From 7d75e864b1e566f78b53c63f21ac9f296b65d17d Mon Sep 17 00:00:00 2001
From: Thomas Harte <thomas.harte@gmail.com>
Date: Sun, 18 Feb 2018 22:09:03 -0500
Subject: [PATCH] Ensures thread safety of usages of `bestEffortLock`.

---
 .../Documents/MachineDocument.swift           | 20 ++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/OSBindings/Mac/Clock Signal/Documents/MachineDocument.swift b/OSBindings/Mac/Clock Signal/Documents/MachineDocument.swift
index 8fbdad7fc..34ea26be3 100644
--- a/OSBindings/Mac/Clock Signal/Documents/MachineDocument.swift	
+++ b/OSBindings/Mac/Clock Signal/Documents/MachineDocument.swift	
@@ -18,8 +18,10 @@ class MachineDocument:
 	CSBestEffortUpdaterDelegate,
 	CSAudioQueueDelegate
 {
-	lazy var actionLock = NSLock()
-	lazy var drawLock = NSLock()
+	fileprivate let actionLock = NSLock()
+	fileprivate let drawLock = NSLock()
+	fileprivate let bestEffortLock = NSLock()
+
 	var machine: CSMachine!
 	var name: String! {
 		get {
@@ -77,7 +79,9 @@ class MachineDocument:
 	}
 
 	func machineDidChangeClockIsUnlimited(_ machine: CSMachine!) {
+		bestEffortLock.lock()
 		self.bestEffortUpdater?.runAsUnlimited = machine.clockIsUnlimited
+		bestEffortLock.unlock()
 	}
 
 	fileprivate func setupClockRate() {
@@ -91,20 +95,24 @@ class MachineDocument:
 			self.machine.setAudioSamplingRate(selectedSamplingRate, bufferSize:audioQueue.preferredBufferSize)
 		}
 
+		bestEffortLock.lock()
 		self.bestEffortUpdater?.clockRate = self.machine.clockRate
+		bestEffortLock.unlock()
 	}
 
 	override func close() {
 		optionsPanel?.setIsVisible(false)
 		optionsPanel = nil
 
-		openGLView.delegate = nil
+		bestEffortLock.lock()
 		bestEffortUpdater!.delegate = nil
 		bestEffortUpdater = nil
+		bestEffortLock.unlock()
 
 		actionLock.lock()
 		drawLock.lock()
 		machine = nil
+		openGLView.delegate = nil
 		openGLView.invalidate()
 		actionLock.unlock()
 		drawLock.unlock()
@@ -148,6 +156,7 @@ class MachineDocument:
 	}
 
 	func runForNumberOfCycles(_ numberOfCycles: Int32) {
+		bestEffortLock.lock()
 		if let bestEffortUpdater = bestEffortUpdater {
 			let cyclesToRunFor = min(numberOfCycles, Int32(bestEffortUpdater.clockRate / 10))
 			if actionLock.try() {
@@ -155,15 +164,19 @@ class MachineDocument:
 				actionLock.unlock()
 			}
 		}
+		bestEffortLock.unlock()
 	}
 
 	// MARK: CSAudioQueueDelegate
 	final func audioQueueIsRunningDry(_ audioQueue: CSAudioQueue) {
+		bestEffortLock.lock()
 		bestEffortUpdater?.update()
+		bestEffortLock.unlock()
 	}
 
 	// MARK: CSOpenGLViewDelegate
 	final func openGLView(_ view: CSOpenGLView, drawViewOnlyIfDirty onlyIfDirty: Bool) {
+		bestEffortLock.lock()
 		if let bestEffortUpdater = bestEffortUpdater {
 			bestEffortUpdater.update()
 			if drawLock.try() {
@@ -171,6 +184,7 @@ class MachineDocument:
 				drawLock.unlock()
 			}
 		}
+		bestEffortLock.unlock()
 	}
 
 	final func openGLView(_ view: CSOpenGLView, didReceiveFileAt URL: URL) {