p2pool/data.py

   1 from __future__ import division
   2
   3 import hashlib
   4 import os
   5 import random
   6 import time
   7
   8 from twisted.python import log
   9
  10 import p2pool
  11 from p2pool.bitcoin import data as bitcoin_data, script, sha256
  12 from p2pool.util import math, forest, pack
  13
  14 # hashlink
  15
  16 hash_link_type = pack.ComposedType([
  17     ('state', pack.FixedStrType(32)),
  18     ('extra_data', pack.FixedStrType(0)), # bit of a hack, but since the donation script is at the end, const_ending is long enough to always make this empty
  19     ('length', pack.VarIntType()),
  20 ])
  21
  22 def prefix_to_hash_link(prefix, const_ending=''):
  23     assert prefix.endswith(const_ending), (prefix, const_ending)
  24     x = sha256.sha256(prefix)
  25     return dict(state=x.state, extra_data=x.buf[:max(0, len(x.buf)-len(const_ending))], length=x.length//8)
  26
  27 def check_hash_link(hash_link, data, const_ending=''):
  28     extra_length = hash_link['length'] % (512//8)
  29     assert len(hash_link['extra_data']) == max(0, extra_length - len(const_ending))
  30     extra = (hash_link['extra_data'] + const_ending)[len(hash_link['extra_data']) + len(const_ending) - extra_length:]
  31     assert len(extra) == extra_length
  32     return pack.IntType(256).unpack(hashlib.sha256(sha256.sha256(data, (hash_link['state'], extra, 8*hash_link['length'])).digest()).digest())
  33
  34 # shares
  35
  36 # type:
  37 # 2: share1a
  38 # 3: share1b
  39
  40 share_type = pack.ComposedType([
  41     ('type', pack.VarIntType()),
  42     ('contents', pack.VarStrType()),
  43 ])
  44
  45 def load_share(share, net, peer):
  46     if share['type'] in [0, 1, 2, 3]:
  47         from p2pool import p2p
  48         raise p2p.PeerMisbehavingError('sent an obsolete share')
  49     elif share['type'] == 4:
  50         return Share(net, peer, other_txs=None, **Share.share1a_type.unpack(share['contents']))
  51     elif share['type'] == 5:
  52         share1b = Share.share1b_type.unpack(share['contents'])
  53         return Share(net, peer, merkle_link=bitcoin_data.calculate_merkle_link([0] + [bitcoin_data.hash256(bitcoin_data.tx_type.pack(x)) for x in share1b['other_txs']], 0), **share1b)
  54     else:
  55         raise ValueError('unknown share type: %r' % (share['type'],))
  56
  57 DONATION_SCRIPT = '4104ffd03de44a6e11b9917f3a29f9443283d9871c9d743ef30d5eddcd37094b64d1b3d8090496b53256786bf5c82932ec23c3b74d9f05a6f95a8b5529352656664bac'.decode('hex')
  58
  59 class Share(object):
  60     small_block_header_type = pack.ComposedType([
  61         ('version', pack.VarIntType()), # XXX must be constrained to 32 bits
  62         ('previous_block', pack.PossiblyNoneType(0, pack.IntType(256))),
  63         ('timestamp', pack.IntType(32)),
  64         ('bits', bitcoin_data.FloatingIntegerType()),
  65         ('nonce', pack.IntType(32)),
  66     ])
  67
  68     share_data_type = pack.ComposedType([
  69         ('previous_share_hash', pack.PossiblyNoneType(0, pack.IntType(256))),
  70         ('coinbase', pack.VarStrType()),
  71         ('nonce', pack.IntType(32)),
  72         ('pubkey_hash', pack.IntType(160)),
  73         ('subsidy', pack.IntType(64)),
  74         ('donation', pack.IntType(16)),
  75         ('stale_info', pack.EnumType(pack.IntType(8), dict((k, {0: None, 253: 'orphan', 254: 'doa'}.get(k, 'unk%i' % (k,))) for k in xrange(256)))),
  76         ('desired_version', pack.VarIntType()),
  77     ])
  78
  79     share_info_type = pack.ComposedType([
  80         ('share_data', share_data_type),
  81         ('far_share_hash', pack.PossiblyNoneType(0, pack.IntType(256))),
  82         ('max_bits', bitcoin_data.FloatingIntegerType()),
  83         ('bits', bitcoin_data.FloatingIntegerType()),
  84         ('timestamp', pack.IntType(32)),
  85     ])
  86
  87     share_common_type = pack.ComposedType([
  88         ('min_header', small_block_header_type),
  89         ('share_info', share_info_type),
  90         ('ref_merkle_link', pack.ComposedType([
  91             ('branch', pack.ListType(pack.IntType(256))),
  92             ('index', pack.VarIntType()),
  93         ])),
  94         ('hash_link', hash_link_type),
  95     ])
  96     share1a_type = pack.ComposedType([
  97         ('common', share_common_type),
  98         ('merkle_link', pack.ComposedType([
  99             ('branch', pack.ListType(pack.IntType(256))),
