问题
I've been trying to implement a multi threaded Telegram download client. For single downloads we can simply use the download_media functionality.
But telethon offers iter_download function, as per documenation it is used for streaming which also includes pausing and resuming functionality. We can use this to download a single file with multiple connections.
This is what I've scripted so far. No where to find any solid examples for multi connection download
async def multi_downloader(file, total_size, part, offset, part_size):
f = open('output.mkv.'+str(part), 'wb')
size = 0
global chunk_size
limit = 10485760#closestInteger(part_size / chunk_size, 10485760)
print(limit)
print(part)
async for chunk in client.iter_download(obj, offset = offset, limit = limit, chunk_size = chunk_size, request_size = chunk_size, file_size = total_size):
f.write(chunk)
f.flush()
size += (len(chunk))
if size >= (part_size):
print("Part "+str(part)+" completed. "+str(part_size))
break
f.close()
The thing is it always throws the invalid limit error, if I change the offset for seeking. If the offset is zero then everything is fine.
telethon.errors.rpcerrorlist.LimitInvalidError: An invalid limit was provided. See https://core.telegram.org/api/files#downloading-files (caused by GetFileRequest)
回答1:
We have already made somlething similar which you can find here https://gist.github.com/painor/7e74de80ae0c819d3e9abcf9989a8dd6 . Code :
"""
> Based on parallel_file_transfer.py from mautrix-telegram, with permission to distribute under the MIT license
> Copyright (C) 2019 Tulir Asokan - https://github.com/tulir/mautrix-telegram
"""
import asyncio
import hashlib
import inspect
import logging
import os
from collections import defaultdict
from typing import Optional, List, AsyncGenerator, Union, Awaitable, DefaultDict, Tuple, BinaryIO
import math
from telethon import utils, helpers, TelegramClient
from telethon.crypto import AuthKey
from telethon.network import MTProtoSender
from telethon.tl.functions.auth import ExportAuthorizationRequest, ImportAuthorizationRequest
from telethon.tl.functions.upload import (GetFileRequest, SaveFilePartRequest,
SaveBigFilePartRequest)
from telethon.tl.types import (Document, InputFileLocation, InputDocumentFileLocation,
InputPhotoFileLocation, InputPeerPhotoFileLocation, TypeInputFile,
InputFileBig, InputFile)
log: logging.Logger = logging.getLogger("telethon")
logging.basicConfig(level=logging.WARNING)
TypeLocation = Union[Document, InputDocumentFileLocation, InputPeerPhotoFileLocation,
InputFileLocation, InputPhotoFileLocation]
def stream_file(file_to_stream: BinaryIO, chunk_size=1024):
while True:
data_read = file_to_stream.read(chunk_size)
if not data_read:
break
yield data_read
class DownloadSender:
sender: MTProtoSender
request: GetFileRequest
remaining: int
stride: int
def __init__(self, sender: MTProtoSender, file: TypeLocation, offset: int, limit: int,
stride: int, count: int) -> None:
self.sender = sender
self.request = GetFileRequest(file, offset=offset, limit=limit)
self.stride = stride
self.remaining = count
async def next(self) -> Optional[bytes]:
if not self.remaining:
return None
result = await self.sender.send(self.request)
self.remaining -= 1
self.request.offset += self.stride
return result.bytes
def disconnect(self) -> Awaitable[None]:
return self.sender.disconnect()
class UploadSender:
sender: MTProtoSender
request: Union[SaveFilePartRequest, SaveBigFilePartRequest]
part_count: int
stride: int
previous: Optional[asyncio.Task]
loop: asyncio.AbstractEventLoop
def __init__(self, sender: MTProtoSender, file_id: int, part_count: int, big: bool, index: int,
stride: int, loop: asyncio.AbstractEventLoop) -> None:
self.sender = sender
self.part_count = part_count
if big:
self.request = SaveBigFilePartRequest(file_id, index, part_count, b"")
else:
self.request = SaveFilePartRequest(file_id, index, b"")
self.stride = stride
self.previous = None
self.loop = loop
async def next(self, data: bytes) -> None:
