include/vcl/lazydelete.hxx

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  19
  20 #ifndef _VCL_LAZYDELETE_HXX
  21 #define _VCL_LAZYDELETE_HXX
  22
  23 #include "dllapi.h"
  24
  25 #include <vector>
  26 #include <boost/unordered_map.hpp>
  27 #include <algorithm>
  28
  29 #if OSL_DEBUG_LEVEL > 2
  30 #include <typeinfo>
  31 #include <stdio.h>
  32 #endif
  33
  34 #include <com/sun/star/lang/XComponent.hpp>
  35
  36 namespace vcl
  37 {
  38     /* Helpers for lazy object deletion
  39
  40     With vcl it is often necessary to delete objects (especially Windows)
  41     in the right order as well as in a way ensuring that the deleted objects
  42     are not still on the stack (e.g. deleting a Window in its key handler). To
  43     make this easier a helper class is given here which takes care of both
  44     sorting as well as lazy deletion.
  45
  46     The grisly details:
  47     LazyDelete is a class that LazyDeletor register to. When vcl's event
  48     loop (that is Application::Yield or Application::Reschedule) comes out
  49     of the last level, the LazyDelete::flush is called. This will cause
  50     LazyDelete to delete all registered LazyDeletor objects.
  51
  52     LazyDeletor<T> is a one instance object that contains a list of
  53     <T> objects to be deleted in sorted order. It is derived from
  54     LazyDeletorBase as to be able to register itself in LazyDelete.
  55
  56     The user calls the static method LazyDeletor<T>::Delete( T* ) with the
  57     object to be destroyed lazy. The static method creates the LazyDeletor<T>
  58     (which in turn registers itself in LazyDelete) if this is the first time
  59     a T* is to be destroyed lazy. It then inserts the object. When the LazyDeletor<T>
  60     gets delte it will delete the stored objects in a fashion
  61     that will ensure the correct order of deletion via the specialized is_less method
  62     (e.g. if a Window is a child of another Window and therefore should be destroyed
  63     first it is "less" in this sense)
  64
  65     LazyDelete::flush will be called when the top of the nested event loop is
  66     reached again and will then destroy each registered LazyDeletor<T> which
  67     in turn destroys the objects needed to be destroyed lazily. After this
  68     the state is as before entering the event loop.
  69
  70     Preconditions:
  71     - The class <T> of which objects are to be destroyed needs a virtual
  72     destructor or must be final, else the wrong type will be destroyed.
  73     - The destructor of <T> should call LazyDeletor<T>::Undelete( this ). This
  74     prevents duplicate deletionin case someone destroys the object prematurely.
  75     */
  76
  77     class LazyDeletorBase;
  78     class VCL_DLLPUBLIC LazyDelete
  79     {
  80         public:
  81         /** flush all registered object lists
  82         */
  83         static void flush();
  84         /** register an object list to be destroyed
  85         */
  86         static void addDeletor( LazyDeletorBase* pDeletor );
  87     };
  88
  89     class VCL_DLLPUBLIC LazyDeletorBase
  90     {
  91         friend void LazyDelete::flush();
  92         protected:
  93         LazyDeletorBase();
  94         virtual ~LazyDeletorBase();
  95     };
  96
  97     template < typename T >
  98     class VCL_DLLPUBLIC LazyDeletor : public LazyDeletorBase
  99     {
 100         static LazyDeletor< T >*     s_pOneInstance;
 101
 102         struct DeleteObjectEntry
 103         {
 104             T*      m_pObject;
 105             bool    m_bDeleted;
 106
 107             DeleteObjectEntry() :
 108                 m_pObject( NULL ),
 109                 m_bDeleted( false )
 110             {}
 111
 112             DeleteObjectEntry( T* i_pObject ) :
 113                 m_pObject( i_pObject ),
 114                 m_bDeleted( false )
 115             {}
 116         };
 117
 118         std::vector< DeleteObjectEntry >    m_aObjects;
 119         typedef boost::unordered_map< sal_IntPtr, unsigned int > PtrToIndexMap;
 120         PtrToIndexMap                       m_aPtrToIndex;
 121
