118 lines
3 KiB
Go
118 lines
3 KiB
Go
package nats_driver
|
|
|
|
import (
|
|
"encoding/json"
|
|
"fmt"
|
|
|
|
"github.com/by-cx/lobby/common"
|
|
"github.com/by-cx/lobby/server"
|
|
"github.com/nats-io/nats.go"
|
|
)
|
|
|
|
// NATS drivers is used to send discovery packet to other nodes into the group via NATS messenging protocol.
|
|
type Driver struct {
|
|
NATSUrl string
|
|
NATSDiscoveryChannel string
|
|
|
|
LogChannel chan string
|
|
|
|
nc *nats.Conn
|
|
subscribeListener common.Listener
|
|
unsubscribeListener common.Listener
|
|
}
|
|
|
|
// handler is called asynchronously so and because it cannot log directly to stderr there
|
|
// is channel called LogChannel that can be used to log error messages from this
|
|
func (d *Driver) handler(m *nats.Msg) {
|
|
message := discoveryEnvelope{}
|
|
err := json.Unmarshal(m.Data, &message)
|
|
if err != nil && d.LogChannel != nil {
|
|
d.LogChannel <- fmt.Errorf("decoding message error: %v", err).Error()
|
|
}
|
|
|
|
err = message.Discovery.Validate()
|
|
if err != nil && d.LogChannel != nil {
|
|
d.LogChannel <- fmt.Errorf("validation error: %v", err).Error()
|
|
}
|
|
|
|
if message.Message == "hi" {
|
|
d.subscribeListener(message.Discovery)
|
|
} else if message.Message == "goodbye" {
|
|
d.unsubscribeListener(message.Discovery)
|
|
} else {
|
|
if d.LogChannel != nil {
|
|
d.LogChannel <- "incompatible message"
|
|
}
|
|
}
|
|
|
|
}
|
|
|
|
func (d *Driver) Init() error {
|
|
if d.LogChannel == nil {
|
|
return fmt.Errorf("please initiate LogChannel variable")
|
|
}
|
|
|
|
nc, err := nats.Connect(d.NATSUrl)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
d.nc = nc
|
|
|
|
_, err = nc.Subscribe(d.NATSDiscoveryChannel, d.handler)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Close is called when all is done.
|
|
func (d *Driver) Close() error {
|
|
return d.nc.Drain()
|
|
}
|
|
|
|
// RegisterSubscribeFunction sets the function that will process the incoming messages
|
|
func (d *Driver) RegisterSubscribeFunction(listener common.Listener) {
|
|
d.subscribeListener = listener
|
|
}
|
|
|
|
// RegisterUnsubscribeFunction sets the function that will process the goodbye incoming messages
|
|
func (d *Driver) RegisterUnsubscribeFunction(listener common.Listener) {
|
|
d.unsubscribeListener = listener
|
|
}
|
|
|
|
// SendDiscoveryPacket send discovery packet to the group.
|
|
func (d *Driver) SendDiscoveryPacket(discovery server.Discovery) error {
|
|
envelope := discoveryEnvelope{
|
|
Discovery: discovery,
|
|
Message: "hi",
|
|
}
|
|
|
|
data, err := envelope.Bytes()
|
|
if err != nil {
|
|
return fmt.Errorf("sending discovery formating message error: %v", err)
|
|
}
|
|
err = d.nc.Publish(d.NATSDiscoveryChannel, data)
|
|
if err != nil {
|
|
return fmt.Errorf("sending discovery error: %v", err)
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// SendGoodbyePacket deregister node from the group. It tells everybody that it's going to die.
|
|
func (d *Driver) SendGoodbyePacket(discovery server.Discovery) error {
|
|
envelope := discoveryEnvelope{
|
|
Discovery: discovery,
|
|
Message: "goodbye",
|
|
}
|
|
|
|
data, err := envelope.Bytes()
|
|
if err != nil {
|
|
return fmt.Errorf("sending discovery formating message error: %v", err)
|
|
}
|
|
err = d.nc.Publish(d.NATSDiscoveryChannel, data)
|
|
if err != nil {
|
|
return fmt.Errorf("sending discovery error: %v", err)
|
|
}
|
|
return nil
|
|
}
|