p2pool/util/forest.py

   1 '''
   2 forest data structure
   3 '''
   4
   5 import itertools
   6 import weakref
   7
   8 from p2pool.util import skiplist, variable
   9 from p2pool.bitcoin import data as bitcoin_data
  10
  11
  12 class TrackerSkipList(skiplist.SkipList):
  13     def __init__(self, tracker):
  14         skiplist.SkipList.__init__(self)
  15         self.tracker = tracker
  16
  17         self_ref = weakref.ref(self, lambda _: tracker.removed.unwatch(watch_id))
  18         watch_id = self.tracker.removed.watch(lambda share: self_ref().forget_item(share.hash))
  19
  20     def previous(self, element):
  21         return self.tracker.delta_type.from_element(self.tracker.shares[element]).tail
  22
  23
  24 class DistanceSkipList(TrackerSkipList):
  25     def get_delta(self, element):
  26         return element, 1, self.previous(element)
  27
  28     def combine_deltas(self, (from_hash1, dist1, to_hash1), (from_hash2, dist2, to_hash2)):
  29         if to_hash1 != from_hash2:
  30             raise AssertionError()
  31         return from_hash1, dist1 + dist2, to_hash2
  32
  33     def initial_solution(self, start, (n,)):
  34         return 0, start
  35
  36     def apply_delta(self, (dist1, to_hash1), (from_hash2, dist2, to_hash2), (n,)):
  37         if to_hash1 != from_hash2:
  38             raise AssertionError()
  39         return dist1 + dist2, to_hash2
  40
  41     def judge(self, (dist, hash), (n,)):
  42         if dist > n:
  43             return 1
  44         elif dist == n:
  45             return 0
  46         else:
  47             return -1
  48
  49     def finalize(self, (dist, hash), (n,)):
  50         assert dist == n
  51         return hash
  52
  53 def get_attributedelta_type(attrs): # attrs: {name: func}
  54     class ProtoAttributeDelta(object):
  55         __slots__ = ['head', 'tail'] + attrs.keys()
  56
  57         @classmethod
  58         def get_none(cls, element_id):
  59             return cls(element_id, element_id, **dict((k, 0) for k in attrs))
  60
  61         @classmethod
  62         def from_element(cls, share):
  63             return cls(share.hash, share.previous_hash, **dict((k, v(share)) for k, v in attrs.iteritems()))
  64
  65         def __init__(self, head, tail, **kwargs):
  66             self.head, self.tail = head, tail
  67             for k, v in kwargs.iteritems():
  68                 setattr(self, k, v)
  69
  70         def __add__(self, other):
  71             assert self.tail == other.head
  72             return self.__class__(self.head, other.tail, **dict((k, getattr(self, k) + getattr(other, k)) for k in attrs))
  73
  74         def __sub__(self, other):
  75             if self.head == other.head:
  76                 return self.__class__(other.tail, self.tail, **dict((k, getattr(self, k) - getattr(other, k)) for k in attrs))
  77             elif self.tail == other.tail:
  78                 return self.__class__(self.head, other.head, **dict((k, getattr(self, k) - getattr(other, k)) for k in attrs))
  79             else:
  80                 raise AssertionError()
  81
  82         def __repr__(self):
  83             return '%s(%r, %r%s)' % (self.__class__, self.head, self.tail, ''.join(', %s=%r' % (k, getattr(self, k)) for k in attrs))
  84     ProtoAttributeDelta.attrs = attrs
  85     return ProtoAttributeDelta
  86
  87 AttributeDelta = get_attributedelta_type(dict(
  88     height=lambda share: 1,
  89     work=lambda share: bitcoin_data.target_to_average_attempts(share.target),
  90 ))
  91
  92 class Tracker(object):
  93     def __init__(self, shares=[], delta_type=AttributeDelta):
  94         self.shares = {} # hash -> share
  95         self.reverse_shares = {} # delta.tail -> set of share_hashes
  96
  97         self.heads = {} # head hash -> tail_hash
  98         self.tails = {} # tail hash -> set of head hashes
  99
 100         self.deltas = {} # share_hash -> delta, ref
 101         self.reverse_deltas = {} # ref -> set of share_hashes
 102
 103         self.ref_generator = itertools.count()
