added mutex in python

src/Python/flask/web/app.py

@@ -3,6 +3,7 @@ import paho.mqtt.client as mqtt
 from ultralytics import YOLO
 import cv2
 import numpy as np
+import threading
 
 app = Flask(__name__)
 
@@ -14,6 +15,9 @@ latest_image = None
 processed_image = None
 yolo_results = []
 
+# Lock for thread-safe access to shared variables
+lock = threading.Lock()
+
 # List of class names (example for COCO dataset)
 yolo_classes = list(model.names.values())
 
@@ -22,12 +26,13 @@ def on_message(client, userdata, message):
     if message.topic == "kobuki/data":
         kobuki_message = str(message.payload.decode("utf-8"))
     elif message.topic == "kobuki/cam":
+        with lock: # Lock the shared variables between threads so they can't be accessed at the same time and you cant have half processed images
             latest_image = np.frombuffer(message.payload, np.uint8)
             latest_image = cv2.imdecode(latest_image, cv2.IMREAD_COLOR)
-        processed_image = latest_image.copy()  # Create a copy for processing
             # Process the image with YOLO
             results = model(latest_image)
             yolo_results = []
+            processed_image = latest_image.copy()  # Create a copy for processing
             for result in results:
                 for box in result.boxes:
                     class_id = int(box.cls.item())
@@ -50,7 +55,7 @@ mqtt_client.loop_start()
 mqtt_client.subscribe("kobuki/data")
 mqtt_client.subscribe("kobuki/cam")
 
-mqtt_client.on_message = on_message # this line needs to be under the function definition otherwise it cant find which function it needs to use
+mqtt_client.on_message = on_message  # this line needs to be under the function definition otherwise it can't find which function it needs to use
 
 @app.route('/')
 def index():
@@ -64,6 +69,7 @@ def control():
     else:
         return ('Unauthorized', 401, {'WWW-Authenticate': 'Basic realm="Login Required"'})
 
+
 @app.route('/move', methods=['POST'])
 def move():
     data = request.get_json()
@@ -80,19 +86,24 @@ def move():
 def data():
     return kobuki_message
 
+
 @app.route('/image')
 def image():
     global processed_image
+    with lock: # Lock the shared variables between threads so they can't be accessed at the same time and you cant have half processed images
         if processed_image is not None:
             _, buffer = cv2.imencode('.jpg', processed_image) 
             return Response(buffer.tobytes(), mimetype='image/jpeg')
         else:
             return "No image available", 404
 
+
 @app.route('/yolo_results', methods=['GET'])
 def yolo_results_endpoint():
     global yolo_results
+    with lock:
         return jsonify(yolo_results)
 
+
 if __name__ == '__main__':
     app.run(debug=True, port=5000)