1 ## Copyright 2002 Andrew Loewenstern, All Rights Reserved
11 # The all-powerful, magical Kademlia "k" constant, bucket depth
14 # how many bits wide is our hash?
18 # the local routing table for a kademlia like distributed hash table
20 def __init__(self, node):
21 # this is the root node, a.k.a. US!
23 self.buckets = [KBucket([], 0L, 2L**HASH_LENGTH)]
26 def _bucketIndexForInt(self, int):
27 """returns the index of the bucket that should hold int"""
28 return bisect_left(self.buckets, int)
30 def findNodes(self, id):
31 """ return k nodes in our own local table closest to the ID
32 ignoreSelf means we will return K closest nodes to ourself if we search for our own ID
33 note, K closest nodes may actually include ourself, it's the callers responsibilty to
34 not send messages to itself if it matters
36 if type(id) == StringType:
38 elif type(id) == InstanceType:
40 elif type(id) == IntType or type(id) == LongType:
43 raise TypeError, "findLocalNodes requires an int, string, or Node instance type"
47 def sort(a, b, int=int):
48 """ this function is for sorting nodes relative to the ID we are looking for """
49 x, y = int ^ a.int, int ^ b.int
56 i = self._bucketIndexForInt(int)
58 ## see if this node is already in our table and return it
60 index = self.buckets[i].l.index(int)
64 return [self.buckets[i].l[index]]
66 nodes = nodes + self.buckets[i].l
74 while (len(nodes) < K and (min >= 0 or max < len(self.buckets))):
76 nodes = nodes + self.buckets[min].l
77 if max < len(self.buckets):
78 nodes = nodes + self.buckets[max].l
84 def _splitBucket(self, a):
85 diff = (a.max - a.min) / 2
86 b = KBucket([], a.max - diff, a.max)
87 self.buckets.insert(self.buckets.index(a.min) + 1, b)
89 # transfer nodes to new bucket
91 if anode.int >= a.max:
95 def replaceStaleNode(self, stale, new):
96 """ this is used by clients to replace a node returned by insertNode after
97 it fails to respond to a Pong message
99 i = self._bucketIndexForInt(stale.int)
101 it = self.buckets[i].l.index(stale.int)
105 del(self.buckets[i].l[it])
107 self.buckets[i].l.append(new)
109 def insertNode(self, node, contacted=1):
111 this insert the node, returning None if successful, returns the oldest node in the bucket if it's full
112 the caller responsible for pinging the returned node and calling replaceStaleNode if it is found to be stale!!
113 contacted means that yes, we contacted THEM and we know the node is available
115 assert(node.id != " "*20)
116 # get the bucket for this node
117 i = self. _bucketIndexForInt(node.int)
118 ## check to see if node is in the bucket already
120 it = self.buckets[i].l.index(node.int)
126 node.updateLastSeen()
127 # move node to end of bucket
128 del(self.buckets[i].l[it])
129 # note that we removed the original and replaced it with the new one
130 # utilizing this nodes new contact info
131 self.buckets[i].l.append(node)
132 self.buckets[i].touch()
135 # we don't have this node, check to see if the bucket is full
136 if len(self.buckets[i].l) < K:
137 # no, append this node and return
139 node.updateLastSeen()
140 self.buckets[i].l.append(node)
141 self.buckets[i].touch()
144 # bucket is full, check to see if self.node is in the bucket
146 me = self.buckets[i].l.index(self.node)
148 return self.buckets[i].l[0]
150 ## this bucket is full and contains our node, split the bucket
151 if len(self.buckets) >= HASH_LENGTH:
153 print "Hash Table is FULL! Increase K!"
156 self._splitBucket(self.buckets[i])
158 ## now that the bucket is split and balanced, try to insert the node again
159 return self.insertNode(node)
161 def justSeenNode(self, node):
162 """ call this any time you get a message from a node, to update it in the table if it's there """
164 n = self.findNodes(node.int)[0]
172 def nodeFailed(self, node):
173 """ call this when a node fails to respond to a message, to invalidate that node """
175 n = self.findNodes(node.int)[0]
179 if(n.msgFailed() >= const.MAX_FAILURES):
180 self.replaceStaleNode(n, None)
183 __slots = ['min', 'max', 'lastAccessed']
184 def __init__(self, contents, min, max):
188 self.lastAccessed = time.time()
191 self.lastAccessed = time.time()
193 def getNodeWithInt(self, int):
195 return self.l[self.l.index(int)]
200 return "<KBucket items: %d min: %d\tmax: %d>" % (len(self.l), self.min, self.max)
202 ## comparators, necessary for bisecting list of buckets with a hash expressed as an integer or a distance
203 ## compares integer or node object with the bucket's range
205 if type(a) == InstanceType:
209 if type(a) == InstanceType:
213 if type(a) == InstanceType:
217 if type(a) == InstanceType:
221 if type(a) == InstanceType:
223 return self.min <= a and self.max > a
225 if type(a) == InstanceType:
227 return self.min >= a or self.max < a
234 class TestKTable(unittest.TestCase):
236 self.a = Node().init(hash.newID(), 'localhost', 2002)
237 self.t = KTable(self.a)
239 def test_replace_stale_node(self):
240 self.b = Node().init(hash.newID(), 'localhost', 2003)
241 self.t.replaceStaleNode(self.a, self.b)
242 assert(len(self.t.buckets[0].l) == 1)
243 assert(self.t.buckets[0].l[0].id == self.b.id)
245 if __name__ == "__main__":