Android: Don't hold gameFileCache lock during updateAdditionalMetadata

It seems like we spend a lot of the game list scanning time in
updateAdditionalMetadata, which I suppose makes sense considering
how many different files that function attempts to open.

With the addition of just one little atomic operation, we can make
it safe to call updateAdditionalMetadata without holding a lock.

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheService.java

@@ -194,26 +194,27 @@ public final class GameFileCacheService extends IntentService
       {
         String[] gamePaths = GameFileCache.getAllGamePaths();
 
+        boolean changed;
         synchronized (gameFileCache)
         {
-          boolean changed = gameFileCache.update(gamePaths);
-          if (changed)
-          {
-            updateGameFileArray();
-            sendBroadcast(CACHE_UPDATED);
-          }
+          changed = gameFileCache.update(gamePaths);
+        }
+        if (changed)
+        {
+          updateGameFileArray();
+          sendBroadcast(CACHE_UPDATED);
+        }
 
-          boolean additionalMetadataChanged = gameFileCache.updateAdditionalMetadata();
-          if (additionalMetadataChanged)
-          {
-            updateGameFileArray();
-            sendBroadcast(CACHE_UPDATED);
-          }
+        boolean additionalMetadataChanged = gameFileCache.updateAdditionalMetadata();
+        if (additionalMetadataChanged)
+        {
+          updateGameFileArray();
+          sendBroadcast(CACHE_UPDATED);
+        }
 
-          if (changed || additionalMetadataChanged)
-          {
-            gameFileCache.save();
-          }
+        if (changed || additionalMetadataChanged)
+        {
+          gameFileCache.save();
         }
       }
 

Source/CMakeLists.txt

@@ -14,6 +14,8 @@ 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 (MSVC)

Source/Core/UICommon/GameFileCache.cpp

@@ -4,6 +4,7 @@
 #include "UICommon/GameFileCache.h"
 
 #include <algorithm>
+#include <atomic>
 #include <cstddef>
 #include <functional>
 #include <list>
@@ -202,7 +203,7 @@ bool GameFileCache::UpdateAdditionalMetadata(std::shared_ptr<GameFile>* game_fil
   if (custom_cover_changed)
     copy->CustomCoverCommit();
 
-  *game_file = std::move(copy);
+  std::atomic_store(game_file, std::move(copy));
 
   return true;
 }

Source/VSProps/Base.props

@@ -64,6 +64,8 @@
       <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>
       <PreprocessorDefinitions>USE_UPNP;USE_USBDK;__LIBUSB__;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions>SFML_STATIC;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions>USE_ANALYTICS=1;%(PreprocessorDefinitions)</PreprocessorDefinitions>