 122         /** strict weak ordering funtion to bring objects to be destroyed lazily
 123         in correct order, e.g. for Window objects children before parents
 124         */
 125         static bool is_less( T* left, T* right );
 126
 127         LazyDeletor()  { LazyDelete::addDeletor( this ); }
 128         virtual ~LazyDeletor()
 129         {
 130             #if OSL_DEBUG_LEVEL > 2
 131             fprintf( stderr, "%s %p deleted\n",
 132                      typeid(*this).name(), this );
 133             #endif
 134             if( s_pOneInstance == this ) // sanity check
 135                 s_pOneInstance = NULL;
 136
 137             // do the actual work
 138             unsigned int nCount = m_aObjects.size();
 139             std::vector<T*> aRealDelete;
 140             aRealDelete.reserve( nCount );
 141             for( unsigned int i = 0; i < nCount; i++ )
 142             {
 143                 if( ! m_aObjects[i].m_bDeleted )
 144                 {
 145                     aRealDelete.push_back( m_aObjects[i].m_pObject );
 146                 }
 147             }
 148             // sort the vector of objects to be destroyed
 149             std::sort( aRealDelete.begin(), aRealDelete.end(), is_less );
 150             nCount = aRealDelete.size();
 151             for( unsigned int n = 0; n < nCount; n++ )
 152             {
 153                 #if OSL_DEBUG_LEVEL > 2
 154                 fprintf( stderr, "%s deletes object %p of type %s\n",
 155                          typeid(*this).name(),
 156                          aRealDelete[n],
 157                          typeid(*aRealDelete[n]).name() );
 158                 #endif
 159                 // check if the object to be deleted is not already destroyed
 160                 // as a side effect of a previous lazily destroyed object
 161                 if( ! m_aObjects[ m_aPtrToIndex[ reinterpret_cast<sal_IntPtr>(aRealDelete[n]) ] ].m_bDeleted )
 162                     delete aRealDelete[n];
 163             }
 164         }
 165
 166         public:
 167         /** mark an object for lazy deletion
 168         */
 169         static void Delete( T* i_pObject )
 170         {
 171             if( s_pOneInstance == NULL )
 172                 s_pOneInstance = new LazyDeletor<T>();
 173
 174             // is this object already in the list ?
 175             // if so mark it as not to be deleted; else insert it
 176             PtrToIndexMap::const_iterator dup = s_pOneInstance->m_aPtrToIndex.find( reinterpret_cast<sal_IntPtr>(i_pObject) );
 177             if( dup != s_pOneInstance->m_aPtrToIndex.end() )
 178             {
 179                 s_pOneInstance->m_aObjects[ dup->second ].m_bDeleted = false;
 180             }
 181             else
 182             {
 183                 s_pOneInstance->m_aPtrToIndex[ reinterpret_cast<sal_IntPtr>(i_pObject) ] = s_pOneInstance->m_aObjects.size();
 184                 s_pOneInstance->m_aObjects.push_back( DeleteObjectEntry( i_pObject ) );
 185             }
 186         }
 187         /** unmark an object already marked for lazy deletion
 188         */
 189         static void Undelete( T* i_pObject )
 190         {
 191             if( s_pOneInstance )
 192             {
 193                 PtrToIndexMap::const_iterator it = s_pOneInstance->m_aPtrToIndex.find( reinterpret_cast<sal_IntPtr>(i_pObject) );
 194                 if( it != s_pOneInstance->m_aPtrToIndex.end() )
 195                     s_pOneInstance->m_aObjects[ it->second ].m_bDeleted = true;
 196             }
 197         }
 198     };
 199
 200     /*
 201     class DeleteOnDeinit matches a similar need as LazyDelete for static objects:
 202     you may not access vcl objects after DeInitVCL has been called this includes their destruction
 203     therefore disallowing the existance of static vcl object like e.g. a static BitmapEx
 204     To work around this use DeleteOnDeinit<BitmapEx> which will allow you to have a static object container,
 205     that will have its contents destroyed on DeinitVCL. The single drawback is that you need to check on the
 206     container object whether it still contains content before actually accessing it.
