def AppendEntries(command, cluster_node):
# AppendEntries(<index>, !<var>) or AppendEntries(<index>, <var>, <value>)
log = open("log.txt", 'r+')
params = command.getParams()
# Need to make sure that the commit index is the same as the leader
if cluster_node.commit_index != int(params[0]):
# Replicate log and set commit_index
return parse.Command("print", ["Failed!"])
# Copy file contents into a string
contents = ""
for line in log:
contents = contents + line
# If it should return a value at a specific <var>
if command.shouldReturnVal():
# Find start and end indexes for <value>
if params[1] not in contents:
return parse.Command("print", ["Failed!"])
index = contents.find(params[1])
var = contents[index:index + len(params[1])]
start_index = index + len(params[1]) + 1
temp = contents[start_index:len(contents)]
end_index = temp.index('\n') + start_index
val = contents[start_index:end_index]
return parse.Command("print", [val])
else:
# New value to be added to the beginning of the file
# Edit string and write to the file
cluster_node.commit_index += 1
new_contents = params[1] + ':' + params[2] + '\n'
for i in range(0, len(contents)):
new_contents = new_contents + contents[i]
try:
log.truncate(0)
log.write(new_contents)
log.close()
except IOError:
if command.getCommand() == "LeaderAppend":
return parse.Command("print", ["Failed!"])
if command.getCommand() == "LeaderAppend":
return parse.Command("print", ["Success!"])
def receiveFromClient(self, conn, addr):
threading.Thread(target=self.quitThread, args=(conn,)).start()
while not self.shouldEnd:
# Get command from follower/client
command = parse.Command(None, None, None)
try:
data = conn.recv(self.cluster_node.BUFFER_SIZE)
if not data: continue
command = pickle.loads(data)
except:
break
# Returns something to be printed on both leader and followers
ret_cmd = process.processCommand(command, self.cluster_node, addr)
if ret_cmd:
print(ret_cmd.getParams()[0])
conn.send(pickle.dumps(ret_cmd))
# Once leader has finished the operation, all followers must do the same (as long as it is not a retrieval)
if not command.shouldReturnVal():
self.cluster_node.broadcast(command)
conn.close()
self.cluster_node.followers.remove(conn)
def dumpLog(command, cluster_node):
# dumpLog(<id>)
id = command.getParams()[0]
original_id = ""
if len(command.getParams()) == 1:
command.addParam(cluster_node.IP)
original_id = cluster_node.IP
else:
original_id = command.getParams()[1]
if id == cluster_node.IP:
log = open("log.txt", 'r')
contents = "\n\tMOST RECENT INDEX (TOP)\n"
for line in log:
contents += line
contents += "\n\tOLDEST INDEX (BOTTOM)\n"
return parse.Command("print", [contents, original_id])
elif cluster_node.isLeader():
isFollower = False
for ip in cluster_node.follower_ips:
if ip == id:
isFollower = True
if isFollower:
logRequest = parse.Command("LogRequest", [id, original_id])
cluster_node.broadcast(logRequest)
return None
else:
return parse.Command("print", ["Failed!"])
else:
return None
def ClientCommit(command, cluster_node):
# ClienCommit(!<var>) or ClientCommit(<var>, <value>)
# Process parameters
params = command.getParams()
if command.shouldReturnVal():
# Broadcast
read_entry = parse.Command("AppendEntries",
[cluster_node.commit_index, params[0]],
True)
return AppendEntries(read_entry, cluster_node)
elif cluster_node.isLeader():
new_entry = parse.Command(
"AppendEntries", [cluster_node.commit_index, params[0], params[1]])
cluster_node.broadcast(new_entry)
new_entry = parse.Command(
"LeaderAppend", [cluster_node.commit_index, params[0], params[1]])
return AppendEntries(new_entry, cluster_node)
else:
return None
def run(self):
# Initialize incoming TCP connections
self.s.bind((self.cluster_node.IP, self.cluster_node.port))
self.cluster_node.port = self.s.getsockname()[1]
self.s.listen(5) # number of connections to server
print("Connection IP address: ", self.cluster_node.IP)
print("Connection opened on port: ", self.s.getsockname()[1])
# Handles new connections until it should end
while not self.shouldEnd:
# Accept connection
conn, addr = self.s.accept()
print("Connection from address:", addr)
# Log replication for new followers
log = open("log.txt", 'r')
contents = ""
for line in log:
contents += line
log.close()
conn.send(pickle.dumps(parse.Command("log", [contents, str(self.cluster_node.commit_index)])))
# Append new follower to followers
self.cluster_node.followers.append(conn)
# Handles adding clients and receiving messages
add_client_thread = threading.Thread(target=self.receiveFromClient, args=(conn, addr))
add_client_thread.start()
add_client_thread.join()
conn.close()
print("Connection closed")
def run(self):
print("gets here")
self.s.bind((self.cluster_node.IP, self.cluster_node.port))
election_cmd = parse.Command("election", self.IP, False)
self.cluster_node.broadcast(election_cmd)
def write_init(self):
self.f.write(BOOTSTRAP_SP)
init_cmd = parse.Command("call Sys.init 0")
self.write_call(init_cmd)
def heartbeatTimer(self):
heartbeat_cmd = parse.Command("heartbeat", self.cluster_node.follower_ips)
while not self.shouldEnd:
time.sleep(30) # should be 30 seconds
self.cluster_node.broadcast(heartbeat_cmd)