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micro-service.go
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micro-service.go
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package microservice
import (
"strings"
"time"
"github.com/jurgen-kluft/go-home/config"
logpkg "github.com/jurgen-kluft/go-home/logging"
pubsub "github.com/jurgen-kluft/go-home/nats"
)
// Delegate is a handler that the user can register on a certain received topic
type Delegate func(m *Service, topic string, message []byte) bool
type Message struct {
Topic string
Payload []byte
}
// Service is a convenience setup to implement a micro-service
type Service struct {
Name string
Logger *logpkg.Logger
PubsubRegister []string
PubsubSubscribe []string
Pubsub *pubsub.Context
Handlers map[string]Delegate
CatchHandler Delegate
ProcessMessages chan *Message
}
func New(name string) *Service {
service := &Service{}
service.Name = name
service.Logger = logpkg.New(name)
service.Logger.AddEntry("pubsub")
service.Logger.AddEntry(name)
service.PubsubRegister = make([]string, 0, 10)
service.PubsubSubscribe = make([]string, 0, 10)
service.Handlers = make(map[string]Delegate)
service.ProcessMessages = make(chan *Message, 128)
return service
}
func (m *Service) Register(r string) error {
if m.Pubsub == nil {
// Not connected yet, just add it to the list
m.PubsubRegister = append(m.PubsubRegister, r)
} else {
// We are connected, also call Register on pubsub
m.PubsubRegister = append(m.PubsubRegister, r)
m.Pubsub.Register(r)
}
return nil
}
func (m *Service) Subscribe(r string) error {
if m.Pubsub == nil {
// Not connected yet, just add it to the list
m.PubsubSubscribe = append(m.PubsubSubscribe, r)
} else {
// We are connected, also call Subscribe on pubsub
m.PubsubSubscribe = append(m.PubsubSubscribe, r)
m.Pubsub.Subscribe(r)
}
return nil
}
func (m *Service) RegisterAndSubscribe(register []string, subscribe []string) {
for _, r := range register {
m.Register(r)
}
for _, r := range subscribe {
m.Subscribe(r)
}
}
func (m *Service) RegisterHandler(topic string, delegate Delegate) {
m.Handlers[topic] = delegate
natstopic := strings.Replace(topic, "/", ".", -1)
natstopic = strings.TrimSuffix(natstopic, ".")
m.Handlers[natstopic] = delegate
}
func matchTopic(etopic string, itopic string) bool {
ei := 0
ii := 0
cs := true
for ei < len(etopic) && ii < len(itopic) {
echar := etopic[ei]
ichar := itopic[ii]
if (echar == '/' || echar == '.') && (ichar == '/' || ichar == '.') {
cs = true
ei++
ii++
} else if cs && etopic[ei] == '*' { // chapter start ?
// consume chapter from itopic
ei++
for ii < len(itopic) && (itopic[ii] != '/' && itopic[ii] != '.') {
ii++
}
if ii == len(itopic) {
return false
}
cs = false
} else if echar != ichar {
return false
} else {
ei++
ii++
cs = false
}
}
return ei == len(etopic) && ii == len(itopic)
}
func (m *Service) FindHandler(itopic string) (delegate Delegate, exists bool) {
for etopic, edelegate := range m.Handlers {
if matchTopic(etopic, itopic) {
return edelegate, true
}
}
return nil, false
}
func (m *Service) Loop() {
quit := false
for !quit {
m.Pubsub = pubsub.New(config.PubSubCfg)
err := m.Pubsub.Connect(m.Name, m.PubsubRegister, m.PubsubSubscribe)
if err == nil {
m.Logger.LogInfo("pubsub", "connected")
connected := true
for connected {
select {
case msg := <-m.ProcessMessages:
topic := msg.Topic
delegate, exists := m.FindHandler(topic)
if exists {
if !delegate(m, topic, msg.Payload) {
connected = false
quit = true
}
}
case msg := <-m.Pubsub.InMsgs:
topic := m.Pubsub.Topic(msg)
delegate, exists := m.Handlers[topic]
if exists {
if !delegate(m, topic, m.Pubsub.Payload(msg)) {
connected = false
quit = true
}
} else {
delegate, exists := m.Handlers["*"]
if exists {
if !delegate(m, topic, m.Pubsub.Payload(msg)) {
connected = false
quit = true
}
}
if topic == "client/disconnected/" || topic == "client.disconnected" {
m.Logger.LogInfo("pubsub", "disconnected")
connected = false
}
}
}
}
m.Pubsub.Close()
}
if err != nil {
m.Logger.LogError(m.Name, err.Error())
}
if !quit {
m.Logger.LogInfo("pubsub", "Waiting 5 seconds before re-connecting..")
time.Sleep(5 * time.Second)
} else {
m.Logger.LogInfo("pubsub", "End.")
}
}
}