 100             ('index', pack.IntType(0)), # it will always be 0
 101         ])),
 102     ])
 103     share1b_type = pack.ComposedType([
 104         ('common', share_common_type),
 105         ('other_txs', pack.ListType(bitcoin_data.tx_type)),
 106     ])
 107
 108     ref_type = pack.ComposedType([
 109         ('identifier', pack.FixedStrType(64//8)),
 110         ('share_info', share_info_type),
 111     ])
 112
 113     gentx_before_refhash = pack.VarStrType().pack(DONATION_SCRIPT) + pack.IntType(64).pack(0) + pack.VarStrType().pack('\x20' + pack.IntType(256).pack(0))[:2]
 114
 115     @classmethod
 116     def generate_transaction(cls, tracker, share_data, block_target, desired_timestamp, desired_target, ref_merkle_link, net):
 117         previous_share = tracker.shares[share_data['previous_share_hash']] if share_data['previous_share_hash'] is not None else None
 118
 119         height, last = tracker.get_height_and_last(share_data['previous_share_hash'])
 120         assert height >= net.REAL_CHAIN_LENGTH or last is None
 121         if height < net.TARGET_LOOKBEHIND:
 122             pre_target3 = net.MAX_TARGET
 123         else:
 124             attempts_per_second = get_pool_attempts_per_second(tracker, share_data['previous_share_hash'], net.TARGET_LOOKBEHIND, min_work=True, integer=True)
 125             pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1 if attempts_per_second else 2**256-1
 126             pre_target2 = math.clip(pre_target, (previous_share.max_target*9//10, previous_share.max_target*11//10))
 127             pre_target3 = math.clip(pre_target2, (0, net.MAX_TARGET))
 128         max_bits = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 129         bits = bitcoin_data.FloatingInteger.from_target_upper_bound(math.clip(desired_target, (pre_target3//10, pre_target3)))
 130
 131         weights, total_weight, donation_weight = tracker.get_cumulative_weights(share_data['previous_share_hash'],
 132             min(height, net.REAL_CHAIN_LENGTH),
 133             65535*net.SPREAD*bitcoin_data.target_to_average_attempts(block_target),
 134         )
 135         assert total_weight == sum(weights.itervalues()) + donation_weight, (total_weight, sum(weights.itervalues()) + donation_weight)
 136
 137         amounts = dict((script, share_data['subsidy']*(199*weight)//(200*total_weight)) for script, weight in weights.iteritems()) # 99.5% goes according to weights prior to this share
 138         this_script = bitcoin_data.pubkey_hash_to_script2(share_data['pubkey_hash'])
 139         amounts[this_script] = amounts.get(this_script, 0) + share_data['subsidy']//200 # 0.5% goes to block finder
 140         amounts[DONATION_SCRIPT] = amounts.get(DONATION_SCRIPT, 0) + share_data['subsidy'] - sum(amounts.itervalues()) # all that's left over is the donation weight and some extra satoshis due to rounding
 141
 142         if sum(amounts.itervalues()) != share_data['subsidy'] or any(x < 0 for x in amounts.itervalues()):
 143             raise ValueError()
 144
 145         dests = sorted(amounts.iterkeys(), key=lambda script: (script == DONATION_SCRIPT, amounts[script], script))[-4000:] # block length limit, unlikely to ever be hit
 146
 147         share_info = dict(
 148             share_data=share_data,
 149             far_share_hash=None if last is None and height < 99 else tracker.get_nth_parent_hash(share_data['previous_share_hash'], 99),
 150             max_bits=max_bits,
 151             bits=bits,
 152             timestamp=math.clip(desired_timestamp, (
 153                 (previous_share.timestamp + net.SHARE_PERIOD) - (net.SHARE_PERIOD - 1), # = previous_share.timestamp + 1
 154                 (previous_share.timestamp + net.SHARE_PERIOD) + (net.SHARE_PERIOD - 1),
 155             )) if previous_share is not None else desired_timestamp,
 156         )
 157
 158         return share_info, dict(
 159             version=1,
 160             tx_ins=[dict(
 161                 previous_output=None,
 162                 sequence=None,
 163                 script=share_data['coinbase'].ljust(2, '\x00'),
 164             )],
 165             tx_outs=[dict(value=amounts[script], script=script) for script in dests if amounts[script] or script == DONATION_SCRIPT] + [dict(
 166                 value=0,
 167                 script='\x20' + cls.get_ref_hash(net, share_info, ref_merkle_link),
 168             )],
