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. previously: 254*perfect_round(my_stale_prop), None if no shares
  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, **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] + [bitcoin_data.hash256(bitcoin_data.tx_type.pack(x)) for x in 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(bitcoin_data.block_header_type.pack(header))
 119         self.header_hash = bitcoin_data.hash256(bitcoin_data.block_header_type.pack(header))
 120
 121         self.hash = bitcoin_data.hash256(share1a_type.pack(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.hash256(bitcoin_data.tx_type.pack(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     assert dist >= 2
 176     near = tracker.shares[previous_share_hash]
 177     far = tracker.shares[tracker.get_nth_parent_hash(previous_share_hash, dist - 1)]
 178     attempts = tracker.get_work(near.hash) - tracker.get_work(far.hash)
 179     time = near.timestamp - far.timestamp
 180     if time <= 0:
 181         time = 1
 182     return attempts//time
 183
 184 def get_average_stale_prop(tracker, share_hash, lookbehind):
 185     def stales_per_share(share):
 186         if share.share_data['stale_info'] == 253: # orphan
 187             return 1
 188         elif share.share_data['stale_info'] == 254: # doa
 189             return 1
 190         elif share.share_data['stale_info'] == 0:
 191             return 0
 192         elif share.share_data['stale_info'] == 255: # temporary hack until everyone uses new-style stale data
 193             return 0
 194         else:
 195             return 1/(254/share.share_data['stale_info'] - 1) # converts stales/shares to stales/nonstales
 196             # 0 and 254 case are taken care of above and this will soon be removed anyway
 197     stales = sum(stales_per_share(share) for share in tracker.get_chain(share_hash, lookbehind))
 198     return stales/(lookbehind + stales)
 199
 200 def generate_transaction(tracker, share_data, block_target, desired_timestamp, net):
 201     previous_share_hash = share_data['previous_share_hash']
 202     new_script = share_data['new_script']
 203     subsidy = share_data['subsidy']
 204     donation = share_data['donation']
 205     assert 0 <= donation <= 65535
 206
 207     if len(share_data['coinbase']) > 100:
 208         raise ValueError('coinbase too long!')
 209
 210     previous_share = tracker.shares[previous_share_hash] if previous_share_hash is not None else None
 211
 212     chain_length = getattr(net, 'REAL_CHAIN_LENGTH_FUNC', lambda _: net.REAL_CHAIN_LENGTH)(previous_share.timestamp if previous_share is not None else None)
 213
 214     height, last = tracker.get_height_and_last(previous_share_hash)
 215     assert height >= chain_length or last is None
 216     if height < net.TARGET_LOOKBEHIND:
 217         bits = bitcoin_data.FloatingInteger.from_target_upper_bound(net.MAX_TARGET)
 218     else:
 219         attempts_per_second = get_pool_attempts_per_second(tracker, previous_share_hash, net.TARGET_LOOKBEHIND)
 220         pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1
 221         pre_target2 = math.clip(pre_target, (previous_share.target*9//10, previous_share.target*11//10))
 222         pre_target3 = math.clip(pre_target2, (0, net.MAX_TARGET))
 223         bits = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 224
 225     attempts_to_block = bitcoin_data.target_to_average_attempts(block_target)
 226     max_att = net.SPREAD * attempts_to_block
 227
 228     this_att = min(bitcoin_data.target_to_average_attempts(bits.target), max_att)
 229     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))
