import asyncio import typing import logging from lbrynet.utils import drain_tasks, cache_concurrent from lbrynet.blob_exchange.client import request_blob if typing.TYPE_CHECKING: from lbrynet.conf import Config from lbrynet.dht.node import Node from lbrynet.dht.peer import KademliaPeer from lbrynet.blob.blob_manager import BlobManager from lbrynet.blob.blob_file import AbstractBlob log = logging.getLogger(__name__) class BlobDownloader: BAN_FACTOR = 2.0 # fixme: when connection manager gets implemented, move it out from here def __init__(self, loop: asyncio.BaseEventLoop, config: 'Config', blob_manager: 'BlobManager', peer_queue: asyncio.Queue): self.loop = loop self.config = config self.blob_manager = blob_manager self.peer_queue = peer_queue self.active_connections: typing.Dict['KademliaPeer', asyncio.Task] = {} # active request_blob calls self.ignored: typing.Dict['KademliaPeer', int] = {} self.scores: typing.Dict['KademliaPeer', int] = {} self.failures: typing.Dict['KademliaPeer', int] = {} self.connections: typing.Dict['KademliaPeer', asyncio.Transport] = {} self.time_since_last_blob = loop.time() def should_race_continue(self, blob: 'AbstractBlob'): if len(self.active_connections) >= self.config.max_connections_per_download: return False # if a peer won 3 or more blob races and is active as a downloader, stop the race so bandwidth improves # the safe net side is that any failure will reset the peer score, triggering the race back # TODO: this is a good idea for low bandwidth, but doesnt play nice on high bandwidth # for peer, task in self.active_connections.items(): # if self.scores.get(peer, 0) >= 0 and self.rounds_won.get(peer, 0) >= 3 and not task.done(): # return False return not (blob.get_is_verified() or not blob.is_writeable()) async def request_blob_from_peer(self, blob: 'AbstractBlob', peer: 'KademliaPeer'): if blob.get_is_verified(): return self.scores[peer] = self.scores.get(peer, 0) - 1 # starts losing score, to account for cancelled ones transport = self.connections.get(peer) start = self.loop.time() bytes_received, transport = await request_blob( self.loop, blob, peer.address, peer.tcp_port, self.config.peer_connect_timeout, self.config.blob_download_timeout, connected_transport=transport ) if bytes_received == blob.get_length(): self.time_since_last_blob = self.loop.time() if not transport and peer not in self.ignored: self.ignored[peer] = self.loop.time() log.debug("drop peer %s:%i", peer.address, peer.tcp_port) self.failures[peer] = self.failures.get(peer, 0) + 1 if peer in self.connections: del self.connections[peer] elif transport: log.debug("keep peer %s:%i", peer.address, peer.tcp_port) if bytes_received: self.failures[peer] = 0 self.connections[peer] = transport rough_speed = (bytes_received / (self.loop.time() - start)) if bytes_received else 0 self.scores[peer] = rough_speed async def new_peer_or_finished(self): active_tasks = list(self.active_connections.values()) + [asyncio.sleep(0.2)] await asyncio.wait(active_tasks, loop=self.loop, return_when='FIRST_COMPLETED') def cleanup_active(self): to_remove = [peer for (peer, task) in self.active_connections.items() if task.done()] for peer in to_remove: del self.active_connections[peer] def clearbanned(self): now = self.loop.time() if now - self.time_since_last_blob > 60.0: return timeout_for = lambda peer: (self.failures.get(peer, 0) ** self.BAN_FACTOR) - 1.0 forgiven = [banned_peer for banned_peer, when in self.ignored.items() if now - when > timeout_for(banned_peer)] log.warning([(timeout_for(peer), when) for peer, when in self.ignored.items()]) self.peer_queue.put_nowait(forgiven) for banned_peer in forgiven: self.ignored.pop(banned_peer) @cache_concurrent async def download_blob(self, blob_hash: str, length: typing.Optional[int] = None) -> 'AbstractBlob': blob = self.blob_manager.get_blob(blob_hash, length) if blob.get_is_verified(): return blob try: while not blob.get_is_verified(): batch: typing.List['KademliaPeer'] = [] while not self.peer_queue.empty(): batch.extend(self.peer_queue.get_nowait()) batch.sort(key=lambda p: self.scores.get(p, 0), reverse=True) log.debug( "running, %d peers, %d ignored, %d active", len(batch), len(self.ignored), len(self.active_connections) ) for peer in batch: if not self.should_race_continue(blob): break if peer not in self.active_connections and peer not in self.ignored: log.debug("request %s from %s:%i", blob_hash[:8], peer.address, peer.tcp_port) t = self.loop.create_task(self.request_blob_from_peer(blob, peer)) self.active_connections[peer] = t await self.new_peer_or_finished() self.cleanup_active() if batch: to_re_add = list(set(batch).difference(self.ignored)) if to_re_add: self.peer_queue.put_nowait(to_re_add) else: self.clearbanned() else: self.clearbanned() blob.close() log.debug("downloaded %s", blob_hash[:8]) return blob finally: re_add = set() while self.active_connections: peer, t = self.active_connections.popitem() t.cancel() re_add.add(peer) re_add = re_add.difference(self.ignored) if re_add: self.peer_queue.put_nowait(list(re_add)) blob.close() def close(self): self.scores.clear() self.ignored.clear() for transport in self.connections.values(): transport.close() async def download_blob(loop, config: 'Config', blob_manager: 'BlobManager', node: 'Node', blob_hash: str) -> 'AbstractBlob': search_queue = asyncio.Queue(loop=loop, maxsize=config.max_connections_per_download) search_queue.put_nowait(blob_hash) peer_queue, accumulate_task = node.accumulate_peers(search_queue) downloader = BlobDownloader(loop, config, blob_manager, peer_queue) try: return await downloader.download_blob(blob_hash) finally: if accumulate_task and not accumulate_task.done(): accumulate_task.cancel() downloader.close()