def stabilize (self):
"""
implements stabilize code of Chord's paper, fig 6
with some error handling
returns: naught
"""
self.debug (1, "stab!")
# * we must have a head to talk to
succ= self.getSucc ()
if succ:
self._succLock.acquire ()
self.debug (2, "stab-2!")
try:
(url, key)= succ.pred ()
self.debug (1, "stab-3! key: %s" % str(key))
# None,None means he has none
if key and ooBetween (self.key (), key, succ.key ()):
# save it for restoring on exception
self._prevSucc= succ
succ= self._peers.getNavel (url, key)
self.debug (1, "stab-4!")
self.setSucc (succ)
self.debug (1, "stab-5!")
try:
# do not give data to ourselves
self.debug (1, 'notifying w/ %s' % succ)
if succ.notify (self.params ()):
self.keypass ()
except UmbDead:
self.debug (1, "%s:%s's dead, Jim!" % (url, key))
# self.delNavel (key)
# this one's dead; restore the previous one
self.setSucc (self._prevSucc)
# should we notify the old one?
else:
# don't care about this
self.debug (1, 'notifying w/ %s' % succ)
succ.notify (self.params ())
except UmbDead:
self.debug (1, "%s's dead, Jim!" % (self._succ.key ()))
# self.delNavel (self._succ.key ())
self.setSucc (None)
self._succLock.release ()
self.debug (1, 'stab finished')
def notify (self, url, key):
"""
implements chord's notify.
returns: True if the notifying peer is now our pred, False otherwise
"""
result= False
self.debug (1, "notify!")
self._predLock.acquire ()
self.debug (2, "pred locked")
pred= self.getPred ()
prevPred= pred
if not pred or ooBetween (pred.key (), key, self.key ()):
# self.debug (1, "set %s,%s as new pred" % (url, key))
pred= self._peers.getNavel (url, key)
self.setPred (pred)
# don't talk in the brain
if not pred==self._self:
# give our data so he makes a backup
self.debug (1, 'giving data as backup')
# this may fail
try:
given= self.giveData (self.key (), self._succ.key (), self.Set)
pred.backupData (given)
# shouldn't we also tell him to forget about anything else?
# nope
if prevPred:
# no more business w/ him
prevPred.close ()
# gotta save it for later ref.
self._prevPred= prevPred
except UmbDead:
self.debug (1, '\'tis dead, Jim!')
self.setPred (prevPred)
result= True
self._predLock.release ()
self.debug (2, "pred released")
return result
