How to use the zstandard.COMPRESSION_RECOMMENDED_INPUT_SIZE function in zstandard

source = io.BytesIO()
        source.write(b"f" * zstd.COMPRESSION_RECOMMENDED_INPUT_SIZE)
        source.write(b"o")
        source.seek(0)

        # Creating an iterator should not perform any compression until
        # first read.
        it = cctx.read_to_iter(source, size=len(source.getvalue()))
        self.assertEqual(source.tell(), 0)

        # We should have exactly 2 output chunks.
        chunks = []
        chunk = next(it)
        self.assertIsNotNone(chunk)
        self.assertEqual(source.tell(), zstd.COMPRESSION_RECOMMENDED_INPUT_SIZE)
        chunks.append(chunk)
        chunk = next(it)
        self.assertIsNotNone(chunk)
        chunks.append(chunk)

        self.assertEqual(source.tell(), len(source.getvalue()))

        with self.assertRaises(StopIteration):
            next(it)

        # And again for good measure.
        with self.assertRaises(StopIteration):
            next(it)

        # We should get the same output as the one-shot compression mechanism.
        self.assertEqual(b"".join(chunks), cctx.compress(source.getvalue()))

def test_read_large(self):
        cctx = zstd.ZstdCompressor(level=1, write_content_size=False)

        source = io.BytesIO()
        source.write(b"f" * zstd.COMPRESSION_RECOMMENDED_INPUT_SIZE)
        source.write(b"o")
        source.seek(0)

        # Creating an iterator should not perform any compression until
        # first read.
        it = cctx.read_to_iter(source, size=len(source.getvalue()))
        self.assertEqual(source.tell(), 0)

        # We should have exactly 2 output chunks.
        chunks = []
        chunk = next(it)
        self.assertIsNotNone(chunk)
        self.assertEqual(source.tell(), zstd.COMPRESSION_RECOMMENDED_INPUT_SIZE)
        chunks.append(chunk)
        chunk = next(it)
        self.assertIsNotNone(chunk)

def add(self, src, name=None, stop_event=None):
        name = name or os.path.basename(src)
        self.log(logging.DEBUG, "Add %s into %s", src, self.archive_path(name))

        cctx = zstd.ZstdCompressor(compression_params=self.zstd_params)
        try:
            with open(src, "rb") as ifh, open(self.archive_path(name), "wb") as ofh:
                with cctx.stream_writer(ofh) as writer:
                    while True:
                        if stop_event and stop_event.is_set():
                            raise CancelledError()

                        data = ifh.read(zstd.COMPRESSION_RECOMMENDED_INPUT_SIZE)
                        if not data:
                            break

                        if stop_event and stop_event.is_set():
                            raise CancelledError()
                        writer.write(data)
        except:
            if os.path.exists(self.archive_path(name)):
                os.remove(self.archive_path(name))
            raise

        return self.archive_path(name)