diff --git a/include/binder/IBinder.h b/include/binder/IBinder.h
index 749a977..81b56c2 100644
--- a/include/binder/IBinder.h
+++ b/include/binder/IBinder.h
@@ -98,7 +98,7 @@
      * Register the @a recipient for a notification if this binder
      * goes away.  If this binder object unexpectedly goes away
      * (typically because its hosting process has been killed),
-     * then DeathRecipient::binderDied() will be called with a referene
+     * then DeathRecipient::binderDied() will be called with a reference
      * to this.
      *
      * The @a cookie is optional -- if non-NULL, it should be a
diff --git a/include/utils/RefBase.h b/include/utils/RefBase.h
index c24c0db..f355087 100644
--- a/include/utils/RefBase.h
+++ b/include/utils/RefBase.h
@@ -18,16 +18,19 @@
 #define ANDROID_REF_BASE_H
 
 #include <cutils/atomic.h>
-#include <utils/TextOutput.h>
 
 #include <stdint.h>
 #include <sys/types.h>
 #include <stdlib.h>
+#include <string.h>
+
+#include <utils/StrongPointer.h>
 
 // ---------------------------------------------------------------------------
 namespace android {
 
-template<typename T> class wp;
+class TextOutput;
+TextOutput& printWeakPointer(TextOutput& to, const void* val);
 
 // ---------------------------------------------------------------------------
 
@@ -47,15 +50,15 @@
     return m_ptr _op_ o;                                        \
 }
 
-#define COMPARE(_op_)                                           \
-COMPARE_WEAK(_op_)                                              \
-inline bool operator _op_ (const wp<T>& o) const {              \
-    return m_ptr _op_ o.m_ptr;                                  \
-}                                                               \
-template<typename U>                                            \
-inline bool operator _op_ (const wp<U>& o) const {              \
-    return m_ptr _op_ o.m_ptr;                                  \
-}
+// ---------------------------------------------------------------------------
+
+class ReferenceMover;
+class ReferenceConverterBase {
+public:
+    virtual size_t getReferenceTypeSize() const = 0;
+    virtual void* getReferenceBase(void const*) const = 0;
+    inline virtual ~ReferenceConverterBase() { }
+};
 
 // ---------------------------------------------------------------------------
 
@@ -112,6 +115,8 @@
         getWeakRefs()->trackMe(enable, retain); 
     }
 
+    typedef RefBase basetype;
+
 protected:
                             RefBase();
     virtual                 ~RefBase();
@@ -135,6 +140,11 @@
     virtual void            onLastWeakRef(const void* id);
 
 private:
+    friend class ReferenceMover;
+    static void moveReferences(void* d, void const* s, size_t n,
+            const ReferenceConverterBase& caster);
+
+private:
     friend class weakref_type;
     class weakref_impl;
     
@@ -163,10 +173,17 @@
     inline int32_t getStrongCount() const {
         return mCount;
     }
-    
+
+    typedef LightRefBase<T> basetype;
+
 protected:
     inline ~LightRefBase() { }
-    
+
+private:
+    friend class ReferenceMover;
+    inline static void moveReferences(void* d, void const* s, size_t n,
+            const ReferenceConverterBase& caster) { }
+
 private:
     mutable volatile int32_t mCount;
 };
@@ -174,66 +191,6 @@
 // ---------------------------------------------------------------------------
 
 template <typename T>
-class sp
-{
-public:
-    typedef typename RefBase::weakref_type weakref_type;
-    
-    inline sp() : m_ptr(0) { }
-
-    sp(T* other);
-    sp(const sp<T>& other);
-    template<typename U> sp(U* other);
-    template<typename U> sp(const sp<U>& other);
-
-    ~sp();
-    
-    // Assignment
-
-    sp& operator = (T* other);
-    sp& operator = (const sp<T>& other);
-    
-    template<typename U> sp& operator = (const sp<U>& other);
-    template<typename U> sp& operator = (U* other);
-    
-    //! Special optimization for use by ProcessState (and nobody else).
-    void force_set(T* other);
-    
-    // Reset
-    
-    void clear();
-    
-    // Accessors
-
-    inline  T&      operator* () const  { return *m_ptr; }
-    inline  T*      operator-> () const { return m_ptr;  }
-    inline  T*      get() const         { return m_ptr; }
-
-    // Operators
-        
-    COMPARE(==)
-    COMPARE(!=)
-    COMPARE(>)
-    COMPARE(<)
-    COMPARE(<=)
-    COMPARE(>=)
-
-private:    
-    template<typename Y> friend class sp;
-    template<typename Y> friend class wp;
-
-    // Optimization for wp::promote().
-    sp(T* p, weakref_type* refs);
-    
-    T*              m_ptr;
-};
-
-template <typename T>
-TextOutput& operator<<(TextOutput& to, const sp<T>& val);
-
-// ---------------------------------------------------------------------------
-
-template <typename T>
 class wp
 {
 public:
@@ -326,114 +283,12 @@
 template <typename T>
 TextOutput& operator<<(TextOutput& to, const wp<T>& val);
 
