public CachedPage GetPage(CachedStream owner, long offset)
{
offset &= CachedPage._outPageBits;
if (_lastAccessedPage != null && _lastAccessedPage.Offset == offset)
{
return(_lastAccessedPage);
}
int shiftedOffset = (int)(offset >> CachedPage._pageShiftBits);
CachedPage result = (CachedPage)_pagesCache.TryKey(shiftedOffset);
if (result == null)
{
long bytes2End = owner.Length - offset;
if (bytes2End < 0)
{
bytes2End = 0;
}
if (_freePage == null)
{
result = new CachedPage(owner, offset);
}
else
{
result = _freePage;
result.Offset = offset;
}
result.Size = (bytes2End >= CachedPage._pageSize) ? CachedPage._pageSize : (int)bytes2End;
_pagesCache.CacheObject(shiftedOffset, result);
result.Load();
}
_lastAccessedPage = result;
return(result);
}
public override int Read(byte[] buffer, int offset, int count)
{
int savedOffset = offset;
while (count > 0)
{
if (_position == _length)
{
throw new EndOfStreamException();
}
CachedPage page = _cachingStrategy.GetPage(this, _position);
int pageIndex = (int)_position & CachedPage._inPageBits;
int readBytes = page.Read(pageIndex, buffer, offset, count);
_position += readBytes;
offset += readBytes;
count -= readBytes;
}
return(offset - savedOffset);
}
private byte this[long index]
{
get
{
if (index >= _length)
{
throw new EndOfStreamException();
}
CachedPage page = _cachingStrategy.GetPage(this, index);
return(page[(int)index & CachedPage._inPageBits]);
}
set
{
CachedPage page = _cachingStrategy.GetPage(this, index);
page[(int)index & CachedPage._inPageBits] = value;
if (index >= _length)
{
_length = index + 1;
}
}
}
public override void Write(byte[] buffer, int offset, int count)
{
while (count > 0)
{
CachedPage page = _cachingStrategy.GetPage(this, _position);
int pageIndex = (int)_position & CachedPage._inPageBits;
int pageBytes = CachedPage._pageSize - pageIndex;
if (pageBytes > count)
{
pageBytes = count;
}
page.Write(buffer, offset, pageIndex, pageBytes);
count -= pageBytes;
_position += pageBytes;
offset += pageBytes;
if (_position > _length)
{
_length = _position;
}
}
}
public CachedPage GetPage(CachedStream owner, long offset)
{
offset &= CachedPage._outPageBits;
if (_lastAccessedPage != null && Object.ReferenceEquals(_lastAccessedPage.Owner, owner) &&
_lastAccessedPage.Offset == offset)
{
return(_lastAccessedPage);
}
_searchKey._owner = owner;
_searchKey._offset = (int)(offset >> CachedPage._pageShiftBits);
CachedPage result = (CachedPage)_pagesCache.TryKey(_searchKey);
if (result == null)
{
long bytes2End = owner.Length - offset;
if (bytes2End < 0)
{
bytes2End = 0;
}
if (_freePage == null)
{
result = new CachedPage(owner, offset);
}
else
{
result = _freePage;
result.Owner = owner;
result.Offset = offset;
_freePage = null;
}
result.Size = (bytes2End >= CachedPage._pageSize) ? CachedPage._pageSize : (int)bytes2End;
_pagesCache.CacheObject(_searchKey.Clone(), result);
result.Load();
}
_lastAccessedPage = result;
return(result);
}
