lbry-sdk/lbrynet/stream/downloader.py

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import asyncio
import typing
import logging
import binascii
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from lbrynet.error import DownloadSDTimeout
from lbrynet.utils import resolve_host
from lbrynet.stream.descriptor import StreamDescriptor
from lbrynet.blob_exchange.downloader import BlobDownloader
from lbrynet.dht.peer import KademliaPeer
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if typing.TYPE_CHECKING:
from lbrynet.conf import Config
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from lbrynet.dht.node import Node
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from lbrynet.blob.blob_manager import BlobManager
from lbrynet.blob.blob_file import AbstractBlob
from lbrynet.blob.blob_info import BlobInfo
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log = logging.getLogger(__name__)
class StreamDownloader:
def __init__(self, loop: asyncio.BaseEventLoop, config: 'Config', blob_manager: 'BlobManager', sd_hash: str,
descriptor: typing.Optional[StreamDescriptor] = None):
self.loop = loop
self.config = config
self.blob_manager = blob_manager
self.sd_hash = sd_hash
self.search_queue = asyncio.Queue(loop=loop) # blob hashes to feed into the iterative finder
self.peer_queue = asyncio.Queue(loop=loop) # new peers to try
self.blob_downloader = BlobDownloader(self.loop, self.config, self.blob_manager, self.peer_queue)
self.descriptor: typing.Optional[StreamDescriptor] = descriptor
self.node: typing.Optional['Node'] = None
self.accumulate_task: typing.Optional[asyncio.Task] = None
self.fixed_peers_handle: typing.Optional[asyncio.Handle] = None
self.fixed_peers_delay: typing.Optional[float] = None
self.added_fixed_peers = False
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self.time_to_descriptor: typing.Optional[float] = None
self.time_to_first_bytes: typing.Optional[float] = None
async def add_fixed_peers(self):
def _delayed_add_fixed_peers():
self.added_fixed_peers = True
self.peer_queue.put_nowait([
KademliaPeer(self.loop, address=address, tcp_port=port + 1)
for address, port in addresses
])
if not self.config.reflector_servers:
return
addresses = [
(await resolve_host(url, port + 1, proto='tcp'), port)
for url, port in self.config.reflector_servers
]
if 'dht' in self.config.components_to_skip or not self.node or not \
len(self.node.protocol.routing_table.get_peers()):
self.fixed_peers_delay = 0.0
else:
self.fixed_peers_delay = self.config.fixed_peer_delay
self.fixed_peers_handle = self.loop.call_later(self.fixed_peers_delay, _delayed_add_fixed_peers)
async def load_descriptor(self):
# download or get the sd blob
sd_blob = self.blob_manager.get_blob(self.sd_hash)
if not sd_blob.get_is_verified():
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try:
now = self.loop.time()
sd_blob = await asyncio.wait_for(
self.blob_downloader.download_blob(self.sd_hash),
self.config.blob_download_timeout, loop=self.loop
)
log.info("downloaded sd blob %s", self.sd_hash)
self.time_to_descriptor = self.loop.time() - now
except asyncio.TimeoutError:
raise DownloadSDTimeout(self.sd_hash)
# parse the descriptor
self.descriptor = await StreamDescriptor.from_stream_descriptor_blob(
self.loop, self.blob_manager.blob_dir, sd_blob
)
log.info("loaded stream manifest %s", self.sd_hash)
async def start(self, node: typing.Optional['Node'] = None):
# set up peer accumulation
if node:
self.node = node
_, self.accumulate_task = self.node.accumulate_peers(self.search_queue, self.peer_queue)
await self.add_fixed_peers()
# start searching for peers for the sd hash
self.search_queue.put_nowait(self.sd_hash)
log.info("searching for peers for stream %s", self.sd_hash)
if not self.descriptor:
await self.load_descriptor()
# add the head blob to the peer search
self.search_queue.put_nowait(self.descriptor.blobs[0].blob_hash)
log.info("added head blob to peer search for stream %s", self.sd_hash)
if not await self.blob_manager.storage.stream_exists(self.sd_hash):
await self.blob_manager.storage.store_stream(
self.blob_manager.get_blob(self.sd_hash, length=self.descriptor.length), self.descriptor
)
async def download_stream_blob(self, blob_info: 'BlobInfo') -> 'AbstractBlob':
if not filter(lambda blob: blob.blob_hash == blob_info.blob_hash, self.descriptor.blobs[:-1]):
raise ValueError(f"blob {blob_info.blob_hash} is not part of stream with sd hash {self.sd_hash}")
blob = await self.blob_downloader.download_blob(blob_info.blob_hash, blob_info.length)
return blob
def _decrypt_blob(self, blob_info: 'BlobInfo', blob: 'AbstractBlob'):
return blob.decrypt(
binascii.unhexlify(self.descriptor.key.encode()), binascii.unhexlify(blob_info.iv.encode())
)
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async def decrypt_blob(self, blob_info: 'BlobInfo', blob: 'AbstractBlob') -> bytes:
return await self.loop.run_in_executor(None, self._decrypt_blob, blob_info, blob)
async def read_blob(self, blob_info: 'BlobInfo') -> bytes:
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start = None
if self.time_to_first_bytes is None:
start = self.loop.time()
blob = await self.download_stream_blob(blob_info)
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decrypted = await self.decrypt_blob(blob_info, blob)
if start:
self.time_to_first_bytes = self.loop.time() - start
return decrypted
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def stop(self):
if self.accumulate_task:
self.accumulate_task.cancel()
self.accumulate_task = None
if self.fixed_peers_handle:
self.fixed_peers_handle.cancel()
self.fixed_peers_handle = None
self.blob_downloader.close()