-#undef COMPARE
 #undef COMPARE_WEAK
 
 // ---------------------------------------------------------------------------
 // No user serviceable parts below here.
 
 template<typename T>
-sp<T>::sp(T* other)
-    : m_ptr(other)
-{
-    if (other) other->incStrong(this);
-}
-
-template<typename T>
-sp<T>::sp(const sp<T>& other)
-    : m_ptr(other.m_ptr)
-{
-    if (m_ptr) m_ptr->incStrong(this);
-}
-
-template<typename T> template<typename U>
-sp<T>::sp(U* other) : m_ptr(other)
-{
-    if (other) other->incStrong(this);
-}
-
-template<typename T> template<typename U>
-sp<T>::sp(const sp<U>& other)
-    : m_ptr(other.m_ptr)
-{
-    if (m_ptr) m_ptr->incStrong(this);
-}
-
-template<typename T>
-sp<T>::~sp()
-{
-    if (m_ptr) m_ptr->decStrong(this);
-}
-
-template<typename T>
-sp<T>& sp<T>::operator = (const sp<T>& other) {
-    T* otherPtr(other.m_ptr);
-    if (otherPtr) otherPtr->incStrong(this);
-    if (m_ptr) m_ptr->decStrong(this);
-    m_ptr = otherPtr;
-    return *this;
-}
-
-template<typename T>
-sp<T>& sp<T>::operator = (T* other)
-{
-    if (other) other->incStrong(this);
-    if (m_ptr) m_ptr->decStrong(this);
-    m_ptr = other;
-    return *this;
-}
-
-template<typename T> template<typename U>
-sp<T>& sp<T>::operator = (const sp<U>& other)
-{
-    U* otherPtr(other.m_ptr);
-    if (otherPtr) otherPtr->incStrong(this);
-    if (m_ptr) m_ptr->decStrong(this);
-    m_ptr = otherPtr;
-    return *this;
-}
-
-template<typename T> template<typename U>
-sp<T>& sp<T>::operator = (U* other)
-{
-    if (other) other->incStrong(this);
-    if (m_ptr) m_ptr->decStrong(this);
-    m_ptr = other;
-    return *this;
-}
-
-template<typename T>    
-void sp<T>::force_set(T* other)
-{
-    other->forceIncStrong(this);
-    m_ptr = other;
-}
-
-template<typename T>
-void sp<T>::clear()
-{
-    if (m_ptr) {
-        m_ptr->decStrong(this);
-        m_ptr = 0;
-    }
-}
-
-template<typename T>
-sp<T>::sp(T* p, weakref_type* refs)
-    : m_ptr((p && refs->attemptIncStrong(this)) ? p : 0)
-{
-}
-
-template <typename T>
-inline TextOutput& operator<<(TextOutput& to, const sp<T>& val)
-{
-    to << "sp<>(" << val.get() << ")";
-    return to;
-}
-
-// ---------------------------------------------------------------------------
-
-template<typename T>
 wp<T>::wp(T* other)
     : m_ptr(other)
 {
@@ -570,7 +425,11 @@
 template<typename T>
 sp<T> wp<T>::promote() const
 {
-    return sp<T>(m_ptr, m_refs);
+    sp<T> result;
+    if (m_ptr && m_refs->attemptIncStrong(&result)) {
+        result.set_pointer(m_ptr);
+    }
+    return result;
 }
 
 template<typename T>
@@ -585,10 +444,80 @@
 template <typename T>
 inline TextOutput& operator<<(TextOutput& to, const wp<T>& val)
 {
-    to << "wp<>(" << val.unsafe_get() << ")";
-    return to;
+    return printWeakPointer(to, val.unsafe_get());
 }
 
