p2pool/data.py

   1 from __future__ import division
   2
   3 import hashlib
   4 import os
   5 import random
   6 import sys
   7 import time
   8
   9 from twisted.python import log
  10
  11 import p2pool
  12 from p2pool.bitcoin import data as bitcoin_data, script, sha256
  13 from p2pool.util import math, forest, pack
  14
  15 # hashlink
  16
  17 hash_link_type = pack.ComposedType([
  18     ('state', pack.FixedStrType(32)),
  19     ('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
  20     ('length', pack.VarIntType()),
  21 ])
  22
  23 def prefix_to_hash_link(prefix, const_ending=''):
  24     assert prefix.endswith(const_ending), (prefix, const_ending)
  25     x = sha256.sha256(prefix)
  26     return dict(state=x.state, extra_data=x.buf[:max(0, len(x.buf)-len(const_ending))], length=x.length//8)
  27
  28 def check_hash_link(hash_link, data, const_ending=''):
  29     extra_length = hash_link['length'] % (512//8)
  30     assert len(hash_link['extra_data']) == max(0, extra_length - len(const_ending))
  31     extra = (hash_link['extra_data'] + const_ending)[len(hash_link['extra_data']) + len(const_ending) - extra_length:]
  32     assert len(extra) == extra_length
  33     return pack.IntType(256).unpack(hashlib.sha256(sha256.sha256(data, (hash_link['state'], extra, 8*hash_link['length'])).digest()).digest())
  34
  35 # shares
  36
  37 share_type = pack.ComposedType([
  38     ('type', pack.VarIntType()),
  39     ('contents', pack.VarStrType()),
  40 ])
  41
  42 def load_share(share, net, peer):
  43     if share['type'] in [0, 1, 2, 3, 4, 5, 6, 7, 8]:
  44         from p2pool import p2p
  45         raise p2p.PeerMisbehavingError('sent an obsolete share')
  46     elif share['type'] == Share.VERSION:
  47         return Share(net, peer, Share.share_type.unpack(share['contents']))
  48     else:
  49         raise ValueError('unknown share type: %r' % (share['type'],))
  50
  51 DONATION_SCRIPT = '4104ffd03de44a6e11b9917f3a29f9443283d9871c9d743ef30d5eddcd37094b64d1b3d8090496b53256786bf5c82932ec23c3b74d9f05a6f95a8b5529352656664bac'.decode('hex')
  52
  53 class Share(object):
  54     VERSION = 9
  55     SUCCESSOR = None
  56
  57     other_txs = None
  58
  59     small_block_header_type = pack.ComposedType([
  60         ('version', pack.VarIntType()),
  61         ('previous_block', pack.PossiblyNoneType(0, pack.IntType(256))),
  62         ('timestamp', pack.IntType(32)),
  63         ('bits', bitcoin_data.FloatingIntegerType()),
  64         ('nonce', pack.IntType(32)),
  65     ])
  66
  67     share_info_type = pack.ComposedType([
  68         ('share_data', 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         ('new_transaction_hashes', pack.ListType(pack.IntType(256))),
  79         ('transaction_hash_refs', pack.ListType(pack.ComposedType([ # compressed by referencing previous shares' hashes
  80             ('share_count', pack.VarIntType()),
  81             ('tx_count', pack.VarIntType()),
  82         ]))),
  83         ('far_share_hash', pack.PossiblyNoneType(0, pack.IntType(256))),
  84         ('max_bits', bitcoin_data.FloatingIntegerType()),
  85         ('bits', bitcoin_data.FloatingIntegerType()),
  86         ('timestamp', pack.IntType(32)),
  87     ])
  88
  89     share_type = pack.ComposedType([
  90         ('min_header', small_block_header_type),
  91         ('share_info', share_info_type),
  92         ('ref_merkle_link', pack.ComposedType([
  93             ('branch', pack.ListType(pack.IntType(256))),
  94             ('index', pack.IntType(0)),
  95         ])),
  96         ('last_txout_nonce', pack.IntType(32)),
  97         ('hash_link', hash_link_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
 104     ref_type = pack.ComposedType([
 105         ('identifier', pack.FixedStrType(64//8)),
 106         ('share_info', share_info_type),
 107     ])
 108
 109     gentx_before_refhash = pack.VarStrType().pack(DONATION_SCRIPT) + pack.IntType(64).pack(0) + pack.VarStrType().pack('\x24' + pack.IntType(256).pack(0) + pack.IntType(32).pack(0))[:2]
 110
 111     @classmethod
 112     def generate_transaction(cls, tracker, share_data, block_target, desired_timestamp, desired_target, ref_merkle_link, desired_other_transaction_hashes, net, known_txs=None, last_txout_nonce=0):
 113         previous_share = tracker.items[share_data['previous_share_hash']] if share_data['previous_share_hash'] is not None else None
