Tôi cũng xóa các tập tin. Sau đó, tôi vẽ lại xem ứng dụng và người dùng sử dụng:: Leave () để tuyên truyền các lỗi để Uikon có thể hiển thị một thông báo lỗi tương ứng với mã lỗi. Thử nghiệm này, nếu bạn thích, bằng cách chèn người sử dụng:: Leave (KErrDiskFull) một nơi nào đó trong WriteFileL (). | Request the window server to draw the bitmap Delete the bitmap. By the time the client s buffer is flushed and executed by the window server the third step above the bitmap could have been deleted. To avoid this the FBS client-side implementation calls the window server client s Flush function through an interface function before sending the FBS message to delete the bitmap. Note As well as handling ROM- and RAM-resident bitmaps the FBS also handles ROM- and RAM-resident fonts. The precise details are different from those for bitmaps but the motivations for using a server to share font data are essentially the same. The shared memory technique is not without cost The shared heap is mapped to different addresses in different processes. This means that conventional pointers cannot be used within the heap a handle system has to be used instead. The shared heap is not the default heap for either client or server process. This means that the default operator new and operator delete don t work. For both the above reasons objects designed for use in the default user heap cannot be placed onto a shared heap. New classes must be written specially for this purpose. You have to use mutex synchronization to control access to objects on the shared heap. You have to make sure that things stay in sync when you delete objects that are shared with other servers. For the font and bitmap server these costs are low because the shared heap contains large-scale objects fonts and bitmaps and because the usage patterns of these objects minimize the difficulties of mutex-based sharing. In addition the benefits of sharing are very high because of the intensity of operations involving bit-blitting the enormous difference the efficient implementation makes to users perceptions of system efficiency the size of the objects that would have to be exchanged using client-server transactions if the shared heap was not available. Other shared-heap server designs have been implemented on Symbian OS .
