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 xnode = self.buckets[i].l[it]
129 del(self.buckets[i].l[it])
130 # note that we removed the original and replaced it with the new one
131 # utilizing this nodes new contact info
132 self.buckets[i].l.append(xnode)
133 self.buckets[i].touch()
136 # we don't have this node, check to see if the bucket is full
137 if len(self.buckets[i].l) < K:
138 # no, append this node and return
140 node.updateLastSeen()
141 self.buckets[i].l.append(node)
142 self.buckets[i].touch()
145 # bucket is full, check to see if self.node is in the bucket
147 me = self.buckets[i].l.index(self.node)
149 return self.buckets[i].l[0]
151 ## this bucket is full and contains our node, split the bucket
152 if len(self.buckets) >= HASH_LENGTH:
154 print "Hash Table is FULL! Increase K!"
157 self._splitBucket(self.buckets[i])
159 ## now that the bucket is split and balanced, try to insert the node again
160 return self.insertNode(node)
162 def justSeenNode(self, node):
163 """ call this any time you get a message from a node, to update it in the table if it's there """
165 n = self.findNodes(node.int)[0]
173 def nodeFailed(self, node):
174 """ call this when a node fails to respond to a message, to invalidate that node """
176 n = self.findNodes(node.int)[0]
180 if(n.msgFailed() >= const.MAX_FAILURES):
181 self.replaceStaleNode(n, None)
184 __slots = ['min', 'max', 'lastAccessed']
185 def __init__(self, contents, min, max):
189 self.lastAccessed = time.time()
192 self.lastAccessed = time.time()
194 def getNodeWithInt(self, int):
196 return self.l[self.l.index(int)]
201 return "<KBucket items: %d min: %d\tmax: %d>" % (len(self.l), self.min, self.max)
203 ## comparators, necessary for bisecting list of buckets with a hash expressed as an integer or a distance
204 ## compares integer or node object with the bucket's range
206 if type(a) == InstanceType:
210 if type(a) == InstanceType:
214 if type(a) == InstanceType:
218 if type(a) == InstanceType:
222 if type(a) == InstanceType:
224 return self.min <= a and self.max > a
226 if type(a) == InstanceType:
228 return self.min >= a or self.max < a
235 class TestKTable(unittest.TestCase):
237 self.a = Node().init(hash.newID(), 'localhost', 2002)
238 self.t = KTable(self.a)
240 def test_replace_stale_node(self):
241 self.b = Node().init(hash.newID(), 'localhost', 2003)
242 self.t.replaceStaleNode(self.a, self.b)
243 assert(len(self.t.buckets[0].l) == 1)
244 assert(self.t.buckets[0].l[0].id == self.b.id)
246 if __name__ == "__main__":