 114
 115         height, last = tracker.get_height_and_last(share_data['previous_share_hash'])
 116         assert height >= net.REAL_CHAIN_LENGTH or last is None
 117         if height < net.TARGET_LOOKBEHIND:
 118             pre_target3 = net.MAX_TARGET
 119         else:
 120             attempts_per_second = get_pool_attempts_per_second(tracker, share_data['previous_share_hash'], net.TARGET_LOOKBEHIND, min_work=True, integer=True)
 121             pre_target = 2**256//(net.SHARE_PERIOD*attempts_per_second) - 1 if attempts_per_second else 2**256-1
 122             pre_target2 = math.clip(pre_target, (previous_share.max_target*9//10, previous_share.max_target*11//10))
 123             pre_target3 = math.clip(pre_target2, (net.MIN_TARGET, net.MAX_TARGET))
 124         max_bits = bitcoin_data.FloatingInteger.from_target_upper_bound(pre_target3)
 125         bits = bitcoin_data.FloatingInteger.from_target_upper_bound(math.clip(desired_target, (pre_target3//10, pre_target3)))
 126
 127         weights, total_weight, donation_weight = tracker.get_cumulative_weights(share_data['previous_share_hash'],
 128             min(height, net.REAL_CHAIN_LENGTH),
 129             65535*net.SPREAD*bitcoin_data.target_to_average_attempts(block_target),
 130         )
 131         assert total_weight == sum(weights.itervalues()) + donation_weight, (total_weight, sum(weights.itervalues()) + donation_weight)
 132
 133         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
 134         this_script = bitcoin_data.pubkey_hash_to_script2(share_data['pubkey_hash'])
 135         amounts[this_script] = amounts.get(this_script, 0) + share_data['subsidy']//200 # 0.5% goes to block finder
 136         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
 137
 138         if sum(amounts.itervalues()) != share_data['subsidy'] or any(x < 0 for x in amounts.itervalues()):
 139             raise ValueError()
 140
 141         dests = sorted(amounts.iterkeys(), key=lambda script: (script == DONATION_SCRIPT, amounts[script], script))[-4000:] # block length limit, unlikely to ever be hit
 142
 143         new_transaction_hashes = []
 144         new_transaction_size = 0
 145         transaction_hash_refs = []
 146         other_transaction_hashes = []
 147
 148         for tx_hash in desired_other_transaction_hashes:
 149             for i, share in enumerate(tracker.get_chain(share_data['previous_share_hash'], min(height, 100))):
 150                 if tx_hash in share.new_transaction_hashes:
 151                     this = dict(share_count=i+1, tx_count=share.new_transaction_hashes.index(tx_hash))
 152                     break
 153             else:
 154                 if known_txs is not None:
 155                     this_size = bitcoin_data.tx_type.packed_size(known_txs[tx_hash])
 156                     if new_transaction_size + this_size > 50000: # only allow 50 kB of new txns/share
 157                         break
 158                     new_transaction_size += this_size
 159                 new_transaction_hashes.append(tx_hash)
 160                 this = dict(share_count=0, tx_count=len(new_transaction_hashes)-1)
 161             transaction_hash_refs.append(this)
 162             other_transaction_hashes.append(tx_hash)
 163
 164         share_info = dict(
 165             share_data=share_data,
 166             far_share_hash=None if last is None and height < 99 else tracker.get_nth_parent_hash(share_data['previous_share_hash'], 99),
 167             max_bits=max_bits,
 168             bits=bits,
 169             timestamp=math.clip(desired_timestamp, (
 170                 (previous_share.timestamp + net.SHARE_PERIOD) - (net.SHARE_PERIOD - 1), # = previous_share.timestamp + 1
 171                 (previous_share.timestamp + net.SHARE_PERIOD) + (net.SHARE_PERIOD - 1),
 172             )) if previous_share is not None else desired_timestamp,
 173             new_transaction_hashes=new_transaction_hashes,
 174             transaction_hash_refs=transaction_hash_refs,
 175         )
 176
 177         gentx = dict(
 178             version=1,
 179             tx_ins=[dict(
 180                 previous_output=None,
 181                 sequence=None,
 182                 script=share_data['coinbase'],
 183             )],
 184             tx_outs=[dict(value=amounts[script], script=script) for script in dests if amounts[script] or script == DONATION_SCRIPT] + [dict(
