def setr(key, value, dest_host, dest_port_low, dest_port_high, timeout):
try:
viewleader_sock = common_functions.create_connection(dest_host, dest_port_low, dest_port_high, timeout, True)
active_servers, epoch = get_viewleader_info(viewleader_sock)
except Exception as e:
print ("Couldn't establish a connection with viewleader: ", e)
viewleader_sock.close()
try:
viewleader_sock = common_functions.create_connection(dest_host, dest_port_low, dest_port_high, timeout, True)
replica_buckets = get_replica_buckets(viewleader_sock, {'cmd': 'get_buckets', 'key': key, 'val': value})
print ("Replicas : {}".format(replica_buckets))
except Exception as e:
print ("Couldn't establish a connection with viewleader: ", e)
viewleader_sock.close()
length_of_bucket = len(replica_buckets)
if (length_of_bucket == 0):
return "Cannot store value because no servers are available."
else:
if (distributed_commit(replica_buckets, key, dest_host, dest_port_low, dest_port_high, 3)):
broadcast(replica_buckets, {'cmd': 'setr', 'key': key, 'val': value, 'id': 0}, epoch, 5)
broadcast(replica_buckets, {'cmd': 'remove_commit', 'key': key, 'id': 0}, epoch, 5)
return "Stored values in replica servers."
else:
broadcast(replica_buckets, {'cmd': 'remove_commit', 'key': key, 'id': 0}, epoch, 5)
return "Cannot store value because one of the servers aborted."
def send_and_recv_heartbeat(self, src_port):
# print ('Sending heartbeat msg to viewleader...')
try:
sock = common_functions.create_connection(self.view_leader_ip,
39000, 39010, 1, False)
except Exception as e:
print("Couldn't establish a connection with viewleader: ", e)
common_functions.send_msg(sock, {
'cmd': 'heartbeat',
'args': [str(self.unique_id), src_port]
}, False)
recvd_msg = common_functions.recv_msg(sock, False)
sock.close()
if (recvd_msg is not None):
status = recvd_msg[0]
try:
sock = common_functions.create_connection(self.view_leader_ip,
39000, 39010, 1, False)
except Exception as e:
print("Couldn't establish a connection with viewleader: ", e)
common_functions.send_msg(sock, {'cmd': 'update_view'}, False)
curr_epoch = common_functions.recv_msg(sock, False)['Current Epoch']
# print ("Updating our epoch to {}...".format(curr_epoch))
self.epoch = curr_epoch
sock.close()
def getr(key, dest_host, dest_port_low, dest_port_high, timeout):
try:
viewleader_sock = common_functions.create_connection(dest_host, dest_port_low, dest_port_high, timeout, True)
except Exception as e:
print ("Couldn't establish a connection with viewleader: ", e)
active_servers, epoch = get_viewleader_info(viewleader_sock)
viewleader_sock.close()
viewleader_sock = common_functions.create_connection(dest_host, dest_port_low, dest_port_high, timeout, True)
replica_buckets = get_replica_buckets(viewleader_sock, {'cmd': 'get_buckets', 'key': key})
viewleader_sock.close()
response = broadcast(replica_buckets, {'cmd': 'getr', 'key': key, 'id': 0}, epoch, 5)
return response
def accept_and_handle_messages(self, bound_socket, src_port,
view_leader_ip):
# Accept connections forever
while True:
try:
sock, (addr, accepted_port) = bound_socket.accept(
) # Returns the socket, address and port of the connection
if (accepted_port
is not None): # checks if there is an accepted_port
print("Accepting connection from host " + addr)
# receives decoded message length and message from client; if can't throw's an error
try:
recvd_msg = common_functions.recv_msg(sock)
except ConnectionResetError:
print("Connection dropped.")
except AttributeError:
print("Cannot decode message.")
response_dict = self.process_msg_from_client(recvd_msg)
# sends encoded message length and message to client; if can't throw's an error
try:
common_functions.send_msg(sock, response_dict)
except:
print("Can't send over whole message.")
sock.close()
except socket.timeout:
try:
print('Sending heartbeat msg to viewleader...')
