
return duration, relayTo, nil
}