 185                 value=0,
 186                 script='\x24' + cls.get_ref_hash(net, share_info, ref_merkle_link) + pack.IntType(32).pack(last_txout_nonce),
 187             )],
 188             lock_time=0,
 189         )
 190
 191         def get_share(header, transactions):
 192             min_header=dict(header);del min_header['merkle_root']
 193             return cls(net, None, dict(
 194                 min_header=min_header,
 195                 share_info=share_info,
 196                 ref_merkle_link=dict(branch=[], index=0),
 197                 last_txout_nonce=last_txout_nonce,
 198                 hash_link=prefix_to_hash_link(bitcoin_data.tx_type.pack(gentx)[:-32-4-4], cls.gentx_before_refhash),
 199                 merkle_link=bitcoin_data.calculate_merkle_link([None] + other_transaction_hashes, 0),
 200             ))
 201
 202         return share_info, gentx, other_transaction_hashes, get_share
 203
 204     @classmethod
 205     def get_ref_hash(cls, net, share_info, ref_merkle_link):
 206         return pack.IntType(256).pack(bitcoin_data.check_merkle_link(bitcoin_data.hash256(cls.ref_type.pack(dict(
 207             identifier=net.IDENTIFIER,
 208             share_info=share_info,
 209         ))), ref_merkle_link))
 210
 211     __slots__ = 'net peer contents min_header share_info hash_link merkle_link hash share_data max_target target timestamp previous_hash new_script desired_version gentx_hash header pow_hash header_hash new_transaction_hashes time_seen'.split(' ')
 212
 213     def __init__(self, net, peer, contents):
 214         self.net = net
 215         self.peer = peer
 216         self.contents = contents
 217
 218         self.min_header = contents['min_header']
 219         self.share_info = contents['share_info']
 220         self.hash_link = contents['hash_link']
 221         self.merkle_link = contents['merkle_link']
 222
 223         if not (2 <= len(self.share_info['share_data']['coinbase']) <= 100):
 224             raise ValueError('''bad coinbase size! %i bytes''' % (len(self.share_info['share_data']['coinbase']),))
 225
 226         if len(self.merkle_link['branch']) > 16:
 227             raise ValueError('merkle branch too long!')
 228
 229         assert not self.hash_link['extra_data'], repr(self.hash_link['extra_data'])
 230
 231         self.share_data = self.share_info['share_data']
 232         self.max_target = self.share_info['max_bits'].target
 233         self.target = self.share_info['bits'].target
 234         self.timestamp = self.share_info['timestamp']
 235         self.previous_hash = self.share_data['previous_share_hash']
 236         self.new_script = bitcoin_data.pubkey_hash_to_script2(self.share_data['pubkey_hash'])
 237         self.desired_version = self.share_data['desired_version']
 238
 239         n = set()
 240         for x in self.share_info['transaction_hash_refs']:
 241             assert x['share_count'] < 110
 242             if x['share_count'] == 0:
 243                 n.add(x['tx_count'])
 244         assert n == set(range(len(self.share_info['new_transaction_hashes'])))
 245
 246         self.gentx_hash = check_hash_link(
 247             self.hash_link,
 248             self.get_ref_hash(net, self.share_info, contents['ref_merkle_link']) + pack.IntType(32).pack(self.contents['last_txout_nonce']) + pack.IntType(32).pack(0),
 249             self.gentx_before_refhash,
 250         )
 251         merkle_root = bitcoin_data.check_merkle_link(self.gentx_hash, self.merkle_link)
 252         self.header = dict(self.min_header, merkle_root=merkle_root)
 253         self.pow_hash = net.PARENT.POW_FUNC(bitcoin_data.block_header_type.pack(self.header))
 254         self.hash = self.header_hash = bitcoin_data.hash256(bitcoin_data.block_header_type.pack(self.header))
 255
 256         if self.target > net.MAX_TARGET:
 257             from p2pool import p2p
 258             raise p2p.PeerMisbehavingError('share target invalid')
 259
 260         if self.pow_hash > self.target:
 261             from p2pool import p2p
 262             raise p2p.PeerMisbehavingError('share PoW invalid')
 263
 264         self.new_transaction_hashes = self.share_info['new_transaction_hashes']
 265
 266         # XXX eww
 267         self.time_seen = time.time()
 268
 269     def __repr__(self):
 270         return 'Share' + repr((self.net, self.peer, self.contents))
 271
 272     def as_share(self):
