Observable stream that tries to control back pressure

ObservableStream

        public IObservable<byte[]> GetFileData(string filePath, IObservable<bool> continueReading)
        {
            AsyncSubject<byte[]> ret = new AsyncSubject<byte[]>();

            Observable.Start(() =>
            {
                using (var stream = new MemoryStream())
                {
                    int streamPos = 0;
                    byte[] buffer = new byte[128];

                    continueReading.Subscribe(_ =>
                    {
                        stream.Read(buffer, streamPos, buffer.Length);

                        streamPos += buffer.Length;

                        ret.OnNext(buffer);

                    }, Scheduler.CurrentThread);
                }
            });

            return ret;
        }

        public void StartSyncing()
        {
            Upload(GetFileData(_dbPath), new AsyncSubject<bool>());
        }

        public void Upload(IObservable<byte[]> fileStream, AsyncSubject<bool> continueReading )
        {
            fileStream.Subscribe(bytes =>
            {
                using (var dropboxStream = new MemoryStream())
                {
                    dropboxStream.Write(bytes);
                    continueReading.OnNext(true);
                }
            });
        }