148 lines
6.7 KiB
Python
148 lines
6.7 KiB
Python
import asyncio
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import typing
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import logging
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from lbrynet.utils import drain_tasks, cache_concurrent
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from lbrynet.blob_exchange.client import request_blob
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if typing.TYPE_CHECKING:
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from lbrynet.conf import Config
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from lbrynet.dht.node import Node
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from lbrynet.dht.peer import KademliaPeer
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from lbrynet.blob.blob_manager import BlobManager
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from lbrynet.blob.blob_file import AbstractBlob
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log = logging.getLogger(__name__)
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class BlobDownloader:
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BAN_FACTOR = 2.0 # fixme: when connection manager gets implemented, move it out from here
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def __init__(self, loop: asyncio.BaseEventLoop, config: 'Config', blob_manager: 'BlobManager',
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peer_queue: asyncio.Queue):
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self.loop = loop
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self.config = config
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self.blob_manager = blob_manager
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self.peer_queue = peer_queue
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self.active_connections: typing.Dict['KademliaPeer', asyncio.Task] = {} # active request_blob calls
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self.ignored: typing.Dict['KademliaPeer', int] = {}
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self.scores: typing.Dict['KademliaPeer', int] = {}
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self.failures: typing.Dict['KademliaPeer', int] = {}
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self.connections: typing.Dict['KademliaPeer', asyncio.Transport] = {}
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def should_race_continue(self, blob: 'AbstractBlob'):
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if len(self.active_connections) >= self.config.max_connections_per_download:
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return False
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# if a peer won 3 or more blob races and is active as a downloader, stop the race so bandwidth improves
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# the safe net side is that any failure will reset the peer score, triggering the race back
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# TODO: this is a good idea for low bandwidth, but doesnt play nice on high bandwidth
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# for peer, task in self.active_connections.items():
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# if self.scores.get(peer, 0) >= 0 and self.rounds_won.get(peer, 0) >= 3 and not task.done():
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# return False
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return not (blob.get_is_verified() or not blob.is_writeable())
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async def request_blob_from_peer(self, blob: 'AbstractBlob', peer: 'KademliaPeer'):
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if blob.get_is_verified():
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return
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self.scores[peer] = self.scores.get(peer, 0) - 1 # starts losing score, to account for cancelled ones
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transport = self.connections.get(peer)
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start = self.loop.time()
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bytes_received, transport = await request_blob(
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self.loop, blob, peer.address, peer.tcp_port, self.config.peer_connect_timeout,
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self.config.blob_download_timeout, connected_transport=transport
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)
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if not transport and peer not in self.ignored:
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self.ignored[peer] = self.loop.time()
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log.debug("drop peer %s:%i", peer.address, peer.tcp_port)
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self.failures[peer] = self.failures.get(peer, 0) + 1
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if peer in self.connections:
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del self.connections[peer]
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elif transport:
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log.debug("keep peer %s:%i", peer.address, peer.tcp_port)
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if bytes_received:
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self.failures[peer] = 0
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self.connections[peer] = transport
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rough_speed = (bytes_received / (self.loop.time() - start)) if bytes_received else 0
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self.scores[peer] = rough_speed
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async def new_peer_or_finished(self):
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active_tasks = list(self.active_connections.values()) + [asyncio.sleep(0.2)]
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await asyncio.wait(active_tasks, loop=self.loop, return_when='FIRST_COMPLETED')
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def cleanup_active(self):
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to_remove = [peer for (peer, task) in self.active_connections.items() if task.done()]
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for peer in to_remove:
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del self.active_connections[peer]
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def clearbanned(self):
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now = self.loop.time()
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timeout_for = lambda peer: min(30.0, (self.failures.get(peer, 0) ** self.BAN_FACTOR) - 1.0)
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forgiven = [banned_peer for banned_peer, when in self.ignored.items() if now - when > timeout_for(banned_peer)]
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self.peer_queue.put_nowait(forgiven)
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for banned_peer in forgiven:
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self.ignored.pop(banned_peer)
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@cache_concurrent
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async def download_blob(self, blob_hash: str, length: typing.Optional[int] = None) -> 'AbstractBlob':
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blob = self.blob_manager.get_blob(blob_hash, length)
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if blob.get_is_verified():
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return blob
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try:
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while not blob.get_is_verified():
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batch: typing.List['KademliaPeer'] = []
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while not self.peer_queue.empty():
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batch.extend(self.peer_queue.get_nowait())
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batch.sort(key=lambda p: self.scores.get(p, 0), reverse=True)
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log.debug(
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"running, %d peers, %d ignored, %d active",
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len(batch), len(self.ignored), len(self.active_connections)
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)
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for peer in batch:
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if not self.should_race_continue(blob):
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break
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if peer not in self.active_connections and peer not in self.ignored:
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log.debug("request %s from %s:%i", blob_hash[:8], peer.address, peer.tcp_port)
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t = self.loop.create_task(self.request_blob_from_peer(blob, peer))
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self.active_connections[peer] = t
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await self.new_peer_or_finished()
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self.cleanup_active()
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if batch:
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to_re_add = list(set(batch).difference(self.ignored))
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if to_re_add:
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self.peer_queue.put_nowait(to_re_add)
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else:
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self.clearbanned()
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else:
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self.clearbanned()
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blob.close()
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log.debug("downloaded %s", blob_hash[:8])
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return blob
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finally:
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re_add = set()
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while self.active_connections:
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peer, t = self.active_connections.popitem()
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t.cancel()
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re_add.add(peer)
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re_add = re_add.difference(self.ignored)
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if re_add:
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self.peer_queue.put_nowait(list(re_add))
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blob.close()
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def close(self):
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self.scores.clear()
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self.ignored.clear()
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for transport in self.connections.values():
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transport.close()
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async def download_blob(loop, config: 'Config', blob_manager: 'BlobManager', node: 'Node',
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blob_hash: str) -> 'AbstractBlob':
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search_queue = asyncio.Queue(loop=loop, maxsize=config.max_connections_per_download)
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search_queue.put_nowait(blob_hash)
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peer_queue, accumulate_task = node.accumulate_peers(search_queue)
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downloader = BlobDownloader(loop, config, blob_manager, peer_queue)
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try:
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return await downloader.download_blob(blob_hash)
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finally:
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if accumulate_task and not accumulate_task.done():
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accumulate_task.cancel()
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downloader.close()
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