 104         self.delta_refs = {} # ref -> delta
 105         self.reverse_delta_refs = {} # delta.tail -> ref
 106
 107         self.added = variable.Event()
 108         self.removed = variable.Event()
 109
 110         self.get_nth_parent_hash = DistanceSkipList(self)
 111
 112         self.delta_type = delta_type
 113
 114         for share in shares:
 115             self.add(share)
 116
 117     def add(self, share):
 118         assert not isinstance(share, (int, long, type(None)))
 119         delta = self.delta_type.from_element(share)
 120
 121         if delta.head in self.shares:
 122             raise ValueError('share already present')
 123
 124         if delta.head in self.tails:
 125             heads = self.tails.pop(delta.head)
 126         else:
 127             heads = set([delta.head])
 128
 129         if delta.tail in self.heads:
 130             tail = self.heads.pop(delta.tail)
 131         else:
 132             tail = self.get_last(delta.tail)
 133
 134         self.shares[delta.head] = share
 135         self.reverse_shares.setdefault(delta.tail, set()).add(delta.head)
 136
 137         self.tails.setdefault(tail, set()).update(heads)
 138         if delta.tail in self.tails[tail]:
 139             self.tails[tail].remove(delta.tail)
 140
 141         for head in heads:
 142             self.heads[head] = tail
 143
 144         self.added.happened(share)
 145
 146     def remove(self, share_hash):
 147         assert isinstance(share_hash, (int, long, type(None)))
 148         if share_hash not in self.shares:
 149             raise KeyError()
 150
 151         share = self.shares[share_hash]
 152         del share_hash
 153
 154         delta = self.delta_type.from_element(share)
 155
 156         children = self.reverse_shares.get(delta.head, set())
 157
 158         if delta.head in self.heads and delta.tail in self.tails:
 159             tail = self.heads.pop(delta.head)
 160             self.tails[tail].remove(delta.head)
 161             if not self.tails[delta.tail]:
 162                 self.tails.pop(delta.tail)
 163         elif delta.head in self.heads:
 164             tail = self.heads.pop(delta.head)
 165             self.tails[tail].remove(delta.head)
 166             if self.reverse_shares[delta.tail] != set([delta.head]):
 167                 pass # has sibling
 168             else:
 169                 self.tails[tail].add(delta.tail)
 170                 self.heads[delta.tail] = tail
 171         elif delta.tail in self.tails and len(self.reverse_shares[delta.tail]) <= 1:
 172             # move delta refs referencing children down to this, so they can be moved up in one step
 173             if delta.tail in self.reverse_delta_refs:
 174                 for x in list(self.reverse_deltas.get(self.reverse_delta_refs.get(delta.head, object()), set())):
 175                     self.get_last(x)
 176                 assert delta.head not in self.reverse_delta_refs, list(self.reverse_deltas.get(self.reverse_delta_refs.get(delta.head, None), set()))
 177
 178             heads = self.tails.pop(delta.tail)
 179             for head in heads:
 180                 self.heads[head] = delta.head
 181             self.tails[delta.head] = set(heads)
 182
 183             # move ref pointing to this up
 184             if delta.tail in self.reverse_delta_refs:
 185                 assert delta.head not in self.reverse_delta_refs, list(self.reverse_deltas.get(self.reverse_delta_refs.get(delta.head, object()), set()))
 186
 187                 ref = self.reverse_delta_refs[delta.tail]
 188                 cur_delta = self.delta_refs[ref]
 189                 assert cur_delta.tail == delta.tail
 190                 self.delta_refs[ref] = cur_delta - self.delta_type.from_element(share)
 191                 assert self.delta_refs[ref].tail == delta.head
 192                 del self.reverse_delta_refs[delta.tail]
 193                 self.reverse_delta_refs[delta.head] = ref
 194         else:
 195             raise NotImplementedError()
 196
 197         # delete delta entry and ref if it is empty