+// ---------------------------------------------------------------------------
+
+// this class just serves as a namespace so TYPE::moveReferences can stay
+// private.
+
+class ReferenceMover {
+    // StrongReferenceCast and WeakReferenceCast do the impedance matching
+    // between the generic (void*) implementation in Refbase and the strongly typed
+    // template specializations below.
+
+    template <typename TYPE>
+    struct StrongReferenceCast : public ReferenceConverterBase {
+        virtual size_t getReferenceTypeSize() const { return sizeof( sp<TYPE> ); }
+        virtual void* getReferenceBase(void const* p) const {
+            sp<TYPE> const* sptr(reinterpret_cast<sp<TYPE> const*>(p));
+            return static_cast<typename TYPE::basetype *>(sptr->get());
+        }
+    };
+
+    template <typename TYPE>
+    struct WeakReferenceCast : public ReferenceConverterBase {
+        virtual size_t getReferenceTypeSize() const { return sizeof( wp<TYPE> ); }
+        virtual void* getReferenceBase(void const* p) const {
+            wp<TYPE> const* sptr(reinterpret_cast<wp<TYPE> const*>(p));
+            return static_cast<typename TYPE::basetype *>(sptr->unsafe_get());
+        }
+    };
+
+public:
+    template<typename TYPE> static inline
+    void move_references(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
+        memmove(d, s, n*sizeof(sp<TYPE>));
+        StrongReferenceCast<TYPE> caster;
+        TYPE::moveReferences(d, s, n, caster);
+    }
+    template<typename TYPE> static inline
+    void move_references(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
+        memmove(d, s, n*sizeof(wp<TYPE>));
+        WeakReferenceCast<TYPE> caster;
+        TYPE::moveReferences(d, s, n, caster);
+    }
+};
+
+// specialization for moving sp<> and wp<> types.
+// these are used by the [Sorted|Keyed]Vector<> implementations
+// sp<> and wp<> need to be handled specially, because they do not
+// have trivial copy operation in the general case (see RefBase.cpp
+// when DEBUG ops are enabled), but can be implemented very
+// efficiently in most cases.
+
+template<typename TYPE> inline
+void move_forward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
+    ReferenceMover::move_references(d, s, n);
+}
+
+template<typename TYPE> inline
+void move_backward_type(sp<TYPE>* d, sp<TYPE> const* s, size_t n) {
+    ReferenceMover::move_references(d, s, n);
+}
+
+template<typename TYPE> inline
+void move_forward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
+    ReferenceMover::move_references(d, s, n);
+}
+
+template<typename TYPE> inline
+void move_backward_type(wp<TYPE>* d, wp<TYPE> const* s, size_t n) {
+    ReferenceMover::move_references(d, s, n);
+}
+
+
 }; // namespace android
 
