def stabilize(self):
try:
s = self.send(self.state.successor, 'get_predecessor')
resp = s.recv(1024).decode('utf-8')
if resp != 'None':
x_ip, x_port = resp.split(':')
x = Address(x_ip, x_port)
s.close()
if in_range(x.__hash__(), self.state.id,
self.state.successor.__hash__()):
self.state.lock.acquire()
self.state.finger[0] = x.__hash__()
self.state.successor = x
self.state.addr_dict[str(x.__hash__())] = x
self.state.lock.release()
# else:
except:
self.state.lock.acquire()
del self.state.addr_dict[str(self.state.successor.__hash__())]
self.state.successor = self.state.local_address
self.state.finger[0] = self.state.id
self.state.lock.release()
self.send(self.state.successor,
'notify {} {}'.format(self.state.ip,
self.state.port)).close()
def fix_finger(self):
self.state.lock.acquire()
self.state.i = self.state.i + 1
if self.state.i > M:
self.state.i = 1
s = self.send(self.state.local_address, 'find_successor {}'.format((self.state.id + pow(2, self.state.i-1)) % 2**M))
n_ip, n_port = s.recv(1024).decode('utf-8').split(':')
n = Address(n_ip, n_port)
s.close()
self.state.addr_dict[str(n.__hash__())] = n
self.state.finger[self.state.i-1] = n.__hash__()
# debug(self, "Finger:", self.state.finger)
self.state.lock.release()
def notify(self, ip, port):
n_ = Address(ip, port)
if self.state.predecessor == None or\
in_range(n_.__hash__(), self.state.predecessor.__hash__(), self.state.id):
self.state.lock.acquire()
self.state.predecessor = n_
self.state.lock.release()
class State:
def __init__(self, port=8000):
self.in_ring = False # becomes True when this node has created or joined a ring
self.ip = socket.gethostbyname(socket.gethostname())
self.port = port
self.local_address = Address(self.ip, self.port)
self.id = self.local_address.__hash__()
self.predecessor = None
self.successor = None
self.finger = [None] * M # contains finger nodes' Chord ids
self.addr_dict = {
} # key: a Chord id; value: corresponding Address (IP/port)
self.i = 1
self.lock = Lock()
def __init__(self, address):
# ip addresses
self._address = address
self._base_address = address[0]
# all slots, a ring
nodes = [None for x in range(NUM_SLOTS)]
self._nodes = nodes
# create an initial nodes and add it to the Chord ring
addr = Address(self._base_address)
index = addr.__hash__()
# avoid collision of hashing
while self._nodes[index] is not None:
index = (index + 1) % NUM_SLOTS
self._nodes[index] = Node(addr, self)
for x in range(1, len(address)):
self.addNode(address[x], self._base_address)
class Local(object):
def __init__(self, local_address, remote_address=None):
self.address_ = Address(quick_lazy_ip(), local_address.port)
self.local_addr = local_address
print("self id = %s" % self.id())
self.shutdown_ = False
# list of successors
self.successors_ = []
# join the DHT
self.join(remote_address)
# we don't have deamons until we start
self.daemons_ = {}
# initially no commands
self.command_ = []