 273         return dict(type=self.VERSION, contents=self.share_type.pack(self.contents))
 274
 275     def check(self, tracker):
 276         from p2pool import p2p
 277         if self.share_data['previous_share_hash'] is not None:
 278             previous_share = tracker.items[self.share_data['previous_share_hash']]
 279             if type(self) is type(previous_share):
 280                 pass
 281             elif type(self) is type(previous_share).SUCCESSOR:
 282                 if tracker.get_height(previous_share.hash) < self.net.CHAIN_LENGTH:
 283                     from p2pool import p2p
 284                     raise p2p.PeerMisbehavingError('switch without enough history')
 285
 286                 # switch only valid if 85% of hashes in [self.net.CHAIN_LENGTH*9//10, self.net.CHAIN_LENGTH] for new version
 287                 counts = get_desired_version_counts(tracker,
 288                     tracker.get_nth_parent_hash(previous_share.hash, self.net.CHAIN_LENGTH*9//10), self.net.CHAIN_LENGTH//10)
 289                 if counts.get(self.VERSION, 0) < sum(counts.itervalues())*85//100:
 290                     raise p2p.PeerMisbehavingError('switch without enough hash power upgraded')
 291             else:
 292                 raise p2p.PeerMisbehavingError('''%s can't follow %s''' % (type(self).__name__, type(previous_share).__name__))
 293
 294         other_tx_hashes = [tracker.items[tracker.get_nth_parent_hash(self.hash, x['share_count'])].share_info['new_transaction_hashes'][x['tx_count']] for x in self.share_info['transaction_hash_refs']]
 295
 296         share_info, gentx, other_tx_hashes2, get_share = self.generate_transaction(tracker, self.share_info['share_data'], self.header['bits'].target, self.share_info['timestamp'], self.share_info['bits'].target, self.contents['ref_merkle_link'], other_tx_hashes, self.net, last_txout_nonce=self.contents['last_txout_nonce'])
 297         assert other_tx_hashes2 == other_tx_hashes
 298         if share_info != self.share_info:
 299             raise ValueError('share_info invalid')
 300         if bitcoin_data.hash256(bitcoin_data.tx_type.pack(gentx)) != self.gentx_hash:
 301             raise ValueError('''gentx doesn't match hash_link''')
 302
 303         if bitcoin_data.calculate_merkle_link([None] + other_tx_hashes, 0) != self.merkle_link:
 304             raise ValueError('merkle_link and other_tx_hashes do not match')
 305
 306         return gentx # only used by as_block
 307
 308     def get_other_tx_hashes(self, tracker):
 309         parents_needed = max(x['share_count'] for x in self.share_info['transaction_hash_refs']) if self.share_info['transaction_hash_refs'] else 0
 310         parents = tracker.get_height(self.hash) - 1
 311         if parents < parents_needed:
 312             return None
 313         last_shares = list(tracker.get_chain(self.hash, parents_needed + 1))
 314         return [last_shares[x['share_count']].share_info['new_transaction_hashes'][x['tx_count']] for x in self.share_info['transaction_hash_refs']]
 315
 316     def _get_other_txs(self, tracker, known_txs):
 317         other_tx_hashes = self.get_other_tx_hashes(tracker)
 318         if other_tx_hashes is None:
 319             return None # not all parents present
 320
 321         if not all(tx_hash in known_txs for tx_hash in other_tx_hashes):
 322             return None # not all txs present
 323
 324         return [known_txs[tx_hash] for tx_hash in other_tx_hashes]
 325
 326     def should_punish_reason(self, previous_block, bits, tracker, known_txs):
 327         if (self.header['previous_block'], self.header['bits']) != (previous_block, bits) and self.header_hash != previous_block and self.peer is not None:
 328             return True, 'Block-stale detected! %x < %x' % (self.header['previous_block'], previous_block)
 329
 330         if self.pow_hash <= self.header['bits'].target:
 331             return -1, 'block solution'
 332
 333         other_txs = self._get_other_txs(tracker, known_txs)
 334         if other_txs is None:
 335             if self.time_seen is not None: # ignore if loaded from ShareStore
 336                 return True, 'not all txs present'
 337         else:
 338             all_txs_size = sum(bitcoin_data.tx_type.packed_size(tx) for tx in other_txs)
 339             if all_txs_size > 1000000:
 340                 return True, 'txs over block size limit'
 341