if self.previous:
await self.previous
self.previous = self.loop.create_task(self._next(data))
async def _next(self, data: bytes) -> None:
self.request.bytes = data
log.debug(f"Sending file part {self.request.file_part}/{self.part_count}"
f" with {len(data)} bytes")
await self.sender.send(self.request)
self.request.file_part += self.stride
async def disconnect(self) -> None:
if self.previous:
await self.previous
return await self.sender.disconnect()
class ParallelTransferrer:
client: TelegramClient
loop: asyncio.AbstractEventLoop
dc_id: int
senders: Optional[List[Union[DownloadSender, UploadSender]]]
auth_key: AuthKey
upload_ticker: int
def __init__(self, client: TelegramClient, dc_id: Optional[int] = None) -> None:
self.client = client
self.loop = self.client.loop
self.dc_id = dc_id or self.client.session.dc_id
self.auth_key = (None if dc_id and self.client.session.dc_id != dc_id
else self.client.session.auth_key)
self.senders = None
self.upload_ticker = 0
async def _cleanup(self) -> None:
await asyncio.gather(*[sender.disconnect() for sender in self.senders])
self.senders = None
@staticmethod
def _get_connection_count(file_size: int, max_count: int = 20,
full_size: int = 100 * 1024 * 1024) -> int:
if file_size > full_size:
return max_count
return math.ceil((file_size / full_size) * max_count)
async def _init_download(self, connections: int, file: TypeLocation, part_count: int,
part_size: int) -> None:
minimum, remainder = divmod(part_count, connections)
def get_part_count() -> int:
nonlocal remainder
if remainder > 0:
remainder -= 1
return minimum + 1
return minimum
# The first cross-DC sender will export+import the authorization, so we always create it
# before creating any other senders.
self.senders = [
await self._create_download_sender(file, 0, part_size, connections * part_size,
get_part_count()),
*await asyncio.gather(
*[self._create_download_sender(file, i, part_size, connections * part_size,
get_part_count())
for i in range(1, connections)])
]
async def _create_download_sender(self, file: TypeLocation, index: int, part_size: int,
stride: int,
part_count: int) -> DownloadSender:
return DownloadSender(await self._create_sender(), file, index * part_size, part_size,
stride, part_count)
async def _init_upload(self, connections: int, file_id: int, part_count: int, big: bool
) -> None:
self.senders = [
await self._create_upload_sender(file_id, part_count, big, 0, connections),
*await asyncio.gather(
*[self._create_upload_sender(file_id, part_count, big, i, connections)
for i in range(1, connections)])
]
async def _create_upload_sender(self, file_id: int, part_count: int, big: bool, index: int,
stride: int) -> UploadSender:
return UploadSender(await self._create_sender(), file_id, part_count, big, index, stride,
loop=self.loop)
async def _create_sender(self) -> MTProtoSender:
dc = await self.client._get_dc(self.dc_id)
sender = MTProtoSender(self.auth_key, self.loop, loggers=self.client._log)
await sender.connect(self.client._connection(dc.ip_address, dc.port, dc.id,
loop=self.loop, loggers=self.client._log,
proxy=self.client._proxy))
if not self.auth_key:
log.debug(f"Exporting auth to DC {self.dc_id}")
auth = await self.client(ExportAuthorizationRequest(self.dc_id))
req = self.client._init_with(ImportAuthorizationRequest(
id=auth.id, bytes=auth.bytes
))
await sender.send(req)
self.auth_key = sender.auth_key
return sender
async def init_upload(self, file_id: int, file_size: int, part_size_kb: Optional[float] = None,
connection_count: Optional[int] = None) -> Tuple[int, int, bool]:
connection_count = connection_count or self._get_connection_count(file_size)
print("init_upload count is ", connection_count)
part_size = (part_size_kb or utils.get_appropriated_part_size(file_size)) * 1024
part_count = (file_size + part_size - 1) // part_size
is_large = file_size > 10 * 1024 * 1024
await self._init_upload(connection_count, file_id, part_count, is_large)
return part_size, part_count, is_large