sock = common_functions.create_connection(
'localhost', 39000, 39010, 1, False)
try:
common_functions.send_msg(
sock, {
'cmd':
'heartbeat',
'args': [
str(self.unique_id), src_port,
self.view_leader_ip
]
})
except:
print("Can't send over whole message.")
sock.close()
try:
recvd_msg = common_functions.recv_msg(sock)
except ConnectionResetError:
print("Connection dropped.")
except AttributeError:
print("Cannot decode message.")
print('Receiving response...')
if (recvd_msg is not None):
print(str(recvd_msg))
sock.close()
except Exception as e:
print(
'Heartbeat rejected, will try again in 10 seconds...')
continue
def get_replica_buckets(dest_host, dest_port_low, dest_port_high, timeout,
key):
viewleader_sock = common_functions.create_connection(
dest_host, dest_port_low, dest_port_high, timeout, True)
view, epoch = get_viewleader_info(viewleader_sock)
viewleader_sock.close()
replica_buckets = DHT.bucket_allocator(key, view)
return replica_buckets
def start(self):
args = self.parse_cmd_arguments()
# if the optional argument "--server" is used,
# then set localhost as this computer's IP. else, return error and exit.
if (args.server is not None):
if (args.cmd is None):
print ("RPC command not provided.")
sys.exit()
viewleader_args = ['query_servers', 'lock_get', 'lock_release']
self.timeout = 1
# sets destination port ranges and destination hosts based on the RPC functions called
if (args.cmd in viewleader_args):
self.dest_host = str(args.viewleader)
self.dest_port_low = 39000
self.dest_port_high = 39010
self.dest_name = 'viewleader'
elif (args.cmd == 'getr' or args.cmd == 'setr'):
self.dest_host = str(args.viewleader)
self.dest_port_low = 39000
self.dest_port_high = 39010
self.dest_name = 'viewleader_and_server'
else:
self.dest_host = str(args.server)
self.dest_port_low = 38000
self.dest_port_high = 38010
self.dest_name = 'server'
args_dict = self.create_dict(args)
stop = False
sock = None
if (self.dest_name == 'viewleader_and_server'):
stop = True
if (args.cmd == 'getr'):
print (client_rpc.getr(args.key, self.dest_host, self.dest_port_low, self.dest_port_high, self.timeout))
else:
print (client_rpc.setr(args.key, args.val, self.dest_host, self.dest_port_low, self.dest_port_high, self.timeout))
while (stop == False):
sock = common_functions.create_connection(self.dest_host, self.dest_port_low, self.dest_port_high, self.timeout, True)
# sends encoded message length and message to server/viewleader; if can't throw's an error
common_functions.send_msg(sock, args_dict, True)
recvd_msg = common_functions.recv_msg(sock, True)
if (recvd_msg == "{'status': 'retry'}"):
print (str(recvd_msg))
time.sleep(5) # delays for 5 seconds and then tries again
else:
print (str(recvd_msg))
stop = True
if (sock is not None):
sock.close()
sys.exit()
def run_consensus_alg(self, sock, cmd, args):
proposal_num = len(self.log) # proposal number is equivalent to length of log
msg = {'cmd': 'prepare', 'proposal_num': proposal_num} # prepare message; Phase 1
print ("Broadcasting prepare message to replicas...")
