fix a memory leak and memory corruption in RefBase

we would leak a weakref_impl if a RefBase was never incWeak()'ed.
there was also a dangling pointer that would cause memory corruption
and double-delete when a custom destroyer was used to delay the
execution of ~RefBase.

it turns out that the custom destroyer feature caused most of the
problems, so it's now gone. The only client was SurfaceFlinger
who now handles things on its own.

RefBase is essentially back its "gingerbread" state, but the
code was slightly cleaned-up.

Bug: 5151207, 5084978
Change-Id: Id6ef1d707f96d96366f75068f77b30e0ce2722a5

1 files changed, 7 insertions, 17 deletions

diff --git a/include/utils/RefBase.h b/include/utils/RefBase.h
index ca17082..c7a9b78 100644
--- a/include/utils/RefBase.h
+++ b/include/utils/RefBase.h
@@ -80,9 +80,12 @@ public:
         void                incWeak(const void* id);
         void                decWeak(const void* id);
         
+        // acquires a strong reference if there is already one.
         bool                attemptIncStrong(const void* id);
         
-        //! This is only safe if you have set OBJECT_LIFETIME_FOREVER.
+        // acquires a weak reference if there is already one.
+        // This is not always safe. see ProcessState.cpp and BpBinder.cpp
+        // for proper use.
         bool                attemptIncWeak(const void* id);
 
         //! DEBUGGING ONLY: Get current weak ref count.
@@ -116,28 +119,15 @@ public:
 
     typedef RefBase basetype;
 
-    // used to override the RefBase destruction.
-    class Destroyer {
-        friend class RefBase;
-        friend class weakref_type;
-    public:
-        virtual ~Destroyer();
-    private:
-        virtual void destroy(RefBase const* base) = 0;
-    };
-
-    // Make sure to never acquire a strong reference from this function. The
-    // same restrictions than for destructors apply.
-    void setDestroyer(Destroyer* destroyer);
-
 protected:
                             RefBase();
     virtual                 ~RefBase();
 
     //! Flags for extendObjectLifetime()
     enum {
+        OBJECT_LIFETIME_STRONG  = 0x0000,
         OBJECT_LIFETIME_WEAK    = 0x0001,
-        OBJECT_LIFETIME_FOREVER = 0x0003
+        OBJECT_LIFETIME_MASK    = 0x0001
     };
     
             void            extendObjectLifetime(int32_t mode);
@@ -163,7 +153,7 @@ private:
     
                             RefBase(const RefBase& o);
             RefBase&        operator=(const RefBase& o);
-            
+
         weakref_impl* const mRefs;
 };