 207
 208     caveat: when constructing a vcl object, you certainly want to ensure that InitVCL has run already.
 209     However this is not necessarily the case when using a class static member or a file level static variable.
 210     In these cases make judicious use of the set() method of DeleteOnDeinit, but beware of the changing
 211     ownership.
 212
 213     example use case: use a lazy initialized on call BitmapEx in a paint method. Of course a paint method
 214     would not normally be called after DeInitVCL anyway, so the check might not be necessary in a
 215     Window::Paint implementation, but always checking is a good idea.
 216
 217     SomeWindow::Paint()
 218     {
 219         static vcl::DeleteOnDeinit< BitmapEx > aBmp( new BitmapEx( ResId( 1000, myResMgr ) ) );
 220
 221         if( aBmp.get() ) // check whether DeInitVCL has been called already
 222             DrawBitmapEx( Point( 10, 10 ), *aBmp.get() );
 223     }
 224     */
 225
 226     class VCL_DLLPUBLIC DeleteOnDeinitBase
 227     {
 228     public:
 229         static void SAL_DLLPRIVATE ImplDeleteOnDeInit();
 230         virtual ~DeleteOnDeinitBase();
 231     protected:
 232         static void addDeinitContainer( DeleteOnDeinitBase* i_pContainer );
 233
 234         virtual void doCleanup() = 0;
 235     };
 236
 237     template < typename T >
 238     class DeleteOnDeinit : public DeleteOnDeinitBase
 239     {
 240         T* m_pT;
 241         virtual void doCleanup() { delete m_pT; m_pT = NULL; }
 242     public:
 243         DeleteOnDeinit( T* i_pT ) : m_pT( i_pT ) { addDeinitContainer( this ); }
 244         virtual ~DeleteOnDeinit() {}
 245
 246         // get contents
 247         T* get() { return m_pT; }
 248
 249         // set contents, returning old contents
 250         // ownership is transferred !
 251         T* set( T* i_pNew ) { T* pOld = m_pT; m_pT = i_pNew; return pOld; }
 252
 253         // set contents, deleting old contents
 254         // ownership is transferred !
 255         void reset( T* i_pNew = NULL )
 256             { OSL_ASSERT( i_pNew != m_pT || i_pNew == NULL ); T* pOld = m_pT; m_pT = i_pNew; delete pOld; }
 257     };
 258
 259     /** Similar to DeleteOnDeinit, the DeleteUnoReferenceOnDeinit
 260         template class makes sure that a static UNO object is disposed
 261         and released at the right time.
 262
 263         Use like
 264             static DeleteUnoReferenceOnDeinit<lang::XMultiServiceFactory>
 265                 xStaticFactory (<create factory object>);
 266             Reference<lang::XMultiServiceFactory> xFactory (xStaticFactory.get());
 267             if (xFactory.is())
 268                 <do something with xFactory>
 269     */
 270     template <typename I>
 271     class DeleteUnoReferenceOnDeinit : public ::vcl::DeleteOnDeinitBase
 272     {
 273         ::com::sun::star::uno::Reference<I> m_xI;
 274         virtual void doCleanup() { set(NULL); }
 275     public:
 276         DeleteUnoReferenceOnDeinit(const ::com::sun::star::uno::Reference<I>& r_xI ) : m_xI( r_xI ) {
 277             addDeinitContainer( this ); }
 278         virtual ~DeleteUnoReferenceOnDeinit() {}
 279
 280         ::com::sun::star::uno::Reference<I> get (void) { return m_xI; }
 281
 282         void set (const ::com::sun::star::uno::Reference<I>& r_xNew )
 283         {
 284             ::com::sun::star::uno::Reference< ::com::sun::star::lang::XComponent> xComponent (m_xI, ::com::sun::star::uno::UNO_QUERY);
 285             m_xI = r_xNew;
 286             if (xComponent.is()) try
 287             {
 288                 xComponent->dispose();
 289             }
 290             catch( ::com::sun::star::uno::Exception& )
 291             {
 292             }
 293         }
 294     };
 295 }
 296
 297 #endif
 298
 299 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */