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transceiver.go
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transceiver.go
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package transceiver
import (
"strings"
"sync"
"time"
webSocket "github.com/Dharitri-org/drtg-communication/websocket"
"github.com/Dharitri-org/drtg-communication/websocket/data"
"github.com/Dharitri-org/drtg-core/core"
"github.com/Dharitri-org/drtg-core/core/check"
"github.com/Dharitri-org/drtg-core/core/closing"
"github.com/gorilla/websocket"
)
// ArgsTransceiver holds the arguments that are needed for a transceiver
type ArgsTransceiver struct {
PayloadConverter webSocket.PayloadConverter
Log core.Logger
RetryDurationInSec int
AckTimeoutInSec int
BlockingAckOnError bool
WithAcknowledge bool
PayloadVersion uint32
}
type wsTransceiver struct {
payloadParser webSocket.PayloadConverter
payloadHandler webSocket.PayloadHandler
mutPayloadHandler sync.RWMutex
log core.Logger
safeCloser core.SafeCloser
retryDuration time.Duration
ackTimeout time.Duration
mapAck map[uint64]chan struct{}
mutMapAck sync.Mutex
counter uint64
blockingAckOnError bool
withAcknowledge bool
payloadVersion uint32
}
// NewTransceiver will create a new instance of transceiver
func NewTransceiver(args ArgsTransceiver) (*wsTransceiver, error) {
err := checkArgs(args)
if err != nil {
return nil, err
}
return &wsTransceiver{
log: args.Log,
retryDuration: time.Duration(args.RetryDurationInSec) * time.Second,
ackTimeout: time.Duration(args.AckTimeoutInSec) * time.Second,
blockingAckOnError: args.BlockingAckOnError,
safeCloser: closing.NewSafeChanCloser(),
payloadHandler: webSocket.NewNilPayloadHandler(),
payloadParser: args.PayloadConverter,
withAcknowledge: args.WithAcknowledge,
payloadVersion: args.PayloadVersion,
mapAck: make(map[uint64]chan struct{}),
}, nil
}
func checkArgs(args ArgsTransceiver) error {
if check.IfNil(args.Log) {
return core.ErrNilLogger
}
if check.IfNil(args.PayloadConverter) {
return data.ErrNilPayloadConverter
}
if args.RetryDurationInSec == 0 {
return data.ErrZeroValueRetryDuration
}
if args.WithAcknowledge && args.AckTimeoutInSec == 0 {
return data.ErrZeroValueAckTimeout
}
return nil
}
// SetPayloadHandler will set the payload handler
func (wt *wsTransceiver) SetPayloadHandler(handler webSocket.PayloadHandler) error {
if check.IfNil(handler) {
return data.ErrNilPayloadProcessor
}
wt.mutPayloadHandler.Lock()
defer wt.mutPayloadHandler.Unlock()
wt.payloadHandler = handler
return nil
}
// Listen will listen for messages from the provided connection
func (wt *wsTransceiver) Listen(connection webSocket.WSConClient) (closed bool) {
timer := time.NewTimer(wt.retryDuration)
defer timer.Stop()
for {
_, message, err := connection.ReadMessage()
if err == nil {
wt.verifyPayloadAndSendAckIfNeeded(connection, message)
continue
}
_, isConnectionClosed := err.(*websocket.CloseError)
if !strings.Contains(err.Error(), data.ClosedConnectionMessage) && !isConnectionClosed {
wt.log.Warn("wt.Listen()-> connection problem", "error", err.Error())
}
if isConnectionClosed {
wt.log.Info("received connection close")
return true
}
timer.Reset(wt.retryDuration)
select {
case <-wt.safeCloser.ChanClose():
return
case <-timer.C:
}
}
}
func (wt *wsTransceiver) verifyPayloadAndSendAckIfNeeded(connection webSocket.WSConClient, payload []byte) {
if len(payload) == 0 {
wt.log.Debug("wt.verifyPayloadAndSendAckIfNeeded(): empty payload")
return
}
wsMessage, err := wt.payloadParser.ExtractWsMessage(payload)
