5 files changed, 47 insertions, 15 deletions

diff --git a/src/corelib/tools/qarraydata.cpp b/src/corelib/tools/qarraydata.cpp
index 1145ecb4f4..c6e96c78a9 100644
--- a/src/corelib/tools/qarraydata.cpp
+++ b/src/corelib/tools/qarraydata.cpp
@@ -45,9 +45,10 @@ QT_BEGIN_NAMESPACE
 
 const QArrayData QArrayData::shared_null = { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, 0, 0 };
 const QArrayData QArrayData::shared_empty = { Q_REFCOUNT_INITIALIZE_STATIC, 0, 0, 0, 0 };
+const QArrayData QArrayData::unsharable_empty = { { Q_BASIC_ATOMIC_INITIALIZER(0) }, 0, 0, 0, 0 };
 
 QArrayData *QArrayData::allocate(size_t objectSize, size_t alignment,
-        size_t capacity, bool reserve)
+        size_t capacity, bool reserve, bool sharable)
 {
     // Alignment is a power of two
     Q_ASSERT(alignment >= Q_ALIGNOF(QArrayData)
@@ -55,7 +56,9 @@ QArrayData *QArrayData::allocate(size_t objectSize, size_t alignment,
 
     // Don't allocate empty headers
     if (!capacity)
-        return const_cast<QArrayData *>(&shared_empty);
+        return sharable
+            ? const_cast<QArrayData *>(&shared_empty)
+            : const_cast<QArrayData *>(&unsharable_empty);
 
     // Allocate extra (alignment - Q_ALIGNOF(QArrayData)) padding bytes so we
     // can properly align the data array. This assumes malloc is able to
@@ -69,7 +72,7 @@ QArrayData *QArrayData::allocate(size_t objectSize, size_t alignment,
         quintptr data = (quintptr(header) + sizeof(QArrayData) + alignment - 1)
                 & ~(alignment - 1);
 
-        header->ref.initializeOwned();
+        header->ref.atomic.store(sharable ? 1 : 0);
         header->size = 0;
         header->alloc = capacity;
         header->capacityReserved = reserve;
@@ -87,6 +90,9 @@ void QArrayData::deallocate(QArrayData *data, size_t objectSize,
             && !(alignment & (alignment - 1)));
     Q_UNUSED(objectSize) Q_UNUSED(alignment)
 
+    if (data == &unsharable_empty)
+        return;
+
     qFree(data);
 }
 
diff --git a/src/corelib/tools/qarraydata.h b/src/corelib/tools/qarraydata.h
index b7ab59257f..1fd60e2155 100644
--- a/src/corelib/tools/qarraydata.h
+++ b/src/corelib/tools/qarraydata.h
@@ -74,12 +74,13 @@ struct Q_CORE_EXPORT QArrayData
     }
 
     static QArrayData *allocate(size_t objectSize, size_t alignment,
-            size_t capacity, bool reserve) Q_REQUIRED_RESULT;
+            size_t capacity, bool reserve, bool sharable) Q_REQUIRED_RESULT;
     static void deallocate(QArrayData *data, size_t objectSize,
             size_t alignment);
 
     static const QArrayData shared_null;
     static const QArrayData shared_empty;
+    static const QArrayData unsharable_empty;
 };
 
 template <class T>
@@ -99,11 +100,11 @@ struct QTypedArrayData
 
     class AlignmentDummy { QArrayData header; T data; };
 
-    static QTypedArrayData *allocate(size_t capacity, bool reserve = false)
-            Q_REQUIRED_RESULT
+    static QTypedArrayData *allocate(size_t capacity, bool reserve = false,
+            bool sharable = true) Q_REQUIRED_RESULT
     {
         return static_cast<QTypedArrayData *>(QArrayData::allocate(sizeof(T),
-                    Q_ALIGNOF(AlignmentDummy), capacity, reserve));
+                    Q_ALIGNOF(AlignmentDummy), capacity, reserve, sharable));
     }
 
     static void deallocate(QArrayData *data)
@@ -122,6 +123,12 @@ struct QTypedArrayData
         return static_cast<QTypedArrayData *>(
                 const_cast<QArrayData *>(&QArrayData::shared_empty));
     }
+
+    static QTypedArrayData *unsharableEmpty()
+    {
+        return static_cast<QTypedArrayData *>(
+                const_cast<QArrayData *>(&QArrayData::unsharable_empty));
+    }
 };
 
 template <class T, size_t N>
diff --git a/src/corelib/tools/qarraydataops.h b/src/corelib/tools/qarraydataops.h
index e7c66a456b..a3c372fe6b 100644
--- a/src/corelib/tools/qarraydataops.h
+++ b/src/corelib/tools/qarraydataops.h
@@ -61,7 +61,7 @@ struct QPodArrayOps
 {
     void copyAppend(const T *b, const T *e)
     {
-        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(!this->ref.isShared());
         Q_ASSERT(b < e);
         Q_ASSERT(size_t(e - b) <= this->alloc - uint(this->size));
 