# is this id within our range?
def is_ours(self, id):
assert id >= 0 and id < SIZE
return inrange(id, self.predecessor_.id(1), self.id(1))
def shutdown(self):
self.shutdown_ = Trues
self.socket_.shutdown(socket.SHUT_RDWR)
self.socket_.close()
# logging function
def log(self, info):
f = open("./chord.log", "a+")
f.write(str(self.id()) + " : " + info + "\n")
f.close()
#print str(self.id()) + " : " + info
def start(self):
# start the daemons
self.daemons_['run'] = Daemon(self, 'run')
self.daemons_['fix_fingers'] = Daemon(self, 'fix_fingers')
self.daemons_['stabilize'] = Daemon(self, 'stabilize')
self.daemons_['update_successors'] = Daemon(self, 'update_successors')
for key in self.daemons_:
self.daemons_[key].start()
self.log("started")
def ping(self):
return True
def join(self, remote_address=None):
# initially just set successor
print "joining"
self.finger_ = [None for x in range(LOGSIZE)]
self.predecessor_ = None
if remote_address:
print "poking", remote_address
remote = Remote(remote_address)
print "fingering"
self.finger_[0] = remote.find_successor(self.id())
else:
self.finger_[0] = self
print "joined"
self.log("joined")
@repeat_and_sleep(STABILIZE_INT)
@retry_on_socket_error(STABILIZE_RET)
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 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
@repeat_and_sleep(FIX_FINGERS_INT)
def fix_fingers(self):
# Randomly select an entry in finger_ table and update its value
self.log("fix_fingers")
i = random.randrange(LOGSIZE - 1) + 1
self.finger_[i] = self.find_successor(self.id(1 << i))
# Keep calling us
return True
@repeat_and_sleep(UPDATE_SUCCESSORS_INT)
@retry_on_socket_error(UPDATE_SUCCESSORS_RET)
def update_successors(self):
self.log("update successor")
suc = self.successor()
# if we are not alone in the ring, calculate
if suc.id() != self.id():
successors = [suc]
suc_list = suc.get_successors()
if suc_list and len(suc_list):
successors += suc_list
# if everything worked, we update
self.successors_ = successors
return True
def get_successors(self):
self.log("get_successors")
return [(node.address_.ip, node.address_.port)
for node in self.successors_[:N_SUCCESSORS - 1]]
def id(self, offset=0):
return (self.address_.__hash__() + offset) % SIZE
def successor(self):
# We make sure to return an existing successor, there `might`
# be redundance between finger_[0] and successors_[0], but
# it doesn't harm
for remote in [self.finger_[0]] + self.successors_:
#print remote.address_
if remote.ping():
self.finger_[0] = remote
return remote
print("No successor available, aborting")
self.shutdown_ = True
sys.exit(-1)
def predecessor(self):
return self.predecessor_
#@retry_on_socket_error(FIND_SUCCESSOR_RET)
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()
#@retry_on_socket_error(FIND_PREDECESSOR_RET)
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_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 run(self):
# should have a threadpool here :/
# listen to incomming connections
self.socket_ = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.socket_.bind((self.local_addr.ip, int(self.local_addr.port)))
self.socket_.listen(10)
while 1:
self.log("run loop")
try:
conn, addr = self.socket_.accept()
except socket.error:
self.shutdown_ = True
break
request = read_from_socket(conn)
command = request.split(' ')[0]
# we take the command out
request = request[len(command) + 1:]
# defaul : "" = not respond anything
result = json.dumps("")
if command == 'get_successor':
successor = self.successor()
result = json.dumps(
(successor.address_.ip, successor.address_.port))
if command == 'get_predecessor':
# we can only reply if we have a predecessor
if self.predecessor_ != None:
predecessor = self.predecessor_
result = json.dumps(
(predecessor.address_.ip, predecessor.address_.port))
if command == 'find_successor':
successor = self.find_successor(int(request))
result = json.dumps(
(successor.address_.ip, successor.address_.port))
if command == 'closest_preceding_finger':
closest = self.closest_preceding_finger(int(request))
result = json.dumps(
(closest.address_.ip, closest.address_.port))
if command == 'notify':
npredecessor = Address(
request.split(' ')[0], int(request.split(' ')[1]))
self.notify(Remote(npredecessor))
if command == 'get_successors':
result = json.dumps(self.get_successors())
# or it could be a user specified operation
for t in self.command_:
if command == t[0]:
result = t[1](request)
send_to_socket(conn, result)
conn.close()
if command == 'shutdown':
self.socket_.close()
self.shutdown_ = True
self.log("shutdown started")
break
self.log("execution terminated")
def register_command(self, cmd, callback):
self.command_.append((cmd, callback))
def unregister_command(self, cmd):
pass
class Local(object):
def __init__(self, local_address, remote_address = None):
self.address_ = Address(quick_lazy_ip(),local_address.port)
self.local_addr = local_address
print("self id = %s" % self.id())
self.shutdown_ = False
# list of successors
self.successors_ = []
# join the DHT
self.join(remote_address)
# we don't have deamons until we start
self.daemons_ = {}
# initially no commands
self.command_ = []
