p2pool/data.py

   1 from __future__ import division
   2
   3 import random
   4 import time
   5 import os
   6
   7 from twisted.python import log
   8
   9 import p2pool
  10 from p2pool import skiplists
  11 from p2pool.bitcoin import data as bitcoin_data, script
  12 from p2pool.util import math, forest, pack
  13
  14
  15 share_data_type = pack.ComposedType([
  16     ('previous_share_hash', pack.PossiblyNoneType(0, pack.IntType(256))),
  17     ('coinbase', pack.VarStrType()),
  18     ('nonce', pack.VarStrType()),
  19     ('new_script', pack.VarStrType()),
  20     ('subsidy', pack.IntType(64)),
  21     ('donation', pack.IntType(16)),
  22     ('stale_info', pack.IntType(8)), # 0 nothing, 253 orphan, 254 doa
  23 ])
  24
  25 share_info_type = pack.ComposedType([
  26     ('share_data', share_data_type),
  27     ('bits', bitcoin_data.FloatingIntegerType()),
  28     ('timestamp', pack.IntType(32)),
  29 ])
  30
  31 share1a_type = pack.ComposedType([
  32     ('header', bitcoin_data.block_header_type),
  33     ('share_info', share_info_type),
  34     ('merkle_branch', bitcoin_data.merkle_branch_type),
  35 ])
  36
  37 share1b_type = pack.ComposedType([
  38     ('header', bitcoin_data.block_header_type),
  39     ('share_info', share_info_type),
  40     ('other_txs', pack.ListType(bitcoin_data.tx_type)),
  41 ])
  42
  43 # type:
  44 # 0: share1a
  45 # 1: share1b
  46
  47 share_type = pack.ComposedType([
  48     ('type', pack.VarIntType()),
  49     ('contents', pack.VarStrType()),
  50 ])
  51
  52 class Share(object):
  53     __slots__ = 'header previous_block share_info merkle_branch other_txs timestamp share_data new_script subsidy previous_hash previous_share_hash target nonce pow_hash header_hash hash time_seen peer donation net'.split(' ')
  54
  55     @classmethod
  56     def from_share(cls, share, net):
  57         if share['type'] == 0:
  58             res = cls.from_share1a(share1a_type.unpack(share['contents']), net)
  59             if not (res.pow_hash > res.header['bits'].target):
  60                 raise ValueError('invalid share type')
  61             return res
  62         elif share['type'] == 1:
  63             res = cls.from_share1b(share1b_type.unpack(share['contents']), net)
  64             if not (res.pow_hash <= res.header['bits'].target):
  65                 raise ValueError('invalid share type')
  66             return res
  67         else:
  68             raise ValueError('unknown share type: %r' % (share['type'],))
  69
  70     @classmethod
  71     def from_share1a(cls, share1a, net):
  72         return cls(net, **share1a)
  73
  74     @classmethod
  75     def from_share1b(cls, share1b, net):
  76         return cls(net, merkle_branch=bitcoin_data.calculate_merkle_branch([0] + [bitcoin_data.hash256(bitcoin_data.tx_type.pack(x)) for x in share1b['other_txs']], 0), **share1b)
  77
  78     def __init__(self, net, header, share_info, merkle_branch, other_txs=None):
  79         self.net = net
  80
  81         if p2pool.DEBUG and other_txs is not None and bitcoin_data.calculate_merkle_branch([0] + [bitcoin_data.hash256(bitcoin_data.tx_type.pack(x)) for x in other_txs], 0) != merkle_branch:
  82             raise ValueError('merkle_branch and other_txs do not match')
  83
  84         if len(merkle_branch) > 16:
  85             raise ValueError('merkle_branch too long!')
  86
  87         self.header = header
  88         self.previous_block = header['previous_block']
  89         self.share_info = share_info
  90         self.merkle_branch = merkle_branch
  91
  92         self.share_data = self.share_info['share_data']
  93         self.target = self.share_info['bits'].target
  94         self.timestamp = self.share_info['timestamp']
  95
  96         self.new_script = self.share_data['new_script']
  97         self.subsidy = self.share_data['subsidy']
  98         self.donation = self.share_data['donation']
  99
 100         if len(self.new_script) > 100:
 101             raise ValueError('new_script too long!')