 // ---------------------------------------------------------------------------
diff --git a/include/utils/StrongPointer.h b/include/utils/StrongPointer.h
new file mode 100644
index 0000000..a8c9897
--- /dev/null
+++ b/include/utils/StrongPointer.h
@@ -0,0 +1,220 @@
+/*
+ * Copyright (C) 2005 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_STRONG_POINTER_H
+#define ANDROID_STRONG_POINTER_H
+
+#include <cutils/atomic.h>
+
+#include <stdint.h>
+#include <sys/types.h>
+#include <stdlib.h>
+
+// ---------------------------------------------------------------------------
+namespace android {
+
+class TextOutput;
+TextOutput& printStrongPointer(TextOutput& to, const void* val);
+
+template<typename T> class wp;
+
+// ---------------------------------------------------------------------------
+
+#define COMPARE(_op_)                                           \
+inline bool operator _op_ (const sp<T>& o) const {              \
+    return m_ptr _op_ o.m_ptr;                                  \
+}                                                               \
+inline bool operator _op_ (const T* o) const {                  \
+    return m_ptr _op_ o;                                        \
+}                                                               \
+template<typename U>                                            \
+inline bool operator _op_ (const sp<U>& o) const {              \
+    return m_ptr _op_ o.m_ptr;                                  \
+}                                                               \
+template<typename U>                                            \
+inline bool operator _op_ (const U* o) const {                  \
+    return m_ptr _op_ o;                                        \
+}                                                               \
+inline bool operator _op_ (const wp<T>& o) const {              \
+    return m_ptr _op_ o.m_ptr;                                  \
+}                                                               \
+template<typename U>                                            \
+inline bool operator _op_ (const wp<U>& o) const {              \
+    return m_ptr _op_ o.m_ptr;                                  \
+}
+
+// ---------------------------------------------------------------------------
+
+template <typename T>
+class sp
+{
+public:
+    inline sp() : m_ptr(0) { }
+
+    sp(T* other);
+    sp(const sp<T>& other);
+    template<typename U> sp(U* other);
+    template<typename U> sp(const sp<U>& other);
+
+    ~sp();
+
+    // Assignment
+
+    sp& operator = (T* other);
+    sp& operator = (const sp<T>& other);
+
+    template<typename U> sp& operator = (const sp<U>& other);
+    template<typename U> sp& operator = (U* other);
+
+    //! Special optimization for use by ProcessState (and nobody else).
+    void force_set(T* other);
+
+    // Reset
+
+    void clear();
+
+    // Accessors
+
+    inline  T&      operator* () const  { return *m_ptr; }
+    inline  T*      operator-> () const { return m_ptr;  }
+    inline  T*      get() const         { return m_ptr; }
+
+    // Operators
+
+    COMPARE(==)
+    COMPARE(!=)
+    COMPARE(>)
+    COMPARE(<)
+    COMPARE(<=)
+    COMPARE(>=)
+
+private:    
+    template<typename Y> friend class sp;
+    template<typename Y> friend class wp;
+    void set_pointer(T* ptr);
+    T* m_ptr;
+};
+
+#undef COMPARE
+
+template <typename T>
+TextOutput& operator<<(TextOutput& to, const sp<T>& val);
+
+// ---------------------------------------------------------------------------
+// No user serviceable parts below here.
+
+template<typename T>
+sp<T>::sp(T* other)
+: m_ptr(other)
+  {
+    if (other) other->incStrong(this);
+  }
+
+template<typename T>
+sp<T>::sp(const sp<T>& other)
+: m_ptr(other.m_ptr)
+  {
+    if (m_ptr) m_ptr->incStrong(this);
+  }
+
+template<typename T> template<typename U>
+sp<T>::sp(U* other) : m_ptr(other)
+{
+    if (other) other->incStrong(this);
+}
+
+template<typename T> template<typename U>
+sp<T>::sp(const sp<U>& other)
+: m_ptr(other.m_ptr)
+  {
+    if (m_ptr) m_ptr->incStrong(this);
+  }
+
+template<typename T>
+sp<T>::~sp()
+{
+    if (m_ptr) m_ptr->decStrong(this);
+}
+
+template<typename T>
+sp<T>& sp<T>::operator = (const sp<T>& other) {
+    T* otherPtr(other.m_ptr);
+    if (otherPtr) otherPtr->incStrong(this);
+    if (m_ptr) m_ptr->decStrong(this);
+    m_ptr = otherPtr;
+    return *this;
+}
+
+template<typename T>
+sp<T>& sp<T>::operator = (T* other)
+{
+    if (other) other->incStrong(this);
+    if (m_ptr) m_ptr->decStrong(this);
+    m_ptr = other;
+    return *this;
+}
+
+template<typename T> template<typename U>
+sp<T>& sp<T>::operator = (const sp<U>& other)
+{
+    U* otherPtr(other.m_ptr);
+    if (otherPtr) otherPtr->incStrong(this);
+    if (m_ptr) m_ptr->decStrong(this);
+    m_ptr = otherPtr;
+    return *this;
+}
+
+template<typename T> template<typename U>
+sp<T>& sp<T>::operator = (U* other)
+{
+    if (other) other->incStrong(this);
+    if (m_ptr) m_ptr->decStrong(this);
+    m_ptr = other;
+    return *this;
+}
+
+template<typename T>    
+void sp<T>::force_set(T* other)
+{
+    other->forceIncStrong(this);
+    m_ptr = other;
+}
+
+template<typename T>
+void sp<T>::clear()
+{
+    if (m_ptr) {
+        m_ptr->decStrong(this);
+        m_ptr = 0;
+    }
+}
+
+template<typename T>
+void sp<T>::set_pointer(T* ptr) {
+    m_ptr = ptr;
+}
+
+template <typename T>
+inline TextOutput& operator<<(TextOutput& to, const sp<T>& val)
+{
+    return printStrongPointer(to, val.get());
+}
+
+}; // namespace android
+
+// ---------------------------------------------------------------------------
+
+#endif // ANDROID_STRONG_POINTER_H
diff --git a/include/utils/TypeHelpers.h b/include/utils/TypeHelpers.h
index 2ff2749..a1663f3 100644
--- a/include/utils/TypeHelpers.h
+++ b/include/utils/TypeHelpers.h
@@ -37,18 +37,6 @@
 template <typename T> struct trait_pointer      { enum { value = false }; };    
 template <typename T> struct trait_pointer<T*>  { enum { value = true }; };
 
-// sp<> can be trivially moved
-template <typename T> class sp;
-template <typename T> struct trait_trivial_move< sp<T> >{
-    enum { value = true }; 
-};
-
-// wp<> can be trivially moved
-template <typename T> class wp;
-template <typename T> struct trait_trivial_move< wp<T> >{ 
-    enum { value = true }; 
-};
-
 template <typename TYPE>
 struct traits {
     enum {
@@ -217,7 +205,6 @@
     }
 }
 
-
 // ---------------------------------------------------------------------------
 
