private Page Refresh(Page page)
{
MRU.Remove(page);
MRU.Add(page);
return page;
}
public void Save(Page page)
{
byte[] buffer = new byte[Constants.PAGESIZE];
for(int i = 0; i < buffer.Length; i++) {
buffer[i] = (byte) page.Data[i];
}
stream.Position = page.FileIndex * Constants.PAGESIZE;
stream.Write(buffer, 0, Constants.PAGESIZE);
page.PinCount++;
page.UltimoAcesso = DateTime.Now.ToFileTimeUtc();
}
private void Load(Page page)
{
byte[] buffer = new byte[Constants.PAGESIZE];
stream.Position = page.FileIndex * Constants.PAGESIZE;
stream.Read(buffer, 0, Constants.PAGESIZE);
for(int i = 0; i < buffer.Length; i++) {
page.Data[i] = buffer[i];
}
page.Dirt = false;
page.PinCount=1;
page.UltimoAcesso = DateTime.Now.ToFileTimeUtc();
}
public Page this[int index]
{
get{
if(index > Constants.MAXPAGES-1)
throw new IndexOutOfRangeException("O numero maximo de paginas no disco eh "+Constants.MAXPAGES);
Page page = LocatePageIndex(index);
if(page == null) {
if(MRU.Count == Constants.MAXMEMORYPAGES) {
if(politica == PoliticaDeSubstituicao.LRU)
MRU.Remove(GetLastRecentlyUsed());
else if(politica == PoliticaDeSubstituicao.LRU)
MRU.Remove(GetMostRecentlyUsed());
else
MRU.Remove(GetRandomPage());
}
page = new Page();
page.FileIndex = index;
Pages.Add(page);
Load(page);
}
return Refresh(page);
}
}
