Replace logger with a Logger interface to allow for custom loggers.

channel.go

@@ -9,21 +9,21 @@ import (
 )
 
 type channelManager struct {
-	logger              logger
+	logger              Logger
 	url                 string
 	channel             *amqp.Channel
 	channelMux          *sync.RWMutex
 	notifyCancelOrClose chan error
 }
 
-func newChannelManager(url string, logging bool) (*channelManager, error) {
+func newChannelManager(url string, log Logger) (*channelManager, error) {
 	ch, err := getNewChannel(url)
 	if err != nil {
 		return nil, err
 	}
 
 	chManager := channelManager{
-		logger:              logger{logging: logging},
+		logger:              log,
 		url:                 url,
 		channel:             ch,
 		channelMux:          &sync.RWMutex{},
@@ -56,14 +56,14 @@ func (chManager *channelManager) startNotifyCancelOrClosed() {
 	notifyCancelChan = chManager.channel.NotifyCancel(notifyCancelChan)
 	select {
 	case err := <-notifyCloseChan:
-		chManager.logger.Println("attempting to reconnect to amqp server after close")
+		chManager.logger.Printf("attempting to reconnect to amqp server after close")
 		chManager.reconnectWithBackoff()
-		chManager.logger.Println("successfully reconnected to amqp server after close")
+		chManager.logger.Printf("successfully reconnected to amqp server after close")
 		chManager.notifyCancelOrClose <- err
 	case err := <-notifyCancelChan:
-		chManager.logger.Println("attempting to reconnect to amqp server after cancel")
+		chManager.logger.Printf("attempting to reconnect to amqp server after cancel")
 		chManager.reconnectWithBackoff()
-		chManager.logger.Println("successfully reconnected to amqp server after cancel")
+		chManager.logger.Printf("successfully reconnected to amqp server after cancel")
 		chManager.notifyCancelOrClose <- errors.New(err)
 	}
 	close(notifyCancelChan)

consume.go

@@ -9,13 +9,15 @@ import (
 // Consumer allows you to create and connect to queues for data consumption.
 type Consumer struct {
 	chManager *channelManager
-	logger    logger
+	logger    Logger
 }
 
 // ConsumerOptions are used to describe a consumer's configuration.
 // Logging set to true will enable the consumer to print to stdout
+// Logger specifies a custom Logger interface implementation overruling Logging.
 type ConsumerOptions struct {
 	Logging bool
+	Logger  Logger
 }
 
 // Delivery captures the fields for a previously delivered message resident in
@@ -31,14 +33,17 @@ func NewConsumer(url string, optionFuncs ...func(*ConsumerOptions)) (Consumer, e
 	for _, optionFunc := range optionFuncs {
 		optionFunc(options)
 	}
+	if options.Logger == nil {
+		options.Logger = &nolog{} // default no logging
+	}
 
-	chManager, err := newChannelManager(url, options.Logging)
+	chManager, err := newChannelManager(url, options.Logger)
 	if err != nil {
 		return Consumer{}, err
 	}
 	consumer := Consumer{
 		chManager: chManager,
-		logger:    logger{logging: options.Logging},
+		logger:    options.Logger,
 	}
 	return consumer, nil
 }
@@ -46,6 +51,16 @@ func NewConsumer(url string, optionFuncs ...func(*ConsumerOptions)) (Consumer, e
 // WithConsumerOptionsLogging sets logging to true on the consumer options
 func WithConsumerOptionsLogging(options *ConsumerOptions) {
 	options.Logging = true
+	options.Logger = &stdlog{}
+}
+
+// WithConsumerOptionsLogger sets logging to a custom interface.
+// Use WithConsumerOptionsLogging to just log to stdout.
+func WithConsumerOptionsLogger(log Logger) func(options *ConsumerOptions) {
+	return func(options *ConsumerOptions) {
+		options.Logging = true
+		options.Logger = log
+	}
 }
 
 // getDefaultConsumeOptions descibes the options that will be used when a value isn't provided
@@ -330,12 +345,18 @@ func (consumer Consumer) startGoroutines(
 					continue
 				}
 				if handler(Delivery{msg}) {
-					msg.Ack(false)
+					err := msg.Ack(false)
+					if err != nil {
+						consumer.logger.Printf("can't ack message: %v", err)
+					}
 				} else {
-					msg.Nack(false, true)
+					err := msg.Nack(false, true)
+					if err != nil {
+						consumer.logger.Printf("can't nack message: %v", err)
+					}
 				}
 			}
-			consumer.logger.Println("rabbit consumer goroutine closed")
+			consumer.logger.Printf("rabbit consumer goroutine closed")
 		}()
 	}
 	consumer.logger.Printf("Processing messages on %v goroutines", consumeOptions.Concurrency)