 169             lock_time=0,
 170         )
 171
 172     @classmethod
 173     def get_ref_hash(cls, net, share_info, ref_merkle_link):
 174         return pack.IntType(256).pack(bitcoin_data.check_merkle_link(bitcoin_data.hash256(cls.ref_type.pack(dict(
 175             identifier=net.IDENTIFIER,
 176             share_info=share_info,
 177         ))), ref_merkle_link))
 178
 179     __slots__ = 'net peer common min_header share_info hash_link merkle_link other_txs hash share_data max_target target timestamp previous_hash new_script desired_version gentx_hash header pow_hash header_hash time_seen'.split(' ')
 180
 181     def __init__(self, net, peer, common, merkle_link, other_txs):
 182         self.net = net
 183         self.peer = peer
 184         self.common = common
 185         self.min_header = common['min_header']
 186         self.share_info = common['share_info']
 187         self.hash_link = common['hash_link']
 188         self.merkle_link = merkle_link
 189         self.other_txs = other_txs
 190
 191         if len(self.share_info['share_data']['coinbase']) > 100:
 192             raise ValueError('''coinbase too large! %i bytes''' % (len(self.self.share_data['coinbase']),))
 193
 194         if len(merkle_link['branch']) > 16:
 195             raise ValueError('merkle branch too long!')
 196
 197         if p2pool.DEBUG and other_txs is not None and bitcoin_data.calculate_merkle_link([0] + [bitcoin_data.hash256(bitcoin_data.tx_type.pack(x)) for x in other_txs], 0) != merkle_link:
 198             raise ValueError('merkle_link and other_txs do not match')
 199
 200         assert not self.hash_link['extra_data'], repr(self.hash_link['extra_data'])
 201
 202         self.share_data = self.share_info['share_data']
 203         self.max_target = self.share_info['max_bits'].target
 204         self.target = self.share_info['bits'].target
 205         self.timestamp = self.share_info['timestamp']
 206         self.previous_hash = self.share_data['previous_share_hash']
 207         self.new_script = bitcoin_data.pubkey_hash_to_script2(self.share_data['pubkey_hash'])
 208         self.desired_version = self.share_data['desired_version']
 209
 210         self.gentx_hash = check_hash_link(
 211             self.hash_link,
 212             self.get_ref_hash(net, self.share_info, common['ref_merkle_link']) + pack.IntType(32).pack(0),
 213             self.gentx_before_refhash,
 214         )
 215         merkle_root = bitcoin_data.check_merkle_link(self.gentx_hash, merkle_link)
 216         self.header = dict(self.min_header, merkle_root=merkle_root)
 217         self.pow_hash = net.PARENT.POW_FUNC(bitcoin_data.block_header_type.pack(self.header))
 218         self.hash = self.header_hash = bitcoin_data.hash256(bitcoin_data.block_header_type.pack(self.header))
 219
 220         if self.pow_hash > self.target:
 221             from p2pool import p2p
 222             raise p2p.PeerMisbehavingError('share PoW invalid')
 223
 224         if other_txs is not None and not self.pow_hash <= self.header['bits'].target:
 225             raise ValueError('other_txs provided when not a block solution')
 226         if other_txs is None and self.pow_hash <= self.header['bits'].target:
 227             raise ValueError('other_txs not provided when a block solution')
 228
 229         # XXX eww
 230         self.time_seen = time.time()
 231
 232     def __repr__(self):
 233         return '<Share %s>' % (' '.join('%s=%r' % (k, getattr(self, k)) for k in self.__slots__),)
 234
 235     def as_share(self):
 236         if not self.pow_hash <= self.header['bits'].target: # share1a
 237             return dict(type=4, contents=self.share1a_type.pack(dict(common=self.common, merkle_link=self.merkle_link)))
 238         else: # share1b
 239             return dict(type=5, contents=self.share1b_type.pack(dict(common=self.common, other_txs=self.other_txs)))
 240
 241     def check(self, tracker):
 242         share_info, gentx = self.generate_transaction(tracker, self.share_info['share_data'], self.header['bits'].target, self.share_info['timestamp'], self.share_info['bits'].target, self.common['ref_merkle_link'], self.net)
 243         if share_info != self.share_info:
 244             raise ValueError('share_info invalid')
 245         if bitcoin_data.hash256(bitcoin_data.tx_type.pack(gentx)) != self.gentx_hash:
 246             raise ValueError('''gentx doesn't match hash_link''')
