PyBitmessage-2021-04-27/src/network/downloadthread.py

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"""
src/network/downloadthread.py
=============================
"""
import time
import addresses
import helper_random
import protocol
from dandelion import Dandelion
from inventory import Inventory
from network.connectionpool import BMConnectionPool
from objectracker import missingObjects
from threads import StoppableThread
class DownloadThread(StoppableThread):
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"""Thread-based class for downloading from connections"""
minPending = 200
maxRequestChunk = 1000
requestTimeout = 60
cleanInterval = 60
requestExpires = 3600
def __init__(self):
super(DownloadThread, self).__init__(name="Downloader")
self.lastCleaned = time.time()
def cleanPending(self):
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"""Expire pending downloads eventually"""
deadline = time.time() - DownloadThread.requestExpires
try:
toDelete = [k for k, v in missingObjects.iteritems() if v < deadline]
except RuntimeError:
pass
else:
for i in toDelete:
del missingObjects[i]
self.lastCleaned = time.time()
def run(self):
while not self._stopped:
requested = 0
# Choose downloading peers randomly
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connections = [
x for x in
BMConnectionPool().inboundConnections.values() + BMConnectionPool().outboundConnections.values()
if x.fullyEstablished]
helper_random.randomshuffle(connections)
try:
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requestChunk = max(int(min(DownloadThread.maxRequestChunk, len(missingObjects)) / len(connections)), 1)
except ZeroDivisionError:
requestChunk = 1
for i in connections:
now = time.time()
# avoid unnecessary delay
if i.skipUntil >= now:
continue
try:
request = i.objectsNewToMe.randomKeys(requestChunk)
except KeyError:
continue
payload = bytearray()
chunkCount = 0
for chunk in request:
if chunk in Inventory() and not Dandelion().hasHash(chunk):
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try:
del i.objectsNewToMe[chunk]
except KeyError:
pass
continue
payload.extend(chunk)
chunkCount += 1
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missingObjects[chunk] = now
if not chunkCount:
continue
payload[0:0] = addresses.encodeVarint(chunkCount)
i.append_write_buf(protocol.CreatePacket('getdata', payload))
self.logger.debug(
'%s:%i Requesting %i objects',
i.destination.host, i.destination.port, chunkCount)
requested += chunkCount
if time.time() >= self.lastCleaned + DownloadThread.cleanInterval:
self.cleanPending()
if not requested:
self.stop.wait(1)