optimise UNO Sequence destructor

to avoid expensive function calls until the refcount reaches 0

Signed-off-by: Stephan Bergmann <sbergman@redhat.com>, slightly changing it to
add a uno_type_sequence_destroy to uno/sequence2.h instead of a
uno_type_destructSequence to uno/data.h.

Change-Id: I3bbff3294f2b515fc3c68c4c6c1cb16829f5cc44

cppu/source/uno/destr.hxx

@@ -19,6 +19,10 @@
 #ifndef INCLUDED_CPPU_SOURCE_UNO_DESTR_HXX
 #define INCLUDED_CPPU_SOURCE_UNO_DESTR_HXX
 
+#include <sal/config.h>
+
+#include <cassert>
+
 #include "prim.hxx"
 
 
@@ -255,6 +259,35 @@ inline sal_Int32 idestructElements(
     }
 }
 
+inline void idestroySequence(
+    uno_Sequence * pSeq,
+    typelib_TypeDescriptionReference * pType,
+    typelib_TypeDescription * pTypeDescr,
+    uno_ReleaseFunc release )
+{
+    assert(pSeq != nullptr);
+    assert(pSeq->nRefCount == 0);
+    if (pSeq->nElements > 0)
+    {
+        if (pTypeDescr)
+        {
+            idestructElements(
+                pSeq->elements,
+                ((typelib_IndirectTypeDescription *) pTypeDescr)->pType, 0,
+                pSeq->nElements, release );
+        }
+        else
+        {
+            TYPELIB_DANGER_GET( &pTypeDescr, pType );
+            idestructElements(
+                pSeq->elements,
+                ((typelib_IndirectTypeDescription *) pTypeDescr)->pType, 0,
+                pSeq->nElements, release );
+            TYPELIB_DANGER_RELEASE( pTypeDescr );
+        }
+    }
+    ::rtl_freeMemory( pSeq );
+}
 
 inline void idestructSequence(
     uno_Sequence * pSeq,
@@ -264,30 +297,10 @@ inline void idestructSequence(
 {
     if (osl_atomic_decrement( &pSeq->nRefCount ) == 0)
     {
-        if (pSeq->nElements > 0)
-        {
-            if (pTypeDescr)
-            {
-                idestructElements(
-                    pSeq->elements,
-                    ((typelib_IndirectTypeDescription *) pTypeDescr)->pType, 0,
-                    pSeq->nElements, release );
-            }
-            else
-            {
-                TYPELIB_DANGER_GET( &pTypeDescr, pType );
-                idestructElements(
-                    pSeq->elements,
-                    ((typelib_IndirectTypeDescription *) pTypeDescr)->pType, 0,
-                    pSeq->nElements, release );
-                TYPELIB_DANGER_RELEASE( pTypeDescr );
-            }
-        }
-        ::rtl_freeMemory( pSeq );
+        idestroySequence(pSeq, pType, pTypeDescr, release);
     }
 }
 
-
 inline void _destructData(
     void * pValue,
     typelib_TypeDescriptionReference * pType,

cppu/source/uno/sequence.cxx

@@ -920,6 +920,14 @@ void SAL_CALL uno_type_sequence_assign(
     }
 }
 
+void uno_type_sequence_destroy(
+    uno_Sequence * sequence, typelib_TypeDescriptionReference * type,
+    uno_ReleaseFunc release)
+    SAL_THROW_EXTERN_C()
+{
+    idestroySequence(sequence, type, nullptr, release);
+}
+
 }
 
 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */

cppu/util/cppu.map

@@ -145,6 +145,11 @@ UDK_3.3 {   # OOo 2.4
         cppu_unsatisfied_iset_msg;
 } UDK_3.2;
 
+LIBO_UDK_4.4 { # symbols available in >= LibO 4.4
+    global:
+        uno_type_sequence_destroy;
+} UDK_3.3;
+
 # Unique libstdc++ symbols:
 GLIBCXX_3.4 {
     global:

include/com/sun/star/uno/Sequence.hxx

@@ -95,9 +95,12 @@ inline Sequence< E >::Sequence( sal_Int32 len )
 template< class E >
 inline Sequence< E >::~Sequence()
 {
-    const Type & rType = ::cppu::getTypeFavourUnsigned( this );
-    ::uno_type_destructData(
-        this, rType.getTypeLibType(), (uno_ReleaseFunc)cpp_release );
+    if (osl_atomic_decrement( &_pSequence->nRefCount ) == 0)
+    {
+        const Type & rType = ::cppu::getTypeFavourUnsigned( this );
+        uno_type_sequence_destroy(
+            _pSequence, rType.getTypeLibType(), (uno_ReleaseFunc)cpp_release );
+    }
 }
 
 template< class E >

include/uno/sequence2.h

@@ -172,6 +172,20 @@ CPPU_DLLPUBLIC sal_Bool SAL_CALL uno_type_sequence_realloc(
     uno_ReleaseFunc release )
     SAL_THROW_EXTERN_C();
 
+/** Destroy a sequence whose reference count has dropped to zero.
+
+    @param sequence must be non-null, sequence->nRefCount must be zero
+    @param type the type of the sequence, must be non-null
+    @param release function called each time an interface needs to be release,
+        must be non-null
+
+    @since LibreOffice 4.4
+*/
+CPPU_DLLPUBLIC void SAL_CALL uno_type_sequence_destroy(
+    uno_Sequence * sequence, struct _typelib_TypeDescriptionReference * type,
+    uno_ReleaseFunc release)
+    SAL_THROW_EXTERN_C();
+
 #ifdef __cplusplus
 }
 #endif