/
subscriber.go
330 lines (275 loc) · 8.17 KB
/
subscriber.go
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package mbus
import (
"encoding/json"
"time"
"sync"
"net/url"
"fmt"
"os"
"code.cloudfoundry.org/clock"
"code.cloudfoundry.org/lager"
"github.com/nats-io/nats"
"github.com/pkg/errors"
)
const (
registerMessagesReceived = "registerMessagesReceived"
)
type ServiceDiscoveryStartMessage struct {
Id string `json:"id"`
Host string `json:"host"`
MinimumRegisterIntervalInSeconds int `json:"minimumRegisterIntervalInSeconds"`
PruneThresholdInSeconds int `json:"pruneThresholdInSeconds"`
}
type SubscriberOpts struct {
ID string
MinimumRegisterIntervalInSeconds int
PruneThresholdInSeconds int
AcceptTLS bool
}
type RegistryMessage struct {
IP string `json:"host"`
InfraNames []string `json:"uris"`
EndpointUpdatedAt int64 `json:"endpoint_updated_at_ns"`
}
//go:generate counterfeiter -o fakes/address_table.go --fake-name AddressTable . AddressTable
type AddressTable interface {
Add(infraNames []string, ip string)
Remove(infraNames []string, ip string)
PausePruning()
ResumePruning()
SetWarm()
}
type Subscriber struct {
natsConnProvider NatsConnProvider
subOpts SubscriberOpts
warmingDuration time.Duration
table AddressTable
logger lager.Logger
recorder routeMessageRecorder
localIP string
natsClient NatsConn
once sync.Once
metricsSender metricsSender
clock clock.Clock
}
//go:generate counterfeiter -o fakes/nats_conn.go --fake-name NatsConn . NatsConn
type NatsConn interface {
PublishMsg(m *nats.Msg) error
Close()
Flush() error
ConnectedUrl() string
Subscribe(string, nats.MsgHandler) (*nats.Subscription, error)
}
//go:generate counterfeiter -o fakes/nats_conn_provider.go --fake-name NatsConnProvider . NatsConnProvider
type NatsConnProvider interface {
Connection(opts ...nats.Option) (NatsConn, error)
}
//go:generate counterfeiter -o fakes/metrics_sender.go --fake-name MetricsSender . metricsSender
type metricsSender interface {
IncrementCounter(string)
}
//go:generate counterfeiter -o fakes/route_message_recorder.go --fake-name RouteMessageRecorder . routeMessageRecorder
type routeMessageRecorder interface {
RecordMessageTransitTime(time int64)
}
func NewSubscriber(
natsConnProvider NatsConnProvider,
subOpts SubscriberOpts,
warmingDuration time.Duration,
table AddressTable,
localIP string,
recorder routeMessageRecorder,
logger lager.Logger,
metricsSender metricsSender,
clock clock.Clock,
) *Subscriber {
return &Subscriber{
natsConnProvider: natsConnProvider,
subOpts: subOpts,
warmingDuration: warmingDuration,
table: table,
recorder: recorder,
logger: logger,
localIP: localIP,
metricsSender: metricsSender,
clock: clock,
}
}
func (s *Subscriber) Run(signals <-chan os.Signal, ready chan<- struct{}) error {
err := s.RunOnce()
if err != nil {
return err
}
close(ready)
for {
select {
case <-signals:
s.Close()
return nil
}
}
}
func (s *Subscriber) RunOnce() error {
var err error
s.once.Do(func() {
var natsClient NatsConn
natsClient, err = s.natsConnProvider.Connection(
nats.ReconnectHandler(nats.ConnHandler(func(conn *nats.Conn) {
{
url, err := url.Parse(conn.ConnectedUrl())
if err == nil {
s.logger.Info(
"ReconnectHandler reconnected to nats server",
lager.Data{"nats_host": url.Scheme + "://" + url.Host}, //don't leak creds
)
}
}
s.table.ResumePruning()
s.sendStartMessage()
})),
nats.DisconnectHandler(nats.ConnHandler(func(conn *nats.Conn) {
s.logger.Info(
"DisconnectHandler disconnected from nats server",
lager.Data{"last_error": conn.LastError()},
)
s.table.PausePruning()
})),
nats.ClosedHandler(nats.ConnHandler(func(conn *nats.Conn) {
s.logger.Info(
"ClosedHandler unexpected close of nats connection",
lager.Data{"last_error": conn.LastError()},
)
})),
nats.MaxReconnects(-1),
)
if err != nil {
err = errors.Wrap(err, "unable to create nats connection")
return
}