 /*
diff --git a/include/utils/threads.h b/include/utils/threads.h
index 1bcfaed..41e5766 100644
--- a/include/utils/threads.h
+++ b/include/utils/threads.h
@@ -527,9 +527,10 @@
     static  int             _threadLoop(void* user);
     const   bool            mCanCallJava;
             thread_id_t     mThread;
-            Mutex           mLock;
+    mutable Mutex           mLock;
             Condition       mThreadExitedCondition;
             status_t        mStatus;
+    // note that all accesses of mExitPending and mRunning need to hold mLock
     volatile bool           mExitPending;
     volatile bool           mRunning;
             sp<Thread>      mHoldSelf;
diff --git a/libs/utils/RefBase.cpp b/libs/utils/RefBase.cpp
index 0bd1af4..0fd404d 100644
--- a/libs/utils/RefBase.cpp
+++ b/libs/utils/RefBase.cpp
@@ -20,9 +20,9 @@
 
 #include <utils/Atomic.h>
 #include <utils/CallStack.h>
-#include <utils/KeyedVector.h>
 #include <utils/Log.h>
 #include <utils/threads.h>
+#include <utils/TextOutput.h>
 
 #include <stdlib.h>
 #include <stdio.h>
@@ -34,6 +34,7 @@
 
 // compile with refcounting debugging enabled
 #define DEBUG_REFS                      0
+#define DEBUG_REFS_FATAL_SANITY_CHECKS  0
 #define DEBUG_REFS_ENABLED_BY_DEFAULT   1
 #define DEBUG_REFS_CALLSTACK_ENABLED    1
 
@@ -69,8 +70,10 @@
 
     void addStrongRef(const void* /*id*/) { }
     void removeStrongRef(const void* /*id*/) { }
+    void renameStrongRefId(const void* /*old_id*/, const void* /*new_id*/) { }
     void addWeakRef(const void* /*id*/) { }
     void removeWeakRef(const void* /*id*/) { }
+    void renameWeakRefId(const void* /*old_id*/, const void* /*new_id*/) { }
     void printRefs() const { }
     void trackMe(bool, bool) { }
 
@@ -86,39 +89,73 @@
         , mTrackEnabled(!!DEBUG_REFS_ENABLED_BY_DEFAULT)
         , mRetain(false)
     {
-        //LOGI("NEW weakref_impl %p for RefBase %p", this, base);
     }
     
     ~weakref_impl()
     {
-        LOG_ALWAYS_FATAL_IF(!mRetain && mStrongRefs != NULL, "Strong references remain!");
-        LOG_ALWAYS_FATAL_IF(!mRetain && mWeakRefs != NULL, "Weak references remain!");
+        bool dumpStack = false;
+        if (!mRetain && mStrongRefs != NULL) {
+            dumpStack = true;
+#if DEBUG_REFS_FATAL_SANITY_CHECKS
+            LOG_ALWAYS_FATAL("Strong references remain!");
+#else
+            LOGE("Strong references remain!");
+#endif
+        }
+
+        if (!mRetain && mWeakRefs != NULL) {
+            dumpStack = true;
+#if DEBUG_REFS_FATAL_SANITY_CHECKS
+            LOG_ALWAYS_FATAL("Weak references remain!");
+#else
+            LOGE("Weak references remain!");
+#endif
+        }
+
+        if (dumpStack) {
+            CallStack stack;
+            stack.update();
+            stack.dump();
+        }
     }
 
-    void addStrongRef(const void* id)
-    {
+    void addStrongRef(const void* id) {
+        //LOGD_IF(mTrackEnabled,
+        //        "addStrongRef: RefBase=%p, id=%p", mBase, id);
         addRef(&mStrongRefs, id, mStrong);
     }
 
-    void removeStrongRef(const void* id)
-    {
-        if (!mRetain)
+    void removeStrongRef(const void* id) {
+        //LOGD_IF(mTrackEnabled,
+        //        "removeStrongRef: RefBase=%p, id=%p", mBase, id);
+        if (!mRetain) {
             removeRef(&mStrongRefs, id);
-        else
+        } else {
             addRef(&mStrongRefs, id, -mStrong);
+        }
     }
 
-    void addWeakRef(const void* id)
-    {
+    void renameStrongRefId(const void* old_id, const void* new_id) {
+        //LOGD_IF(mTrackEnabled,
+        //        "renameStrongRefId: RefBase=%p, oid=%p, nid=%p",
+        //        mBase, old_id, new_id);
+        renameRefsId(mStrongRefs, old_id, new_id);
+    }
+
+    void addWeakRef(const void* id) {
         addRef(&mWeakRefs, id, mWeak);
     }
 
-    void removeWeakRef(const void* id)
-    {
-        if (!mRetain)
+    void removeWeakRef(const void* id) {
+        if (!mRetain) {
             removeRef(&mWeakRefs, id);
-        else
+        } else {
             addRef(&mWeakRefs, id, -mWeak);
+        }
+    }
+
+    void renameWeakRefId(const void* old_id, const void* new_id) {
+        renameRefsId(mWeakRefs, old_id, new_id);
     }
 
     void trackMe(bool track, bool retain)
@@ -132,8 +169,7 @@
         String8 text;
 
