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 memoize, expiring_dict, math, forest
  13
  14
  15 share_data_type = bitcoin_data.ComposedType([
  16     ('previous_share_hash', bitcoin_data.PossiblyNoneType(0, bitcoin_data.HashType())),
  17     ('coinbase', bitcoin_data.VarStrType()),
  18     ('nonce', bitcoin_data.VarStrType()),
  19     ('new_script', bitcoin_data.VarStrType()),
  20     ('subsidy', bitcoin_data.StructType('<Q')),
  21     ('donation', bitcoin_data.StructType('<H')),
  22     ('stale_info', bitcoin_data.StructType('<B')), # 0 nothing, 253 orphan, 254 doa. previously: 254*perfect_round(my_stale_prop), None if no shares
  23 ])
  24
  25 share_info_type = bitcoin_data.ComposedType([
  26     ('share_data', share_data_type),
  27     ('bits', bitcoin_data.FloatingIntegerType()),
  28     ('timestamp', bitcoin_data.StructType('<I')),
  29 ])
  30
  31 share1a_type = bitcoin_data.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 = bitcoin_data.ComposedType([
  38     ('header', bitcoin_data.block_header_type),
  39     ('share_info', share_info_type),
  40     ('other_txs', bitcoin_data.ListType(bitcoin_data.tx_type)),
  41 ])
  42
  43 # type:
  44 # 0: share1a
  45 # 1: share1b
  46
  47 share_type = bitcoin_data.ComposedType([
  48     ('type', bitcoin_data.VarIntType()),
  49     ('contents', bitcoin_data.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, **share1b)
  77
  78     def __init__(self, net, header, share_info, merkle_branch=None, other_txs=None):
  79         self.net = net
  80
  81         if merkle_branch is None and other_txs is None:
  82             raise ValueError('need either merkle_branch or other_txs')
  83         if other_txs is not None:
  84             new_merkle_branch = bitcoin_data.calculate_merkle_branch([0] + map(bitcoin_data.tx_type.hash256, other_txs), 0)
  85             if merkle_branch is not None:
  86                 if merke_branch != new_merkle_branch:
  87                     raise ValueError('invalid merkle_branch and other_txs')
  88             merkle_branch = new_merkle_branch
  89
  90         if len(merkle_branch) > 16:
  91             raise ValueError('merkle_branch too long!')
  92
  93         self.header = header
  94         self.previous_block = header['previous_block']
  95         self.share_info = share_info
  96         self.merkle_branch = merkle_branch
  97
  98         self.share_data = self.share_info['share_data']
  99         self.target = self.share_info['bits'].target
 100         self.timestamp = self.share_info['timestamp']
 101
 102         self.new_script = self.share_data['new_script']
 103         self.subsidy = self.share_data['subsidy']
 104         self.donation = self.share_data['donation']
 105
 106         if len(self.new_script) > 100:
 107             raise ValueError('new_script too long!')
 108
 109         self.previous_hash = self.previous_share_hash = self.share_data['previous_share_hash']
 110         self.nonce = self.share_data['nonce']
 111
 112         if len(self.nonce) > 100:
 113             raise ValueError('nonce too long!')
 114
 115         if len(self.share_data['coinbase']) > 100:
 116             raise ValueError('''coinbase too large! %i bytes''' % (len(self.share_data['coinbase']),))
 117
 118         self.pow_hash = net.PARENT.POW_FUNC(header)
 119         self.header_hash = bitcoin_data.block_header_type.hash256(header)
 120
 121         self.hash = share1a_type.hash256(self.as_share1a())
 122
 123         if self.pow_hash > self.target:
 124             print 'hash %x' % self.pow_hash
 125             print 'targ %x' % self.target
 126             raise ValueError('not enough work!')
 127
 128         self.other_txs = other_txs if self.pow_hash <= self.header['bits'].target else None
 129
 130         # XXX eww
 131         self.time_seen = time.time()
 132         self.peer = None
 133
 134     def __repr__(self):
 135         return '<Share %s>' % (' '.join('%s=%r' % (k, getattr(self, k)) for k in self.__slots__),)
 136
 137     def check(self, tracker):
 138         if script.get_sigop_count(self.new_script) > 1:
 139             raise ValueError('too many sigops!')
