Mainflux.mainflux/mqtt/forwarder.go

62 lines
1.4 KiB
Go
Raw Normal View History

2020-05-07 15:34:09 +08:00
// Copyright (c) Mainflux
// SPDX-License-Identifier: Apache-2.0
package mqtt
import (
"fmt"
"strings"
log "github.com/mainflux/mainflux/logger"
"github.com/mainflux/mainflux/pkg/messaging"
2020-05-07 15:34:09 +08:00
)
const (
channels = "channels"
messages = "messages"
)
// Forwarder specifies MQTT forwarder interface API.
type Forwarder interface {
// Forward subscribes to the Subscriber and
// publishes messages using provided Publisher.
Forward(sub messaging.Subscriber, pub messaging.Publisher) error
}
type forwarder struct {
topic string
logger log.Logger
}
// NewForwarder returns new Forwarder implementation.
func NewForwarder(topic string, logger log.Logger) Forwarder {
return forwarder{
topic: topic,
logger: logger,
}
}
func (f forwarder) Forward(sub messaging.Subscriber, pub messaging.Publisher) error {
return sub.Subscribe(f.topic, f.handle(pub))
}
func (f forwarder) handle(pub messaging.Publisher) messaging.MessageHandler {
return func(msg messaging.Message) error {
if msg.Protocol == protocol {
return nil
}
// Use concatenation instead of mft.Sprintf for the
// sake of simplicity and performance.
topic := channels + "/" + msg.Channel + "/" + messages
if msg.Subtopic != "" {
topic += "/" + strings.ReplaceAll(msg.Subtopic, ".", "/")
}
go func() {
if err := pub.Publish(topic, msg); err != nil {
f.logger.Warn(fmt.Sprintf("Failed to forward message: %s", err))
}
}()
return nil
}
}