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consumer.go
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consumer.go
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package amqp
import (
"fmt"
"time"
"github.com/lunarway/release-manager/internal/log"
"github.com/pkg/errors"
"github.com/streadway/amqp"
)
type consumer struct {
channel *amqp.Channel
queue *amqp.Queue
}
func newConsumer(amqpConn *amqp.Connection, exchangeName, queueName, routingKey string, prefetch int) (*consumer, error) {
channel, err := amqpConn.Channel()
if err != nil {
return nil, errors.WithMessage(err, "get channel")
}
if prefetch > 0 {
err := channel.Qos(prefetch, 0, false)
if err != nil {
return nil, errors.WithMessage(err, "set prefetch with qos")
}
}
amqpQueue, err := channel.QueueDeclare(
queueName, // name
true, // durable
false, // delete when unused
false, // exclusive
false, // no-wait
nil, // arguments
)
if err != nil {
return nil, errors.WithMessage(err, "declare queue")
}
err = channel.QueueBind(queueName, routingKey, exchangeName, false, nil)
if err != nil {
return nil, errors.WithMessage(err, "bind to queue")
}
return &consumer{
channel: channel,
queue: &amqpQueue,
}, nil
}
func (c *consumer) Close() error {
// TODO: stop consuming messages with c.channel.Cancel() and wait for the
// consumer to complete before closing the connection to avoid dropping
// inflight messages.
err := c.channel.Close()
if err != nil {
return errors.WithMessage(err, "close amqp channel")
}
return nil
}
func (c *consumer) Start(logger *log.Logger, handlers map[string]func([]byte) error, errorHandler func(msgType string, msgBody []byte, err error)) error {
msgs, err := c.channel.Consume(
c.queue.Name, // queue
"release-manager", // consumer
false, // auto-ack
false, // exclusive
false, // no-local
false, // no-wait
nil, // args
)
if err != nil {
return errors.WithMessage(err, "consume messages")
}
for msg := range msgs {
logger := logger.With(
"routingKey", msg.RoutingKey,
"messageId", msg.MessageId,
"eventType", msg.Type,
"correlationId", msg.CorrelationId,
"headers", fmt.Sprintf("%#v", msg.Headers),
)
logger.Infof("Received message type=%s from exchange=%s routingKey=%s messageId=%s correlationId=%s timestamp=%s", msg.Type, msg.Exchange, msg.RoutingKey, msg.MessageId, msg.CorrelationId, msg.Timestamp)
now := time.Now()
handler, ok := handlers[msg.Type]
if !ok {
logger.With("res", map[string]interface{}{
"status": "failed",
"error": "unprocessable",
}).Errorf("[consumer] [UNPROCESSABLE] Failed to handle message: no handler registered for event type '%s': dropping it", msg.Type)
err := msg.Nack(false, false)
if err != nil {
logger.Errorf("Failed to nack message: %v", err)
}
continue
}
err := handler(msg.Body)
duration := time.Since(now).Milliseconds()
if err != nil {
res := map[string]interface{}{
"status": "failed",
"responseTime": duration,
"error": fmt.Sprintf("%+v", err),
"redelivered": msg.Redelivered,
}
if msg.Redelivered {
logger.With("res", res).Errorf("[consumer] [FAILED] Failed to handle message: trigger error handling and nacking with no requeue")
errorHandler(msg.Type, msg.Body, err)
err = msg.Nack(false, false)
if err != nil {
logger.Errorf("Failed to nack message: %v", err)
}
continue
}
logger.With("res", res).Errorf("[consumer] [FAILED] Failed to handle message: requeuing")
err = msg.Nack(false, true)
if err != nil {
logger.Errorf("Failed to nack message: %v", err)
}
continue
}
logger.With("res", map[string]interface{}{
"status": "ok",
"responseTime": duration,
"redelivered": msg.Redelivered,
}).Info("[OK] Event handled successfully")
err = msg.Ack(false)
if err != nil {
logger.Errorf("Failed to ack message: %v", err)
}
}
return nil
}