Tools.h++ Manual

21-100 104011 Tandem Computers Incorporated
21
Public constructor RWDiskPageHeap(const char* filename=0,
unsigned nbufs=10,
unsigned pgsize=512);
Constructs a new disk-based page heap. The heap will use a file with filename
filename , otherwise it will negotiate with the operating system for a
temporary filename. The number of buffers, each the size of the page size, will
be nbufs . No more than this many pages can be locked at any one time. The
size of each page is given by pgsize . To see whether a valid
RWDiskPageHeap has been constructed, call member function isValid() .
virtual ~RWDiskPageHeap();
Returns any resources used by the disk page heap back to the operating
system. All pages should have been deallocated before the destructor is called.
Public member functions virtual RWHandle allocate();
Redefined from class RWVirtualPageHeap . Allocates a page off the disk page
heap and returns a handle for it. If there is no more space (for example, the
disk is full) then returns zero.
virtual void deallocate(RWHandle h);
Redefined from class RWBufferedPageHeap . Deallocate the page associated
with handle h . It is not an error to deallocate a zero handle.
virtual void dirty(RWHandle h);
Inherited from RWBufferedPageHeap .
RWBoolean isValid() const;
Returns TRUE if this is a valid RWDiskPageHeap .
virtual void* lock(RWHandle h);
Inherited from RWBufferedPageHeap .
virtual void unlock(RWHandle h) = 0;
Inherited from RWBufferedPageHeap .