async def upload(self, part: bytes) -> None:
await self.senders[self.upload_ticker].next(part)
self.upload_ticker = (self.upload_ticker + 1) % len(self.senders)
async def finish_upload(self) -> None:
await self._cleanup()
async def download(self, file: TypeLocation, file_size: int,
part_size_kb: Optional[float] = None,
connection_count: Optional[int] = None) -> AsyncGenerator[bytes, None]:
connection_count = connection_count or self._get_connection_count(file_size)
print("download count is ", connection_count)
part_size = (part_size_kb or utils.get_appropriated_part_size(file_size)) * 1024
part_count = math.ceil(file_size / part_size)
log.debug("Starting parallel download: "
f"{connection_count} {part_size} {part_count} {file!s}")
await self._init_download(connection_count, file, part_count, part_size)
part = 0
while part < part_count:
tasks = []
for sender in self.senders:
tasks.append(self.loop.create_task(sender.next()))
for task in tasks:
data = await task
if not data:
break
yield data
part += 1
log.debug(f"Part {part} downloaded")
log.debug("Parallel download finished, cleaning up connections")
await self._cleanup()
parallel_transfer_locks: DefaultDict[int, asyncio.Lock] = defaultdict(lambda: asyncio.Lock())
async def _internal_transfer_to_telegram(client: TelegramClient,
response: BinaryIO,
progress_callback: callable
) -> Tuple[TypeInputFile, int]:
file_id = helpers.generate_random_long()
file_size = os.path.getsize(response.name)
hash_md5 = hashlib.md5()
uploader = ParallelTransferrer(client)
part_size, part_count, is_large = await uploader.init_upload(file_id, file_size)
buffer = bytearray()
for data in stream_file(response):
if progress_callback:
r = progress_callback(response.tell(), file_size)
if inspect.isawaitable(r):
await r
if not is_large:
hash_md5.update(data)
if len(buffer) == 0 and len(data) == part_size:
await uploader.upload(data)
continue
new_len = len(buffer) + len(data)
if new_len >= part_size:
cutoff = part_size - len(buffer)
buffer.extend(data[:cutoff])
await uploader.upload(bytes(buffer))
buffer.clear()
buffer.extend(data[cutoff:])
else:
buffer.extend(data)
if len(buffer) > 0:
await uploader.upload(bytes(buffer))
await uploader.finish_upload()
if is_large:
return InputFileBig(file_id, part_count, "upload"), file_size
else:
return InputFile(file_id, part_count, "upload", hash_md5.hexdigest()), file_size
async def download_file(client: TelegramClient,
location: TypeLocation,
out: BinaryIO,
progress_callback: callable = None
) -> BinaryIO:
size = location.size
dc_id, location = utils.get_input_location(location)
# We lock the transfers because telegram has connection count limits
downloader = ParallelTransferrer(client, dc_id)
downloaded = downloader.download(location, size)
async for x in downloaded:
out.write(x)
if progress_callback:
r = progress_callback(out.tell(), size)
if inspect.isawaitable(r):
await r
return out
async def upload_file(client: TelegramClient,
file: BinaryIO,
progress_callback: callable = None,
) -> TypeInputFile:
res = (await _internal_transfer_to_telegram(client, file, progress_callback))[0]
return res
usage :
to download files :
await download_file(client, msg.document, file, progress_callback=prog)
to upload files :
result = await parallel_transfer_to_telegram(client, file, progress_callback=prog)
await client.send_file(event.chat_id, file=result)
Known issues :
if you are using a bot account the DC ID might be messed up so you would need to do this just after calling .start() :
config = await client(functions.help.GetConfigRequest())
for option in config.dc_options:
if option.ip_address == client.session.server_address:
if client.session.dc_id != option.id:
log.warning(f"Fixed DC ID in session from {client.session.dc_id} to {option.id}")
client.session.set_dc(option.id, option.ip_address, option.port)
client.session.save()
break
来源：https://stackoverflow.com/questions/59801767/how-to-correctly-use-the-iter-download-functionality-for-multi-connection-downlo