 198         if delta.head in self.deltas:
 199             delta1, ref = self.deltas.pop(delta.head)
 200             self.reverse_deltas[ref].remove(delta.head)
 201             if not self.reverse_deltas[ref]:
 202                 del self.reverse_deltas[ref]
 203                 delta2 = self.delta_refs.pop(ref)
 204                 del self.reverse_delta_refs[delta2.tail]
 205
 206         self.shares.pop(delta.head)
 207         self.reverse_shares[delta.tail].remove(delta.head)
 208         if not self.reverse_shares[delta.tail]:
 209             self.reverse_shares.pop(delta.tail)
 210
 211         self.removed.happened(share)
 212
 213     def get_height(self, share_hash):
 214         return self.get_delta(share_hash).height
 215
 216     def get_work(self, share_hash):
 217         return self.get_delta(share_hash).work
 218
 219     def get_last(self, share_hash):
 220         return self.get_delta(share_hash).tail
 221
 222     def get_height_and_last(self, share_hash):
 223         delta = self.get_delta(share_hash)
 224         return delta.height, delta.tail
 225
 226     def get_height_work_and_last(self, share_hash):
 227         delta = self.get_delta(share_hash)
 228         return delta.height, delta.work, delta.tail
 229
 230     def _get_delta(self, share_hash):
 231         if share_hash in self.deltas:
 232             delta1, ref = self.deltas[share_hash]
 233             delta2 = self.delta_refs[ref]
 234             res = delta1 + delta2
 235         else:
 236             res = self.delta_type.from_element(self.shares[share_hash])
 237         assert res.head == share_hash
 238         return res
 239
 240     def _set_delta(self, share_hash, delta):
 241         other_share_hash = delta.tail
 242         if other_share_hash not in self.reverse_delta_refs:
 243             ref = self.ref_generator.next()
 244             assert ref not in self.delta_refs
 245             self.delta_refs[ref] = self.delta_type.get_none(other_share_hash)
 246             self.reverse_delta_refs[other_share_hash] = ref
 247             del ref
 248
 249         ref = self.reverse_delta_refs[other_share_hash]
 250         ref_delta = self.delta_refs[ref]
 251         assert ref_delta.tail == other_share_hash
 252
 253         if share_hash in self.deltas:
 254             prev_ref = self.deltas[share_hash][1]
 255             self.reverse_deltas[prev_ref].remove(share_hash)
 256             if not self.reverse_deltas[prev_ref] and prev_ref != ref:
 257                 self.reverse_deltas.pop(prev_ref)
 258                 x = self.delta_refs.pop(prev_ref)
 259                 self.reverse_delta_refs.pop(x.tail)
 260         self.deltas[share_hash] = delta - ref_delta, ref
 261         self.reverse_deltas.setdefault(ref, set()).add(share_hash)
 262
 263     def get_delta(self, share_hash):
 264         assert isinstance(share_hash, (int, long, type(None)))
 265         delta = self.delta_type.get_none(share_hash)
 266         updates = []
 267         while delta.tail in self.shares:
 268             updates.append((delta.tail, delta))
 269             this_delta = self._get_delta(delta.tail)
 270             delta += this_delta
 271         for update_hash, delta_then in updates:
 272             self._set_delta(update_hash, delta - delta_then)
 273         return delta
 274
 275     def get_chain(self, start_hash, length):
 276         assert length <= self.get_height(start_hash)
 277         for i in xrange(length):
 278             yield self.shares[start_hash]
 279             start_hash = self.delta_type.from_element(self.shares[start_hash]).tail
 280
 281     def is_child_of(self, share_hash, possible_child_hash):
 282         height, last = self.get_height_and_last(share_hash)
 283         child_height, child_last = self.get_height_and_last(possible_child_hash)
 284         if child_last != last:
 285             return None # not connected, so can't be determined
 286         height_up = child_height - height
 287         return height_up >= 0 and self.get_nth_parent_hash(possible_child_hash, height_up) == share_hash