 140
 141         share_info, gentx = generate_transaction(tracker, self.share_info['share_data'], self.header['bits'].target, self.share_info['timestamp'], self.net)
 142         if share_info != self.share_info:
 143             raise ValueError('share difficulty invalid')
 144
 145         if bitcoin_data.check_merkle_branch(bitcoin_data.tx_type.hash256(gentx), 0, self.merkle_branch) != self.header['merkle_root']:
 146             raise ValueError('''gentx doesn't match header via merkle_branch''')
 147
 148     def as_share(self):
 149         if self.pow_hash > self.header['bits'].target: # share1a
 150             return dict(type=0, contents=share1a_type.pack(self.as_share1a()))
 151         elif self.pow_hash <= self.header['bits'].target: # share1b
 152             return dict(type=1, contents=share1b_type.pack(self.as_share1b()))
 153         else:
 154             raise AssertionError()
 155
 156     def as_share1a(self):
 157         return dict(header=self.header, share_info=self.share_info, merkle_branch=self.merkle_branch)
 158
 159     def as_share1b(self):
 160         if self.other_txs is None:
 161             raise ValueError('share does not contain all txs')
 162
 163         return dict(header=self.header, share_info=self.share_info, other_txs=self.other_txs)
 164
 165     def as_block(self, tracker):
 166         if self.other_txs is None:
 167             raise ValueError('share does not contain all txs')
 168
 169         share_info, gentx = generate_transaction(tracker, self.share_info['share_data'], self.header['bits'].target, self.share_info['timestamp'], self.net)
 170         assert share_info == self.share_info
 171
 172         return dict(header=self.header, txs=[gentx] + self.other_txs)
 173
 174 def get_pool_attempts_per_second(tracker, previous_share_hash, dist):
 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     def stales_per_share(share):
 185         if share.share_data['stale_info'] == 253: # orphan
 186             return 1
 187         elif share.share_data['stale_info'] == 254: # doa
 188             return 1
 189         elif share.share_data['stale_info'] == 0:
 190             return 0
 191         elif share.share_data['stale_info'] == 255: # temporary hack until everyone uses new-style stale data
 192             return 0
 193         else:
 194             return 1/(254/share.share_data['stale_info'] - 1) # converts stales/shares to stales/nonstales
 195             # 0 and 254 case are taken care of above and this will soon be removed anyway
 196     stales = sum(stales_per_share(share) for share in tracker.get_chain(share_hash, lookbehind))
 197     return stales/(lookbehind + stales)
 198
 199 def generate_transaction(tracker, share_data, block_target, desired_timestamp, net):
 200     previous_share_hash = share_data['previous_share_hash']
 201     new_script = share_data['new_script']
 202     subsidy = share_data['subsidy']
 203     donation = share_data['donation']
 204     assert 0 <= donation <= 65535
 205
 206     if len(share_data['coinbase']) > 100:
 207         raise ValueError('coinbase too long!')
 208
 209     previous_share = tracker.shares[previous_share_hash] if previous_share_hash is not None else None
 210
 211     chain_length = getattr(net, 'REAL_CHAIN_LENGTH_FUNC', lambda _: net.REAL_CHAIN_LENGTH)(previous_share.timestamp if previous_share is not None else None)
 212
 213     height, last = tracker.get_height_and_last(previous_share_hash)
 214     assert height >= chain_length or last is None
 215     if height < net.TARGET_LOOKBEHIND:
 216         bits = bitcoin_data.FloatingInteger.from_target_upper_bound(net.MAX_TARGET)
 217     else:
 218         attempts_per_second = get_pool_attempts_per_second(tracker, previous_share_hash, net.TARGET_LOOKBEHIND)
 219         pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1