# is this id within our range?
def is_ours(self, id):
assert id >= 0 and id < SIZE
return inrange(id, self.predecessor_.id(1), self.id(1))
def shutdown(self):
self.shutdown_ = Trues
self.socket_.shutdown(socket.SHUT_RDWR)
self.socket_.close()
# logging function
def log(self, info):
f = open("./chord.log", "a+")
f.write(str(self.id()) + " : " + info + "\n")
f.close()
#print str(self.id()) + " : " + info
def start(self):
# start the daemons
self.daemons_['run'] = Daemon(self, 'run')
self.daemons_['fix_fingers'] = Daemon(self, 'fix_fingers')
self.daemons_['stabilize'] = Daemon(self, 'stabilize')
self.daemons_['update_successors'] = Daemon(self, 'update_successors')
for key in self.daemons_:
self.daemons_[key].start()
self.log("started")
def ping(self):
return True
def join(self, remote_address = None):
# initially just set successor
print "joining"
self.finger_ = [None for x in range(LOGSIZE)]
self.predecessor_ = None
if remote_address:
print "poking", remote_address
remote = Remote(remote_address)
print "fingering"
self.finger_[0] = remote.find_successor(self.id())
else:
self.finger_[0] = self
print "joined"
self.log("joined")
@repeat_and_sleep(STABILIZE_INT)
@retry_on_socket_error(STABILIZE_RET)
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 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
@repeat_and_sleep(FIX_FINGERS_INT)
def fix_fingers(self):
# Randomly select an entry in finger_ table and update its value
self.log("fix_fingers")
i = random.randrange(LOGSIZE - 1) + 1
self.finger_[i] = self.find_successor(self.id(1<<i))
# Keep calling us
return True
@repeat_and_sleep(UPDATE_SUCCESSORS_INT)
@retry_on_socket_error(UPDATE_SUCCESSORS_RET)
def update_successors(self):
self.log("update successor")
suc = self.successor()
# if we are not alone in the ring, calculate
if suc.id() != self.id():
successors = [suc]
suc_list = suc.get_successors()
if suc_list and len(suc_list):
successors += suc_list
# if everything worked, we update
self.successors_ = successors
return True
def get_successors(self):
self.log("get_successors")
return [(node.address_.ip, node.address_.port) for node in self.successors_[:N_SUCCESSORS-1]]
def id(self, offset = 0):
return (self.address_.__hash__() + offset) % SIZE
def successor(self):
# We make sure to return an existing successor, there `might`
# be redundance between finger_[0] and successors_[0], but
# it doesn't harm
for remote in [self.finger_[0]] + self.successors_:
#print remote.address_
if remote.ping():
self.finger_[0] = remote
return remote
print("No successor available, aborting")
self.shutdown_ = True
sys.exit(-1)
def predecessor(self):
return self.predecessor_
#@retry_on_socket_error(FIND_SUCCESSOR_RET)
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()
#@retry_on_socket_error(FIND_PREDECESSOR_RET)
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_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 run(self):
# should have a threadpool here :/
# listen to incomming connections
self.socket_ = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.socket_.bind((self.local_addr.ip, int(self.local_addr.port)))
self.socket_.listen(10)
while 1:
self.log("run loop")
try:
conn, addr = self.socket_.accept()
except socket.error:
self.shutdown_ = True
break
request = read_from_socket(conn)
command = request.split(' ')[0]
# we take the command out
request = request[len(command) + 1:]
# defaul : "" = not respond anything
result = json.dumps("")
if command == 'get_successor':
successor = self.successor()
result = json.dumps((successor.address_.ip, successor.address_.port))
if command == 'get_predecessor':
# we can only reply if we have a predecessor
if self.predecessor_ != None:
predecessor = self.predecessor_
result = json.dumps((predecessor.address_.ip, predecessor.address_.port))
if command == 'find_successor':
successor = self.find_successor(int(request))
result = json.dumps((successor.address_.ip, successor.address_.port))
if command == 'closest_preceding_finger':
closest = self.closest_preceding_finger(int(request))
result = json.dumps((closest.address_.ip, closest.address_.port))
if command == 'notify':
npredecessor = Address(request.split(' ')[0], int(request.split(' ')[1]))
self.notify(Remote(npredecessor))
if command == 'get_successors':
result = json.dumps(self.get_successors())
# or it could be a user specified operation
for t in self.command_:
if command == t[0]:
result = t[1](request)
send_to_socket(conn, result)
conn.close()
if command == 'shutdown':
self.socket_.close()
self.shutdown_ = True
self.log("shutdown started")
break
self.log("execution terminated")
def register_command(self, cmd, callback):
self.command_.append((cmd, callback))
def unregister_command(self, cmd):
pass