 342             new_txs_size = sum(bitcoin_data.tx_type.packed_size(known_txs[tx_hash]) for tx_hash in self.share_info['new_transaction_hashes'])
 343             if new_txs_size > 50000:
 344                 return True, 'new txs over limit'
 345
 346         return False, None
 347
 348     def as_block(self, tracker, known_txs):
 349         other_txs = self._get_other_txs(tracker, known_txs)
 350         if other_txs is None:
 351             return None # not all txs present
 352         return dict(header=self.header, txs=[self.check(tracker)] + other_txs)
 353
 354
 355 class WeightsSkipList(forest.TrackerSkipList):
 356     # share_count, weights, total_weight
 357
 358     def get_delta(self, element):
 359         from p2pool.bitcoin import data as bitcoin_data
 360         share = self.tracker.items[element]
 361         att = bitcoin_data.target_to_average_attempts(share.target)
 362         return 1, {share.new_script: att*(65535-share.share_data['donation'])}, att*65535, att*share.share_data['donation']
 363
 364     def combine_deltas(self, (share_count1, weights1, total_weight1, total_donation_weight1), (share_count2, weights2, total_weight2, total_donation_weight2)):
 365         return share_count1 + share_count2, math.add_dicts(weights1, weights2), total_weight1 + total_weight2, total_donation_weight1 + total_donation_weight2
 366
 367     def initial_solution(self, start, (max_shares, desired_weight)):
 368         assert desired_weight % 65535 == 0, divmod(desired_weight, 65535)
 369         return 0, None, 0, 0
 370
 371     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)):
 372         if total_weight1 + total_weight2 > desired_weight and share_count2 == 1:
 373             assert (desired_weight - total_weight1) % 65535 == 0
 374             script, = weights2.iterkeys()
 375             new_weights = {script: (desired_weight - total_weight1)//65535*weights2[script]//(total_weight2//65535)}
 376             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)
 377         return share_count1 + share_count2, (weights_list, weights2), total_weight1 + total_weight2, total_donation_weight1 + total_donation_weight2
 378
 379     def judge(self, (share_count, weights_list, total_weight, total_donation_weight), (max_shares, desired_weight)):
 380         if share_count > max_shares or total_weight > desired_weight:
 381             return 1
 382         elif share_count == max_shares or total_weight == desired_weight:
 383             return 0
 384         else:
 385             return -1
 386
 387     def finalize(self, (share_count, weights_list, total_weight, total_donation_weight), (max_shares, desired_weight)):
 388         assert share_count <= max_shares and total_weight <= desired_weight
 389         assert share_count == max_shares or total_weight == desired_weight
 390         return math.add_dicts(*math.flatten_linked_list(weights_list)), total_weight, total_donation_weight
 391
 392 class OkayTracker(forest.Tracker):
 393     def __init__(self, net):
 394         forest.Tracker.__init__(self, delta_type=forest.get_attributedelta_type(dict(forest.AttributeDelta.attrs,
 395             work=lambda share: bitcoin_data.target_to_average_attempts(share.target),
 396             min_work=lambda share: bitcoin_data.target_to_average_attempts(share.max_target),
 397         )))
 398         self.net = net
 399         self.verified = forest.SubsetTracker(delta_type=forest.get_attributedelta_type(dict(forest.AttributeDelta.attrs,
 400             work=lambda share: bitcoin_data.target_to_average_attempts(share.target),
 401         )), subset_of=self)
 402         self.get_cumulative_weights = WeightsSkipList(self)
 403
 404     def attempt_verify(self, share):
 405         if share.hash in self.verified.items:
 406             return True
 407         height, last = self.get_height_and_last(share.hash)
 408         if height < self.net.CHAIN_LENGTH + 1 and last is not None:
 409             raise AssertionError()
 410         try:
 411             share.check(self)
 412         except:
 413             log.err(None, 'Share check failed:')
 414             return False
 415         else:
 416             self.verified.add(share)
 417             return True
 418
 419     def think(self, block_rel_height_func, previous_block, bits, known_txs):
 420         desired = set()
 421
 422         # O(len(self.heads))
 423         #   make 'unverified heads' set?