 102
 103         self.previous_hash = self.previous_share_hash = self.share_data['previous_share_hash']
 104         self.nonce = self.share_data['nonce']
 105
 106         if len(self.nonce) > 100:
 107             raise ValueError('nonce too long!')
 108
 109         if len(self.share_data['coinbase']) > 100:
 110             raise ValueError('''coinbase too large! %i bytes''' % (len(self.share_data['coinbase']),))
 111
 112         self.pow_hash = net.PARENT.POW_FUNC(bitcoin_data.block_header_type.pack(header))
 113         self.header_hash = bitcoin_data.hash256(bitcoin_data.block_header_type.pack(header))
 114
 115         self.hash = bitcoin_data.hash256(share1a_type.pack(self.as_share1a()))
 116
 117         if self.pow_hash > self.target:
 118             print 'hash %x' % self.pow_hash
 119             print 'targ %x' % self.target
 120             raise ValueError('not enough work!')
 121
 122         if other_txs is not None and not self.pow_hash <= self.header['bits'].target:
 123             raise ValueError('other_txs provided when not a block solution')
 124         if other_txs is None and self.pow_hash <= self.header['bits'].target:
 125             raise ValueError('other_txs not provided when a block solution')
 126
 127         self.other_txs = other_txs
 128
 129         # XXX eww
 130         self.time_seen = time.time()
 131         self.peer = None
 132
 133     def __repr__(self):
 134         return '<Share %s>' % (' '.join('%s=%r' % (k, getattr(self, k)) for k in self.__slots__),)
 135
 136     def check(self, tracker):
 137         if script.get_sigop_count(self.new_script) > 1:
 138             raise ValueError('too many sigops!')
 139
 140         share_info, gentx = generate_transaction(tracker, self.share_info['share_data'], self.header['bits'].target, self.share_info['timestamp'], self.net)
 141         if share_info != self.share_info:
 142             raise ValueError('share difficulty invalid')
 143
 144         if bitcoin_data.check_merkle_branch(bitcoin_data.hash256(bitcoin_data.tx_type.pack(gentx)), 0, self.merkle_branch) != self.header['merkle_root']:
 145             raise ValueError('''gentx doesn't match header via merkle_branch''')
 146
 147     def as_share(self):
 148         if self.pow_hash > self.header['bits'].target: # share1a
 149             return dict(type=0, contents=share1a_type.pack(self.as_share1a()))
 150         elif self.pow_hash <= self.header['bits'].target: # share1b
 151             return dict(type=1, contents=share1b_type.pack(self.as_share1b()))
 152         else:
 153             raise AssertionError()
 154
 155     def as_share1a(self):
 156         return dict(header=self.header, share_info=self.share_info, merkle_branch=self.merkle_branch)
 157
 158     def as_share1b(self):
 159         if self.other_txs is None:
 160             raise ValueError('share does not contain all txs')
 161
 162         return dict(header=self.header, share_info=self.share_info, other_txs=self.other_txs)
 163
 164     def as_block(self, tracker):
 165         if self.other_txs is None:
 166             raise ValueError('share does not contain all txs')
 167
 168         share_info, gentx = generate_transaction(tracker, self.share_info['share_data'], self.header['bits'].target, self.share_info['timestamp'], self.net)
 169         assert share_info == self.share_info
 170
 171         return dict(header=self.header, txs=[gentx] + self.other_txs)
 172
 173 def get_pool_attempts_per_second(tracker, previous_share_hash, dist):
 174     assert dist >= 2
 175     near = tracker.shares[previous_share_hash]
 176     far = tracker.shares[tracker.get_nth_parent_hash(previous_share_hash, dist - 1)]
 177     attempts = tracker.get_work(near.hash) - tracker.get_work(far.hash)
 178     time = near.timestamp - far.timestamp
 179     if time <= 0:
 180         time = 1
 181     return attempts//time
 182
 183 def get_average_stale_prop(tracker, share_hash, lookbehind):
 184     stales = sum(1 for share in tracker.get_chain(share_hash, lookbehind) if share.share_data['stale_info'] in [253, 254])
 185     return stales/(lookbehind + stales)
 186
 187 def generate_transaction(tracker, share_data, block_target, desired_timestamp, net):
 188     previous_share_hash = share_data['previous_share_hash']
 189     new_script = share_data['new_script']
 190     subsidy = share_data['subsidy']
 191     donation = share_data['donation']
 192     assert 0 <= donation <= 65535
 193
 194     if len(share_data['coinbase']) > 100:
 195         raise ValueError('coinbase too long!')
