From 51debaeb47de93edec1ba10161df74a2f7f49209 Mon Sep 17 00:00:00 2001
From: JosJuice <josjuice@gmail.com>
Date: Tue, 27 Sep 2022 18:57:42 +0200
Subject: [PATCH] Revert "Android: Don't hold gameFileCache lock during
 updateAdditionalMetadata"

This reverts commit fb265b610de08df5509e56beeb3dbff68f7d4396.

The optimization in that commit is safe when the executor thread is
writing and the GUI thread is reading, but I had failed to take into
account that it's unsafe when the GUI thread is writing and the executor
thread is reading. (The native UpdateAdditionalMetadata function loops
through m_cached_files, which is unsafe if another thread is adding
elements to m_cached_files simultaneously.)

Losing out on this optimization isn't too bad, because
719930bb390ed0020b99a7942289d83218e99d69 makes it very unlikely that
both threads will want the lock at the same time.
---
 .../services/GameFileCacheManager.java        | 29 +++++++++----------
 Source/CMakeLists.txt                         |  2 --
 Source/Core/UICommon/GameFileCache.cpp        |  3 +-
 Source/VSProps/Base.Dolphin.props             |  2 --
 4 files changed, 15 insertions(+), 21 deletions(-)

diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheManager.java b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheManager.java
index b359915901..4e883413b4 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheManager.java
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheManager.java
@@ -227,25 +227,24 @@ public final class GameFileCacheManager
     {
       String[] gamePaths = GameFileCache.getAllGamePaths();
 
-      boolean changed;
       synchronized (sGameFileCache)
       {
-        changed = sGameFileCache.update(gamePaths);
-      }
-      if (changed)
-      {
-        updateGameFileArray();
-      }
+        boolean changed = sGameFileCache.update(gamePaths);
+        if (changed)
+        {
+          updateGameFileArray();
+        }
 
-      boolean additionalMetadataChanged = sGameFileCache.updateAdditionalMetadata();
-      if (additionalMetadataChanged)
-      {
-        updateGameFileArray();
-      }
+        boolean additionalMetadataChanged = sGameFileCache.updateAdditionalMetadata();
+        if (additionalMetadataChanged)
+        {
+          updateGameFileArray();
+        }
 
-      if (changed || additionalMetadataChanged)
-      {
-        sGameFileCache.save();
+        if (changed || additionalMetadataChanged)
+        {
+          sGameFileCache.save();
+        }
       }
     }
 
diff --git a/Source/CMakeLists.txt b/Source/CMakeLists.txt
index 7e5b548864..4a4cd61b51 100644
--- a/Source/CMakeLists.txt
+++ b/Source/CMakeLists.txt
@@ -13,8 +13,6 @@ if(CMAKE_SYSTEM_NAME MATCHES "Windows")
   add_definitions(-D_CRT_SECURE_NO_DEPRECATE)
   add_definitions(-D_CRT_NONSTDC_NO_WARNINGS)
   add_definitions(-D_SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING)
-  # The replacement for the old atomic shared_ptr functions was added in C++20, so we can't use it yet
-  add_definitions(-D_SILENCE_CXX20_OLD_SHARED_PTR_ATOMIC_SUPPORT_DEPRECATION_WARNING)
 endif()
 
 if (NOT MSVC)
diff --git a/Source/Core/UICommon/GameFileCache.cpp b/Source/Core/UICommon/GameFileCache.cpp
index f9b26d344d..59c4c9a292 100644
--- a/Source/Core/UICommon/GameFileCache.cpp
+++ b/Source/Core/UICommon/GameFileCache.cpp
@@ -4,7 +4,6 @@
 #include "UICommon/GameFileCache.h"
 
 #include <algorithm>
-#include <atomic>
 #include <cstddef>
 #include <functional>
 #include <list>
@@ -204,7 +203,7 @@ bool GameFileCache::UpdateAdditionalMetadata(std::shared_ptr<GameFile>* game_fil
   if (custom_cover_changed)
     copy->CustomCoverCommit();
 
-  std::atomic_store(game_file, std::move(copy));
+  *game_file = std::move(copy);
 
   return true;
 }
diff --git a/Source/VSProps/Base.Dolphin.props b/Source/VSProps/Base.Dolphin.props
index 43af6653a1..aadb04d5dd 100644
--- a/Source/VSProps/Base.Dolphin.props
+++ b/Source/VSProps/Base.Dolphin.props
@@ -29,8 +29,6 @@
       <PreprocessorDefinitions>_WINSOCK_DEPRECATED_NO_WARNINGS;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <!--Currently needed for some code in StringUtil used only on Android-->
       <PreprocessorDefinitions>_SILENCE_CXX17_CODECVT_HEADER_DEPRECATION_WARNING;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-      <!--The replacement for the old atomic shared_ptr functions was added in C++20, so we can't use it yet-->
-      <PreprocessorDefinitions>_SILENCE_CXX20_OLD_SHARED_PTR_ATOMIC_SUPPORT_DEPRECATION_WARNING;%(PreprocessorDefinitions)</PreprocessorDefinitions>
 
       <!--Dolphin-specific definitions-->
       <PreprocessorDefinitions Condition="'$(Platform)'=='x64'">_ARCH_64=1;_M_X86=1;_M_X86_64=1;%(PreprocessorDefinitions)</PreprocessorDefinitions>