def find_successor(self, id):
self.log("find_successor of {}".format(id))
# if self._predecessor exists, and _predecessor.id < id < self.id, the successor is current node
if self._predecessor and inrange(id, self._predecessor.id(),
self.id()):
return self
return self.find_predecessor(id).successor()
def init_finger(self, remote_address=None):
if remote_address:
# get the arbitrary node in which the target node want to join
remote_node = self._remote.getRemoteNode(remote_address)
# successor
successor = self.successor()
if successor is None:
successor = remote_node.find_successor(self.id())
self._successor = successor
# initialize finger table
for x in range(1, M_BIT):
start_id = (self.id() + 2**x) % NUM_SLOTS
self._finger[x] = FingerEntry(start_id, None)
for x in range(0, M_BIT - 1):
start_id = self._finger[x + 1].start
if inrange(start_id, self.id(), self._finger[x].node.id()):
self._finger[x + 1].node = self._finger[x].node
else:
#
successor = self.find_successor(start_id)
self._finger[x + 1] = FingerEntry(start_id, successor)
else:
# n is the only node in the network
for x in range(0, M_BIT):
start_id = math.floor((self.id() + 2**x) % NUM_SLOTS)
self._finger[x] = FingerEntry(start_id, self)
self.print_finger('init_finger')
def closest_preceding_finger(self, id):
# first fingers in decreasing distance, then successors in
# increasing distance.
self.log("closest_preceding_finger")
for remote in reversed(self.successors_ + self.finger_):
if remote != None and inrange(remote.id(), self.id(1), id) and remote.ping():
return remote
return self
def find_predecessor(self, id):
self.log("find_predecessor")
node = self
# If we are alone in the ring, we are the pred(id)
if node.successor().id() == node.id():
return node
while not inrange(id, node.id(1), node.successor().id(1)):
node = node.closest_preceding_finger(id)
return node
def find_predecessor(self, id):
self.log("find_predecessor")
node = self
# If we are alone in the ring, we are the pred(id)
if node.successor().id() == node.id():
return node
while not inrange(id, node.id(1), node.successor().id(1)):
node = node.closest_preceding_finger(id)
return node
def _closest_preceding_node(self, id):
# from m down to 1
for x in reversed(range(len(self._finger))):
entry = self._finger[x]
if entry != None and entry.node != None and inrange(
entry.node.id(), self.id(), id):
return entry.node
return self
def find_successor(self, id):
# The successor of a key can be us iff
# - we have a pred(n)
# - id is in (pred(n), n]
self.log("find_successor")
if self.predecessor() and \
inrange(id, self.predecessor().id(1), self.id(1)):
return self
node = self.find_predecessor(id)
return node.successor()
def find_successor(self, id):
# The successor of a key can be us iff
# - we have a pred(n)
# - id is in (pred(n), n]
self.log("find_successor")
if self.predecessor() and \
inrange(id, self.predecessor().id(1), self.id(1)):
return self
node = self.find_predecessor(id)
return node.successor()
def findPredecessor(self, id): node = self if node.successor().id() == node.id(): return node try: while node and not address.inrange(id, node.id(1), node.successor().id(1)): node = node.closestPrecedingFinger(id) return node except: pass
def find_predecessor(self, id):
lg = "find_predecessor of: {}".format(id)
self.log(lg)
node = self
# when the ring only has one node, node.id is the same as node.successor.id,
# if we are alone in the ring, we are the pred(id)
if node.id() == node.successor().id():
return node
while not inrange(id, node.id(), node.successor().id() + 1):
node = node._closest_preceding_node(id)
return node
def stabilize(self, ret = True): suc = self.successor() if suc.id() != self._finger[0].id(): self._finger[0] = suc x = suc.predecessor() if x != None and \ address.inrange(x.id(), self.id(1), suc.id()) and \ self.id(1) != suc.id() and \ x.ping(): self._finger[0] = x self.successor().notify(self) return ret
def notify(self, remote):