 196
 197     previous_share = tracker.shares[previous_share_hash] if previous_share_hash is not None else None
 198
 199     chain_length = getattr(net, 'REAL_CHAIN_LENGTH_FUNC', lambda _: net.REAL_CHAIN_LENGTH)(previous_share.timestamp if previous_share is not None else None)
 200
 201     height, last = tracker.get_height_and_last(previous_share_hash)
 202     assert height >= chain_length or last is None
 203     if height < net.TARGET_LOOKBEHIND:
 204         bits = bitcoin_data.FloatingInteger.from_target_upper_bound(net.MAX_TARGET)
 205     else:
 206         attempts_per_second = get_pool_attempts_per_second(tracker, previous_share_hash, net.TARGET_LOOKBEHIND)
 207         pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1
 208         pre_target2 = math.clip(pre_target, (previous_share.target*9//10, previous_share.target*11//10))
 209         pre_target3 = math.clip(pre_target2, (0, net.MAX_TARGET))
 210         bits = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 211
 212     attempts_to_block = bitcoin_data.target_to_average_attempts(block_target)
 213     max_att = net.SPREAD * attempts_to_block
 214
 215     this_att = min(bitcoin_data.target_to_average_attempts(bits.target), max_att)
 216     other_weights, other_total_weight, other_donation_weight = tracker.get_cumulative_weights(previous_share_hash, min(height, chain_length), 65535*max(0, max_att - this_att))
 217     assert other_total_weight == sum(other_weights.itervalues()) + other_donation_weight, (other_total_weight, sum(other_weights.itervalues()) + other_donation_weight)
 218     weights, total_weight, donation_weight = math.add_dicts({new_script: this_att*(65535-donation)}, other_weights), this_att*65535 + other_total_weight, this_att*donation + other_donation_weight
 219     assert total_weight == sum(weights.itervalues()) + donation_weight, (total_weight, sum(weights.itervalues()) + donation_weight)
 220
 221     SCRIPT = '4104ffd03de44a6e11b9917f3a29f9443283d9871c9d743ef30d5eddcd37094b64d1b3d8090496b53256786bf5c82932ec23c3b74d9f05a6f95a8b5529352656664bac'.decode('hex')
 222
 223     # 1 satoshi is always donated so that a list of p2pool generated blocks can be easily found by looking at the donation address
 224     amounts = dict((script, (subsidy-1)*(199*weight)//(200*total_weight)) for (script, weight) in weights.iteritems())
 225     amounts[new_script] = amounts.get(new_script, 0) + (subsidy-1)//200
 226     amounts[SCRIPT] = amounts.get(SCRIPT, 0) + (subsidy-1)*(199*donation_weight)//(200*total_weight)
 227     amounts[SCRIPT] = amounts.get(SCRIPT, 0) + subsidy - sum(amounts.itervalues()) # collect any extra satoshis :P
 228
 229     if sum(amounts.itervalues()) != subsidy:
 230         raise ValueError()
 231     if any(x < 0 for x in amounts.itervalues()):
 232         raise ValueError()
 233
 234     dests = sorted(amounts.iterkeys(), key=lambda script: (amounts[script], script))
 235     dests = dests[-4000:] # block length limit, unlikely to ever be hit
 236
 237     share_info = dict(
 238         share_data=share_data,
 239         bits=bits,
 240         timestamp=math.clip(desired_timestamp, (previous_share.timestamp - 60, previous_share.timestamp + 60)) if previous_share is not None else desired_timestamp,
 241     )
 242
 243     return share_info, dict(
 244         version=1,
 245         tx_ins=[dict(
 246             previous_output=None,
 247             sequence=None,
 248             script=share_data['coinbase'].ljust(2, '\x00'),
 249         )],
 250         tx_outs=[dict(value=0, script='\x20' + pack.IntType(256).pack(bitcoin_data.hash256(share_info_type.pack(share_info))))] + [dict(value=amounts[script], script=script) for script in dests if amounts[script]],
 251         lock_time=0,
 252     )
 253
 254 class OkayTracker(forest.Tracker):
 255     def __init__(self, net, my_share_hashes, my_doa_share_hashes):
 256         forest.Tracker.__init__(self)
 257         self.net = net
 258         self.verified = forest.Tracker(delta_type=forest.get_attributedelta_type(dict(forest.AttributeDelta.attrs,
 259             my_count=lambda share: 1 if share.hash in my_share_hashes else 0,
 260             my_doa_count=lambda share: 1 if share.hash in my_doa_share_hashes else 0,
 261             my_orphan_announce_count=lambda share: 1 if share.hash in my_share_hashes and share.share_data['stale_info'] == 253 else 0,
