I'm new to Python so this could be a simple fix.
I am using Flask and sockets for this Python project. I am starting the socket on another thread so I can actively listen for new messages. I have an array variable called 'SocketConnections' that is within my UdpComms class. The variable gets a new 'Connection' appended to it when a new socket connection is made. That works correctly. My issue is that when I try to read 'SocketConnections' from outside of the thread looking in, it is an empty array.
server.py
from flask import Flask, jsonify
import UdpComms as U
app = Flask(__name__)
@app.route('/api/talk', methods=['POST'])
def talk():
global global_server_socket
apples = global_server_socket.SocketConnections
return jsonify(message=apples)
global_server_socket = None
def start_server():
global global_server_socket
sock = U.UdpComms(udpIP="127.0.0.1", portTX=8000, portRX=8001, enableRX=True, suppressWarnings=True)
i = 0
global_server_socket = sock
while True:
i += 1
data = sock.ReadReceivedData() # read data
if data != None: # if NEW data has been received since last ReadReceivedData function call
print(data) # print new received data
time.sleep(1)
if __name__ == '__main__':
server_thread = threading.Thread(target=start_server)
server_thread.start()
app.run(debug=True,host='192.168.0.25')
UdpComms.py
import json
import uuid
class UdpComms():
def __init__(self,udpIP,portTX,portRX,enableRX=False,suppressWarnings=True):
self.SocketConnections = []
import socket
self.udpIP = udpIP
self.udpSendPort = portTX
self.udpRcvPort = portRX
self.enableRX = enableRX
self.suppressWarnings = suppressWarnings # when true warnings are suppressed
self.isDataReceived = False
self.dataRX = None
# Connect via UDP
self.udpSock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) # internet protocol, udp (DGRAM) socket
self.udpSock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) # allows the address/port to be reused immediately instead of it being stuck in the TIME_WAIT state waiting for late packets to arrive.
self.udpSock.bind((udpIP, portRX))
# Create Receiving thread if required
if enableRX:
import threading
self.rxThread = threading.Thread(target=self.ReadUdpThreadFunc, daemon=True)
self.rxThread.start()
def __del__(self):
self.CloseSocket()
def CloseSocket(self):
# Function to close socket
self.udpSock.close()
def SendData(self, strToSend):
# Use this function to send string to C#
self.udpSock.sendto(bytes(strToSend,'utf-8'), (self.udpIP, self.udpSendPort))
def SendDataAddress(self, strToSend, guid):
# Use this function to send string to C#
print('finding connection: ' + guid)
if self.SocketConnections:
connection = self.GetConnectionByGUID(guid)
print('found connection: ' + guid)
if connection is not None:
self.udpSock.sendto(bytes(strToSend,'utf-8'), connection.Address)
def ReceiveData(self):
if not self.enableRX: # if RX is not enabled, raise error
raise ValueError("Attempting to receive data without enabling this setting. Ensure this is enabled from the constructor")
data = None
try:
data, _ = self.udpSock.recvfrom(1024)
print('Socket data recieved from: ', _)
if self.IsNewConnection(_) == True:
print('New socket')
self.SendDataAddress("INIT:" + self.SocketConnections[-1].GUID, self.SocketConnections[-1].GUID)
data = data.decode('utf-8')
except WindowsError as e:
if e.winerror == 10054: # An error occurs if you try to receive before connecting to other application
if not self.suppressWarnings:
print("Are You connected to the other application? Connect to it!")
else:
pass
else:
raise ValueError("Unexpected Error. Are you sure that the received data can be converted to a string")
return data
def ReadUdpThreadFunc(self): # Should be called from thread
self.isDataReceived = False # Initially nothing received
while True:
data = self.ReceiveData() # Blocks (in thread) until data is returned (OR MAYBE UNTIL SOME TIMEOUT AS WELL)
self.dataRX = data # Populate AFTER new data is received
self.isDataReceived = True
# When it reaches here, data received is available
def ReadReceivedData(self):
data = None
if self.isDataReceived: # if data has been received
self.isDataReceived = False
data = self.dataRX
self.dataRX = None # Empty receive buffer
if data != None and data.startswith('DIALOG:'): #send it info
split = data.split(':')[1]
return data
class Connection:
def __init__(self, gUID, address) -> None:
self.GUID = gUID
self.Address = address
def IsNewConnection(self, address):
for connection in self.SocketConnections:
if connection.Address == address:
return False
print('Appending new connection...')
connection = self.Connection(str(uuid.uuid4()),address)
self.SocketConnections.append(connection)
return True
def GetConnectionByGUID(self, guid):
for connection in self.SocketConnections:
if connection.GUID == guid:
return connection
return None
As mentioned above. When IsNewConnection() is called in UdpComms it does append a new object to SocketConnections. It's just trying to view the SocketConnections in the app.route that is empty. My plans are to be able to send socket messages from the app.routes
from Why can't I access a specific variable inside of a threaded class
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