# Someone thinks they are our predecessor, they are iff
# - we don't have a predecessor
# OR
# - the new node r is in the range (pred(n), n)
# OR
# - our previous predecessor is dead
self.log("notify")
if self.predecessor() == None or \
inrange(remote.id(), self.predecessor().id(1), self.id()) or \
not self.predecessor().ping():
self.predecessor_ = remote
def notify(self, remote):
# Someone thinks they are our predecessor, they are iff
# - we don't have a predecessor
# OR
# - the new node r is in the range (pred(n), n)
# OR
# - our previous predecessor is dead
self.log("notify")
if self.predecessor() == None or \
inrange(remote.id(), self.predecessor().id(1), self.id()) or \
not self.predecessor().ping():
self.predecessor_ = remote
def stabilize(self):
if self._leave:
return
# prevent successor failure
successor = self.successor()
pre = successor._predecessor
if pre is not None and inrange(pre.id(), self.id(), successor.id()):
self.log('stabilize calls update_successor')
self.update_successor(pre)
successor.notify(self)
self.print_finger('stabilize')
threading.Timer(2, self.stabilize).start()
def notify(self, remote):
# Someone thinks they are our predecessor, they are iff
# - we don't have a predecessor
# OR
# - the new node r is in the range (pred(n), n)
# OR
# - our previous predecessor is dead
self.log("notified by: " + str(remote.address_))
if self.predecessor_ == None or \
inrange(remote.id(), self.predecessor_.id(1), self.id()) or \
not self.predecessor_.ping():
self.predecessor_ = remote
self.log('notify: new predecessor set: ' + str(remote.address_))
if self.notify_handler_ is not None:
self.notify_handler_(self.predecessor_)
def stabilize(self):
self.log("stabilize")
suc = self.successor()
# We may have found that x is our new successor iff
# - x = pred(suc(n))
# - x exists
# - x is in range (n, suc(n))
# - [n+1, suc(n)) is non-empty
# fix finger_[0] if successor failed
if suc.id() != self.finger_[0].id():
self.finger_[0] = suc
x = suc.predecessor()
if x != None and \
inrange(x.id(), self.id(1), suc.id()) and \
self.id(1) != suc.id() and \
x.ping():
self.finger_[0] = x
# We notify our new successor about us
self.successor().notify(self)
# Keep calling us
return True
def stabilize(self):
self.log("stabilize")
suc = self.successor()
# We may have found that x is our new successor iff
# - x = pred(suc(n))
# - x exists
# - x is in range (n, suc(n))
# - [n+1, suc(n)) is non-empty
# fix finger_[0] if successor failed
if suc.id() != self.finger_[0].id():
self.finger_[0] = suc
x = suc.predecessor()
if x != None and \
inrange(x.id(), self.id(1), suc.id()) and \
self.id(1) != suc.id() and \
x.ping():
self.finger_[0] = x
# We notify our new successor about us
self.successor().notify(self)
# Keep calling us
return True
def is_ours(self, id):
assert id >= 0 and id < SIZE
return inrange(id, self.predecessor_.id(1), self.id(1))
def update_finger(self, successor, index):
if self._finger[index] is not None:
if inrange(successor.id(),
self.id() - 1, self._finger[index].node.id()):
self._finger[index].node = successor
self._predecessor.update_finger(successor, index)
def notify(self, pre):
# check if pre is the new predecessor
if (self._predecessor is None
or inrange(pre.id(), self._predecessor.id(), self.id())):
self._predecessor = pre
def isOurs(self, id): assert id >= 0 and id < SIZE return address.inrange(id, self._pred.id(1), self.id(1))
def is_ours(self, id): assert id >= 0 and id < SIZE return inrange(id, self.predecessor_.id(1), self.id(1))
def notify(self, remote): if self.predecessor() == None or \ address.inrange(remote.id(), self.predecessor().id(1), self.id()) or \ not self.predecessor().ping(): self._pred = remote
def is_ours(self, id):
assert id >= 0 and id < SIZE
pred = self.predecessor_
if pred is None:
return True
return inrange(id, pred.id(1), self.id(1))
def closestPrecedingFinger(self, id): lists = self._succ + self._finger for remote in reversed(lists): if remote != None and address.inrange(remote.id(), self.id(1), id) and remote.ping(): return remote return self
