internal void UpdateState(string directory, ref FileChangeList changes, ref FileSystemEntry file)
        {
            int index = _state.IndexOf(directory, file.FileName);

            if (index == -1) // file added
            {
                string path = file.FileName.ToString();

                changes.AddAdded(directory, path.ToString());

                var newFileState = new FileState(directory, path);
                newFileState.LastWriteTimeUtc = file.LastWriteTimeUtc;
                newFileState.Length           = file.Length;
                newFileState._version         = _version;
                _state.Add(directory, path, newFileState);
                return;
            }

            _state.Values[index]._version = _version;

            FileState previousState = _state.Values[index];

            if (file.LastWriteTimeUtc != previousState.LastWriteTimeUtc || file.Length != previousState.Length)
            {
                changes.AddChanged(directory, previousState.Path);
                _state.Values[index].LastWriteTimeUtc = file.LastWriteTimeUtc;
                _state.Values[index].Length           = file.Length;
            }
        }
        private void Resize()
        {
            // this is because sometimes we just need to garbade collect instead of increase size
            int newSize = Math.Max(Count * 2, 4);

            PathToFileStateHashtable bigger = new PathToFileStateHashtable(newSize);

            foreach (FileState existingValue in this)
            {
                bigger.Add(existingValue.Directory, existingValue.Path, existingValue);
            }
            Values  = bigger.Values;
            Buckets = bigger.Buckets;
            this._nextValuesIndex = bigger._nextValuesIndex;
            this.Count            = bigger.Count;
        }