responses = self.broadcast(msg, self.view_leader_list)
if (self.has_quorum(responses)):
for response in responses:
status = None
num_logs_replica_needs = None
logs_leader_is_missing = None
try:
replica_addr = response['addr']
replica_port = response['port']
status = response['status']
if (status == 'ok'):
status = 'accept' # accept message; Phase 2
else:
status = 'reject'
except Exception:
continue
try:
num_logs_replica_needs = response['num_logs_replica_needs']
except Exception:
pass
try:
logs_leader_is_missing = response['logs_leader_is_missing']
except Exception:
pass
# if there are logs that the replicas need, sends it to them. Also
# sends updated proposal numbers and the requested command
if (num_logs_replica_needs):
print ("num_logs_replica_needs: {}".format(num_logs_replica_needs))
logs_to_replay = self.log[len(self.log) - num_logs_replica_needs:]
print ("logs_to_replay: {}".format(len(logs_to_replay)))
msg = {'cmd' : status, 'logs_replica_needs' : logs_to_replay,
'new_proposal_num': len(self.log), 'new_cmd': cmd, 'args': args}
elif (logs_leader_is_missing):
msg = {'cmd' : status, 'new_proposal_num': len(self.log), 'new_cmd': cmd, 'args': args}
elif (status):
msg = {'cmd' : status, 'new_proposal_num': len(self.log), 'new_cmd': cmd, 'args': args}
if (status == 'accept'):
sock = common_functions.create_connection(replica_addr, replica_port, replica_port, 1, False)
common_functions.send_msg(sock, msg, False)
if (sock):
sock.close()
return True
else:
return False
def rebalance(self, old_view, new_view, epoch_op):
for ((addr, port), server_id) in new_view:
try:
server_sock = common_functions.create_connection(
addr, port, port, None, False)
except Exception as e:
print("Couldn't establish a connection with replica: ", e)
common_functions.send_msg(
server_sock, {
'cmd': 'rebalance',
'old_view': old_view,
'new_view': new_view,
'op': epoch_op
}, False)
server_sock.close()
def broadcast(self, msg, replicas):
responses = []
leader_hostname = self.leader[0]
leader_port = str(self.leader[1])
for replica in replicas:
addr, port = replica
# checks to see if the replica has the same addr/port as the leader; if so,
# don't broadcast to it
if ((addr, port) != (leader_hostname, leader_port)):
sock = common_functions.create_connection(addr, port, port, 1, False)
if (sock):
common_functions.send_msg(sock, msg, False)
recvd_msg = common_functions.recv_msg(sock, False)
if (recvd_msg):
responses.append(recvd_msg)
sock.close()
return responses
def broadcast(replicas, object_to_send, epoch, timeout):
response_key = None
rpc_command = object_to_send['cmd']
abort = False
votes = []
for ((addr, port), server_id) in replicas:
if (rpc_command == 'request_vote'):
object_to_send['epoch'] = epoch
object_to_send['server_id'] = str(server_id)
try:
server_sock = common_functions.create_connection(
addr, port, port, timeout, False)
common_functions.send_msg(server_sock, object_to_send, False)
if (rpc_command == 'request_vote'):
vote = common_functions.recv_msg(server_sock, False)
print("Accepting vote from " + addr)
if (vote == 'abort'):
abort = True
return {'cmd': 'abort'}
if (rpc_command == 'getr'):
response_key = common_functions.recv_msg(
server_sock, False
) # desired value associated with the given key from DHT
if (response_key is not None):
return response_key
elif (rpc_command == 'setr'):
response_key = common_functions.recv_msg(server_sock, False)
server_sock.close()
except socket.timeout:
if (rpc_command == 'request_vote'):
abort = True
return {'cmd': 'abort'}
if (sock is None):
print(
"Couldn't connect to current replica server...will continue on remaining replicas: "
)
if (rpc_command == 'request_vote'):
return {'cmd': 'commit'}
if (response_key is not None):
result = "No key found in any of the replica servers."
response_key = {'status': 'fail', 'result': result}
return response_key
def distributed_commit(replicas, key, dest_host, dest_port_low, dest_port_high,
timeout):
viewleader_sock = common_functions.create_connection(
dest_host, dest_port_low, dest_port_high, timeout, True)
active_servers, epoch = get_viewleader_info(viewleader_sock)
viewleader_sock.close()
votes_received = 0
votes_expected = len(active_servers)
vote_request = {'cmd': 'request_vote', 'key': key}
response = broadcast(replicas, vote_request, epoch, 5)
vote = response['cmd']
# sending global abort
if (vote == 'abort'):
print("Commit failed. Aborting...")
return False
# sending global commit
else:
print("Commit succeeded.")
