/
subscriber.go
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/
subscriber.go
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package amqp
import (
"context"
"sync"
"time"
"github.com/pkg/errors"
"go.uber.org/atomic"
"go.uber.org/multierr"
"github.com/wfusion/gofusion/common/infra/watermill"
"github.com/wfusion/gofusion/common/infra/watermill/message"
amqp "github.com/rabbitmq/amqp091-go"
)
type Subscriber struct {
*ConnectionWrapper
config Config
closedChan chan struct{}
closeSubscriber func() error
subscriberWaitGroup *sync.WaitGroup
}
func NewSubscriber(config Config, logger watermill.LoggerAdapter) (*Subscriber, error) {
if err := config.ValidateSubscriber(); err != nil {
return nil, err
}
conn, err := NewConnection(config.Connection, logger)
if err != nil {
return nil, err
}
var closed atomic.Uint32
closedChan := make(chan struct{})
var subscriberWaitGroup sync.WaitGroup
// Close the subscriber AND the connection when the subscriber is closed,
// since this subscriber owns the connection.
closeSubscriber := func() error {
if !closed.CompareAndSwap(0, 1) {
// Already closed.
return nil
}
logger.Debug("[Common] watermill amqp closing subscriber", nil)
close(closedChan)
subscriberWaitGroup.Wait()
logger.Debug("[Common] watermill amqp closing connection", nil)
return conn.Close()
}
return &Subscriber{
ConnectionWrapper: conn,
config: config,
closedChan: closedChan,
closeSubscriber: closeSubscriber,
subscriberWaitGroup: &subscriberWaitGroup,
}, nil
}
func NewSubscriberWithConnection(config Config,
logger watermill.LoggerAdapter, conn *ConnectionWrapper) (*Subscriber, error) {
if err := config.ValidateSubscriberWithConnection(); err != nil {
return nil, err
}
var closed atomic.Uint32
closedChan := make(chan struct{})
var subscriberWaitGroup sync.WaitGroup
// Shared connections should not be closed by the subscriber. Just close the subscriber.
closeSubscriber := func() error {
if !closed.CompareAndSwap(0, 1) {
// Already closed.
return nil
}
logger.Debug("[Common] watermill amqp closing subscriber", nil)
close(closedChan)
subscriberWaitGroup.Wait()
return nil
}
return &Subscriber{
ConnectionWrapper: conn,
config: config,
closedChan: closedChan,
closeSubscriber: closeSubscriber,
subscriberWaitGroup: &subscriberWaitGroup,
}, nil
}
// Subscribe consumes messages from AMQP broker.
//
// Watermill's topic in Subscribe is not mapped to AMQP's topic, but depending on configuration it can be mapped
// to exchange, queue or routing key.
// For detailed description of nomenclature mapping, please check "Nomenclature" paragraph in doc.go file.
func (s *Subscriber) Subscribe(ctx context.Context, topic string) (<-chan *message.Message, error) {
if s.Closed() {
return nil, errors.New("pub/sub is closedChan")
}
if !s.IsConnected() {
return nil, errors.New("not connected to AMQP")
}
logFields := watermill.LogFields{"topic": topic}
out := make(chan *message.Message)
queueName := s.config.Queue.GenerateName(topic)
logFields["amqp_queue_name"] = queueName
exchangeName := s.config.Exchange.GenerateName(topic)
logFields["amqp_exchange_name"] = exchangeName
if err := s.prepareConsume(queueName, exchangeName, logFields); err != nil {
return nil, errors.Wrap(err, "failed to prepare consume")
}
s.subscriberWaitGroup.Add(1)
s.connectionWaitGroup.Add(1)
go func(ctx context.Context) {
defer func() {
close(out)
s.logger.Info("[Common] watermill stopped consuming from AMQP channel", logFields)
s.connectionWaitGroup.Done()
s.subscriberWaitGroup.Done()
}()
ReconnectLoop:
for {
s.logger.Debug("[Common] watermill amqp waiting for s.connected or s.closing in reconnect loop",
logFields)
// to avoid race conditions with <-s.connected
select {
case <-s.closing:
s.logger.Debug("[Common] watermill amqp stopping reconnect loop (already closing)", logFields)
break ReconnectLoop
case <-s.closedChan:
s.logger.Debug("[Common] watermill amqp stopping reconnect loop (subscriber closing)", logFields)
break ReconnectLoop
default:
// not closing yet
}
select {
case <-s.connected:
s.logger.Debug("[Common] watermill amqp connection established in ReconnectLoop", logFields)
// runSubscriber blocks until connection fails or Close() is called
s.runSubscriber(ctx, out, queueName, exchangeName, logFields)
case <-s.closing:
s.logger.Debug("[Common] watermill amqp stopping reconnect loop (closing)", logFields)
break ReconnectLoop
case <-ctx.Done():
s.logger.Debug("[Common] watermill amqp stopping reconnect loop (ctx done)", logFields)
break ReconnectLoop
}
time.Sleep(time.Millisecond * 100)
}
}(ctx)
return out, nil
}
func (s *Subscriber) SubscribeInitialize(topic string) (err error) {
if s.Closed() {
return errors.New("pub/sub is closed")
}
if !s.IsConnected() {
return errors.New("not connected to AMQP")
}
logFields := watermill.LogFields{"topic": topic}
queueName := s.config.Queue.GenerateName(topic)
logFields["amqp_queue_name"] = queueName
exchangeName := s.config.Exchange.GenerateName(topic)
logFields["amqp_exchange_name"] = exchangeName
s.logger.Info("[Common] watermill amqp initializing subscribe", logFields)
return errors.Wrap(s.prepareConsume(queueName, exchangeName, logFields), "failed to prepare consume")
}
// Close closes all subscriptions with their output channels.
func (s *Subscriber) Close() error {
return s.closeSubscriber()
}
func (s *Subscriber) prepareConsume(queueName string, exchangeName string, logFields watermill.LogFields) (err error) {
channel, err := s.openSubscribeChannel(logFields)
if err != nil {
return err
}
defer func() {
if channelCloseErr := channel.Close(); channelCloseErr != nil {
err = multierr.Append(err, channelCloseErr)
}
}()
if err = s.config.TopologyBuilder.BuildTopology(channel, queueName, exchangeName, s.config, s.logger); err != nil {
return err
}
s.logger.Debug("[Common] watermill amqp queue bound to exchange", logFields)
return nil
}
func (s *Subscriber) runSubscriber(
ctx context.Context,
out chan *message.Message,
queueName string,
exchangeName string,
logFields watermill.LogFields,
) {
channel, err := s.openSubscribeChannel(logFields)
if err != nil {
s.logger.Error("[Common] watermill amqp failed to open channel", err, logFields)
return
}
defer func() {
if err := channel.Close(); err != nil {
s.logger.Error("[Common] watermill amqp failed to close channel", err, logFields)
}
}()
notifyCloseChannel := channel.NotifyClose(make(chan *amqp.Error, 1))
sub := subscription{
out: out,
logFields: logFields,
notifyCloseChannel: notifyCloseChannel,
channel: channel,
queueName: queueName,
logger: s.logger,
closing: s.closing,
closedChan: s.closedChan,
config: s.config,
}
s.logger.Info("[Common] watermill starting consuming from AMQP channel", logFields)
sub.ProcessMessages(ctx)
}
func (s *Subscriber) openSubscribeChannel(logFields watermill.LogFields) (*amqp.Channel, error) {
if !s.IsConnected() {
return nil, errors.New("not connected to AMQP")
}
channel, err := s.amqpConnection.Channel()
if err != nil {
return nil, errors.Wrap(err, "cannot open channel")
}
s.logger.Debug("[Common] watermill amqp channel opened", logFields)
if s.config.Consume.Qos != (QosConfig{}) {
if err := channel.Qos(
s.config.Consume.Qos.PrefetchCount,
s.config.Consume.Qos.PrefetchSize,
s.config.Consume.Qos.Global,
); err != nil {
return nil, errors.Wrap(err, "failed to set channel Qos")
}
s.logger.Debug("[Common] watermill amqp qos set", logFields)
}
return channel, nil
}
type subscription struct {
out chan *message.Message