s.natsClient = natsClient
{
url, err := url.Parse(natsClient.ConnectedUrl())
if err == nil {
s.logger.Info(
"Connected to NATS server",
lager.Data{"nats_host": url.Scheme + "://" + url.Host},
)
}
}
err = s.sendStartMessage()
if err != nil {
return
}
err = s.setupGreetMsgHandler()
if err != nil {
return
}
err = s.setupAddressMessageHandler()
if err != nil {
return
}
go func() {
<-s.clock.After(s.warmingDuration)
s.table.SetWarm()
}()
})
if err != nil {
s.Close()
}
return err
}
func (s *Subscriber) sendStartMessage() error {
msg := &nats.Msg{
Subject: "service-discovery.start",
Data: s.subscriptionOptionsJSON(),
}
err := s.natsClient.PublishMsg(msg)
if err != nil {
return errors.Wrap(err, "unable to publish a start message")
}
s.logger.Info("service-discovery.start-message-published", lager.Data(map[string]interface{}{
"subscription_options": string(s.subscriptionOptionsJSON()),
}))
return nil
}
func (s *Subscriber) Close() {
if s.natsClient != nil {
s.natsClient.Close()
}
}
func (s *Subscriber) setupGreetMsgHandler() error {
discoveryMessageJson := s.subscriptionOptionsJSON()
_, err := s.natsClient.Subscribe("service-discovery.greet", nats.MsgHandler(func(greetMsg *nats.Msg) {
err := s.natsClient.PublishMsg(&nats.Msg{
Subject: greetMsg.Reply,
Data: discoveryMessageJson,
})
if err != nil {
s.logger.Error("GreetMsgHandler unable to publish response to greet messages", err)
}
s.logger.Info("service-discovery.greet-response-published")
}))
if err != nil {
s.logger.Error("setupGreetMsgHandler unable to subscribe to greet messages", err)
return err
}
err = s.natsClient.Flush()
if err != nil {
s.logger.Error("setupGreetMsgHandler unable to flush subscribe greet message", err)
return err
}
return nil
}
func (s *Subscriber) setupAddressMessageHandler() error {
_, err := s.natsClient.Subscribe("service-discovery.register", nats.MsgHandler(func(msg *nats.Msg) {
registryMessage := &RegistryMessage{}
err := json.Unmarshal(msg.Data, registryMessage)
if err != nil || registryMessage.IP == "" || len(registryMessage.InfraNames) == 0 {
s.logger.Info("AddressMessageHandler received a malformed register message", lager.Data(map[string]interface{}{
"msgJson": string(msg.Data),
}))
return
}
s.recorder.RecordMessageTransitTime(registryMessage.EndpointUpdatedAt)
s.metricsSender.IncrementCounter(registerMessagesReceived)
s.logger.Debug("AddressMessageHandler register msg received", lager.Data(map[string]interface{}{
"msgJson": string(msg.Data),
}))
s.table.Add(registryMessage.InfraNames, registryMessage.IP)
}))
if err != nil {
s.logger.Error("setupAddressMessageHandler unable to subscribe to service-discovery.register", err)
return err
}
_, err = s.natsClient.Subscribe("service-discovery.unregister", nats.MsgHandler(func(msg *nats.Msg) {
registryMessage := &RegistryMessage{}
err := json.Unmarshal(msg.Data, registryMessage)
if err != nil || len(registryMessage.InfraNames) == 0 {
s.logger.Info("AddressMessageHandler received a malformed unregister message", lager.Data(map[string]interface{}{
"msgJson": string(msg.Data),
}))
return
}
s.logger.Debug("AddressMessageHandler unregister msg received", lager.Data(map[string]interface{}{
"msgJson": string(msg.Data),
}))
s.table.Remove(registryMessage.InfraNames, registryMessage.IP)
}))
if err != nil {
s.logger.Error("setupAddressMessageHandler unable to subscribe to service-discovery.unregister", err)
return err
}
return nil
}
func (s *Subscriber) subscriptionOptionsJSON() []byte {
discoveryMessageJson, err := json.Marshal(ServiceDiscoveryStartMessage{
Id: s.subOpts.ID,
Host: s.localIP,
MinimumRegisterIntervalInSeconds: s.subOpts.MinimumRegisterIntervalInSeconds,
PruneThresholdInSeconds: s.subOpts.PruneThresholdInSeconds,
})
if err != nil {
panic(fmt.Sprintf("Unable to marshal subsription options: %v", err))
}
return discoveryMessageJson
}