examples/logger/main.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"log"
+
+	rabbitmq "github.com/wagslane/go-rabbitmq"
+)
+
+// CustomLog is used in WithPublisherOptionsLogger to create a custom logger.
+type CustomLog struct{}
+
+func (c *CustomLog) Printf(fmt string, args ...interface{}) {
+	log.Printf("mylogger: "+fmt, args...)
+}
+
+func main() {
+	mylogger := &CustomLog{}
+
+	publisher, returns, err := rabbitmq.NewPublisher(
+		"amqp://guest:guest@localhost",
+		rabbitmq.WithPublisherOptionsLogger(mylogger),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+	err = publisher.Publish(
+		[]byte("hello, world"),
+		[]string{"routing_key"},
+		rabbitmq.WithPublishOptionsContentType("application/json"),
+		rabbitmq.WithPublishOptionsMandatory,
+		rabbitmq.WithPublishOptionsPersistentDelivery,
+		rabbitmq.WithPublishOptionsExchange("events"),
+	)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	go func() {
+		for r := range returns {
+			log.Printf("message returned from server: %s", string(r.Body))
+		}
+	}()
+}

logger.go

@@ -5,20 +5,22 @@ import (
 	"log"
 )
 
-type logger struct {
-	logging bool
+// Logger is the interface to send logs to. It can be set using
+// WithPublisherOptionsLogger() or WithConsumerOptionsLogger().
+type Logger interface {
+	Printf(string, ...interface{})
 }
 
 const loggingPrefix = "gorabbit"
 
-func (l logger) Printf(format string, v ...interface{}) {
-	if l.logging {
-		log.Printf(fmt.Sprintf("%s: %s", loggingPrefix, format), v...)
-	}
-}
+// stdlog logs to stdout using go's default logger.
+type stdlog struct{}
 
-func (l logger) Println(v ...interface{}) {
-	if l.logging {
-		log.Println(loggingPrefix, fmt.Sprintf("%v", v...))
-	}
+func (l stdlog) Printf(format string, v ...interface{}) {
+	log.Printf(fmt.Sprintf("%s: %s", loggingPrefix, format), v...)
 }
+
+// nolog does not log at all, this is the default.
+type nolog struct{}
+
+func (l nolog) Printf(format string, v ...interface{}) {}

publish.go

@@ -85,18 +85,29 @@ type Publisher struct {
 	disablePublishDueToFlow    bool
 	disablePublishDueToFlowMux *sync.RWMutex
 
-	logger logger
+	logger Logger
 }
 
 // PublisherOptions are used to describe a publisher's configuration.
 // Logging set to true will enable the consumer to print to stdout
 type PublisherOptions struct {
 	Logging bool
+	Logger  Logger
 }
 
 // WithPublisherOptionsLogging sets logging to true on the consumer options
 func WithPublisherOptionsLogging(options *PublisherOptions) {
 	options.Logging = true
+	options.Logger = &stdlog{}
+}
+
+// WithPublisherOptionLogger sets logging to a custom interface.
+// Use WithPublisherOptionsLogging to just log to stdout.
+func WithPublisherOptionsLogger(log Logger) func(options *PublisherOptions) {
+	return func(options *PublisherOptions) {
+		options.Logging = true
+		options.Logger = log
+	}
 }
 
 // NewPublisher returns a new publisher with an open channel to the cluster.
@@ -109,8 +120,11 @@ func NewPublisher(url string, optionFuncs ...func(*PublisherOptions)) (Publisher
 	for _, optionFunc := range optionFuncs {
 		optionFunc(options)
 	}
+	if options.Logger == nil {
+		options.Logger = &nolog{} // default no logging
+	}
 
-	chManager, err := newChannelManager(url, options.Logging)
+	chManager, err := newChannelManager(url, options.Logger)
 	if err != nil {
 		return Publisher{}, nil, err
 	}
@@ -120,7 +134,7 @@ func NewPublisher(url string, optionFuncs ...func(*PublisherOptions)) (Publisher
 		notifyFlowChan:             make(chan bool),
 		disablePublishDueToFlow:    false,
 		disablePublishDueToFlowMux: &sync.RWMutex{},
-		logger:                     logger{logging: options.Logging},
+		logger:                     options.Logger,
 	}
 
 	returnAMQPChan := make(chan amqp.Return)
@@ -182,13 +196,13 @@ func (publisher *Publisher) Publish(
 func (publisher *Publisher) startNotifyFlowHandler() {
 	for ok := range publisher.notifyFlowChan {
 		publisher.disablePublishDueToFlowMux.Lock()
-		publisher.logger.Println("pausing publishing due to flow request from server")
+		publisher.logger.Printf("pausing publishing due to flow request from server")
 		if ok {
 			publisher.disablePublishDueToFlow = false
 		} else {
 			publisher.disablePublishDueToFlow = true
 		}
 		publisher.disablePublishDueToFlowMux.Unlock()
-		publisher.logger.Println("resuming publishing due to flow request from server")
+		publisher.logger.Printf("resuming publishing due to flow request from server")
 	}
 }