 230     assert other_total_weight == sum(other_weights.itervalues()) + other_donation_weight, (other_total_weight, sum(other_weights.itervalues()) + other_donation_weight)
 231     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
 232     assert total_weight == sum(weights.itervalues()) + donation_weight, (total_weight, sum(weights.itervalues()) + donation_weight)
 233
 234     SCRIPT = '4104ffd03de44a6e11b9917f3a29f9443283d9871c9d743ef30d5eddcd37094b64d1b3d8090496b53256786bf5c82932ec23c3b74d9f05a6f95a8b5529352656664bac'.decode('hex')
 235
 236     # 1 satoshi is always donated so that a list of p2pool generated blocks can be easily found by looking at the donation address
 237     amounts = dict((script, (subsidy-1)*(199*weight)//(200*total_weight)) for (script, weight) in weights.iteritems())
 238     amounts[new_script] = amounts.get(new_script, 0) + (subsidy-1)//200
 239     amounts[SCRIPT] = amounts.get(SCRIPT, 0) + (subsidy-1)*(199*donation_weight)//(200*total_weight)
 240     amounts[SCRIPT] = amounts.get(SCRIPT, 0) + subsidy - sum(amounts.itervalues()) # collect any extra satoshis :P
 241
 242     if sum(amounts.itervalues()) != subsidy:
 243         raise ValueError()
 244     if any(x < 0 for x in amounts.itervalues()):
 245         raise ValueError()
 246
 247     dests = sorted(amounts.iterkeys(), key=lambda script: (amounts[script], script))
 248     dests = dests[-4000:] # block length limit, unlikely to ever be hit
 249
 250     share_info = dict(
 251         share_data=share_data,
 252         bits=bits,
 253         timestamp=math.clip(desired_timestamp, (previous_share.timestamp - 60, previous_share.timestamp + 60)) if previous_share is not None else desired_timestamp,
 254     )
 255
 256     return share_info, dict(
 257         version=1,
 258         tx_ins=[dict(
 259             previous_output=None,
 260             sequence=None,
 261             script=share_data['coinbase'].ljust(2, '\x00'),
 262         )],
 263         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]],
 264         lock_time=0,
 265     )
 266
 267 class OkayTracker(forest.Tracker):
 268     def __init__(self, net, my_share_hashes, my_doa_share_hashes):
 269         forest.Tracker.__init__(self)
 270         self.net = net
 271         self.verified = forest.Tracker(delta_type=forest.get_attributedelta_type(dict(forest.AttributeDelta.attrs,
 272             my_count=lambda share: 1 if share.hash in my_share_hashes else 0,
 273             my_doa_count=lambda share: 1 if share.hash in my_doa_share_hashes else 0,
 274             my_orphan_announce_count=lambda share: 1 if share.hash in my_share_hashes and share.share_data['stale_info'] == 253 else 0,
 275             my_dead_announce_count=lambda share: 1 if share.hash in my_share_hashes and share.share_data['stale_info'] == 254 else 0,
 276         )))
 277         self.verified.get_nth_parent_hash = self.get_nth_parent_hash # self is a superset of self.verified
 278
 279         self.get_cumulative_weights = skiplists.WeightsSkipList(self)
 280
 281     def attempt_verify(self, share):
 282         if share.hash in self.verified.shares:
 283             return True
 284         height, last = self.get_height_and_last(share.hash)
 285         if height < self.net.CHAIN_LENGTH + 1 and last is not None:
 286             raise AssertionError()
 287         try:
 288             share.check(self)
 289         except:
 290             log.err(None, 'Share check failed:')
 291             return False
 292         else:
 293             self.verified.add(share)
 294             return True
 295
 296     def think(self, ht, previous_block):
 297         desired = set()
 298
 299         # O(len(self.heads))
 300         #   make 'unverified heads' set?
