LayoutLib: Hold onto delegate references.

When an object is given a delegate to hold onto, keep
the reference to the delegate instead of its native integer.

Also change the way the finalizer works by not explicitely deleting
the delegate. Instead we want the delegate to be deleted when
nothing holds a reference to it. To do this, instead of using
a regular SparseArray, we use a SparseArray of WeakReferences.
Because the main Java object that "owns" the delegate does not
actually holds a reference to the delegate, we fake this by
having the delegate manager hold a reference to delegates for
the main object. This is added/removed as the object is created
and the native finalized is called.

This makes layoutlib behave more like the JNI code where the native
objects are reference counted, and where the Java object can be
deleted but the delegate it owns is kept around (usually because
another type of delegates hold a reference on it.)

To properly handle the WeakReferences, we need to be able to
regularly clear the SparseArray of WeakReference that were
referencing objects that have been GC'ed.
Since the SparseArray is regularly being compacted (actually only
when items are removed), we use a custom SparseWeakArray (started
as a straight copy of SparseArray) that handles the WeakReference
and takes care of compacting the array by removing deleted indices
and WeakReference that returns null. Since our specific use case
doesn't call actually delete() or remove(), the compacting
only happens when the array needs to be resized.

Change-Id: Iacc5c1ff5b21732b8816fda87eb090da12d034e0

1 files changed, 3 insertions, 3 deletions

diff --git a/tools/layoutlib/bridge/src/android/graphics/Bitmap_Delegate.java b/tools/layoutlib/bridge/src/android/graphics/Bitmap_Delegate.java
index 0c87766..b6d5725 100644
--- a/tools/layoutlib/bridge/src/android/graphics/Bitmap_Delegate.java
+++ b/tools/layoutlib/bridge/src/android/graphics/Bitmap_Delegate.java
@@ -245,12 +245,12 @@ public final class Bitmap_Delegate {
 
     @LayoutlibDelegate
     /*package*/ static void nativeDestructor(int nativeBitmap) {
-        sManager.removeDelegate(nativeBitmap);
+        sManager.removeJavaReferenceFor(nativeBitmap);
     }
 
     @LayoutlibDelegate
     /*package*/ static void nativeRecycle(int nativeBitmap) {
-        sManager.removeDelegate(nativeBitmap);
+        sManager.removeJavaReferenceFor(nativeBitmap);
     }
 
     @LayoutlibDelegate
@@ -522,7 +522,7 @@ public final class Bitmap_Delegate {
 
     private static Bitmap createBitmap(Bitmap_Delegate delegate, boolean isMutable, int density) {
         // get its native_int
-        int nativeInt = sManager.addDelegate(delegate);
+        int nativeInt = sManager.addNewDelegate(delegate);
 
         // and create/return a new Bitmap with it
         return new Bitmap(nativeInt, null /* buffer */, isMutable, null /*ninePatchChunk*/, density);