 247         return gentx # only used by as_block
 248
 249     def as_block(self, tracker):
 250         if self.other_txs is None:
 251             raise ValueError('share does not contain all txs')
 252         return dict(header=self.header, txs=[self.check(tracker)] + self.other_txs)
 253
 254 class WeightsSkipList(forest.TrackerSkipList):
 255     # share_count, weights, total_weight
 256
 257     def get_delta(self, element):
 258         from p2pool.bitcoin import data as bitcoin_data
 259         share = self.tracker.shares[element]
 260         att = bitcoin_data.target_to_average_attempts(share.target)
 261         return 1, {share.new_script: att*(65535-share.share_data['donation'])}, att*65535, att*share.share_data['donation']
 262
 263     def combine_deltas(self, (share_count1, weights1, total_weight1, total_donation_weight1), (share_count2, weights2, total_weight2, total_donation_weight2)):
 264         return share_count1 + share_count2, math.add_dicts(weights1, weights2), total_weight1 + total_weight2, total_donation_weight1 + total_donation_weight2
 265
 266     def initial_solution(self, start, (max_shares, desired_weight)):
 267         assert desired_weight % 65535 == 0, divmod(desired_weight, 65535)
 268         return 0, None, 0, 0
 269
 270     def apply_delta(self, (share_count1, weights_list, total_weight1, total_donation_weight1), (share_count2, weights2, total_weight2, total_donation_weight2), (max_shares, desired_weight)):
 271         if total_weight1 + total_weight2 > desired_weight and share_count2 == 1:
 272             assert (desired_weight - total_weight1) % 65535 == 0
 273             script, = weights2.iterkeys()
 274             new_weights = {script: (desired_weight - total_weight1)//65535*weights2[script]//(total_weight2//65535)}
 275             return share_count1 + share_count2, (weights_list, new_weights), desired_weight, total_donation_weight1 + (desired_weight - total_weight1)//65535*total_donation_weight2//(total_weight2//65535)
 276         return share_count1 + share_count2, (weights_list, weights2), total_weight1 + total_weight2, total_donation_weight1 + total_donation_weight2
 277
 278     def judge(self, (share_count, weights_list, total_weight, total_donation_weight), (max_shares, desired_weight)):
 279         if share_count > max_shares or total_weight > desired_weight:
 280             return 1
 281         elif share_count == max_shares or total_weight == desired_weight:
 282             return 0
 283         else:
 284             return -1
 285
 286     def finalize(self, (share_count, weights_list, total_weight, total_donation_weight), (max_shares, desired_weight)):
 287         assert share_count <= max_shares and total_weight <= desired_weight
 288         assert share_count == max_shares or total_weight == desired_weight
 289         return math.add_dicts(*math.flatten_linked_list(weights_list)), total_weight, total_donation_weight
 290
 291 class OkayTracker(forest.Tracker):
 292     def __init__(self, net, my_share_hashes, my_doa_share_hashes):
 293         forest.Tracker.__init__(self, delta_type=forest.get_attributedelta_type(dict(forest.AttributeDelta.attrs,
 294             work=lambda share: bitcoin_data.target_to_average_attempts(share.target),
 295             min_work=lambda share: bitcoin_data.target_to_average_attempts(share.max_target),
 296         )))
 297         self.net = net
 298         self.verified = forest.Tracker(delta_type=forest.get_attributedelta_type(dict(forest.AttributeDelta.attrs,
 299             work=lambda share: bitcoin_data.target_to_average_attempts(share.target),
 300             my_count=lambda share: 1 if share.hash in my_share_hashes else 0,
 301             my_doa_count=lambda share: 1 if share.hash in my_doa_share_hashes else 0,
 302             my_orphan_announce_count=lambda share: 1 if share.hash in my_share_hashes and share.share_data['stale_info'] == 'orphan' else 0,
 303             my_dead_announce_count=lambda share: 1 if share.hash in my_share_hashes and share.share_data['stale_info'] == 'doa' else 0,
 304         )), subset_of=self)
 305         self.get_cumulative_weights = WeightsSkipList(self)
 306
 307     def attempt_verify(self, share):
 308         if share.hash in self.verified.shares:
 309             return True
 310         height, last = self.get_height_and_last(share.hash)
 311         if height < self.net.CHAIN_LENGTH + 1 and last is not None:
 312             raise AssertionError()
 313         try:
 314             share.check(self)
 315         except:
 316             log.err(None, 'Share check failed:')
 317             return False
 318         else:
 319             self.verified.add(share)
 320             return True
 321
 322     def think(self, block_rel_height_func, previous_block, bits):
 323         desired = set()
 324
 325         # O(len(self.heads))
 326         #   make 'unverified heads' set?
 327         # for each overall head, attempt verification
 328         # if it fails, attempt on parent, and repeat
 329         # if no successful verification because of lack of parents, request parent
 330         bads = set()
 331         for head in set(self.heads) - set(self.verified.heads):
 332             head_height, last = self.get_height_and_last(head)
 333
 334             for share in self.get_chain(head, head_height if last is None else min(5, max(0, head_height - self.net.CHAIN_LENGTH))):
 335                 if self.attempt_verify(share):
 336                     break
 337                 if share.hash in self.heads:
 338                     bads.add(share.hash)
 339             else:
 340                 if last is not None:
 341                     desired.add((
 342                         self.shares[random.choice(list(self.reverse_shares[last]))].peer,
 343                         last,
 344                         max(x.timestamp for x in self.get_chain(head, min(head_height, 5))),
 345                         min(x.target for x in self.get_chain(head, min(head_height, 5))),
 346                     ))
 347         for bad in bads:
 348             assert bad not in self.verified.shares
 349             assert bad in self.heads
 350             if p2pool.DEBUG:
 351                 print "BAD", bad
 352             self.remove(bad)
 353
 354         # try to get at least CHAIN_LENGTH height for each verified head, requesting parents if needed
 355         for head in list(self.verified.heads):
 356             head_height, last_hash = self.verified.get_height_and_last(head)
 357             last_height, last_last_hash = self.get_height_and_last(last_hash)
 358             # XXX review boundary conditions
 359             want = max(self.net.CHAIN_LENGTH - head_height, 0)
 360             can = max(last_height - 1 - self.net.CHAIN_LENGTH, 0) if last_last_hash is not None else last_height
 361             get = min(want, can)
 362             #print 'Z', head_height, last_hash is None, last_height, last_last_hash is None, want, can, get
 363             for share in self.get_chain(last_hash, get):
 364                 if not self.attempt_verify(share):
 365                     break
 366             if head_height < self.net.CHAIN_LENGTH and last_last_hash is not None:
 367                 desired.add((
 368                     self.shares[random.choice(list(self.verified.reverse_shares[last_hash]))].peer,
 369                     last_last_hash,
 370                     max(x.timestamp for x in self.get_chain(head, min(head_height, 5))),
 371                     min(x.target for x in self.get_chain(head, min(head_height, 5))),
 372                 ))
 373
 374         # decide best tree
 375         decorated_tails = sorted((self.score(max(self.verified.tails[tail_hash], key=self.verified.get_work), block_rel_height_func), tail_hash) for tail_hash in self.verified.tails)
 376         if p2pool.DEBUG:
 377             print len(decorated_tails), 'tails:'
 378             for score, tail_hash in decorated_tails:
 379                 print format_hash(tail_hash), score
 380         best_tail_score, best_tail = decorated_tails[-1] if decorated_tails else (None, None)
 381
 382         # decide best verified head
 383         decorated_heads = sorted(((
 384             self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 385             #self.shares[h].peer is None,
 386             self.shares[h].pow_hash <= self.shares[h].header['bits'].target, # is block solution
 387             (self.shares[h].header['previous_block'], self.shares[h].header['bits']) == (previous_block, bits) or self.shares[h].peer is None,
 388             -self.shares[h].time_seen,
 389         ), h) for h in self.verified.tails.get(best_tail, []))
 390         if p2pool.DEBUG:
 391             print len(decorated_heads), 'heads. Top 10:'