 262             my_dead_announce_count=lambda share: 1 if share.hash in my_share_hashes and share.share_data['stale_info'] == 254 else 0,
 263         )))
 264         self.verified.get_nth_parent_hash = self.get_nth_parent_hash # self is a superset of self.verified
 265
 266         self.get_cumulative_weights = skiplists.WeightsSkipList(self)
 267
 268     def attempt_verify(self, share):
 269         if share.hash in self.verified.shares:
 270             return True
 271         height, last = self.get_height_and_last(share.hash)
 272         if height < self.net.CHAIN_LENGTH + 1 and last is not None:
 273             raise AssertionError()
 274         try:
 275             share.check(self)
 276         except:
 277             log.err(None, 'Share check failed:')
 278             return False
 279         else:
 280             self.verified.add(share)
 281             return True
 282
 283     def think(self, ht, previous_block):
 284         desired = set()
 285
 286         # O(len(self.heads))
 287         #   make 'unverified heads' set?
 288         # for each overall head, attempt verification
 289         # if it fails, attempt on parent, and repeat
 290         # if no successful verification because of lack of parents, request parent
 291         bads = set()
 292         for head in set(self.heads) - set(self.verified.heads):
 293             head_height, last = self.get_height_and_last(head)
 294
 295             for share in self.get_chain(head, head_height if last is None else min(5, max(0, head_height - self.net.CHAIN_LENGTH))):
 296                 if self.attempt_verify(share):
 297                     break
 298                 if share.hash in self.heads:
 299                     bads.add(share.hash)
 300             else:
 301                 if last is not None:
 302                     desired.add((self.shares[random.choice(list(self.reverse_shares[last]))].peer, last))
 303         for bad in bads:
 304             assert bad not in self.verified.shares
 305             assert bad in self.heads
 306             if p2pool.DEBUG:
 307                 print "BAD", bad
 308             self.remove(bad)
 309
 310         # try to get at least CHAIN_LENGTH height for each verified head, requesting parents if needed
 311         for head in list(self.verified.heads):
 312             head_height, last_hash = self.verified.get_height_and_last(head)
 313             last_height, last_last_hash = self.get_height_and_last(last_hash)
 314             # XXX review boundary conditions
 315             want = max(self.net.CHAIN_LENGTH - head_height, 0)
 316             can = max(last_height - 1 - self.net.CHAIN_LENGTH, 0) if last_last_hash is not None else last_height
 317             get = min(want, can)
 318             #print 'Z', head_height, last_hash is None, last_height, last_last_hash is None, want, can, get
 319             for share in self.get_chain(last_hash, get):
 320                 if not self.attempt_verify(share):
 321                     break
 322             if head_height < self.net.CHAIN_LENGTH and last_last_hash is not None:
 323                 desired.add((self.verified.shares[random.choice(list(self.verified.reverse_shares[last_hash]))].peer, last_last_hash))
 324         if p2pool.DEBUG:
 325             print len(self.verified.tails), "tails:"
 326             for x in self.verified.tails:
 327                 print format_hash(x), self.score(max(self.verified.tails[x], key=self.verified.get_height), ht)
 328
 329         # decide best tree
 330         best_tail = max(self.verified.tails, key=lambda h: self.score(max(self.verified.tails[h], key=self.verified.get_height), ht)) if self.verified.tails else None
 331         # decide best verified head
 332         scores = sorted(self.verified.tails.get(best_tail, []), key=lambda h: (
 333             self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 334             #self.verified.shares[h].peer is None,
 335             0 if self.verified.shares[h].peer is None else ht.get_height_rel_highest(self.verified.shares[h].previous_block),
 336             -self.verified.shares[h].time_seen
 337         ))
 338
 339
 340         if p2pool.DEBUG:
 341             print len(self.verified.tails), "chain tails and", len(self.verified.tails.get(best_tail, [])), 'chain heads. Top 10 heads:'
 342             if len(scores) > 10:
 343                 print '    ...'
