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