 220         pre_target2 = math.clip(pre_target, (previous_share.target*9//10, previous_share.target*11//10))
 221         pre_target3 = math.clip(pre_target2, (0, net.MAX_TARGET))
 222         bits = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 223
 224     attempts_to_block = bitcoin_data.target_to_average_attempts(block_target)
 225     max_att = net.SPREAD * attempts_to_block
 226
 227     this_att = min(bitcoin_data.target_to_average_attempts(bits.target), max_att)
 228     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))
 229     assert other_total_weight == sum(other_weights.itervalues()) + other_donation_weight, (other_total_weight, sum(other_weights.itervalues()) + other_donation_weight)
 230     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
 231     assert total_weight == sum(weights.itervalues()) + donation_weight, (total_weight, sum(weights.itervalues()) + donation_weight)
 232
 233     SCRIPT = '4104ffd03de44a6e11b9917f3a29f9443283d9871c9d743ef30d5eddcd37094b64d1b3d8090496b53256786bf5c82932ec23c3b74d9f05a6f95a8b5529352656664bac'.decode('hex')
 234
 235     # 1 satoshi is always donated so that a list of p2pool generated blocks can be easily found by looking at the donation address
 236     amounts = dict((script, (subsidy-1)*(199*weight)//(200*total_weight)) for (script, weight) in weights.iteritems())
 237     amounts[new_script] = amounts.get(new_script, 0) + (subsidy-1)//200
 238     amounts[SCRIPT] = amounts.get(SCRIPT, 0) + (subsidy-1)*(199*donation_weight)//(200*total_weight)
 239     amounts[SCRIPT] = amounts.get(SCRIPT, 0) + subsidy - sum(amounts.itervalues()) # collect any extra satoshis :P
 240
 241     if sum(amounts.itervalues()) != subsidy:
 242         raise ValueError()
 243     if any(x < 0 for x in amounts.itervalues()):
 244         raise ValueError()
 245
 246     dests = sorted(amounts.iterkeys(), key=lambda script: (amounts[script], script))
 247     dests = dests[-4000:] # block length limit, unlikely to ever be hit
 248
 249     share_info = dict(
 250         share_data=share_data,
 251         bits=bits,
 252         timestamp=math.clip(desired_timestamp, (previous_share.timestamp - 60, previous_share.timestamp + 60)) if previous_share is not None else desired_timestamp,
 253     )
 254
 255     return share_info, dict(
 256         version=1,
 257         tx_ins=[dict(
 258             previous_output=None,
 259             sequence=None,
 260             script=share_data['coinbase'].ljust(2, '\x00'),
 261         )],
 262         tx_outs=[dict(value=0, script='\x20' + bitcoin_data.HashType().pack(share_info_type.hash256(share_info)))] + [dict(value=amounts[script], script=script) for script in dests if amounts[script]],
 263         lock_time=0,
 264     )
 265
 266
 267 class OkayTracker(forest.Tracker):
 268     def __init__(self, net):
 269         forest.Tracker.__init__(self)
 270         self.net = net
 271         self.verified = forest.Tracker()
 272         self.verified.get_nth_parent_hash = self.get_nth_parent_hash # self is a superset of self.verified
 273
 274         self.get_cumulative_weights = skiplists.WeightsSkipList(self)
 275
 276     def attempt_verify(self, share):
 277         if share.hash in self.verified.shares:
 278             return True
 279         height, last = self.get_height_and_last(share.hash)
 280         if height < self.net.CHAIN_LENGTH + 1 and last is not None:
 281             raise AssertionError()
 282         try:
 283             share.check(self)
 284         except:
 285             log.err(None, 'Share check failed:')
 286             return False
 287         else:
 288             self.verified.add(share)
 289             return True
 290
 291     def think(self, ht, previous_block):
 292         desired = set()
 293
 294         # O(len(self.heads))
 295         #   make 'unverified heads' set?