 344             for h in scores[-10:]:
 345                 print '   ', format_hash(h), format_hash(self.verified.shares[h].previous_hash), (
 346                     self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 347                     self.verified.shares[h].peer is None,
 348                     0 if self.verified.shares[h].peer is None else ht.get_height_rel_highest(self.verified.shares[h].previous_block),
 349                     -self.verified.shares[h].time_seen
 350                 )
 351
 352         # eat away at heads
 353         if scores:
 354             for i in xrange(1000):
 355                 to_remove = set()
 356                 for share_hash, tail in self.heads.iteritems():
 357                     if share_hash in scores[-5:]:
 358                         #print 1
 359                         continue
 360                     if self.shares[share_hash].time_seen > time.time() - 300:
 361                         #print 2
 362                         continue
 363                     if share_hash not in self.verified.shares and max(self.shares[after_tail_hash].time_seen for after_tail_hash in self.reverse_shares.get(tail)) > time.time() - 120: # XXX stupid
 364                         #print 3
 365                         continue
 366                     to_remove.add(share_hash)
 367                 if not to_remove:
 368                     break
 369                 for share_hash in to_remove:
 370                     self.remove(share_hash)
 371                     if share_hash in self.verified.shares:
 372                         self.verified.remove(share_hash)
 373                 #print "_________", to_remove
 374
 375         # drop tails
 376         for i in xrange(1000):
 377             to_remove = set()
 378             for tail, heads in self.tails.iteritems():
 379                 if min(self.get_height(head) for head in heads) < 2*self.net.CHAIN_LENGTH + 10:
 380                     continue
 381                 for aftertail in self.reverse_shares.get(tail, set()):
 382                     if len(self.reverse_shares[self.shares[aftertail].previous_hash]) > 1: # XXX
 383                         print "raw"
 384                         continue
 385                     to_remove.add(aftertail)
 386             if not to_remove:
 387                 break
 388             # if removed from this, it must be removed from verified
 389             #start = time.time()
 390             for aftertail in to_remove:
 391                 if self.shares[aftertail].previous_hash not in self.tails:
 392                     print "erk", aftertail, self.shares[aftertail].previous_hash
 393                     continue
 394                 self.remove(aftertail)
 395                 if aftertail in self.verified.shares:
 396                     self.verified.remove(aftertail)
 397             #end = time.time()
 398             #print "removed! %i %f" % (len(to_remove), (end - start)/len(to_remove))
 399
 400         best = scores[-1] if scores else None
 401
 402         if best is not None:
 403             best_share = self.verified.shares[best]
 404             if ht.get_height_rel_highest(best_share.header['previous_block']) < ht.get_height_rel_highest(previous_block) and best_share.header_hash != previous_block and best_share.peer is not None:
 405                 if p2pool.DEBUG:
 406                     print 'Stale detected! %x < %x' % (best_share.header['previous_block'], previous_block)
 407                 best = best_share.previous_hash
 408
 409         return best, desired
 410
 411     def score(self, share_hash, ht):
 412         head_height = self.verified.get_height(share_hash)
 413         if head_height < self.net.CHAIN_LENGTH:
 414             return head_height, None
 415
 416         end_point = self.verified.get_nth_parent_hash(share_hash, self.net.CHAIN_LENGTH*15//16)
 417
 418         block_height = max(ht.get_height_rel_highest(share.header['previous_block']) for share in
 419             self.verified.get_chain(end_point, self.net.CHAIN_LENGTH//16))
 420
 421         return self.net.CHAIN_LENGTH, (self.verified.get_work(share_hash) - self.verified.get_work(end_point))//(0 - block_height + 1)
 422
 423 def format_hash(x):
 424     if x is None:
 425         return 'xxxxxxxx'
 426     return '%08x' % (x % 2**32)
 427
 428 class ShareStore(object):
 429     def __init__(self, prefix, net):
 430         self.filename = prefix
 431         self.dirname = os.path.dirname(os.path.abspath(prefix))
 432         self.filename = os.path.basename(os.path.abspath(prefix))
 433         self.net = net