if err != nil {
wt.log.Warn("wt.verifyPayloadAndSendAckIfNeeded: cannot extract payload data", "error", err.Error())
return
}
if wsMessage.Type == data.AckMessage {
wt.handleAckMessage(wsMessage.Counter)
return
}
if wsMessage.Type != data.PayloadMessage {
wt.log.Debug("received an unknown message type", "message type received", wsMessage.Type)
return
}
err = wt.payloadHandler.ProcessPayload(wsMessage.Payload, wsMessage.Topic, wsMessage.Version)
if err != nil && wt.blockingAckOnError {
wt.log.Warn("wt.payloadHandler.ProcessPayload: cannot handle payload", "error", err)
return
}
wt.sendAckIfNeeded(connection, wsMessage)
}
func (wt *wsTransceiver) handleAckMessage(counter uint64) {
wt.mutMapAck.Lock()
defer wt.mutMapAck.Unlock()
ch, found := wt.mapAck[counter]
if !found {
wt.log.Warn("wsTransceiver.handleAckMessage invalid counter received", "received", counter)
return
}
close(ch)
delete(wt.mapAck, counter)
}
func (wt *wsTransceiver) sendAckIfNeeded(connection webSocket.WSConClient, wsMessage *data.WsMessage) {
if !wsMessage.WithAcknowledge {
return
}
timer := time.NewTimer(wt.retryDuration)
defer timer.Stop()
ackWsMessage := &data.WsMessage{
Counter: wsMessage.Counter,
Type: data.AckMessage,
}
wsMessageBytes, errConstruct := wt.payloadParser.ConstructPayload(ackWsMessage)
if errConstruct != nil {
wt.log.Warn("sendAckIfNeeded.ConstructPayload: cannot prepare message", "error", errConstruct)
return
}
for {
timer.Reset(wt.retryDuration)
err := connection.WriteMessage(websocket.BinaryMessage, wsMessageBytes)
if err == nil {
return
}
if !strings.Contains(err.Error(), data.ErrConnectionNotOpen.Error()) {
wt.log.Error("could not write acknowledge message", "error", err.Error(), "retrying in", wt.retryDuration)
}
wt.log.Debug("wt.sendAckIfNeeded(): cannot write ack", "error", err)
select {
case <-timer.C:
case <-wt.safeCloser.ChanClose():
return
}
}
}
// Send will prepare and send the provided WsSendArgs
func (wt *wsTransceiver) Send(payload []byte, topic string, connection webSocket.WSConClient) error {
ch, localCounter := wt.prepareChanAndCounter()
wsMessage := &data.WsMessage{
WithAcknowledge: wt.withAcknowledge,
Counter: localCounter,
Type: data.PayloadMessage,
Payload: payload,
Topic: topic,
Version: wt.payloadVersion,
}
newPayload, err := wt.payloadParser.ConstructPayload(wsMessage)
if err != nil {
return err
}
return wt.sendPayload(newPayload, connection, ch)
}
func (wt *wsTransceiver) prepareChanAndCounter() (chan struct{}, uint64) {
wt.mutMapAck.Lock()
wt.counter++
localCounter := wt.counter
ch := make(chan struct{})
if wt.withAcknowledge {
wt.mapAck[localCounter] = ch
}
wt.mutMapAck.Unlock()
return ch, localCounter
}
func (wt *wsTransceiver) sendPayload(payload []byte, connection webSocket.WSConClient, ch chan struct{}) error {
errSend := connection.WriteMessage(websocket.BinaryMessage, payload)
if errSend != nil {
return errSend
}
if !wt.withAcknowledge {
return nil
}
return wt.waitForAck(ch)
}
func (wt *wsTransceiver) waitForAck(ch chan struct{}) error {
timer := time.NewTimer(wt.ackTimeout)
defer timer.Stop()
select {
case <-ch:
return nil
case <-timer.C:
return data.ErrAckTimeout
case <-wt.safeCloser.ChanClose():
return data.ErrExpectedAckWasNotReceivedOnClose
}
}
// Close will close the underlying ws connection
func (wt *wsTransceiver) Close() error {
defer wt.safeCloser.Close()
err := wt.payloadHandler.Close()
if err != nil {
wt.log.Debug("cannot close the payload handler", "error", err)
}
return err
}