 424         # for each overall head, attempt verification
 425         # if it fails, attempt on parent, and repeat
 426         # if no successful verification because of lack of parents, request parent
 427         bads = set()
 428         for head in set(self.heads) - set(self.verified.heads):
 429             head_height, last = self.get_height_and_last(head)
 430
 431             for share in self.get_chain(head, head_height if last is None else min(5, max(0, head_height - self.net.CHAIN_LENGTH))):
 432                 if self.attempt_verify(share):
 433                     break
 434                 if share.hash in self.heads:
 435                     bads.add(share.hash)
 436             else:
 437                 if last is not None:
 438                     desired.add((
 439                         self.items[random.choice(list(self.reverse[last]))].peer,
 440                         last,
 441                         max(x.timestamp for x in self.get_chain(head, min(head_height, 5))),
 442                         min(x.target for x in self.get_chain(head, min(head_height, 5))),
 443                     ))
 444         for bad in bads:
 445             assert bad not in self.verified.items
 446             assert bad in self.heads
 447             if p2pool.DEBUG:
 448                 print "BAD", bad
 449             self.remove(bad)
 450
 451         # try to get at least CHAIN_LENGTH height for each verified head, requesting parents if needed
 452         for head in list(self.verified.heads):
 453             head_height, last_hash = self.verified.get_height_and_last(head)
 454             last_height, last_last_hash = self.get_height_and_last(last_hash)
 455             # XXX review boundary conditions
 456             want = max(self.net.CHAIN_LENGTH - head_height, 0)
 457             can = max(last_height - 1 - self.net.CHAIN_LENGTH, 0) if last_last_hash is not None else last_height
 458             get = min(want, can)
 459             #print 'Z', head_height, last_hash is None, last_height, last_last_hash is None, want, can, get
 460             for share in self.get_chain(last_hash, get):
 461                 if not self.attempt_verify(share):
 462                     break
 463             if head_height < self.net.CHAIN_LENGTH and last_last_hash is not None:
 464                 desired.add((
 465                     self.items[random.choice(list(self.verified.reverse[last_hash]))].peer,
 466                     last_last_hash,
 467                     max(x.timestamp for x in self.get_chain(head, min(head_height, 5))),
 468                     min(x.target for x in self.get_chain(head, min(head_height, 5))),
 469                 ))
 470
 471         # decide best tree
 472         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)
 473         if p2pool.DEBUG:
 474             print len(decorated_tails), 'tails:'
 475             for score, tail_hash in decorated_tails:
 476                 print format_hash(tail_hash), score
 477         best_tail_score, best_tail = decorated_tails[-1] if decorated_tails else (None, None)
 478
 479         # decide best verified head
 480         decorated_heads = sorted(((
 481             self.verified.get_work(self.verified.get_nth_parent_hash(h, min(5, self.verified.get_height(h)))),
 482             #self.items[h].peer is None,
 483             -self.items[h].should_punish_reason(previous_block, bits, self, known_txs)[0],
 484             -self.items[h].time_seen,
 485         ), h) for h in self.verified.tails.get(best_tail, []))
 486         if p2pool.DEBUG:
 487             print len(decorated_heads), 'heads. Top 10:'
 488             for score, head_hash in decorated_heads[-10:]:
 489                 print '   ', format_hash(head_hash), format_hash(self.items[head_hash].previous_hash), score
 490         best_head_score, best = decorated_heads[-1] if decorated_heads else (None, None)
 491
 492         if best is not None:
 493             best_share = self.items[best]
 494             punish, punish_reason = best_share.should_punish_reason(previous_block, bits, self, known_txs)
 495             if punish > 0:
 496                 print 'Punishing share for %r! Jumping from %s to %s!' % (punish_reason, format_hash(best), format_hash(best_share.previous_hash))
 497                 best = best_share.previous_hash
 498
 499             timestamp_cutoff = min(int(time.time()), best_share.timestamp) - 3600
 500             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
 501         else:
 502             timestamp_cutoff = int(time.time()) - 24*60*60
 503             target_cutoff = 2**256-1
 504
 505         if p2pool.DEBUG:
 506             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))
 507             for peer, hash, ts, targ in desired:
 508                 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
 509
 510         return best, [(peer, hash) for peer, hash, ts, targ in desired if ts >= timestamp_cutoff], decorated_heads
 511