 301         # for each overall head, attempt verification
 302         # if it fails, attempt on parent, and repeat
 303         # if no successful verification because of lack of parents, request parent
 304         bads = set()
 305         for head in set(self.heads) - set(self.verified.heads):
 306             head_height, last = self.get_height_and_last(head)
 307
 308             for share in self.get_chain(head, head_height if last is None else min(5, max(0, head_height - self.net.CHAIN_LENGTH))):
 309                 if self.attempt_verify(share):
 310                     break
 311                 if share.hash in self.heads:
 312                     bads.add(share.hash)
 313             else:
 314                 if last is not None:
 315                     desired.add((self.shares[random.choice(list(self.reverse_shares[last]))].peer, last))
 316         for bad in bads:
 317             assert bad not in self.verified.shares
 318             assert bad in self.heads
 319             if p2pool.DEBUG:
 320                 print "BAD", bad
 321             self.remove(bad)
 322
 323         # try to get at least CHAIN_LENGTH height for each verified head, requesting parents if needed
 324         for head in list(self.verified.heads):
 325             head_height, last_hash = self.verified.get_height_and_last(head)
 326             last_height, last_last_hash = self.get_height_and_last(last_hash)
 327             # XXX review boundary conditions
 328             want = max(self.net.CHAIN_LENGTH - head_height, 0)
 329             can = max(last_height - 1 - self.net.CHAIN_LENGTH, 0) if last_last_hash is not None else last_height
 330             get = min(want, can)
 331             #print 'Z', head_height, last_hash is None, last_height, last_last_hash is None, want, can, get
 332             for share in self.get_chain(last_hash, get):
 333                 if not self.attempt_verify(share):
 334                     break
 335             if head_height < self.net.CHAIN_LENGTH and last_last_hash is not None:
 336                 desired.add((self.verified.shares[random.choice(list(self.verified.reverse_shares[last_hash]))].peer, last_last_hash))
 337         if p2pool.DEBUG:
 338             print len(self.verified.tails), "tails:"
 339             for x in self.verified.tails:
 340                 print format_hash(x), self.score(max(self.verified.tails[x], key=self.verified.get_height), ht)
 341
 342         # decide best tree
 343         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
 344         # decide best verified head
 345         scores = sorted(self.verified.tails.get(best_tail, []), key=lambda h: (
 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
 353         if p2pool.DEBUG:
 354             print len(self.verified.tails), "chain tails and", len(self.verified.tails.get(best_tail, [])), 'chain heads. Top 10 heads:'
 355             if len(scores) > 10:
 356                 print '    ...'
 357             for h in scores[-10:]:
 358                 print '   ', format_hash(h), format_hash(self.verified.shares[h].previous_hash), (
 359                     self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 360                     self.verified.shares[h].peer is None,
 361                     0 if self.verified.shares[h].peer is None else ht.get_height_rel_highest(self.verified.shares[h].previous_block),
 362                     -self.verified.shares[h].time_seen
 363                 )
 364
 365         # eat away at heads
 366         if scores:
 367             for i in xrange(1000):
 368                 to_remove = set()
 369                 for share_hash, tail in self.heads.iteritems():
 370                     if share_hash in scores[-5:]:
 371                         #print 1
 372                         continue
 373                     if self.shares[share_hash].time_seen > time.time() - 300:
 374                         #print 2
 375                         continue
 376                     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
 377                         #print 3
 378                         continue
 379                     to_remove.add(share_hash)
 380                 if not to_remove:
 381                     break
 382                 for share_hash in to_remove:
 383                     self.remove(share_hash)
 384                     if share_hash in self.verified.shares:
 385                         self.verified.remove(share_hash)
 386                 #print "_________", to_remove
 387
 388         # drop tails
 389         for i in xrange(1000):
 390             to_remove = set()
 391             for tail, heads in self.tails.iteritems():
 392                 if min(self.get_height(head) for head in heads) < 2*self.net.CHAIN_LENGTH + 10:
 393                     continue
 394                 for aftertail in self.reverse_shares.get(tail, set()):
 395                     if len(self.reverse_shares[self.shares[aftertail].previous_hash]) > 1: # XXX
 396                         print "raw"
 397                         continue
 398                     to_remove.add(aftertail)
 399             if not to_remove:
 400                 break
 401             # if removed from this, it must be removed from verified
 402             #start = time.time()
 403             for aftertail in to_remove:
 404                 if self.shares[aftertail].previous_hash not in self.tails:
 405                     print "erk", aftertail, self.shares[aftertail].previous_hash
 406                     continue
 407                 self.remove(aftertail)
 408                 if aftertail in self.verified.shares:
 409                     self.verified.remove(aftertail)
 410             #end = time.time()
 411             #print "removed! %i %f" % (len(to_remove), (end - start)/len(to_remove))
 412
 413         best = scores[-1] if scores else None
 414
