Merge pull request #10054 from JosJuice/android-game-cache-lock

Android: Reduce gameFileCache lock contention

2 files changed, 54 insertions, 29 deletions

diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/model/GameFileCache.java b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/model/GameFileCache.java
index a6f5261048..ed0f65741a 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/model/GameFileCache.java
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/model/GameFileCache.java
@@ -96,12 +96,7 @@ public class GameFileCache
     return pathSet;
   }
 
-  /**
-   * Scans through the file system and updates the cache to match.
-   *
-   * @return true if the cache was modified
-   */
-  public boolean update()
+  public static String[] getAllGamePaths()
   {
     boolean recursiveScan = BooleanSetting.MAIN_RECURSIVE_ISO_PATHS.getBooleanGlobal();
 
@@ -109,17 +104,33 @@ public class GameFileCache
 
     String[] folderPaths = folderPathsSet.toArray(new String[0]);
 
-    return update(folderPaths, recursiveScan);
+    return getAllGamePaths(folderPaths, recursiveScan);
   }
 
+  public static native String[] getAllGamePaths(String[] folderPaths, boolean recursiveScan);
+
   public native int getSize();
 
   public native GameFile[] getAllGames();
 
   public native GameFile addOrGet(String gamePath);
 
-  public native boolean update(String[] folderPaths, boolean recursiveScan);
+  /**
+   * Sets the list of games to cache.
+   *
+   * Games which are in the passed-in list but not in the cache are scanned and added to the cache,
+   * and games which are in the cache but not in the passed-in list are removed from the cache.
+   *
+   * @return true if the cache was modified
+   */
+  public native boolean update(String[] gamePaths);
 
+  /**
+   * For each game that already is in the cache, scans the folder that contains the game
+   * for additional metadata files (PNG/XML).
+   *
+   * @return true if the cache was modified
+   */
   public native boolean updateAdditionalMetadata();
 
   public native boolean load();
diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheService.java b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheService.java
index 7cff59a3e9..3be5fb039f 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheService.java
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/services/GameFileCacheService.java
@@ -159,9 +159,20 @@ public final class GameFileCacheService extends IntentService
 
   public static GameFile addOrGet(String gamePath)
   {
-    // The existence of this one function, which is called from one
-    // single place, forces us to use synchronization in onHandleIntent...
-    // A bit annoying, but should be good enough for now
+    // Common case: The game is in the cache, so just grab it from there.
+    // (Actually, addOrGet already checks for this case, but we want to avoid calling it if possible
+    // because onHandleIntent may hold a lock on gameFileCache for extended periods of time.)
+    GameFile[] allGames = gameFiles.get();
+    for (GameFile game : allGames)
+    {
+      if (game.getPath().equals(gamePath))
+      {
+        return game;
+      }
+    }
+
+    // Unusual case: The game wasn't found in the cache.
+    // Scan the game and add it to the cache so that we can return it.
     synchronized (gameFileCache)
     {
       return gameFileCache.addOrGet(gamePath);
@@ -192,26 +203,29 @@ public final class GameFileCacheService extends IntentService
     {
       if (gameFileCache != null)
       {
+        String[] gamePaths = GameFileCache.getAllGamePaths();
+
+        boolean changed;
         synchronized (gameFileCache)
         {
-          boolean changed = gameFileCache.update();
-          if (changed)
-          {
-            updateGameFileArray();
-            sendBroadcast(CACHE_UPDATED);
-          }
-
-          boolean additionalMetadataChanged = gameFileCache.updateAdditionalMetadata();
-          if (additionalMetadataChanged)
-          {
-            updateGameFileArray();
-            sendBroadcast(CACHE_UPDATED);
-          }
-
-          if (changed || additionalMetadataChanged)
-          {
-            gameFileCache.save();
-          }
+          changed = gameFileCache.update(gamePaths);
+        }
+        if (changed)
+        {
+          updateGameFileArray();
+          sendBroadcast(CACHE_UPDATED);
+        }
+
+        boolean additionalMetadataChanged = gameFileCache.updateAdditionalMetadata();
+        if (additionalMetadataChanged)
+        {
+          updateGameFileArray();
+          sendBroadcast(CACHE_UPDATED);
+        }
+
+        if (changed || additionalMetadataChanged)
+        {
+          gameFileCache.save();
         }
       }