 392             for score, head_hash in decorated_heads[-10:]:
 393                 print '   ', format_hash(head_hash), format_hash(self.shares[head_hash].previous_hash), score
 394         best_head_score, best = decorated_heads[-1] if decorated_heads else (None, None)
 395
 396         # eat away at heads
 397         if decorated_heads:
 398             for i in xrange(1000):
 399                 to_remove = set()
 400                 for share_hash, tail in self.heads.iteritems():
 401                     if share_hash in [head_hash for score, head_hash in decorated_heads[-5:]]:
 402                         #print 1
 403                         continue
 404                     if self.shares[share_hash].time_seen > time.time() - 300:
 405                         #print 2
 406                         continue
 407                     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
 408                         #print 3
 409                         continue
 410                     to_remove.add(share_hash)
 411                 if not to_remove:
 412                     break
 413                 for share_hash in to_remove:
 414                     if share_hash in self.verified.shares:
 415                         self.verified.remove(share_hash)
 416                     self.remove(share_hash)
 417                 #print "_________", to_remove
 418
 419         # drop tails
 420         for i in xrange(1000):
 421             to_remove = set()
 422             for tail, heads in self.tails.iteritems():
 423                 if min(self.get_height(head) for head in heads) < 2*self.net.CHAIN_LENGTH + 10:
 424                     continue
 425                 for aftertail in self.reverse_shares.get(tail, set()):
 426                     if len(self.reverse_shares[self.shares[aftertail].previous_hash]) > 1: # XXX
 427                         print "raw"
 428                         continue
 429                     to_remove.add(aftertail)
 430             if not to_remove:
 431                 break
 432             # if removed from this, it must be removed from verified
 433             #start = time.time()
 434             for aftertail in to_remove:
 435                 if self.shares[aftertail].previous_hash not in self.tails:
 436                     print "erk", aftertail, self.shares[aftertail].previous_hash
 437                     continue
 438                 if aftertail in self.verified.shares:
 439                     self.verified.remove(aftertail)
 440                 self.remove(aftertail)
 441             #end = time.time()
 442             #print "removed! %i %f" % (len(to_remove), (end - start)/len(to_remove))
 443
 444         if best is not None:
 445             best_share = self.shares[best]
 446             if (best_share.header['previous_block'], best_share.header['bits']) != (previous_block, bits) and best_share.header_hash != previous_block and best_share.peer is not None:
 447                 if p2pool.DEBUG:
 448                     print 'Stale detected! %x < %x' % (best_share.header['previous_block'], previous_block)
 449                 best = best_share.previous_hash
 450
 451             timestamp_cutoff = min(int(time.time()), best_share.timestamp) - 3600
 452             target_cutoff = 2**256//(self.net.SHARE_PERIOD*best_tail_score[1] + 1) * 2 if best_tail_score[1] is not None else 2**256-1
 453         else:
 454             timestamp_cutoff = int(time.time()) - 24*60*60
 455             target_cutoff = 2**256-1
 456
 457         if p2pool.DEBUG:
 458             print 'Desire %i shares. Cutoff: %s old diff>%.2f' % (len(desired), math.format_dt(time.time() - timestamp_cutoff), bitcoin_data.target_to_difficulty(target_cutoff))
 459             for peer, hash, ts, targ in desired:
 460                 print '   ', '%s:%i' % peer.addr if peer is not None else None, format_hash(hash), math.format_dt(time.time() - ts), bitcoin_data.target_to_difficulty(targ), ts >= timestamp_cutoff, targ <= target_cutoff
 461
 462         return best, [(peer, hash) for peer, hash, ts, targ in desired if ts >= timestamp_cutoff]
 463
 464     def score(self, share_hash, block_rel_height_func):
 465         # returns approximate lower bound on chain's hashrate in the last self.net.CHAIN_LENGTH*15//16*self.net.SHARE_PERIOD time
 466
 467         head_height = self.verified.get_height(share_hash)
 468         if head_height < self.net.CHAIN_LENGTH:
 469             return head_height, None
 470
 471         end_point = self.verified.get_nth_parent_hash(share_hash, self.net.CHAIN_LENGTH*15//16)
 472
 473         block_height = max(block_rel_height_func(share.header['previous_block']) for share in
 474             self.verified.get_chain(end_point, self.net.CHAIN_LENGTH//16))
 475
 476         return self.net.CHAIN_LENGTH, (self.verified.get_work(share_hash) - self.verified.get_work(end_point))//((0 - block_height + 1)*self.net.PARENT.BLOCK_PERIOD)
 477
 478 def get_pool_attempts_per_second(tracker, previous_share_hash, dist, min_work=False, integer=False):
 479     assert dist >= 2
 480     near = tracker.shares[previous_share_hash]
 481     far = tracker.shares[tracker.get_nth_parent_hash(previous_share_hash, dist - 1)]
 482     attempts = tracker.get_delta(near.hash, far.hash).work if not min_work else tracker.get_delta(near.hash, far.hash).min_work
 483     time = near.timestamp - far.timestamp
 484     if time <= 0:
 485         time = 1
 486     if integer:
 487         return attempts//time
 488     return attempts/time
 489
 490 def get_average_stale_prop(tracker, share_hash, lookbehind):
 491     stales = sum(1 for share in tracker.get_chain(share_hash, lookbehind) if share.share_data['stale_info'] is not None)
 492     return stales/(lookbehind + stales)
 493
 494 def get_stale_counts(tracker, share_hash, lookbehind, rates=False):
 495     res = {}
 496     for share in tracker.get_chain(share_hash, lookbehind - 1):
 497         res['good'] = res.get('good', 0) + bitcoin_data.target_to_average_attempts(share.target)
 498         s = share.share_data['stale_info']
 499         if s is not None:
 500             res[s] = res.get(s, 0) + bitcoin_data.target_to_average_attempts(share.target)
 501     if rates:
 502         dt = tracker.shares[share_hash].timestamp - tracker.shares[tracker.get_nth_parent_hash(share_hash, lookbehind - 1)].timestamp
 503         res = dict((k, v/dt) for k, v in res.iteritems())
 504     return res
 505
 506 def get_expected_payouts(tracker, best_share_hash, block_target, subsidy, net):
 507     weights, total_weight, donation_weight = tracker.get_cumulative_weights(best_share_hash, min(tracker.get_height(best_share_hash), net.REAL_CHAIN_LENGTH), 65535*net.SPREAD*bitcoin_data.target_to_average_attempts(block_target))
 508     res = dict((script, subsidy*weight//total_weight) for script, weight in weights.iteritems())
 509     res[DONATION_SCRIPT] = res.get(DONATION_SCRIPT, 0) + subsidy - sum(res.itervalues())
 510     return res
 511
 512 def get_desired_version_counts(tracker, best_share_hash, dist):
 513     res = {}
 514     for share in tracker.get_chain(best_share_hash, dist):
 515         res[share.desired_version] = res.get(share.desired_version, 0) + bitcoin_data.target_to_average_attempts(share.target)
 516     return res
 517
 518 def get_warnings(tracker, current_work, net):
 519     res = []
 520
 521     desired_version_counts = get_desired_version_counts(tracker, current_work.value['best_share_hash'],
 522         min(60*60//net.SHARE_PERIOD, tracker.get_height(current_work.value['best_share_hash'])))
 523     majority_desired_version = max(desired_version_counts, key=lambda k: desired_version_counts[k])
 524     if majority_desired_version not in [0, 1, 2] and desired_version_counts[majority_desired_version] > sum(desired_version_counts.itervalues())/2:
 525         res.append('A MAJORITY OF SHARES CONTAIN A VOTE FOR AN UNSUPPORTED SHARE IMPLEMENTATION! (v%i with %i%% support)\n'
 526             'An upgrade is likely necessary. Check http://p2pool.forre.st/ for more information.' % (
 527                 majority_desired_version, 100*desired_version_counts[majority_desired_version]/sum(desired_version_counts.itervalues())))
 528
 529     return res
 530
 531 def format_hash(x):
 532     if x is None:
 533         return 'xxxxxxxx'
 534     return '%08x' % (x % 2**32)
 535
 536 class ShareStore(object):
 537     def __init__(self, prefix, net):
 538         self.filename = prefix
 539         self.dirname = os.path.dirname(os.path.abspath(prefix))
 540         self.filename = os.path.basename(os.path.abspath(prefix))
 541         self.net = net
 542         self.known = None # will be filename -> set of share hashes, set of verified hashes
 543         self.known_desired = None
 544
 545     def get_shares(self):
 546         if self.known is not None:
