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https://github.com/LonamiWebs/Telethon.git
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Create a method to iterate downloads
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Lonami Exo
parent
a43830d403
commit
0b0f8f4285
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@ -6,6 +6,7 @@ import typing
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from .users import UserMethods
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from .. import utils, helpers, errors, hints
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from ..requestiter import RequestIter
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from ..tl import TLObject, types, functions
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try:
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@ -17,6 +18,140 @@ if typing.TYPE_CHECKING:
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from .telegramclient import TelegramClient
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# Chunk sizes for upload.getFile must be multiples of the smallest size
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MIN_CHUNK_SIZE = 4096
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MAX_CHUNK_SIZE = 512 * 1024
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class _DirectDownloadIter(RequestIter):
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async def _init(
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self, file, dc_id, offset, stride, chunk_size, request_size, file_size
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):
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self.request = functions.upload.GetFileRequest(
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file, offset=offset, limit=request_size)
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self.total = file_size
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self._stride = stride
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self._chunk_size = chunk_size
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self._last_part = None
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self._exported = dc_id and self.client.session.dc_id != dc_id
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if not self._exported:
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# The used sender will also change if ``FileMigrateError`` occurs
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self._sender = self.client._sender
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else:
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try:
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self._sender = await self.client._borrow_exported_sender(dc_id)
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except errors.DcIdInvalidError:
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# Can't export a sender for the ID we are currently in
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config = await self.client(functions.help.GetConfigRequest())
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for option in config.dc_options:
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if option.ip_address == self.client.session.server_address:
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self.client.session.set_dc(
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option.id, option.ip_address, option.port)
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self.client.session.save()
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break
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# TODO Figure out why the session may have the wrong DC ID
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self._sender = self.client._sender
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self._exported = False
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async def _load_next_chunk(self):
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cur = await self._request()
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self.buffer.append(cur)
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if len(cur) < self.request.limit:
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self.left = len(self.buffer)
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await self.close()
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else:
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self.request.offset += self._stride
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async def _request(self):
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try:
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result = await self._sender.send(self.request)
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if isinstance(result, types.upload.FileCdnRedirect):
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raise NotImplementedError # TODO Implement
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else:
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return result.bytes
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except errors.FileMigrateError as e:
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self.client._log[__name__].info('File lives in another DC')
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self._sender = await self.client._borrow_exported_sender(e.new_dc)
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self._exported = True
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return await self._request()
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async def close(self):
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if not self._sender:
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return
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try:
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if self._exported:
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await self.client._return_exported_sender(self._sender)
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elif self._sender != self.client._sender:
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await self._sender.disconnect()
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finally:
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self._sender = None
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async def __aenter__(self):
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pass
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async def __aexit__(self, *args):
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await self.close()
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__enter__ = helpers._sync_enter
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__exit__ = helpers._sync_exit
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class _GenericDownloadIter(_DirectDownloadIter):
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async def _load_next_chunk(self, mask=MIN_CHUNK_SIZE - 1):
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# 1. Fetch enough for one chunk
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data = b''
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# 1.1. ``bad`` is how much into the data we have we need to offset
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bad = self.request.offset & mask
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before = self.request.offset
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# 1.2. We have to fetch from a valid offset, so remove that bad part
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self.request.offset -= bad
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done = False
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while not done and len(data) - bad < self._chunk_size:
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cur = await self._request()
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self.request.offset += self.request.limit
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data += cur
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done = len(cur) < self.request.limit
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# 1.3 Restore our last desired offset
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self.request.offset = before
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# 2. Fill the buffer with the data we have
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# 2.1. Slicing ``bytes`` is expensive, yield ``memoryview`` instead
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mem = memoryview(data)
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# 2.2. The current chunk starts at ``bad`` offset into the data,
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# and each new chunk is ``stride`` bytes apart of the other
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for i in range(bad, len(data), self._stride):
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self.buffer.append(mem[i:i + self._chunk_size])
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# 2.3. We will yield this offset, so move to the next one
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self.request.offset += self._stride
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# 2.4. If we are in the last chunk, we will return the last partial data
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if done:
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self.left = len(self.buffer)
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await self.close()
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return
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# 2.5. If we are not done, we can't return incomplete chunks.
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if len(self.buffer[-1]) != self._chunk_size:
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self._last_part = self.buffer.pop().tobytes()
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# 3. Be careful with the offsets. Re-fetching a bit of data
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# is fine, since it greatly simplifies things.
