Tukukkk

I am working on a client/server tcp project, and I am wondering what a good method for "checking" that the server/client is ready for the data about to be sent.
This is because my client has a gui and I want the server to be ready for any input at any time, and should therefore make sure it isn't trying to send data whilst it is should be sending data

Here is my attempt

Client:

import socket

# Methods of a class

def receiveData(self, FROM=""):

    if self.SENT_LAST:

        print("DATA WAS LAST SENT BY CLIENT, NO CHECK REQUIRED")

    else:

        print("DATA LAST SENT BY CLIENT, CHECK REQUIRED")

        self.sendPickledData("dataReady")

    print("In receive data")

    if FROM:

        print("From:", FROM)

    data = s.recv(4096)

    try:

        data = pickle.loads(data)



    except pickle.UnpicklingError as err:

        errorReport(err)

    time.sleep(0.2)

    self.SENT_LAST = False

    if data != noData:

        print("data :",data)

        return data

    else:

        print("No data found")

        return False



def sendPickledData(self, data, FROM=""):

    if self.SENT_LAST:

        print("DATA WAS LAST SENT BY CLIENT, CHECK REQUIRED")

        checkData = self.receiveData("sendpickled")

        print("CheckData :", checkData)

        if checkData != "dataReady":

            raise ValueError

    else:

        print("DATA LAST SENT BY CLIENT, NO CHECK REQUIRED")

    print("In sendPickle, data :", data)

    if FROM:

        print("From:", FROM)

    data = pickle.dumps(data)

    s.sendall(data)

    time.sleep(0.5)

    self.SENT_LAST = True

    print("Data sent")

Server:

import socket

def receiveData_v2(FROM, FUNC=):

    global SENT_LAST, receive_count

    receive_count += 1

    print("Receive :",receive_count)

    print("Receiving")

    if SENT_LAST:

        print("DATA WAS LAST SENT BY SERVER, NO CHECK REQUIRED")

    if not SENT_LAST:

        print("DATA LAST SENT BY SERVER, CHECK REQUIRED")

        sendPickledData("dataReady")

        SENT_LAST = False



    print("In receive data")



    if FROM:

        print("From:", FROM)



    data = conn.recv(4096)



    try:

        data = pickle.loads(data)

    except pickle.UnpicklingError as err:

        print("Pickling error:")

        print(err)



    if data == PROG_QUIT:

        return data

    elif data == noData:

        return False

    else:

        if FUNC:

            funcData = FUNC(data)

            return funcData

        else:

            return data





def sendPickledData(data):

    global SENT_LAST, send_count

    send_count += 1

    print("Send :",send_count)

    print("sending")

    if SENT_LAST:

        print("DATA WAS LAST SENT BY SERVER, CHECK REQUIRED")

        print("sent last")

        checkData = receiveData_v2("sendpickled")

        print("CheckData :", checkData)

        if checkData != "dataReady":

            raise ValueError

    else:

        print("DATA LAST SENT BY SERVER, NO CHECK REQUIRED")

    print("In sendPickled,nSending:", data)

    data = pickle.dumps(data)

    conn.sendall(data)

    SENT_LAST = True

    conn.sendall(data)

Whenever I try to send data via this method, somehow it ends up de-synching and they will both end up trying to listen for data at the same time. Or receiveData (client) will receive only "dataReady"