         {
-            AutoMutex _l(const_cast<weakref_impl*>(this)->mMutex);
-    
+            Mutex::Autolock _l(const_cast<weakref_impl*>(this)->mMutex);
             char buf[128];
             sprintf(buf, "Strong references on RefBase %p (weakref_type %p):\n", mBase, this);
             text.append(buf);
@@ -172,6 +208,7 @@
     {
         if (mTrackEnabled) {
             AutoMutex _l(mMutex);
+
             ref_entry* ref = new ref_entry;
             // Reference count at the time of the snapshot, but before the
             // update.  Positive value means we increment, negative--we
@@ -181,7 +218,6 @@
 #if DEBUG_REFS_CALLSTACK_ENABLED
             ref->stack.update(2);
 #endif
-            
             ref->next = *refs;
             *refs = ref;
         }
@@ -199,13 +235,37 @@
                     delete ref;
                     return;
                 }
-                
                 refs = &ref->next;
                 ref = *refs;
             }
-            
-            LOG_ALWAYS_FATAL("RefBase: removing id %p on RefBase %p (weakref_type %p) that doesn't exist!",
-                             id, mBase, this);
+
+#if DEBUG_REFS_FATAL_SANITY_CHECKS
+            LOG_ALWAYS_FATAL("RefBase: removing id %p on RefBase %p"
+                    "(weakref_type %p) that doesn't exist!",
+                    id, mBase, this);
+#endif
+
+            LOGE("RefBase: removing id %p on RefBase %p"
+                    "(weakref_type %p) that doesn't exist!",
+                    id, mBase, this);
+
+            CallStack stack;
+            stack.update();
+            stack.dump();
+        }
+    }
+
+    void renameRefsId(ref_entry* r, const void* old_id, const void* new_id)
+    {
+        if (mTrackEnabled) {
+            AutoMutex _l(mMutex);
+            ref_entry* ref = r;
+            while (ref != NULL) {
+                if (ref->id == old_id) {
+                    ref->id = new_id;
+                }
+                ref = ref->next;
+            }
         }
     }
 
@@ -235,44 +295,6 @@
     // on removeref that match the address ones.
     bool mRetain;
 
-#if 0
-    void addRef(KeyedVector<const void*, int32_t>* refs, const void* id)
-    {
-        AutoMutex _l(mMutex);
-        ssize_t i = refs->indexOfKey(id);
-        if (i >= 0) {
-            ++(refs->editValueAt(i));
-        } else {
-            i = refs->add(id, 1);
-        }
-    }
-
-    void removeRef(KeyedVector<const void*, int32_t>* refs, const void* id)
-    {
-        AutoMutex _l(mMutex);
-        ssize_t i = refs->indexOfKey(id);
-        LOG_ALWAYS_FATAL_IF(i < 0, "RefBase: removing id %p that doesn't exist!", id);
-        if (i >= 0) {
-            int32_t val = --(refs->editValueAt(i));
-            if (val == 0) {
-                refs->removeItemsAt(i);
-            }
-        }
-    }
-
-    void printRefs(const KeyedVector<const void*, int32_t>& refs)
-    {
-        const size_t N=refs.size();
-        for (size_t i=0; i<N; i++) {
-            printf("\tID %p: %d remain\n", refs.keyAt(i), refs.valueAt(i));
-        }
-    }
-
-    mutable Mutex mMutex;
-    KeyedVector<const void*, int32_t> mStrongRefs;
-    KeyedVector<const void*, int32_t> mWeakRefs;
-#endif
-
 #endif
 };
 
@@ -281,7 +303,6 @@
 void RefBase::incStrong(const void* id) const
 {
     weakref_impl* const refs = mRefs;
-    refs->addWeakRef(id);
     refs->incWeak(id);
     
     refs->addStrongRef(id);
@@ -313,14 +334,12 @@
             delete this;
         }
     }
-    refs->removeWeakRef(id);
     refs->decWeak(id);
 }
 
 void RefBase::forceIncStrong(const void* id) const
 {
     weakref_impl* const refs = mRefs;
-    refs->addWeakRef(id);
     refs->incWeak(id);
     
     refs->addStrongRef(id);
@@ -372,7 +391,7 @@
         if (impl->mStrong == INITIAL_STRONG_VALUE)
             delete impl->mBase;
         else {
-//            LOGV("Freeing refs %p of old RefBase %p\n", this, impl->mBase);
+            // LOGV("Freeing refs %p of old RefBase %p\n", this, impl->mBase);
             delete impl;
         }
     } else {
@@ -432,7 +451,6 @@
         }
     }
     