 296         # for each overall head, attempt verification
 297         # if it fails, attempt on parent, and repeat
 298         # if no successful verification because of lack of parents, request parent
 299         bads = set()
 300         for head in set(self.heads) - set(self.verified.heads):
 301             head_height, last = self.get_height_and_last(head)
 302
 303             for share in self.get_chain(head, head_height if last is None else min(5, max(0, head_height - self.net.CHAIN_LENGTH))):
 304                 if self.attempt_verify(share):
 305                     break
 306                 if share.hash in self.heads:
 307                     bads.add(share.hash)
 308             else:
 309                 if last is not None:
 310                     desired.add((self.shares[random.choice(list(self.reverse_shares[last]))].peer, last))
 311         for bad in bads:
 312             assert bad not in self.verified.shares
 313             assert bad in self.heads
 314             if p2pool.DEBUG:
 315                 print "BAD", bad
 316             self.remove(bad)
 317
 318         # try to get at least CHAIN_LENGTH height for each verified head, requesting parents if needed
 319         for head in list(self.verified.heads):
 320             head_height, last_hash = self.verified.get_height_and_last(head)
 321             last_height, last_last_hash = self.get_height_and_last(last_hash)
 322             # XXX review boundary conditions
 323             want = max(self.net.CHAIN_LENGTH - head_height, 0)
 324             can = max(last_height - 1 - self.net.CHAIN_LENGTH, 0) if last_last_hash is not None else last_height
 325             get = min(want, can)
 326             #print 'Z', head_height, last_hash is None, last_height, last_last_hash is None, want, can, get
 327             for share in self.get_chain(last_hash, get):
 328                 if not self.attempt_verify(share):
 329                     break
 330             if head_height < self.net.CHAIN_LENGTH and last_last_hash is not None:
 331                 desired.add((self.verified.shares[random.choice(list(self.verified.reverse_shares[last_hash]))].peer, last_last_hash))
 332         if p2pool.DEBUG:
 333             print len(self.verified.tails), "tails:"
 334             for x in self.verified.tails:
 335                 print format_hash(x), self.score(max(self.verified.tails[x], key=self.verified.get_height), ht)
 336
 337         # decide best tree
 338         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
 339         # decide best verified head
 340         scores = sorted(self.verified.tails.get(best_tail, []), key=lambda h: (
 341             self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 342             #self.verified.shares[h].peer is None,
 343             ht.get_height_rel_highest(self.verified.shares[h].previous_block),
 344             -self.verified.shares[h].time_seen
 345         ))
 346
 347
 348         if p2pool.DEBUG:
 349             print len(self.verified.tails), "chain tails and", len(self.verified.tails.get(best_tail, [])), 'chain heads. Top 10 heads:'
 350             if len(scores) > 10:
 351                 print '    ...'
 352             for h in scores[-10:]:
 353                 print '   ', format_hash(h), format_hash(self.verified.shares[h].previous_hash), (
 354                     self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 355                     self.verified.shares[h].peer is None,
 356                     ht.get_height_rel_highest(self.verified.shares[h].previous_block),
 357                     -self.verified.shares[h].time_seen
 358                 )
 359
 360         # eat away at heads
 361         if scores:
 362             for i in xrange(1000):
 363                 to_remove = set()
 364                 for share_hash, tail in self.heads.iteritems():
 365                     if share_hash in scores[-5:]:
 366                         #print 1
 367                         continue
 368                     if self.shares[share_hash].time_seen > time.time() - 300:
 369                         #print 2
 370                         continue
 371                     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
 372                         #print 3
 373                         continue
 374                     to_remove.add(share_hash)
 375                 if not to_remove:
 376                     break
 377                 for share_hash in to_remove:
 378                     self.remove(share_hash)
 379                     if share_hash in self.verified.shares:
 380                         self.verified.remove(share_hash)
 381                 #print "_________", to_remove
 382
 383         # drop tails
 384         for i in xrange(1000):
 385             to_remove = set()
 386             for tail, heads in self.tails.iteritems():
 387                 if min(self.get_height(head) for head in heads) < 2*self.net.CHAIN_LENGTH + 10:
 388                     continue
 389                 for aftertail in self.reverse_shares.get(tail, set()):
 390                     if len(self.reverse_shares[self.shares[aftertail].previous_hash]) > 1: # XXX
 391                         print "raw"
 392                         continue
 393                     to_remove.add(aftertail)
 394             if not to_remove:
 395                 break
 396             # if removed from this, it must be removed from verified
 397             #start = time.time()
 398             for aftertail in to_remove:
 399                 if self.shares[aftertail].previous_hash not in self.tails:
 400                     print "erk", aftertail, self.shares[aftertail].previous_hash
 401                     continue
 402                 self.remove(aftertail)
 403                 if aftertail in self.verified.shares:
 404                     self.verified.remove(aftertail)
 405             #end = time.time()
 406             #print "removed! %i %f" % (len(to_remove), (end - start)/len(to_remove))
 407
 408         best = scores[-1] if scores else None
 409
 410         if best is not None:
 411             best_share = self.verified.shares[best]
 412             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:
 413                 if p2pool.DEBUG:
 414                     print 'Stale detected! %x < %x' % (best_share.header['previous_block'], previous_block)
 415                 best = best_share.previous_hash
 416
 417         return best, desired
 418
 419     @memoize.memoize_with_backing(expiring_dict.ExpiringDict(5, get_touches=False))
 420     def score(self, share_hash, ht):
 421         head_height, last = self.verified.get_height_and_last(share_hash)
 422         score2 = 0
 423         block_height = -1000000
 424         max_height = min(self.net.CHAIN_LENGTH, head_height)
 425         for share in math.reversed(self.verified.get_chain(self.verified.get_nth_parent_hash(share_hash, max_height//2), max_height//2)):
 426             block_height = max(block_height, ht.get_height_rel_highest(share.header['previous_block']))
 427             this_score = (self.verified.get_work(share_hash) - self.verified.get_work(share.hash))//(0 - block_height + 1)
 428             if this_score > score2:
 429                 score2 = this_score
 430         return min(head_height, self.net.CHAIN_LENGTH), score2
 431
 432 def format_hash(x):
 433     if x is None:
 434         return 'xxxxxxxx'
 435     return '%08x' % (x % 2**32)
 436
 437 class ShareStore(object):
 438     def __init__(self, prefix, net):
 439         self.filename = prefix
 440         self.dirname = os.path.dirname(os.path.abspath(prefix))
 441         self.filename = os.path.basename(os.path.abspath(prefix))
 442         self.net = net
 443         self.known = None # will be filename -> set of share hashes, set of verified hashes
 444         self.known_desired = None
 445
 446     def get_shares(self):
 447         if self.known is not None:
 448             raise AssertionError()
 449         known = {}
 450         filenames, next = self.get_filenames_and_next()
 451         for filename in filenames:
 452             share_hashes, verified_hashes = known.setdefault(filename, (set(), set()))
 453             with open(filename, 'rb') as f:
 454                 for line in f:
 455                     try:
 456                         type_id_str, data_hex = line.strip().split(' ')
 457                         type_id = int(type_id_str)
 458                         if type_id == 0:
 459                             pass
 460                         elif type_id == 1:
 461                             pass
 462                         elif type_id == 2:
 463                             verified_hash = int(data_hex, 16)
 464                             yield 'verified_hash', verified_hash
 465                             verified_hashes.add(verified_hash)
 466                         elif type_id == 5:
 467                             share = Share.from_share(share_type.unpack(data_hex.decode('hex')), self.net)
 468                             yield 'share', share
 469                             share_hashes.add(share.hash)
 470                         else:
 471                             raise NotImplementedError("share type %i" % (type_id,))
 472                     except Exception:
 473                         log.err(None, "Error while reading saved shares, continuing where left off:")
 474         self.known = known
 475         self.known_desired = dict((k, (set(a), set(b))) for k, (a, b) in known.iteritems())
 476
 477     def _add_line(self, line):
 478         filenames, next = self.get_filenames_and_next()
 479         if filenames and os.path.getsize(filenames[-1]) < 10e6:
 480             filename = filenames[-1]
 481         else:
 482             filename = next
 483
 484         with open(filename, 'ab') as f:
 485             f.write(line + '\n')
 486
 487         return filename
 488
 489     def add_share(self, share):
 490         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 491             if share.hash in share_hashes:
 492                 break
 493         else:
 494             filename = self._add_line("%i %s" % (5, share_type.pack(share.as_share()).encode('hex')))
 495             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 496             share_hashes.add(share.hash)
 497         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 498         share_hashes.add(share.hash)
 499
 500     def add_verified_hash(self, share_hash):
 501         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 502             if share_hash in verified_hashes:
 503                 break
 504         else:
 505             filename = self._add_line("%i %x" % (2, share_hash))
 506             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 507             verified_hashes.add(share_hash)
 508         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 509         verified_hashes.add(share_hash)
 510
 511     def get_filenames_and_next(self):
 512         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())
 513         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)))
 514
 515     def forget_share(self, share_hash):
 516         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 517             if share_hash in share_hashes:
 518                 share_hashes.remove(share_hash)
 519         self.check_remove()
 520
 521     def forget_verified_share(self, share_hash):
 522         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 523             if share_hash in verified_hashes:
 524                 verified_hashes.remove(share_hash)
 525         self.check_remove()
 526
 527     def check_remove(self):
 528         to_remove = set()
 529         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 530             #print filename, len(share_hashes) + len(verified_hashes)
 531             if not share_hashes and not verified_hashes:
 532                 to_remove.add(filename)
 533         for filename in to_remove:
 534             self.known.pop(filename)
 535             self.known_desired.pop(filename)
 536             os.remove(filename)
 537             print "REMOVED", filename