Free AssetManager weak refs before unmounting

AssetManagers are kept in WeakReference pools so there's a change
another thread in the system_server has opened a file on the external
card. Attempt to force a garbage collection to free these references
each time we're about to unmount a volume on the external storage.

Change-Id: I6e816e8c67b179887e488dc6758b43bcdd5914fb

1 files changed, 25 insertions, 0 deletions

diff --git a/services/java/com/android/server/MountService.java b/services/java/com/android/server/MountService.java
index 6e8b42e..cfba07a 100644
--- a/services/java/com/android/server/MountService.java
+++ b/services/java/com/android/server/MountService.java
@@ -826,6 +826,15 @@ class MountService extends IMountService.Stub
         if (!getVolumeState(path).equals(Environment.MEDIA_MOUNTED)) {
             return VoldResponseCode.OpFailedVolNotMounted;
         }
+
+        /*
+         * Force a GC to make sure AssetManagers in other threads of the
+         * system_server are cleaned up. We have to do this since AssetManager
+         * instances are kept as a WeakReference and it's possible we have files
+         * open on the external storage.
+         */
+        Runtime.getRuntime().gc();
+
         // Redundant probably. But no harm in updating state again.
         mPms.updateExternalMediaStatus(false, false);
         try {
@@ -1277,6 +1286,14 @@ class MountService extends IMountService.Stub
         waitForReady();
         warnOnNotMounted();
 
+        /*
+         * Force a GC to make sure AssetManagers in other threads of the
+         * system_server are cleaned up. We have to do this since AssetManager
+         * instances are kept as a WeakReference and it's possible we have files
+         * open on the external storage.
+         */
+        Runtime.getRuntime().gc();
+
         int rc = StorageResultCode.OperationSucceeded;
         try {
             mConnector.doCommand(String.format("asec destroy %s%s", id, (force ? " force" : "")));
@@ -1341,6 +1358,14 @@ class MountService extends IMountService.Stub
             }
          }
 
+        /*
+         * Force a GC to make sure AssetManagers in other threads of the
+         * system_server are cleaned up. We have to do this since AssetManager
+         * instances are kept as a WeakReference and it's possible we have files
+         * open on the external storage.
+         */
+        Runtime.getRuntime().gc();
+
         int rc = StorageResultCode.OperationSucceeded;
         String cmd = String.format("asec unmount %s%s", id, (force ? " force" : ""));
         try {