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consumer.go
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consumer.go
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package grmq
import (
"context"
"sync"
"github.com/pkg/errors"
amqp "github.com/rabbitmq/amqp091-go"
"github.com/txix-open/grmq/consumer"
"github.com/txix-open/grmq/retry"
)
type Consumer struct {
cfg consumer.Consumer
ch *amqp.Channel
retryer *retry.Retryer
deliveryWg *sync.WaitGroup
workersWg *sync.WaitGroup
workersStop chan struct{}
closeConsumer chan struct{}
observer Observer
unexpectedErr chan *amqp.Error
deliveries <-chan amqp.Delivery
}
func NewConsumer(cfg consumer.Consumer, ch *amqp.Channel, retryPub *Publisher, observer Observer) *Consumer {
var retryer *retry.Retryer
if cfg.RetryPolicy != nil {
retryer = retry.NewRetryer(cfg.Queue, *cfg.RetryPolicy, retryPub)
}
return &Consumer{
cfg: cfg,
ch: ch,
retryer: retryer,
workersWg: &sync.WaitGroup{},
deliveryWg: &sync.WaitGroup{},
unexpectedErr: make(chan *amqp.Error, 1),
workersStop: make(chan struct{}),
closeConsumer: make(chan struct{}),
observer: observer,
}
}
func (c *Consumer) Run() error {
c.unexpectedErr = c.ch.NotifyClose(c.unexpectedErr)
go c.runUnexpectedErrorListener()
if c.cfg.PrefetchCount > 0 {
err := c.ch.Qos(c.cfg.PrefetchCount, 0, false)
if err != nil {
return errors.WithMessage(err, "set qos")
}
}
deliveries, err := c.ch.Consume(c.cfg.Queue, c.cfg.Name, false, false, false, false, nil)
if err != nil {
return errors.WithMessage(err, "begin consume")
}
c.deliveries = deliveries
for i := 0; i < c.cfg.Concurrency; i++ {
c.workersWg.Add(1)
go c.runWorker()
}
return nil
}
func (c *Consumer) runWorker() {
defer c.workersWg.Done()
for {
select {
case delivery, isOpen := <-c.deliveries:
if !isOpen { //normal close
return
}
c.deliveryWg.Add(1)
d := consumer.NewDelivery(c.deliveryWg, &delivery, c.retryer)
c.cfg.Handler().Handle(context.Background(), d)
case <-c.workersStop:
return //unexpected error occurred
}
}
}
func (c *Consumer) runUnexpectedErrorListener() {
for {
select {
case <-c.closeConsumer: //close consumer
return
case err, isOpen := <-c.unexpectedErr:
if !isOpen { //normal close
return
}
if err != nil {
c.observer.ConsumerError(c.cfg, err)
close(c.workersStop) //stop all workers because of unexpected error
return
}
}
}
}
func (c *Consumer) Close() error {
err := c.ch.Cancel(c.cfg.Name, false)
if err != nil {
return errors.WithMessage(err, "channel cancel")
}
close(c.closeConsumer)
if c.cfg.Closer != nil {
c.cfg.Closer.Close()
}
c.workersWg.Wait()
c.deliveryWg.Wait()
err = c.ch.Close()
return errors.WithMessage(err, "channel close")
}