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# The contents of this file are subject to the BitTorrent Open Source License
# Version 1.1 (the License). You may not copy or use this file, in either
# source code or executable form, except in compliance with the License. You
# may obtain a copy of the License at http://www.bittorrent.com/license/.
#
# Software distributed under the License is distributed on an AS IS basis,
# WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
# for the specific language governing rights and limitations under the
# License.
# Written by Bram Cohen
from random import randrange
from math import sqrt
class Choker(object):
def __init__(self, config, schedule, done = lambda: False):
self.config = config
self.schedule = schedule
self.connections = []
self.count = 0
self.done = done
self.unchokes_since_last = 0
schedule(self._round_robin, 10)
def _round_robin(self):
self.schedule(self._round_robin, 10)
self.count += 1
if self.done():
self._rechoke_seed(True)
return
if self.count % 3 == 0:
for i in xrange(len(self.connections)):
u = self.connections[i].upload
if u.choked and u.interested:
self.connections = self.connections[i:] + self.connections[:i]
break
self._rechoke()
def _rechoke(self):
if self.done():
self._rechoke_seed()
return
preferred = []
for i in xrange(len(self.connections)):
c = self.connections[i]
if c.upload.interested and not c.download.is_snubbed() and c.download.have.numfalse:
preferred.append((-c.download.get_rate(), i))
preferred.sort()
prefcount = min(len(preferred), self._max_uploads() -1)
mask = [0] * len(self.connections)
for _, i in preferred[:prefcount]:
mask[i] = 1
count = max(1, self.config['min_uploads'] - prefcount)
for i in xrange(len(self.connections)):
c = self.connections[i]
u = c.upload
if mask[i]:
u.unchoke(self.count)
elif count > 0 and c.download.have.numfalse:
u.unchoke(self.count)
if u.interested:
count -= 1
else:
u.choke()
def _rechoke_seed(self, force_new_unchokes = False):
if force_new_unchokes:
# number of unchokes per 30 second period
i = (self._max_uploads() + 2) // 3
# this is called 3 times in 30 seconds, if i==4 then unchoke 1+1+2
# and so on; substract unchokes recently triggered by disconnects
num_force_unchokes = max(0, (i + self.count % 3) // 3 - \
self.unchokes_since_last)
else:
num_force_unchokes = 0
preferred = []
new_limit = self.count - 3
for i in xrange(len(self.connections)):
c = self.connections[i]
u = c.upload
if not u.choked and u.interested and c.download.have.numfalse:
if u.unchoke_time > new_limit or (
u.buffer and c.connection.is_flushed()):
preferred.append((-u.unchoke_time, -u.get_rate(), i))
else:
preferred.append((1, -u.get_rate(), i))
num_kept = self._max_uploads() - num_force_unchokes
assert num_kept >= 0
preferred.sort()
preferred = preferred[:num_kept]
mask = [0] * len(self.connections)
for _, _, i in preferred:
mask[i] = 1
num_nonpref = self._max_uploads() - len(preferred)
if force_new_unchokes:
self.unchokes_since_last = 0
else:
self.unchokes_since_last += num_nonpref
last_unchoked = None
for i in xrange(len(self.connections)):
c = self.connections[i]
u = c.upload
if not mask[i]:
if not u.interested:
u.choke()
elif u.choked:
if num_nonpref > 0 and c.connection.is_flushed() and c.download.have.numfalse:
u.unchoke(self.count)
num_nonpref -= 1
if num_nonpref == 0:
last_unchoked = i
else:
if num_nonpref == 0 or not c.download.have.numfalse:
u.choke()
else:
num_nonpref -= 1
if num_nonpref == 0:
last_unchoked = i
if last_unchoked is not None:
self.connections = self.connections[last_unchoked + 1:] + \
self.connections[:last_unchoked + 1]
def connection_made(self, connection):
p = randrange(len(self.connections) + 1)
self.connections.insert(p, connection)
def connection_lost(self, connection):
self.connections.remove(connection)
if connection.upload.interested and not connection.upload.choked:
self._rechoke()
def interested(self, connection):
if not connection.upload.choked:
self._rechoke()
def not_interested(self, connection):
if not connection.upload.choked:
self._rechoke()
def _max_uploads(self):
uploads = self.config['max_uploads']
rate = self.config['max_upload_rate']
if uploads > 0:
pass
elif rate <= 0:
uploads = 7 # unlimited, just guess something here...
elif rate < 9:
uploads = 2
elif rate < 15:
uploads = 3
elif rate < 42:
uploads = 4
else:
uploads = int(sqrt(rate * .6))
return uploads
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