Alt approach, respect number of serial listeners

Author: microbit-robert

lib/usb-radio-bridge.ts

@@ -83,7 +83,10 @@ class MicrobitRadioBridgeConnectionImpl
     const currentStatus = this.status;
     if (e.status !== ConnectionStatus.CONNECTED) {
       this.setStatus(e.status);
-      this.serialSession?.dispose();
+      if (this.serialSessionOpen) {
+        // If the session is already closed we don't need to dispose.
+        this.serialSession?.dispose();
+      }
     } else {
       this.status = ConnectionStatus.DISCONNECTED;
       if (

lib/usb.ts

@@ -189,7 +189,7 @@ class MicrobitWebUSBConnectionImpl
         setTimeout(() => {
           if (this.status === ConnectionStatus.CONNECTED) {
             this.unloading = false;
-            if (this.listeningToSerialData) {
+            if (this.eventListeners.serialdata) {
               this.startSerialInternal();
             }
           }
@@ -202,7 +202,9 @@ class MicrobitWebUSBConnectionImpl
   private logging: Logging;
   private deviceSelectionMode: DeviceSelectionMode;
 
-  private listeningToSerialData = false;
+  private eventListeners: Record<string, number> = {
+    serialdata: 0,
+  };
 
   constructor(options: MicrobitWebUSBConnectionOptions = {}) {
     super();
@@ -335,7 +337,7 @@ class MicrobitWebUSBConnectionImpl
         await this.disconnect();
         this.visibilityReconnect = true;
       } else {
-        if (this.listeningToSerialData) {
+        if (this.eventListeners.serialdata) {
           this.log("Reinstating serial after flash");
           if (this.connection.daplink) {
             await this.connection.daplink.connect();
@@ -491,7 +493,7 @@ class MicrobitWebUSBConnectionImpl
     } else {
       await withTimeout(this.connection.reconnectAsync(), 10_000);
     }
-    if (this.listeningToSerialData && !this.flashing) {
+    if (this.eventListeners.serialdata && !this.flashing) {
       this.startSerialInternal();
     }
     this.setStatus(ConnectionStatus.CONNECTED);
@@ -562,12 +564,16 @@ class MicrobitWebUSBConnectionImpl
   protected eventActivated(type: string): void {
     switch (type as keyof SerialConnectionEventMap) {
       case "serialdata": {
+        if (this.eventListeners.serialdata) {
+          this.eventListeners.serialdata++;
+          break;
+        }
         // Prevent starting serial when flashing.
         if (!this.flashing) {
           this.startSerialInternal();
         }
         // Allows for reinstating serial after flashing.
-        this.listeningToSerialData = true;
+        this.eventListeners.serialdata++;
         break;
       }
     }
@@ -576,8 +582,10 @@ class MicrobitWebUSBConnectionImpl
   protected async eventDeactivated(type: string) {
     switch (type as keyof SerialConnectionEventMap) {
       case "serialdata": {
-        this.stopSerialInternal();
-        this.listeningToSerialData = false;
+        this.eventListeners.serialdata--;
+        if (!this.eventListeners.serialdata) {
+          this.stopSerialInternal();
+        }
         break;
       }
     }