logFields watermill.LogFields
notifyCloseChannel chan *amqp.Error
channel *amqp.Channel
queueName string
logger watermill.LoggerAdapter
closing chan struct{}
closedChan chan struct{}
config Config
}
func (s *subscription) ProcessMessages(ctx context.Context) {
amqpMsgs, err := s.createConsumer(s.queueName, s.channel)
if err != nil {
s.logger.Error("[Common] watermill amqp failed to start consuming messages", err, s.logFields)
return
}
ConsumingLoop:
for {
select {
case amqpMsg := <-amqpMsgs:
if err := s.processMessage(ctx, amqpMsg, s.out, s.logFields); err != nil {
s.logger.Error("[Common] watermill amqp processing message failed, sending nack", err, s.logFields)
if err := s.nackMsg(amqpMsg); err != nil {
s.logger.Error("[Common] watermill amqp cannot nack message", err, s.logFields)
// something went really wrong when we cannot nack, let's reconnect
break ConsumingLoop
}
}
continue ConsumingLoop
case <-s.notifyCloseChannel:
s.logger.Error("[Common] watermill amqp channel closed, stopping process messages", nil, s.logFields)
break ConsumingLoop
case <-s.closing:
s.logger.Info("[Common] watermill amqp closing from subscriber received", s.logFields)
break ConsumingLoop
case <-s.closedChan:
s.logger.Info("[Common] watermill amqp subscriber closed", s.logFields)
break ConsumingLoop
case <-ctx.Done():
s.logger.Info("[Common] watermill amqp closing from ctx received", s.logFields)
break ConsumingLoop
}
}
}
func (s *subscription) createConsumer(queueName string, channel *amqp.Channel) (<-chan amqp.Delivery, error) {
amqpMsgs, err := channel.Consume(
queueName,
s.config.Consume.Consumer,
false, // autoAck must be set to false - acks are managed by Watermill
s.config.Consume.Exclusive,
s.config.Consume.NoLocal,
s.config.Consume.NoWait,
s.config.Consume.Arguments,
)
if err != nil {
return nil, errors.Wrap(err, "cannot consume from channel")
}
return amqpMsgs, nil
}
func (s *subscription) processMessage(
ctx context.Context,
amqpMsg amqp.Delivery,
out chan *message.Message,
logFields watermill.LogFields,
) error {
msg, err := s.config.Marshaler.Unmarshal(amqpMsg)
if err != nil {
return err
}
ctx = context.WithValue(ctx, watermill.ContextKeyMessageUUID, msg.UUID)
ctx = context.WithValue(ctx, watermill.ContextKeyRawMessageID, amqpMsg.MessageId)
ctx, cancelCtx := context.WithCancel(ctx)
defer cancelCtx()
msg.Metadata[watermill.ContextKeyMessageUUID] = msg.UUID
msg.Metadata[watermill.ContextKeyRawMessageID] = amqpMsg.MessageId
msg.SetContext(ctx)
msgLogFields := logFields.Add(watermill.LogFields{
"message_raw_id": amqpMsg.MessageId,
"message_uuid": msg.UUID,
})
s.logger.Trace("[Common] watermill amqp unmarshaled message", msgLogFields)
select {
case <-s.closing:
s.logger.Info("[Common] watermill amqp message not consumed, pub/sub is closing", msgLogFields)
return s.nackMsg(amqpMsg)
case <-s.closedChan:
s.logger.Info("[Common] watermill amqp message not consumed, subscriber is closed", msgLogFields)
return s.nackMsg(amqpMsg)
case out <- msg:
s.logger.Trace("[Common] watermill amqp message sent to consumer", msgLogFields)
}
select {
case <-s.closing:
s.logger.Trace("[Common] watermill amqp closing pub/sub, message discarded before ack", msgLogFields)
return s.nackMsg(amqpMsg)
case <-s.closedChan:
s.logger.Info("[Common] watermill amqp message not consumed, subscriber is closed", msgLogFields)
return s.nackMsg(amqpMsg)
case <-msg.Acked():
s.logger.Trace("[Common] watermill amqp message acked", msgLogFields)
return amqpMsg.Ack(false)
case <-msg.Nacked():
s.logger.Trace("[Common] watermill amqp message nacked", msgLogFields)
return s.nackMsg(amqpMsg)
}
}
func (s *subscription) nackMsg(amqpMsg amqp.Delivery) error {
return amqpMsg.Nack(false, !s.config.Consume.NoRequeueOnNack)
}