From 005f0d5723880d5a2a0900e54db220d09fa013ad Mon Sep 17 00:00:00 2001
From: Julian Waller <git@julusian.co.uk>
Date: Wed, 2 Aug 2023 09:48:52 +0100
Subject: [PATCH] fix: disconnect called before connection has completed #107
 (#150)

---
 src/lib/atemSocket.ts | 45 ++++++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 16 deletions(-)

diff --git a/src/lib/atemSocket.ts b/src/lib/atemSocket.ts
index f6f3a4233..b63204a81 100644
--- a/src/lib/atemSocket.ts
+++ b/src/lib/atemSocket.ts
@@ -3,7 +3,7 @@ import { CommandParser } from './atemCommandParser'
 import exitHook = require('exit-hook')
 import { VersionCommand, ISerializableCommand, IDeserializedCommand } from '../commands'
 import { DEFAULT_PORT } from '../atem'
-import { threadedClass, ThreadedClass, ThreadedClassManager, Promisify } from 'threadedclass'
+import { threadedClass, ThreadedClass, ThreadedClassManager } from 'threadedclass'
 import type { AtemSocketChild } from './atemSocketChild'
 
 export interface AtemSocketOptions {
@@ -30,9 +30,11 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 	private readonly _commandParser: CommandParser = new CommandParser()
 
 	private _nextCommandTrackingId = 0
+	private _isDisconnecting = false
 	private _address: string
 	private _port: number = DEFAULT_PORT
 	private _socketProcess: ThreadedClass<AtemSocketChild> | undefined
+	private _creatingSocket: Promise<void> | undefined
 	private _exitUnsubscribe?: () => void
 
 	constructor(options: AtemSocketOptions) {
@@ -45,6 +47,8 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 	}
 
 	public async connect(address?: string, port?: number): Promise<void> {
+		this._isDisconnecting = false
+
 		if (address) {
 			this._address = address
 		}
@@ -53,17 +57,24 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 		}
 
 		if (!this._socketProcess) {
-			this._socketProcess = await this._createSocketProcess()
-			this._exitUnsubscribe = exitHook(() => {
-				this.destroy().catch(() => null)
-			})
-		} else {
-			await this._socketProcess.connect(this._address, this._port)
+			// cache the creation promise, in case `destroy` is called before it completes
+			this._creatingSocket = this._createSocketProcess()
+			await this._creatingSocket
+
+			if (this._isDisconnecting || !this._socketProcess) {
+				throw new Error('Disconnecting')
+			}
 		}
+
+		await this._socketProcess.connect(this._address, this._port)
 	}
 
 	public async destroy(): Promise<void> {
 		await this.disconnect()
+
+		// Ensure thread creation has finished if it was started
+		if (this._creatingSocket) await this._creatingSocket.catch(() => null)
+
 		if (this._socketProcess) {
 			await ThreadedClassManager.destroy(this._socketProcess)
 			this._socketProcess = undefined
@@ -75,6 +86,8 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 	}
 
 	public async disconnect(): Promise<void> {
+		this._isDisconnecting = true
+
 		if (this._socketProcess) {
 			await this._socketProcess.disconnect()
 		}
@@ -91,7 +104,7 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 		commands: Array<{ rawCommand: ISerializableCommand; trackingId: number }>
 	): Promise<void> {
 		if (this._socketProcess) {
-			const commands2 = commands.map((cmd) => {
+			const wrappedCommands = commands.map((cmd) => {
 				if (typeof cmd.rawCommand.serialize !== 'function') {
 					throw new Error(`Command ${cmd.rawCommand.constructor.name} is not serializable`)
 				}
@@ -107,14 +120,14 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 				}
 			})
 
-			await this._socketProcess.sendCommands(commands2)
+			await this._socketProcess.sendCommands(wrappedCommands)
 		} else {
 			throw new Error('Socket process is not open')
 		}
 	}
 
-	private async _createSocketProcess(): Promise<Promisify<AtemSocketChild>> {
-		const socketProcess = await threadedClass<AtemSocketChild, typeof AtemSocketChild>(
+	private async _createSocketProcess(): Promise<void> {
+		this._socketProcess = await threadedClass<AtemSocketChild, typeof AtemSocketChild>(
 			'./atemSocketChild',
 			'AtemSocketChild',
 			[
@@ -147,19 +160,19 @@ export class AtemSocket extends EventEmitter<AtemSocketEvents> {
 			}
 		)
 
-		ThreadedClassManager.onEvent(socketProcess, 'restarted', () => {
+		ThreadedClassManager.onEvent(this._socketProcess, 'restarted', () => {
 			this.connect().catch((error) => {
 				const errorMsg = `Failed to reconnect after respawning socket process: ${error}`
 				this.emit('error', errorMsg)
 			})
 		})
-		ThreadedClassManager.onEvent(socketProcess, 'thread_closed', () => {
+		ThreadedClassManager.onEvent(this._socketProcess, 'thread_closed', () => {
 			this.emit('disconnect')
 		})
 
-		await socketProcess.connect(this._address, this._port)
-
-		return socketProcess
+		this._exitUnsubscribe = exitHook(() => {
+			this.destroy().catch(() => null)
+		})
 	}
 
 	private _parseCommands(buffer: Buffer): IDeserializedCommand[] {