def __init__(self,
blob: Blob,
chunk_size: int = default_chunk_size,
async_queue: Optional[AsyncQueue] = None):
assert chunk_size >= 1
if blob.size is None:
blob.reload()
if blob.chunk_size is None:
# Induce google.cloud.storage.blob to use either google.resumable_media.requests.ChunkedDownload or
# google.resumable_media.requests.RawChunkedDownload, which do not attempt to perform data-integrity checks
# for chunk downloads (checksum headers are not available for chunks).
blob.chunk_size = ceil(
chunk_size / _BLOB_CHUNK_SIZE_UNIT) * _BLOB_CHUNK_SIZE_UNIT
self.blob = blob
self.chunk_size = chunk_size
self._buffer = bytearray()
self._pos = 0
self.number_of_chunks = ceil(
self.blob.size / self.chunk_size) if 0 < self.blob.size else 1
self._unfetched_chunks = [i for i in range(self.number_of_chunks)]
self.future_chunk_downloads: Optional[AsyncQueue]
if async_queue is not None:
self.future_chunk_downloads = async_queue
for chunk_number in self._unfetched_chunks:
self.future_chunk_downloads.put(self._fetch_chunk,
chunk_number)
else:
self.future_chunk_downloads = None