 415         if best is not None:
 416             best_share = self.verified.shares[best]
 417             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:
 418                 if p2pool.DEBUG:
 419                     print 'Stale detected! %x < %x' % (best_share.header['previous_block'], previous_block)
 420                 best = best_share.previous_hash
 421
 422         return best, desired
 423
 424     def score(self, share_hash, ht):
 425         head_height = self.verified.get_height(share_hash)
 426         if head_height < self.net.CHAIN_LENGTH:
 427             return head_height, None
 428
 429         end_point = self.verified.get_nth_parent_hash(share_hash, self.net.CHAIN_LENGTH*15//16)
 430
 431         block_height = max(ht.get_height_rel_highest(share.header['previous_block']) for share in
 432             self.verified.get_chain(end_point, self.net.CHAIN_LENGTH//16))
 433
 434         return self.net.CHAIN_LENGTH, (self.verified.get_work(share_hash) - self.verified.get_work(end_point))//(0 - block_height + 1)
 435
 436 def format_hash(x):
 437     if x is None:
 438         return 'xxxxxxxx'
 439     return '%08x' % (x % 2**32)
 440
 441 class ShareStore(object):
 442     def __init__(self, prefix, net):
 443         self.filename = prefix
 444         self.dirname = os.path.dirname(os.path.abspath(prefix))
 445         self.filename = os.path.basename(os.path.abspath(prefix))
 446         self.net = net
 447         self.known = None # will be filename -> set of share hashes, set of verified hashes
 448         self.known_desired = None
 449
 450     def get_shares(self):
 451         if self.known is not None:
 452             raise AssertionError()
 453         known = {}
 454         filenames, next = self.get_filenames_and_next()
 455         for filename in filenames:
 456             share_hashes, verified_hashes = known.setdefault(filename, (set(), set()))
 457             with open(filename, 'rb') as f:
 458                 for line in f:
 459                     try:
 460                         type_id_str, data_hex = line.strip().split(' ')
 461                         type_id = int(type_id_str)
 462                         if type_id == 0:
 463                             pass
 464                         elif type_id == 1:
 465                             pass
 466                         elif type_id == 2:
 467                             verified_hash = int(data_hex, 16)
 468                             yield 'verified_hash', verified_hash
 469                             verified_hashes.add(verified_hash)
 470                         elif type_id == 5:
 471                             share = Share.from_share(share_type.unpack(data_hex.decode('hex')), self.net)
 472                             yield 'share', share
 473                             share_hashes.add(share.hash)
 474                         else:
 475                             raise NotImplementedError("share type %i" % (type_id,))
 476                     except Exception:
 477                         log.err(None, "Error while reading saved shares, continuing where left off:")
 478         self.known = known
 479         self.known_desired = dict((k, (set(a), set(b))) for k, (a, b) in known.iteritems())
 480
 481     def _add_line(self, line):
 482         filenames, next = self.get_filenames_and_next()
 483         if filenames and os.path.getsize(filenames[-1]) < 10e6:
 484             filename = filenames[-1]
 485         else:
 486             filename = next
 487
 488         with open(filename, 'ab') as f:
 489             f.write(line + '\n')
 490
 491         return filename
 492
 493     def add_share(self, share):
 494         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 495             if share.hash in share_hashes:
 496                 break
 497         else:
 498             filename = self._add_line("%i %s" % (5, share_type.pack(share.as_share()).encode('hex')))
 499             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 500             share_hashes.add(share.hash)
 501         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 502         share_hashes.add(share.hash)
 503
 504     def add_verified_hash(self, share_hash):
 505         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 506             if share_hash in verified_hashes:
 507                 break
 508         else:
 509             filename = self._add_line("%i %x" % (2, share_hash))
 510             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 511             verified_hashes.add(share_hash)
 512         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 513         verified_hashes.add(share_hash)
 514
 515     def get_filenames_and_next(self):
 516         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())
 517         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)))
 518
 519     def forget_share(self, share_hash):
 520         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 521             if share_hash in share_hashes:
 522                 share_hashes.remove(share_hash)
 523         self.check_remove()
 524
 525     def forget_verified_share(self, share_hash):
 526         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 527             if share_hash in verified_hashes:
 528                 verified_hashes.remove(share_hash)
 529         self.check_remove()
 530
 531     def check_remove(self):
 532         to_remove = set()
 533         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 534             #print filename, len(share_hashes) + len(verified_hashes)
 535             if not share_hashes and not verified_hashes:
 536                 to_remove.add(filename)
 537         for filename in to_remove:
 538             self.known.pop(filename)
 539             self.known_desired.pop(filename)
 540             os.remove(filename)
 541             print "REMOVED", filename