-    impl->addWeakRef(id);
     impl->addStrongRef(id);
 
 #if PRINT_REFS
@@ -450,7 +468,7 @@
 bool RefBase::weakref_type::attemptIncWeak(const void* id)
 {
     weakref_impl* const impl = static_cast<weakref_impl*>(this);
-    
+
     int32_t curCount = impl->mWeak;
     LOG_ASSERT(curCount >= 0, "attemptIncWeak called on %p after underflow",
                this);
@@ -497,14 +515,11 @@
 RefBase::RefBase()
     : mRefs(new weakref_impl(this))
 {
-//    LOGV("Creating refs %p with RefBase %p\n", mRefs, this);
 }
 
 RefBase::~RefBase()
 {
-//    LOGV("Destroying RefBase %p (refs %p)\n", this, mRefs);
     if (mRefs->mWeak == 0) {
-//        LOGV("Freeing refs %p of old RefBase %p\n", mRefs, this);
         delete mRefs;
     }
 }
@@ -530,5 +545,37 @@
 void RefBase::onLastWeakRef(const void* /*id*/)
 {
 }
-        
+
+// ---------------------------------------------------------------------------
+
+void RefBase::moveReferences(void* dst, void const* src, size_t n,
+        const ReferenceConverterBase& caster)
+{
+#if DEBUG_REFS
+    const size_t itemSize = caster.getReferenceTypeSize();
+    for (size_t i=0 ; i<n ; i++) {
+        void*       d = reinterpret_cast<void      *>(intptr_t(dst) + i*itemSize);
+        void const* s = reinterpret_cast<void const*>(intptr_t(src) + i*itemSize);
+        RefBase* ref(reinterpret_cast<RefBase*>(caster.getReferenceBase(d)));
+        ref->mRefs->renameStrongRefId(s, d);
+        ref->mRefs->renameWeakRefId(s, d);
+    }
+#endif
+}
+
+// ---------------------------------------------------------------------------
+
+TextOutput& printStrongPointer(TextOutput& to, const void* val)
+{
+    to << "sp<>(" << val << ")";
+    return to;
+}
+
+TextOutput& printWeakPointer(TextOutput& to, const void* val)
+{
+    to << "wp<>(" << val << ")";
+    return to;
+}
+
+
 }; // namespace android
diff --git a/libs/utils/Threads.cpp b/libs/utils/Threads.cpp
index 35dcbcb..8b5da0e 100644
--- a/libs/utils/Threads.cpp
+++ b/libs/utils/Threads.cpp
@@ -675,6 +675,9 @@
         mLock("Thread::mLock"),
         mStatus(NO_ERROR),
         mExitPending(false), mRunning(false)
+#ifdef HAVE_ANDROID_OS
+        , mTid(-1)
+#endif
 {
 }
 
@@ -715,6 +718,7 @@
         res = androidCreateRawThreadEtc(_threadLoop,
                 this, name, priority, stack, &mThread);
     }
+    // The new thread wakes up at _threadLoop, but immediately blocks on mLock
     
     if (res == false) {
         mStatus = UNKNOWN_ERROR;   // something happened!
@@ -730,11 +734,19 @@
     // here merely indicates successfully starting the thread and does not
     // imply successful termination/execution.
     return NO_ERROR;
+
+    // Exiting scope of mLock is a memory barrier and allows new thread to run
 }
 
 int Thread::_threadLoop(void* user)
 {
     Thread* const self = static_cast<Thread*>(user);
+
+    // force a memory barrier before reading any fields, in particular mHoldSelf
+    {
+    Mutex::Autolock _l(self->mLock);
+    }
+
     sp<Thread> strong(self->mHoldSelf);
     wp<Thread> weak(strong);
     self->mHoldSelf.clear();
@@ -753,7 +765,7 @@
             self->mStatus = self->readyToRun();
             result = (self->mStatus == NO_ERROR);
 
-            if (result && !self->mExitPending) {
+            if (result && !self->exitPending()) {
                 // Binder threads (and maybe others) rely on threadLoop
                 // running at least once after a successful ::readyToRun()
                 // (unless, of course, the thread has already been asked to exit
@@ -770,18 +782,21 @@
             result = self->threadLoop();
         }
 
+        // establish a scope for mLock
+        {
+        Mutex::Autolock _l(self->mLock);
         if (result == false || self->mExitPending) {
             self->mExitPending = true;
-            self->mLock.lock();
             self->mRunning = false;
             // clear thread ID so that requestExitAndWait() does not exit if
             // called by a new thread using the same thread ID as this one.
             self->mThread = thread_id_t(-1);
+            // note that interested observers blocked in requestExitAndWait are
+            // awoken by broadcast, but blocked on mLock until break exits scope
             self->mThreadExitedCondition.broadcast();
-            self->mThread = thread_id_t(-1); // thread id could be reused
-            self->mLock.unlock();
             break;
         }
+        }
         
