public StreamID Reference(StreamID streamID)
{
LocalStreamHeader targetHeader;
if (_headers.TryGetValue(streamID, out targetHeader) && (targetHeader.Stream != null) && targetHeader.Stream.Modified)
{
StreamID localStreamID = Allocate();
Stream stream = Open(localStreamID, LockMode.Exclusive);
try
{
Stream targetStream = new CoverStream(targetHeader.Stream);
try
{
StreamUtility.CopyStream(targetStream, stream);
return(localStreamID);
}
finally
{
targetStream.Close();
}
}
finally
{
stream.Close();
Close(localStreamID);
}
}
else
{
StreamID localStreamID = _sourceStreamManager.Reference(streamID);
LocalStreamHeader header = new LocalStreamHeader(localStreamID);
_headers.Add(header);
return(localStreamID);
}
}
// IStreamManager
public StreamID Allocate()
{
// Allocates a new stream in the source stream manager, and saves the header and local cache for it locally
StreamID streamID = _sourceStreamManager.Allocate();
LocalStreamHeader header = new LocalStreamHeader(streamID);
_headers.Add(header);
return(streamID);
}
public Stream Open(StreamID streamID, LockMode mode)
{
// Ensures that the given stream is supported by a local cache and returns a stream accessing it
LocalStreamHeader header;
if (!_headers.TryGetValue(streamID, out header))
{
header = new LocalStreamHeader(streamID, new LocalStream(this, streamID, mode)); //FSourceStreamManager.Open(AStreamID, AMode)));
_headers.Add(header);
}
else if (header.Stream == null)
{
header.Stream = new LocalStream(this, streamID, mode); //, FSourceStreamManager.Open(AStreamID, AMode));
}
return(new CoverStream(header.Stream));
}
