qemu: more refactoring

qmp client is now much more robust (and doesn't fight over itself as much). this should
hopefully completely eliminate the case where display connects but qmp is half connected.

i also forgot QemuDisplay actually emits an event on connection, so we can just use that to
wait for when the display connects. which allows us to set the started state there instead of praying
when the qmp client connects that we are connected to the display roughly at the same time.

i also gated some stuff to require vm state in the server. this is a bit rickity, but does seem to work.

qemu/src/QemuVM.ts

@@ -51,14 +51,14 @@ class SocketWriter implements IQmpClientWriter {
 export class QemuVM extends EventEmitter {
 	private state = VMState.Stopped;
 
+	// QMP stuff.
 	private qmpInstance: QmpClient = new QmpClient();
 	private qmpSocket: Socket | null = null;
-	private qmpConnected = false;
 	private qmpFailCount = 0;
 
 	private qemuProcess: ExecaChildProcess | null = null;
 
-	private display: QemuDisplay | null;
+	private display: QemuDisplay | null = null;
 	private definition: QemuVmDefinition;
 	private addedAdditionalArguments = false;
 
@@ -69,8 +69,6 @@ export class QemuVM extends EventEmitter {
 		this.definition = def;
 		this.logger = new Shared.Logger(`CVMTS.QEMU.QemuVM/${this.definition.id}`);
 
-		this.display = new QemuDisplay(this.GetVncPath());
-
 		let self = this;
 
 		// Handle the STOP event sent when using -no-shutdown
@@ -86,12 +84,16 @@ export class QemuVM extends EventEmitter {
 			self.VMLog().Info('QMP ready');
 
 			this.display = new QemuDisplay(this.GetVncPath());
-			self.display?.Connect();
 
-			// QMP has been connected so the VM is ready to be considered started
+			self.display?.on('connected', () => {
+				// The VM can now be considered started
+				self.VMLog().Info("Display connected");
+				self.SetState(VMState.Started);
+			})
+
+			// now that we've connected to VNC, connect to the display
 			self.qmpFailCount = 0;
-			self.qmpConnected = true;
-			self.SetState(VMState.Started);
+			self.display?.Connect();
 		});
 	}
 
@@ -170,6 +172,10 @@ export class QemuVM extends EventEmitter {
 		return this.display!;
 	}
 
+	GetState() {
+		return this.state;
+	}
+
 	/// Private fun bits :)
 
 	private VMLog() {
@@ -223,7 +229,6 @@ export class QemuVM extends EventEmitter {
 
 			// Disconnect from the display and QMP connections.
 			await self.DisconnectDisplay();
-			await self.DisconnectQmp();
 
 			// Remove the sockets for VNC and QMP.
 			try {
@@ -262,8 +267,10 @@ export class QemuVM extends EventEmitter {
 	private async ConnectQmp() {
 		let self = this;
 
-		if (this.qmpConnected) {
-			this.VMLog().Error('Already connected to QMP!');
+		if (this.qmpSocket) {
+			// This isn't really a problem (since we gate it)
+			// but I'd like to see if i could eliminate this
+			this.VMLog().Warning('QemuVM.ConnectQmp(): Already connected to QMP socket!');
 			return;
 		}
 
@@ -271,20 +278,20 @@ export class QemuVM extends EventEmitter {
 		this.qmpSocket = connect(this.GetQmpPath());
 
 		this.qmpSocket.on('close', async () => {
-			if (self.qmpConnected) {
-				await self.DisconnectQmp();
+			self.qmpSocket?.removeAllListeners();
+			self.qmpSocket = null;
 
-				// If we aren't stopping, then we should care QMP disconnected
-				if (self.state != VMState.Stopping) {
-					if (self.qmpFailCount++ < kMaxFailCount) {
-						self.VMLog().Error(`Failed to connect to QMP ${self.qmpFailCount} times.`);
-						await Shared.Sleep(500);
-						await self.ConnectQmp();
-					} else {
-						self.VMLog().Error(`Reached max retries, giving up.`);
-						await self.Stop();
-						return;
-					}
+			// If we aren't stopping (i.e: disconnection wasn't because we disconnected), 
+			// then we should care QMP disconnected
+			if (self.state != VMState.Stopping) {
+				if (self.qmpFailCount++ < kMaxFailCount) {
+					self.VMLog().Error(`Failed to connect to QMP ${self.qmpFailCount} times.`);
+					await Shared.Sleep(500);
+					await self.ConnectQmp();
+				} else {
+					self.VMLog().Error(`Reached max retries, giving up.`);
+					await self.Stop();
+					return;
 				}
 			}
 		});
@@ -293,10 +300,15 @@ export class QemuVM extends EventEmitter {
 			self.VMLog().Error('QMP socket error: {0}', e.message);
 		});
 
-		// Setup the QMP client.
-		let writer = new SocketWriter(this.qmpSocket, this.qmpInstance);
-		this.qmpInstance.reset();
-		this.qmpInstance.setWriter(writer);
+		this.qmpSocket.on('connect', () => {
+			self.VMLog().Info("Connected to QMP socket");
+
+			// Setup the QMP client.
+			let writer = new SocketWriter(self.qmpSocket!, self.qmpInstance);
+			self.qmpInstance.reset();
+			self.qmpInstance.setWriter(writer);
+		})
+
 	}
 
 	private async DisconnectDisplay() {
@@ -307,13 +319,4 @@ export class QemuVM extends EventEmitter {
 			// oh well lol
 		}
 	}
-
-	private async DisconnectQmp() {
-		if (!this.qmpConnected) return;
-		this.qmpConnected = false;
-
-		if (this.qmpSocket == null) return;
-		this.qmpSocket?.end();
-		this.qmpSocket = null;
-	}
 }