         // Release our strong reference, to let a chance to the thread
         // to die a peaceful death.
@@ -795,6 +810,7 @@
 
 void Thread::requestExit()
 {
+    Mutex::Autolock _l(mLock);
     mExitPending = true;
 }
 
@@ -815,6 +831,8 @@
     while (mRunning == true) {
         mThreadExitedCondition.wait(mLock);
     }
+    // This next line is probably not needed any more, but is being left for
+    // historical reference. Note that each interested party will clear flag.
     mExitPending = false;
 
     return mStatus;
@@ -822,6 +840,7 @@
 
 bool Thread::exitPending() const
 {
+    Mutex::Autolock _l(mLock);
     return mExitPending;
 }
 
diff --git a/services/surfaceflinger/Layer.cpp b/services/surfaceflinger/Layer.cpp
index 0f7d639..57af001 100644
--- a/services/surfaceflinger/Layer.cpp
+++ b/services/surfaceflinger/Layer.cpp
@@ -341,6 +341,45 @@
     drawWithOpenGL(clip, tex);
 }
 
+// As documented in libhardware header, formats in the range
+// 0x100 - 0x1FF are specific to the HAL implementation, and
+// are known to have no alpha channel
+// TODO: move definition for device-specific range into
+// hardware.h, instead of using hard-coded values here.
+#define HARDWARE_IS_DEVICE_FORMAT(f) ((f) >= 0x100 && (f) <= 0x1FF)
+
+bool Layer::needsBlending(const sp<GraphicBuffer>& buffer) const
+{
+    // If buffers where set with eOpaque flag, all buffers are known to
+    // be opaque without having to check their actual format
+    if (mNeedsBlending && buffer != NULL) {
+        PixelFormat format = buffer->getPixelFormat();
+
+        if (HARDWARE_IS_DEVICE_FORMAT(format)) {
+            return false;
+        }
+
+        PixelFormatInfo info;
+        status_t err = getPixelFormatInfo(format, &info);
+        if (!err && info.h_alpha <= info.l_alpha) {
+            return false;
+        }
+    }
+
+    // Return opacity as determined from flags and format options
+    // passed to setBuffers()
+    return mNeedsBlending;
+}
+
+bool Layer::needsBlending() const
+{
+    if (mBufferManager.hasActiveBuffer()) {
+        return needsBlending(mBufferManager.getActiveBuffer());
+    }
+
+    return mNeedsBlending;
+}
+
 bool Layer::needsFiltering() const
 {
     if (!(mFlags & DisplayHardware::SLOW_CONFIG)) {
@@ -588,6 +627,9 @@
     // we retired a buffer, which becomes the new front buffer
 
     const bool noActiveBuffer = !mBufferManager.hasActiveBuffer();
+    const bool activeBlending =
+            noActiveBuffer ? true : needsBlending(mBufferManager.getActiveBuffer());
+
     if (mBufferManager.setActiveBufferIndex(buf) < NO_ERROR) {
         LOGE("retireAndLock() buffer index (%d) out of range", int(buf));
         mPostedDirtyRegion.clear();
@@ -602,6 +644,12 @@
 
     sp<GraphicBuffer> newFrontBuffer(getBuffer(buf));
     if (newFrontBuffer != NULL) {
+        if (!noActiveBuffer && activeBlending != needsBlending(newFrontBuffer)) {
+            // new buffer has different opacity than previous active buffer, need
+            // to recompute visible regions accordingly
+            recomputeVisibleRegions = true;
+        }
+
         // get the dirty region
         // compute the posted region
         const Region dirty(lcblk->getDirtyRegion(buf));
diff --git a/services/surfaceflinger/Layer.h b/services/surfaceflinger/Layer.h
index 2b38414..bccc900 100644
--- a/services/surfaceflinger/Layer.h
+++ b/services/surfaceflinger/Layer.h
@@ -75,7 +75,8 @@
     virtual uint32_t doTransaction(uint32_t transactionFlags);
     virtual void lockPageFlip(bool& recomputeVisibleRegions);
     virtual void unlockPageFlip(const Transform& planeTransform, Region& outDirtyRegion);
-    virtual bool needsBlending() const      { return mNeedsBlending; }
+    virtual bool needsBlending(const sp<GraphicBuffer>& buffer) const;
+    virtual bool needsBlending() const;
     virtual bool needsDithering() const     { return mNeedsDithering; }
     virtual bool needsFiltering() const;
     virtual bool isSecure() const           { return mSecure; }