return True
def rebalance(self, old_view, new_view, epoch_op):
for ((addr, port), server_id) in new_view:
server_sock = common_functions.create_connection(addr, port, port, None, False)
common_functions.send_msg(server_sock, {'cmd': 'rebalance', 'old_view': old_view, 'new_view': new_view, 'op': epoch_op}, False)
server_sock.close()
def start(self):
args = self.parse_cmd_arguments()
# if the optional argument "--server" is used,
# then set localhost as this computer's IP. else, return error and exit.
if (args.server is not None):
if (args.cmd is None):
print("RPC command not provided.")
sys.exit()
# sets destination port ranges and destination hosts based on the RPC functions called
if (args.cmd == 'query_servers') or (args.cmd == 'lock_get') or (
args.cmd == 'lock_release'):
dest_host = str(args.viewleader)
dest_port_low = 39000
dest_port_high = 39010
timeout = 1
else:
dest_host = str(args.server)
dest_port_low = 38000
dest_port_high = 38010
timeout = 1
args_dict = self.create_dict(args)
stop = False
sock = None
while (stop == False):
sock = common_functions.create_connection(dest_host, dest_port_low,
dest_port_high, timeout,
True)
try:
print("Sending RPC msg to viewleader...")
# sends encoded message length and message to server/viewleader; if can't throw's an error
common_functions.send_msg(sock, args_dict)
# receives decoded message length and message from server/viewleader; if can't throw's an error
try:
recvd_msg = common_functions.recv_msg(sock)
if (recvd_msg == "{'status': 'retry'}"):
print(str(recvd_msg))
time.sleep(
5) # delays for 5 seconds and then tries again
else:
print(str(recvd_msg))
stop = True
except ConnectionResetError:
print("Connection dropped.")
sys.exit()
except AttributeError:
print("Cannot decode message.")
if (sock is not None):
sock.close()
sys.exit()
except Exception as e:
print("Failed send over whole message.", e)
if (sock is not None):
sock.close()
sys.exit()
if (sock is not None):
sock.close()
sys.exit()
def rebalance(self, new_view, old_view, epoch_op):
key_to_delete = ''
global key_value_replica
global data_in_view
for [[addr, port], server_id] in new_view:
try:
sock = common_functions.create_connection(
addr, port, port, 5, False)
except Exception as e:
print("Couldn't establish a connection with replica: ", e)
common_functions.send_msg(sock, {'cmd': 'get_data'}, False)
recvd_msg = common_functions.recv_msg(sock, False)
if (recvd_msg is not None):
for key, value in recvd_msg.items():
if (key not in data_in_view):
with self.lock:
data_in_view[key] = value
sock.close()
for key, value in data_in_view.items():
old_replicas = DHT.bucket_allocator(key, old_view)
new_replicas = DHT.bucket_allocator(key, new_view)
for [[addr, port], server_id] in new_replicas:
try:
sock = common_functions.create_connection(
addr, port, port, 5, False)
except Exception as e:
print("Couldn't establish a connection with replica: ", e)
common_functions.send_msg(sock, {
'cmd': 'get_data',
'key': key
}, False)
recvd_msg = common_functions.recv_msg(sock, False)
if (recvd_msg is not None) or (recvd_msg != ''):
key_value_replica = recvd_msg
sock.close()
with self.lock:
# print (key_value_replica)
try:
new_key, new_value = key_value_replica
if (new_key not in self.bucket):
try:
self.bucket[new_key] = new_value
print("Adding {}:{} to current replica...".format(
new_key, new_value))
except LookupError as e:
print(
"Couldn't set the key since there was no such key..."
)
else:
if (epoch_op == 'add'):
if (old_view is not None):
# print ("Old view: {}".format(old_view))
# print ("New view: {}".format(new_view))
# print ("unique_id: {}".format(self.unique_id))
for [[addr, port], server_id] in old_view:
# print ("tuple: {}".format([[addr, port], server_id]))
if (self.unique_id == server_id) and ([[
addr, port
], server_id] not in new_view):
print(
"Deleting {}:{} on old replica...".
format(new_key, new_value))
key_to_delete = new_key
try:
del self.bucket[key_to_delete]
except LookupError:
print(
"Couldn't delete the key since there was no such key..."
)
except Exception as e:
print("No key_value found: ", e)