@@ -71,7 +71,7 @@ struct QPodArrayOps
 
     void copyAppend(size_t n, const T &t)
     {
-        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(!this->ref.isShared());
         Q_ASSERT(n <= this->alloc - uint(this->size));
 
         T *iter = this->end();
@@ -91,7 +91,7 @@ struct QPodArrayOps
 
     void insert(T *where, const T *b, const T *e)
     {
-        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(!this->ref.isShared());
         Q_ASSERT(where >= this->begin() && where < this->end()); // Use copyAppend at end
         Q_ASSERT(b < e);
         Q_ASSERT(e <= where || b > this->end()); // No overlap
@@ -109,7 +109,7 @@ struct QGenericArrayOps
 {
     void copyAppend(const T *b, const T *e)
     {
-        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(!this->ref.isShared());
         Q_ASSERT(b < e);
         Q_ASSERT(size_t(e - b) <= this->alloc - uint(this->size));
 
@@ -122,7 +122,7 @@ struct QGenericArrayOps
 
     void copyAppend(size_t n, const T &t)
     {
-        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(!this->ref.isShared());
         Q_ASSERT(n <= this->alloc - uint(this->size));
 
         T *iter = this->end();
@@ -149,7 +149,7 @@ struct QGenericArrayOps
 
     void insert(T *where, const T *b, const T *e)
     {
-        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(!this->ref.isShared());
         Q_ASSERT(where >= this->begin() && where < this->end()); // Use copyAppend at end
         Q_ASSERT(b < e);
         Q_ASSERT(e <= where || b > this->end()); // No overlap
@@ -222,7 +222,7 @@ struct QMovableArrayOps
 
     void insert(T *where, const T *b, const T *e)
     {
-        Q_ASSERT(this->ref == 1);
+        Q_ASSERT(!this->ref.isShared());
         Q_ASSERT(where >= this->begin() && where < this->end()); // Use copyAppend at end
         Q_ASSERT(b < e);
         Q_ASSERT(e <= where || b > this->end()); // No overlap
diff --git a/src/corelib/tools/qarraydatapointer.h b/src/corelib/tools/qarraydatapointer.h
index f1cd1dc4b1..e42d146c58 100644
--- a/src/corelib/tools/qarraydatapointer.h
+++ b/src/corelib/tools/qarraydatapointer.h
@@ -64,7 +64,9 @@ public:
     }
 
     QArrayDataPointer(const QArrayDataPointer &other)
-        : d((other.d->ref.ref(), other.d))
+        : d(other.d->ref.ref()
+            ? other.d
+            : other.clone())
     {
     }
 
@@ -110,6 +112,22 @@ public:
         return d;
     }
 
+    void setSharable(bool sharable)
+    {
+        if (d->alloc == 0 && d->size == 0) {
+            Q_ASSERT(Data::sharedNull() == d
+                    || Data::sharedEmpty() == d
+                    || Data::unsharableEmpty() == d);
+            d = sharable
+                ? Data::sharedEmpty()
+                : Data::unsharableEmpty();
+            return;
+        }
+
+        detach();
+        d->ref.setSharable(sharable);
+    }
+
     void swap(QArrayDataPointer &other)
     {
         qSwap(d, other.d);
diff --git a/src/corelib/tools/qrefcount.h b/src/corelib/tools/qrefcount.h
index 9478ff1269..bf864f2f58 100644
--- a/src/corelib/tools/qrefcount.h
+++ b/src/corelib/tools/qrefcount.h
@@ -111,6 +111,7 @@ public:
     { return atomic.load(); }
 
     void initializeOwned() { atomic.store(1); }
+    void initializeUnsharable() { atomic.store(0); }
 
     QBasicAtomicInt atomic;
 };