 512     def score(self, share_hash, block_rel_height_func):
 513         # returns approximate lower bound on chain's hashrate in the last self.net.CHAIN_LENGTH*15//16*self.net.SHARE_PERIOD time
 514
 515         head_height = self.verified.get_height(share_hash)
 516         if head_height < self.net.CHAIN_LENGTH:
 517             return head_height, None
 518
 519         end_point = self.verified.get_nth_parent_hash(share_hash, self.net.CHAIN_LENGTH*15//16)
 520
 521         block_height = max(block_rel_height_func(share.header['previous_block']) for share in
 522             self.verified.get_chain(end_point, self.net.CHAIN_LENGTH//16))
 523
 524         return self.net.CHAIN_LENGTH, self.verified.get_delta(share_hash, end_point).work//((0 - block_height + 1)*self.net.PARENT.BLOCK_PERIOD)
 525
 526 def get_pool_attempts_per_second(tracker, previous_share_hash, dist, min_work=False, integer=False):
 527     assert dist >= 2
 528     near = tracker.items[previous_share_hash]
 529     far = tracker.items[tracker.get_nth_parent_hash(previous_share_hash, dist - 1)]
 530     attempts = tracker.get_delta(near.hash, far.hash).work if not min_work else tracker.get_delta(near.hash, far.hash).min_work
 531     time = near.timestamp - far.timestamp
 532     if time <= 0:
 533         time = 1
 534     if integer:
 535         return attempts//time
 536     return attempts/time
 537
 538 def get_average_stale_prop(tracker, share_hash, lookbehind):
 539     stales = sum(1 for share in tracker.get_chain(share_hash, lookbehind) if share.share_data['stale_info'] is not None)
 540     return stales/(lookbehind + stales)
 541
 542 def get_stale_counts(tracker, share_hash, lookbehind, rates=False):
 543     res = {}
 544     for share in tracker.get_chain(share_hash, lookbehind - 1):
 545         res['good'] = res.get('good', 0) + bitcoin_data.target_to_average_attempts(share.target)
 546         s = share.share_data['stale_info']
 547         if s is not None:
 548             res[s] = res.get(s, 0) + bitcoin_data.target_to_average_attempts(share.target)
 549     if rates:
 550         dt = tracker.items[share_hash].timestamp - tracker.items[tracker.get_nth_parent_hash(share_hash, lookbehind - 1)].timestamp
 551         res = dict((k, v/dt) for k, v in res.iteritems())
 552     return res
 553
 554 def get_user_stale_props(tracker, share_hash, lookbehind):
 555     res = {}
 556     for share in tracker.get_chain(share_hash, lookbehind - 1):
 557         stale, total = res.get(share.share_data['pubkey_hash'], (0, 0))
 558         total += 1
 559         if share.share_data['stale_info'] is not None:
 560             stale += 1
 561             total += 1
 562         res[share.share_data['pubkey_hash']] = stale, total
 563     return dict((pubkey_hash, stale/total) for pubkey_hash, (stale, total) in res.iteritems())
 564
 565 def get_expected_payouts(tracker, best_share_hash, block_target, subsidy, net):
 566     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))
 567     res = dict((script, subsidy*weight//total_weight) for script, weight in weights.iteritems())
 568     res[DONATION_SCRIPT] = res.get(DONATION_SCRIPT, 0) + subsidy - sum(res.itervalues())
 569     return res
 570
 571 def get_desired_version_counts(tracker, best_share_hash, dist):
 572     res = {}
 573     for share in tracker.get_chain(best_share_hash, dist):
 574         res[share.desired_version] = res.get(share.desired_version, 0) + bitcoin_data.target_to_average_attempts(share.target)
 575     return res
 576
 577 def get_warnings(tracker, best_share, net, bitcoind_warning, bitcoind_work_value):
 578     res = []
 579
 580     desired_version_counts = get_desired_version_counts(tracker, best_share,
 581         min(net.CHAIN_LENGTH, 60*60//net.SHARE_PERIOD, tracker.get_height(best_share)))
 582     majority_desired_version = max(desired_version_counts, key=lambda k: desired_version_counts[k])
 583     if majority_desired_version > Share.VERSION and desired_version_counts[majority_desired_version] > sum(desired_version_counts.itervalues())/2:
 584         res.append('A MAJORITY OF SHARES CONTAIN A VOTE FOR AN UNSUPPORTED SHARE IMPLEMENTATION! (v%i with %i%% support)\n'
 585             'An upgrade is likely necessary. Check http://p2pool.forre.st/ for more information.' % (
 586                 majority_desired_version, 100*desired_version_counts[majority_desired_version]/sum(desired_version_counts.itervalues())))
 587
 588     if bitcoind_warning is not None:
 589         if 'This is a pre-release test build' not in bitcoind_warning:
 590             res.append('(from bitcoind) %s' % (bitcoind_warning,))
 591
 592     if time.time() > bitcoind_work_value['last_update'] + 60:
 593         res.append('''LOST CONTACT WITH BITCOIND for %s! Check that it isn't frozen or dead!''' % (math.format_dt(time.time() - bitcoind_work_value['last_update']),))
 594
 595     return res
 596
 597 def format_hash(x):
 598     if x is None:
 599         return 'xxxxxxxx'
 600     return '%08x' % (x % 2**32)
 601
 602 class ShareStore(object):