 547             raise AssertionError()
 548         known = {}
 549         filenames, next = self.get_filenames_and_next()
 550         for filename in filenames:
 551             share_hashes, verified_hashes = known.setdefault(filename, (set(), set()))
 552             with open(filename, 'rb') as f:
 553                 for line in f:
 554                     try:
 555                         type_id_str, data_hex = line.strip().split(' ')
 556                         type_id = int(type_id_str)
 557                         if type_id == 0:
 558                             pass
 559                         elif type_id == 1:
 560                             pass
 561                         elif type_id == 2:
 562                             verified_hash = int(data_hex, 16)
 563                             yield 'verified_hash', verified_hash
 564                             verified_hashes.add(verified_hash)
 565                         elif type_id == 5:
 566                             raw_share = share_type.unpack(data_hex.decode('hex'))
 567                             if raw_share['type'] in [0, 1, 2, 3, 6, 7]:
 568                                 continue
 569                             share = load_share(raw_share, self.net, None)
 570                             yield 'share', share
 571                             share_hashes.add(share.hash)
 572                         else:
 573                             raise NotImplementedError("share type %i" % (type_id,))
 574                     except Exception:
 575                         log.err(None, "Error while reading saved shares, continuing where left off:")
 576         self.known = known
 577         self.known_desired = dict((k, (set(a), set(b))) for k, (a, b) in known.iteritems())
 578
 579     def _add_line(self, line):
 580         filenames, next = self.get_filenames_and_next()
 581         if filenames and os.path.getsize(filenames[-1]) < 10e6:
 582             filename = filenames[-1]
 583         else:
 584             filename = next
 585
 586         with open(filename, 'ab') as f:
 587             f.write(line + '\n')
 588
 589         return filename
 590
 591     def add_share(self, share):
 592         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 593             if share.hash in share_hashes:
 594                 break
 595         else:
 596             filename = self._add_line("%i %s" % (5, share_type.pack(share.as_share()).encode('hex')))
 597             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 598             share_hashes.add(share.hash)
 599         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 600         share_hashes.add(share.hash)
 601
 602     def add_verified_hash(self, share_hash):
 603         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 604             if share_hash in verified_hashes:
 605                 break
 606         else:
 607             filename = self._add_line("%i %x" % (2, share_hash))
 608             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 609             verified_hashes.add(share_hash)
 610         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 611         verified_hashes.add(share_hash)
 612
 613     def get_filenames_and_next(self):
 614         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())
 615         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)))
 616
 617     def forget_share(self, share_hash):
 618         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 619             if share_hash in share_hashes:
 620                 share_hashes.remove(share_hash)
 621         self.check_remove()
 622
 623     def forget_verified_share(self, share_hash):
 624         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 625             if share_hash in verified_hashes:
 626                 verified_hashes.remove(share_hash)
 627         self.check_remove()
 628
 629     def check_remove(self):
 630         to_remove = set()
 631         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 632             #print filename, len(share_hashes) + len(verified_hashes)
 633             if not share_hashes and not verified_hashes:
 634                 to_remove.add(filename)
 635         for filename in to_remove:
 636             self.known.pop(filename)
 637             self.known_desired.pop(filename)
 638             os.remove(filename)
 639             print "REMOVED", filename