/// <summary>Writes the buffer to cache using pages</summary>
/// <param name="buffer">source buffer</param>
/// <param name="length">how many bytes to write</param>
/// <exception cref="Db4objects.Db4o.Ext.Db4oIOException"></exception>
public override void Write(byte[] buffer, int length)
{
ValidateReadOnly();
long startAddress = _position;
int bytesToWrite = length;
int bufferOffset = 0;
while (bytesToWrite > 0)
{
// page doesn't need to loadFromDisk if the whole page is dirty
bool loadFromDisk = (bytesToWrite < _pageSize) || (startAddress % _pageSize != 0);
CachedIoAdapter.Page page = GetPage(startAddress, loadFromDisk);
page.EnsureEndAddress(GetLength());
int writtenBytes = page.Write(buffer, bufferOffset, startAddress, bytesToWrite);
FlushIfHeaderBlockPage(page);
MovePageToHead(page);
bytesToWrite -= writtenBytes;
startAddress += writtenBytes;
bufferOffset += writtenBytes;
}
long endAddress = startAddress;
_position = endAddress;
_fileLength = Math.Max(endAddress, _fileLength);
}
/// <exception cref="Db4objects.Db4o.Ext.Db4oIOException"></exception>
private CachedIoAdapter.Page GetPage(long startAddress, bool loadFromDisk)
{
CachedIoAdapter.Page page = GetPageFromCache(startAddress);
if (page != null)
{
if (ContainsHeaderBlock(page))
{
GetPageFromDisk(page, startAddress);
}
page.EnsureEndAddress(_fileLength);
return(page);
}
// in case that page is not found in the cache
page = GetFreePageFromCache();
if (loadFromDisk)
{
GetPageFromDisk(page, startAddress);
}
else
{
ResetPageAddress(page, startAddress);
}
return(page);
}