 603     def __init__(self, prefix, net):
 604         self.filename = prefix
 605         self.dirname = os.path.dirname(os.path.abspath(prefix))
 606         self.filename = os.path.basename(os.path.abspath(prefix))
 607         self.net = net
 608         self.known = None # will be filename -> set of share hashes, set of verified hashes
 609         self.known_desired = None
 610
 611     def get_shares(self):
 612         if self.known is not None:
 613             raise AssertionError()
 614         known = {}
 615         filenames, next = self.get_filenames_and_next()
 616         for filename in filenames:
 617             share_hashes, verified_hashes = known.setdefault(filename, (set(), set()))
 618             with open(filename, 'rb') as f:
 619                 for line in f:
 620                     try:
 621                         type_id_str, data_hex = line.strip().split(' ')
 622                         type_id = int(type_id_str)
 623                         if type_id == 0:
 624                             pass
 625                         elif type_id == 1:
 626                             pass
 627                         elif type_id == 2:
 628                             verified_hash = int(data_hex, 16)
 629                             yield 'verified_hash', verified_hash
 630                             verified_hashes.add(verified_hash)
 631                         elif type_id == 5:
 632                             raw_share = share_type.unpack(data_hex.decode('hex'))
 633                             if raw_share['type'] in [0, 1, 2, 3, 4, 5, 6, 7, 8]:
 634                                 continue
 635                             share = load_share(raw_share, self.net, None)
 636                             yield 'share', share
 637                             share_hashes.add(share.hash)
 638                         else:
 639                             raise NotImplementedError("share type %i" % (type_id,))
 640                     except Exception:
 641                         log.err(None, "HARMLESS error while reading saved shares, continuing where left off:")
 642         self.known = known
 643         self.known_desired = dict((k, (set(a), set(b))) for k, (a, b) in known.iteritems())
 644
 645     def _add_line(self, line):
 646         filenames, next = self.get_filenames_and_next()
 647         if filenames and os.path.getsize(filenames[-1]) < 10e6:
 648             filename = filenames[-1]
 649         else:
 650             filename = next
 651
 652         with open(filename, 'ab') as f:
 653             f.write(line + '\n')
 654
 655         return filename
 656
 657     def add_share(self, share):
 658         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 659             if share.hash in share_hashes:
 660                 break
 661         else:
 662             filename = self._add_line("%i %s" % (5, share_type.pack(share.as_share()).encode('hex')))
 663             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 664             share_hashes.add(share.hash)
 665         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 666         share_hashes.add(share.hash)
 667
 668     def add_verified_hash(self, share_hash):
 669         for filename, (share_hashes, verified_hashes) in self.known.iteritems():
 670             if share_hash in verified_hashes:
 671                 break
 672         else:
 673             filename = self._add_line("%i %x" % (2, share_hash))
 674             share_hashes, verified_hashes = self.known.setdefault(filename, (set(), set()))
 675             verified_hashes.add(share_hash)
 676         share_hashes, verified_hashes = self.known_desired.setdefault(filename, (set(), set()))
 677         verified_hashes.add(share_hash)
 678
 679     def get_filenames_and_next(self):
 680         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())
 681         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)))
 682
 683     def forget_share(self, share_hash):
 684         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 685             if share_hash in share_hashes:
 686                 share_hashes.remove(share_hash)
 687         self.check_remove()
 688
 689     def forget_verified_share(self, share_hash):
 690         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 691             if share_hash in verified_hashes:
 692                 verified_hashes.remove(share_hash)
 693         self.check_remove()
 694
 695     def check_remove(self):
 696         to_remove = set()
 697         for filename, (share_hashes, verified_hashes) in self.known_desired.iteritems():
 698             #print filename, len(share_hashes) + len(verified_hashes)
 699             if not share_hashes and not verified_hashes:
 700                 to_remove.add(filename)
 701         for filename in to_remove:
 702             self.known.pop(filename)
 703             self.known_desired.pop(filename)
 704             os.remove(filename)
 705             print "REMOVED", filename