def open_for_writing(self) -> HashBlobWriter:
if os.path.exists(self.file_path):
raise OSError(f"File already exists '{self.file_path}'")
fut = asyncio.Future(loop=self.loop)
writer = HashBlobWriter(self.blob_hash, self.get_length, fut)
self.writers.append(writer)
fut.add_done_callback(self.writer_finished(writer))
return writer
def open_for_writing(self, peer):
"""
open a blob file to be written by peer, supports concurrent
writers, as long as they are from differnt peers.
returns tuple of (writer, finished_deferred)
writer - a file like object with a write() function, close() when finished
finished_deferred - deferred that is fired when write is finished and returns
a instance of itself as HashBlob
"""
if not peer in self.writers:
log.debug("Opening %s to be written by %s", str(self), str(peer))
finished_deferred = defer.Deferred()
writer = HashBlobWriter(self.get_length, self.writer_finished)
self.writers[peer] = (writer, finished_deferred)
return (writer, finished_deferred)
log.warning("Tried to download the same file twice simultaneously from the same peer")
return None, None
def get_blob_writer(
self,
peer_address: typing.Optional[str] = None,
peer_port: typing.Optional[int] = None) -> HashBlobWriter:
if (peer_address, peer_port) in self.writers and not self.writers[
(peer_address, peer_port)].closed():
raise OSError(
f"attempted to download blob twice from {peer_address}:{peer_port}"
)
fut = asyncio.Future(loop=self.loop)
writer = HashBlobWriter(self.blob_hash, self.get_length, fut)
self.writers[(peer_address, peer_port)] = writer
def remove_writer(_):
if (peer_address, peer_port) in self.writers:
del self.writers[(peer_address, peer_port)]
fut.add_done_callback(remove_writer)
def writer_finished_callback(finished: asyncio.Future):
try:
err = finished.exception()
if err:
raise err
verified_bytes = finished.result()
while self.writers:
_, other = self.writers.popitem()
if other is not writer:
other.close_handle()
self.save_verified_blob(verified_bytes)
except (InvalidBlobHashError, InvalidDataError) as error:
log.warning("writer error downloading %s: %s",
self.blob_hash[:8], str(error))
except (DownloadCancelledError, asyncio.CancelledError,
asyncio.TimeoutError):
pass
fut.add_done_callback(writer_finished_callback)
return writer