// Distance returns the distance metric in this key space
func (s *xorKeySpace) Distance(k1, k2 Key) *big.Int {
// XOR the keys
k3 := u.XOR(k1.Bytes, k2.Bytes)
// interpret it as an integer
dist := big.NewInt(0).SetBytes(k3)
return dist
}
// ID returns the ID of a given Conn.
func ID(c Conn) string {
l := fmt.Sprintf("%s/%s", c.LocalMultiaddr(), c.LocalPeer().ID())
r := fmt.Sprintf("%s/%s", c.RemoteMultiaddr(), c.RemotePeer().ID())
lh := u.Hash([]byte(l))
rh := u.Hash([]byte(r))
ch := u.XOR(lh, rh)
return u.Key(ch).Pretty()
}
// ID is an identifier unique to this connection.
// In MultiConn, this is all the children IDs XORed together.
func (c *MultiConn) ID() string {
c.RLock()
defer c.RUnlock()
ids := []byte(nil)
for i := range c.conns {
if ids == nil {
ids = []byte(i)
} else {
ids = u.XOR(ids, []byte(i))
}
}
return string(ids)
}
func TestDistancesAndCenterSorting(t *testing.T) {
adjs := [][]byte{
[]byte{173, 149, 19, 27, 192, 183, 153, 192, 177, 175, 71, 127, 177, 79, 207, 38, 166, 169, 247, 96, 121, 228, 139, 240, 144, 172, 183, 232, 54, 123, 253, 14},
[]byte{223, 63, 97, 152, 4, 169, 47, 219, 64, 87, 25, 45, 196, 61, 215, 72, 234, 119, 138, 220, 82, 188, 73, 140, 232, 5, 36, 192, 20, 184, 17, 25},
[]byte{73, 176, 221, 176, 149, 143, 22, 42, 129, 124, 213, 114, 232, 95, 189, 154, 18, 3, 122, 132, 32, 199, 53, 185, 58, 157, 117, 78, 52, 146, 157, 127},
[]byte{73, 176, 221, 176, 149, 143, 22, 42, 129, 124, 213, 114, 232, 95, 189, 154, 18, 3, 122, 132, 32, 199, 53, 185, 58, 157, 117, 78, 52, 146, 157, 127},
[]byte{73, 176, 221, 176, 149, 143, 22, 42, 129, 124, 213, 114, 232, 95, 189, 154, 18, 3, 122, 132, 32, 199, 53, 185, 58, 157, 117, 78, 52, 146, 157, 126},
[]byte{73, 0, 221, 176, 149, 143, 22, 42, 129, 124, 213, 114, 232, 95, 189, 154, 18, 3, 122, 132, 32, 199, 53, 185, 58, 157, 117, 78, 52, 146, 157, 127},
}
keys := make([]Key, len(adjs))
for i, a := range adjs {
keys[i] = Key{Space: XORKeySpace, Bytes: a}
}
cmp := func(a int64, b *big.Int) int {
return big.NewInt(a).Cmp(b)
}
if 0 != cmp(0, keys[2].Distance(keys[3])) {
t.Errorf("distance calculation wrong: %v", keys[2].Distance(keys[3]))
}
if 0 != cmp(1, keys[2].Distance(keys[4])) {
t.Errorf("distance calculation wrong: %v", keys[2].Distance(keys[4]))
}
d1 := keys[2].Distance(keys[5])
d2 := u.XOR(keys[2].Bytes, keys[5].Bytes)
d2 = d2[len(keys[2].Bytes)-len(d1.Bytes()):] // skip empty space for big
if !bytes.Equal(d1.Bytes(), d2) {
t.Errorf("bytes should be the same. %v == %v", d1.Bytes(), d2)
}
if -1 != cmp(2<<32, keys[2].Distance(keys[5])) {
t.Errorf("2<<32 should be smaller")
}
keys2 := SortByDistance(XORKeySpace, keys[2], keys)
order := []int{2, 3, 4, 5, 1, 0}
for i, o := range order {
if !bytes.Equal(keys[o].Bytes, keys2[i].Bytes) {
t.Errorf("order is wrong. %d?? %v == %v", o, keys[o], keys2[i])
}
}
}
func commonPrefixLen(a, b ID) int {
return ks.ZeroPrefixLen(u.XOR(a, b))
}
func xor(a, b ID) ID {
return ID(u.XOR(a, b))
}