Issue #191: Fix logs channel race condition

issues/issue_191/process-compose.yaml

@@ -0,0 +1,4 @@
+version: "0.5"
+processes:
+  noisy:
+    command: while true; do date; done

src/api/ws_api.go

@@ -7,6 +7,7 @@ import (
 	"github.com/rs/zerolog/log"
 	"net/http"
 	"strconv"
+	"sync"
 )
 
 var upgrader = websocket.Upgrader{}
@@ -27,23 +28,34 @@ func (api *PcApi) HandleLogsStream(c *gin.Context) {
 
 	done := make(chan struct{})
 	logChan := make(chan LogMessage, 256)
-	connector := pclog.NewConnector(func(messages []string) {
-		for _, message := range messages {
-			msg := LogMessage{
-				Message:     message,
-				ProcessName: procName,
+	chanCloseMtx := &sync.Mutex{}
+	isChannelClosed := false
+	connector := pclog.NewConnector(
+		func(messages []string) {
+			for _, message := range messages {
+				msg := LogMessage{
+					Message:     message,
+					ProcessName: procName,
+				}
+				logChan <- msg
 			}
-			logChan <- msg
-		}
-		if !follow {
-			close(logChan)
-		}
-	},
+			if !follow {
+				chanCloseMtx.Lock()
+				defer chanCloseMtx.Unlock()
+				close(logChan)
+				isChannelClosed = true
+			}
+		},
 		func(message string) (n int, err error) {
 			msg := LogMessage{
 				Message:     message,
 				ProcessName: procName,
 			}
+			chanCloseMtx.Lock()
+			defer chanCloseMtx.Unlock()
+			if isChannelClosed {
+				return 0, nil
+			}
 			logChan <- msg
 			return len(message), nil
 		},

src/client/client.go

@@ -74,7 +74,8 @@ func (p *PcClient) GetLogLength() int {
 }
 
 func (p *PcClient) GetLogsAndSubscribe(name string, observer pclog.LogObserver) error {
-	return p.logger.ReadProcessLogs(name, p.logLength, true, observer)
+	_, err := p.logger.ReadProcessLogs(name, p.logLength, true, observer)
+	return err
 }
 
 func (p *PcClient) UnSubscribeLogger(name string, observer pclog.LogObserver) error {

src/client/logs.go

@@ -27,7 +27,7 @@ func NewLogClient(address, socketPath string) *LogClient {
 	}
 }
 
-func (l *LogClient) ReadProcessLogs(name string, offset int, follow bool, out io.StringWriter) (err error) {
+func (l *LogClient) ReadProcessLogs(name string, offset int, follow bool, out io.StringWriter) (done chan struct{}, err error) {
 
 	url := fmt.Sprintf("ws://%s/process/logs/ws?name=%s&offset=%d&follow=%v", l.address, name, offset, follow)
 	log.Info().Msgf("Connecting to %s", url)
@@ -42,28 +42,14 @@ func (l *LogClient) ReadProcessLogs(name string, offset int, follow bool, out io
 
 	if err != nil {
 		log.Error().Msgf("failed to dial to %s error: %v", url, err)
-		return err
+		return done, err
 	}
 	//defer l.ws.Close()
-	done := make(chan struct{})
+	done = make(chan struct{})
 
 	go l.readLogs(done, l.ws, follow, out)
 
-	/*for {
-		select {
-		case <-done:
-			return nil
-		case <-interrupt:
-			fmt.Println("interrupt")
-
-			select {
-			case <-done:
-			case <-time.After(time.Second):
-			}
-			return nil
-		}
-	}*/
-	return nil
+	return done, nil
 }
 
 // CloseChannel Cleanly close the connection by sending a close message and then

src/cmd/logs.go

@@ -19,15 +19,17 @@ var logsCmd = &cobra.Command{
 		name := args[0]
 
 		logger := getLogClient()
-		err := logger.ReadProcessLogs(name, *pcFlags.LogTailLength, *pcFlags.LogFollow, os.Stdout)
+		done, err := logger.ReadProcessLogs(name, *pcFlags.LogTailLength, *pcFlags.LogFollow, os.Stdout)
 		if err != nil {
 			log.Fatal().Err(err).Msgf("Failed to fetch logs for process %s", name)
 		}
 		interrupt := make(chan os.Signal, 1)
 		signal.Notify(interrupt, os.Interrupt)
 		select {
 		case <-interrupt:
-			fmt.Println("interrupt")
+			_ = logger.CloseChannel()
+			time.Sleep(time.Second)
+		case <-done:
 			_ = logger.CloseChannel()
 			time.Sleep(time.Second)
 		}