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Node.py
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Node.py
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import zlib
import sys
import grpc
import os
import chord_pb2
import chord_pb2_grpc
from concurrent import futures
from contextlib import suppress
node_key_dict = {}
node_id = 0
node_predecessor = ()
M = 0
def get_keys():
return node_key_dict
def get_finger_table():
return node_finger_table
def update_finger_table():
if not node_registered:
return
params = chord_pb2.PopulateFingerTableRequest(node_id=node_id)
response = registry_stub.PopulateFingerTable(params)
global node_predecessor
node_predecessor = (response.predecessor.node_id, response.predecessor.ip_addr_port_num)
global node_finger_table
node_finger_table = []
for entry in response.finger_table:
node_finger_table.append((entry.node_id, entry.ip_addr_port_num))
def in_range(num, start, end):
if start >= end:
if num < start and start <= num + 2** M < end + 2** M:
return True
elif num >= start and start <= num < end + 2** M:
return True
return False
else:
return start <= num < end
def in_range1 (num, start, end):
if start >= end:
if num < start and start < num + 2** M <= end + 2** M:
return True
elif num >= start and start < num <= end + 2** M:
return True
return False
else:
return start < num <= end
def hash_key(key):
hash_value = zlib.adler32(key.encode())
target_id = hash_value % (2 ** M)
return target_id
def lookup(key):
target_id = hash_key(key)
succ = node_finger_table[0][0]
if in_range1 (target_id, node_predecessor[0], node_id):
return (True, node_id)
elif in_range1 (target_id, node_id, succ):
return (False, node_finger_table[0][1])
else:
for i in range(len(node_finger_table)):
if in_range(target_id, node_finger_table[i][0], node_finger_table[i+1][0]):
return (False, node_finger_table[i][1])
def save(key, text):
global node_key_dict
found = lookup(key)
if found[0] == True:
if key not in node_key_dict:
node_key_dict[key] = text
return (True, found[1])
else:
return (False, f"{key} already exists in node {found[1]}")
else:
return forward_save(key, text, found[1])
def forward_save(key, text, target_ip_address_port_num):
channel = grpc.insecure_channel(target_ip_address_port_num)
node_stub = chord_pb2_grpc.ChordServiceStub(channel)
params = chord_pb2.SaveRequest(key=key, text=text)
response = node_stub.Save(params)
if response.successful == True:
return (True, response.node_id)
else:
return (False, response.error_message)
def remove(key):
global node_key_dict
found = lookup(key)
if found[0] == True:
if key in node_key_dict:
del node_key_dict[key]
return (True, found[1])
else:
return (False, f"{key} does not exist in node {found[1]}")
else:
return forward_remove(key, found[1])
def forward_remove(key, target_ip_address_port_num):
channel = grpc.insecure_channel(target_ip_address_port_num)
node_stub = chord_pb2_grpc.ChordServiceStub(channel)
params = chord_pb2.RemoveRequest(key=key)
response = node_stub.Remove(params)
if response.successful == True:
return (True, response.node_id)
else:
return (False, response.error_message)
def find(key):
found = lookup(key)
if found[0] == True:
if key in node_key_dict:
return (True, found[1], f"{node_ip_address}:{node_port_number}")
else:
return (False, f"{key} does not exist in node {found[1]}")
else:
return forward_find(key, found[1])
def forward_find(key, target_ip_address_port_num):
channel = grpc.insecure_channel(target_ip_address_port_num)
node_stub = chord_pb2_grpc.ChordServiceStub(channel)
params = chord_pb2.FindRequest(key=key)
response = node_stub.Find(params)
if response.successful == True:
return (True, response.node_id, response.ip_addr_port_num)
else:
return (False, response.error_message)
def register_self():
params = chord_pb2.RegisterRequest(ip_address=node_ip_address, port_number = node_port_number)
response = registry_stub.Register(params)
if response.node_id !=-1:
global node_id, M, node_registered
node_registered = True
node_id = response.node_id
M = response.m
else:
print(f"{response.error_message}")
terminate()
def get_successor_keys():
target_ip_address_port_num = node_finger_table[0][1]
channel = grpc.insecure_channel(target_ip_address_port_num)
node_stub = chord_pb2_grpc.ChordServiceStub(channel)
params = chord_pb2.GetKeysRequest()
response = node_stub.GetKeys(params)
successor_keys = {}
for key in response.keys:
successor_keys[key.key] = key.value
return successor_keys
def remove_disowned_keys(list_of_keys):
global node_key_dict
for key in list_of_keys:
del node_key_dict[key]
def get_own_keys():
if node_id == node_finger_table[0][0]:
return
global node_key_dict
successor_keys = get_successor_keys()
successor_disowned_keys = []
for key in successor_keys.keys():
if hash_key(key) <= node_id:
node_key_dict[key]= successor_keys[key]
successor_disowned_keys.append(key)
successor_ip_address_port_number = node_finger_table[0][1]
channel = grpc.insecure_channel(successor_ip_address_port_number)
node_stub = chord_pb2_grpc.ChordServiceStub(channel)
params = chord_pb2.RemoveOwnKeysRequest()
params.keys.extend(successor_disowned_keys)
node_stub.RemoveOwnKeys(params)
def quit():
# The node Deregistering itself
params = chord_pb2.DeregisterRequest()
params.node_id = node_id
registry_stub.Deregister(params)
params = chord_pb2.PromptUpdateRequest()
if node_id != node_predecessor[0]:
# Notifying Predecessor
channel = grpc.insecure_channel(node_predecessor[1])
node_stub = chord_pb2_grpc.ChordServiceStub(channel)
node_stub.PromptUpdate(params)
if node_id != node_finger_table[0][0]:
# Notifying Successor
channel = grpc.insecure_channel(node_finger_table[0][1])
node_stub = chord_pb2_grpc.ChordServiceStub(channel)
node_stub.PromptUpdate(params)
# Handing over node's keys to Successor
for key in node_key_dict:
forward_save(key, node_key_dict[key], node_finger_table[0][1])
def terminate():
print("Node is shutting down...")
os._exit(0)
class ChordService(chord_pb2_grpc.ChordServiceServicer):
def Save(self, request, context):
key = request.key
text = request.text
saved = save(key, text)
response = chord_pb2.SaveResponse()
if saved[0] == True:
response.successful = True
response.node_id = saved[1]
else:
response.successful = False
response.error_message = saved[1]
return response
def Remove(self, request, context):
key = request.key
removed = remove(key)
response = chord_pb2.RemoveResponse()
if removed[0] == True:
response.successful = True
response.node_id = removed[1]
else:
response.successful = False
response.error_message = removed[1]
return response
def Find(self, request, context):
key = request.key
found = find(key)
response = chord_pb2.FindResponse()
if found[0] == True:
response.successful = True
response.node_id = found[1]
response.ip_addr_port_num = found[2]
else:
response.successful = False
response.error_message = found[1]
return response
def GetFingerTable(self, request, context):
response = chord_pb2.GetFingerTableResponse()
finger_table = [chord_pb2.IDStringPair(node_id=element[0], ip_addr_port_num=element[1]) for element in node_finger_table]
response.finger_table.extend(finger_table)
return response
def GetKeys(self, request, context):
response = chord_pb2.GetKeysResponse()
keys = [chord_pb2.KeyValuePair(key=key, value=node_key_dict[key]) for key in node_key_dict.keys()]
response.keys.extend(keys)
return response
def RemoveOwnKeys(self, request, context):
disowned_keys = [key for key in request.keys]
remove_disowned_keys(disowned_keys)
response = chord_pb2.RemoveOwnKeysResponse()
return response
def GetSelfType(self, request, context):
response = chord_pb2.GetSelfTypeResponse()
response.type = "Node"
return response
def GetID(self, request, context):
response = chord_pb2.GetIDResponse()
response.id = node_id
return response
def PromptUpdate(self, request, context):
response = chord_pb2.PromptUpdateResponse()
update_finger_table()
return response
def init():
registry_address_port = sys.argv[1]
node_address_port = sys.argv[2]
global registry_ip_address
registry_ip_address = registry_address_port.split(":")[0]
global registry_port_number
registry_port_number = int(registry_address_port.split(":")[1])
global node_ip_address
node_ip_address = node_address_port.split(":")[0]
global node_port_number
node_port_number = int(node_address_port.split(":")[1])
global registry_stub
channel = grpc.insecure_channel(f"{registry_ip_address}:{registry_port_number}")
registry_stub = chord_pb2_grpc.ChordServiceStub(channel)
try:
register_self()
update_finger_table()
get_own_keys()
except grpc.RpcError:
print("Registry is offline.")
terminate()
print("Node joined and finger table populated.")
print(f"assigned node_id={node_id}, successor_id={node_finger_table[0][0]}, predecessor_id={node_predecessor[0]}")
server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
chord_pb2_grpc.add_ChordServiceServicer_to_server(ChordService(), server)
server.add_insecure_port(f"{node_ip_address}:{node_port_number}")
server.start()
while True:
try:
server.wait_for_termination(1)
update_finger_table()
except grpc.RpcError:
print("Registry is offline.")
terminate()
except KeyboardInterrupt:
quit()
print("Node left the ring.")
terminate()
if __name__ == "__main__":
init()