From 202d91334bdf7f5eb097463eca35ef06a1b724b9 Mon Sep 17 00:00:00 2001
From: tverona1 <tverona@hotmail.com>
Date: Sat, 17 Aug 2019 17:34:53 -0700
Subject: [PATCH] Lock around downloading assets

- Added lock around downloading assets to ensure only one download task is running at a time
---
 Assets/Resources/OVRBuildConfig.asset | 2 +-
 Assets/Scripts/AssetsDownloader.cs    | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/Assets/Resources/OVRBuildConfig.asset b/Assets/Resources/OVRBuildConfig.asset
index f2d36f8..cf5cd6c 100644
--- a/Assets/Resources/OVRBuildConfig.asset
+++ b/Assets/Resources/OVRBuildConfig.asset
@@ -12,6 +12,6 @@ MonoBehaviour:
   m_Script: {fileID: 11500000, guid: 20553fac56ec59645857c0732b787431, type: 3}
   m_Name: OVRBuildConfig
   m_EditorClassIdentifier: 
-  androidSDKPath: C:\Users\tvero\AppData\Local\Android\Sdk
+  androidSDKPath: 
   gradlePath: 
   jdkPath: 
diff --git a/Assets/Scripts/AssetsDownloader.cs b/Assets/Scripts/AssetsDownloader.cs
index 0e00784..3639df8 100644
--- a/Assets/Scripts/AssetsDownloader.cs
+++ b/Assets/Scripts/AssetsDownloader.cs
@@ -4,6 +4,7 @@ using System.Collections.Generic;
 using System.IO;
 using System.Text;
 using System.Text.RegularExpressions;
+using System.Threading;
 using System.Threading.Tasks;
 using UnityEngine;
 using UnityEngine.Networking;
@@ -30,6 +31,9 @@ namespace QuestAppLauncher
         // Rate limit in minutes
         const int RateLimitInMins = 5;
 
+        // Used for mutual exclusion when loading assets
+        static SemaphoreSlim semaphoreSlim = new SemaphoreSlim(1, 1);
+
         /// <summary>
         /// Class that tracks each file downloaded.
         /// Used to determine whether an asset has been updated since last download.
@@ -75,6 +79,9 @@ namespace QuestAppLauncher
             // Start background thread
             Task.Run(async () =>
             {
+                // Mutual exclusion while loading assets
+                await AssetsDownloader.semaphoreSlim.WaitAsync();
+
                 // Attach / detatch JNI. Required for any calls into JNI from background threads.
                 AndroidJNI.AttachCurrentThread();
 
@@ -86,6 +93,7 @@ namespace QuestAppLauncher
                 }
                 finally
                 {
+                    AssetsDownloader.semaphoreSlim.Release();
                     AndroidJNI.DetachCurrentThread();
                 }
             }).ContinueWith((downloadedAssets) =>