 434         self.known = None # will be filename -> set of share hashes, set of verified hashes
 435         self.known_desired = None
 436
 437     def get_shares(self):
 438         if self.known is not None:
 439             raise AssertionError()
 440         known = {}
 441         filenames, next = self.get_filenames_and_next()
 442         for filename in filenames:
 443             share_hashes, verified_hashes = known.setdefault(filename, (set(), set()))
 444             with open(filename, 'rb') as f:
 445                 for line in f:
 446                     try:
 447                         type_id_str, data_hex = line.strip().split(' ')
 448                         type_id = int(type_id_str)
 449                         if type_id == 0:
 450                             pass
 451                         elif type_id == 1:
 452                             pass
 453                         elif type_id == 2:
 454                             verified_hash = int(data_hex, 16)
 455                             yield 'verified_hash', verified_hash
 456                             verified_hashes.add(verified_hash)
 457                         elif type_id == 5:
 458                             share = Share.from_share(share_type.unpack(data_hex.decode('hex')), self.net)
 459                             yield 'share', share
 460                             share_hashes.add(share.hash)
 461                         else:
 462                             raise NotImplementedError("share type %i" % (type_id,))
 463                     except Exception:
 464                         log.err(None, "Error while reading saved shares, continuing where left off:")
 465         self.known = known
 466         self.known_desired = dict((k, (set(a), set(b))) for k, (a, b) in known.iteritems())
 467
 468     def _add_line(self, line):
 469         filenames, next = self.get_filenames_and_next()
 470         if filenames and os.path.getsize(filenames[-1]) < 10e6:
 471             filename = filenames[-1]
 472         else:
 473             filename = next
 474
 475         with open(filename, 'ab') as f:
 476             f.write(line + '\n')
 477
 478         return filename
 479
 480     def add_share(self, share):
 481         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 482             if share.hash in share_hashes:
 483                 break
 484         else:
 485             filename = self._add_line("%i %s" % (5, share_type.pack(share.as_share()).encode('hex')))
 486             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 487             share_hashes.add(share.hash)
 488         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 489         share_hashes.add(share.hash)
 490
 491     def add_verified_hash(self, share_hash):
 492         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 493             if share_hash in verified_hashes:
 494                 break
 495         else:
 496             filename = self._add_line("%i %x" % (2, share_hash))
 497             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 498             verified_hashes.add(share_hash)
 499         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 500         verified_hashes.add(share_hash)
 501
 502     def get_filenames_and_next(self):
 503         suffixes = sorted(int(x[len(self.filename):]) for x in os.listdir(self.dirname) if x.startswith(self.filename) and x[len(self.filename):].isdigit())
 504         return [os.path.join(self.dirname, self.filename + str(suffix)) for suffix in suffixes], os.path.join(self.dirname, self.filename + (str(suffixes[-1] + 1) if suffixes else str(0)))
 505
 506     def forget_share(self, share_hash):
 507         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 508             if share_hash in share_hashes:
 509                 share_hashes.remove(share_hash)
 510         self.check_remove()
 511
 512     def forget_verified_share(self, share_hash):
 513         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 514             if share_hash in verified_hashes:
 515                 verified_hashes.remove(share_hash)
 516         self.check_remove()
 517
 518     def check_remove(self):
 519         to_remove = set()
 520         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 521             #print filename, len(share_hashes) + len(verified_hashes)
 522             if not share_hashes and not verified_hashes:
 523                 to_remove.add(filename)
 524         for filename in to_remove:
 525             self.known.pop(filename)
 526             self.known_desired.pop(filename)
 527             os.remove(filename)
 528             print "REMOVED", filename