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# TODO Try to not re-fetch data
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self.request.offset -= self._stride
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class DownloadMethods(UserMethods):
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# region Public methods
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@ -366,6 +501,150 @@ class DownloadMethods(UserMethods):
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if isinstance(file, str) or in_memory:
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f.close()
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def iter_download(
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self: 'TelegramClient',
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file: 'hints.FileLike',
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*,
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offset: int = 0,
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stride: int = None,
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limit: int = None,
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chunk_size: int = None,
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request_size: int = MAX_CHUNK_SIZE,
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file_size: int = None,
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dc_id: int = None
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):
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"""
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Iterates over a file download, yielding chunks of the file.
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This method can be used to stream files in a more convenient
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way, since it offers more control (pausing, resuming, etc.)
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.. note::
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Using a value for `offset` or `stride` which is not a multiple
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of the minimum allowed `request_size`, or if `chunk_size` is
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different from `request_size`, the library will need to do a
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bit more work to fetch the data in the way you intend it to.
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You normally shouldn't worry about this.
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Arguments
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file (`hints.FileLike`):
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The file of which contents you want to iterate over.
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offset (`int`, optional):
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The offset in bytes into the file from where the
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download should start. For example, if a file is
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1024KB long and you just want the last 512KB, you
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would use ``offset=512 * 1024``.
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stride (`int`, optional):
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The stride of each chunk (how much the offset should
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advance between reading each chunk). This parameter
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should only be used for more advanced use cases.
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It must be bigger than or equal to the `chunk_size`.
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limit (`int`, optional):
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The limit for how many *chunks* will be yielded at most.
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chunk_size (`int`, optional):
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The maximum size of the chunks that will be yielded.
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Note that the last chunk may be less than this value.
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By default, it equals to `request_size`.
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request_size (`int`, optional):
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How many bytes will be requested to Telegram when more
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data is required. By default, as many bytes as possible
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are requested. If you would like to request data in
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smaller sizes, adjust this parameter.
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Note that values outside the valid range will be clamped,
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and the final value will also be a multiple of the minimum
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allowed size.
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file_size (`int`, optional):
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If the file size is known beforehand, you should set
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this parameter to said value. Depending on the type of
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the input file passed, this may be set automatically.
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dc_id (`int`, optional):
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The data center the library should connect to in order
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to download the file. You shouldn't worry about this.
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Yields
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``bytes`` objects representing the chunks of the file if the
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right conditions are met, or ``memoryview`` objects instead.
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Example
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.. code-block:: python
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# Streaming `media` to an output file
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# After the iteration ends, the sender is cleaned up
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with open('photo.jpg', 'wb') as fd:
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for chunk client.iter_download(media):
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fd.write(chunk)
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# Fetching only the header of a file (32 bytes)
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# You should manually close the iterator in this case.
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stream = client.iter_download(media, request_size=32)
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header = next(stream)
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stream.close()
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assert len(header) == 32
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# Fetching only the header, inside of an ``async def``
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async def main():
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stream = client.iter_download(media, request_size=32)
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header = await stream.__anext__()
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await stream.close()
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assert len(header) == 32
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"""
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if chunk_size is None:
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chunk_size = request_size
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if limit is None and file_size is not None:
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limit = (file_size + chunk_size - 1) // chunk_size
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if stride is None:
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stride = chunk_size
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elif stride < chunk_size:
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raise ValueError('stride must be >= chunk_size')
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request_size -= request_size % MIN_CHUNK_SIZE
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if request_size < MIN_CHUNK_SIZE:
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request_size = MIN_CHUNK_SIZE
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elif request_size > MAX_CHUNK_SIZE:
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request_size = MAX_CHUNK_SIZE
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old_dc = dc_id
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dc_id, file = utils.get_input_location(file)
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if dc_id is None:
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dc_id = old_dc
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if chunk_size == request_size \
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and offset % MIN_CHUNK_SIZE == 0 \
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and stride % MIN_CHUNK_SIZE == 0:
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cls = _DirectDownloadIter
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self._log[__name__].info('Starting direct file download in chunks of '
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'%d at %d, stride %d', request_size, offset, stride)
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else:
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cls = _GenericDownloadIter
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self._log[__name__].info('Starting indirect file download in chunks of '
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'%d at %d, stride %d', request_size, offset, stride)
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return cls(
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self,
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limit,
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file=file,
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dc_id=dc_id,
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offset=offset,
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stride=stride,
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chunk_size=chunk_size,
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request_size=request_size,
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file_size=file_size
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)
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# endregion
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# region Private methods
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