sharedMem: Fix race condition and sending uninitialized values to the server

TrafficCommunication/useful/sharedMem.py

@@ -28,11 +28,14 @@
 from multiprocessing import RawArray, Lock
 import numpy as np
 
+# Default value to indicate an uninitialized field
+DEFAULT_VALUE: float = -99.9
+
 # Define a class for shared memory
 class sharedMem:
     def __init__(self, mem_size=20):
         self.lock = Lock()  # Create a lock for thread synchronization
-        
+
         # Define the shape of the shared memory
         shared_memory_shape = np.dtype(
             [
@@ -43,7 +46,7 @@ def __init__(self, mem_size=20):
                 ("finishflag", np.bool_),  # Finish flag
             ]
         )
-        
+
         # Create a raw array for shared memory
         array = RawArray("c", mem_size * shared_memory_shape.itemsize)
         shared_memory = np.frombuffer(array, dtype=shared_memory_shape)
@@ -57,9 +60,9 @@ def __init__(self, mem_size=20):
         for mem in self.shared_memory:
             with self.lock:  # Acquire the lock using get_lock()
                 mem["Command"] = "Command_"  # Default command string
-                mem["value1"] = -99.9  # Default value for first value
-                mem["value2"] = -99.9  # Default value for second value
-                mem["value3"] = -99.9  # Default value for third value
+                mem["value1"] = DEFAULT_VALUE
+                mem["value2"] = DEFAULT_VALUE
+                mem["value3"] = DEFAULT_VALUE
                 mem["finishflag"] = False  # Default finish flag
 
     # Method to insert data into shared memory
@@ -73,9 +76,9 @@ def insert(self, msg, values):
             if len(values) > 2:
                 self.shared_memory[self.lastMem]["value3"] = values[2]  # Set the third value
             self.shared_memory[self.lastMem]["finishflag"] = True  # Set the finish flag
-        self.lastMem += 1  # Increment the index of the last memory slot used
-        if self.lastMem == self.mem_size:
-            self.lastMem = 0  # Wrap around if the index exceeds the memory size
+            self.lastMem += 1  # Increment the index of the last memory slot used
+            if self.lastMem == self.mem_size:
+                self.lastMem = 0  # Wrap around if the index exceeds the memory size
 
     # Method to retrieve data from shared memory
     def get(self):
@@ -84,11 +87,11 @@ def get(self):
             for mem in self.shared_memory:
                 if mem["finishflag"]:
                     msg = {"reqORinfo": "info", "type": mem["Command"]}  # Create a message dictionary
-                    if mem["value1"] != 99.9:
+                    if mem["value1"] != DEFAULT_VALUE:
                         msg["value1"] = float(mem["value1"])  # Add the first value to the message
-                    if mem["value2"] != 99.9:
+                    if mem["value2"] != DEFAULT_VALUE:
                         msg["value2"] = float(mem["value2"])  # Add the second value to the message
-                    if mem["value3"] != 99.9:
+                    if mem["value3"] != DEFAULT_VALUE:
                         msg["value3"] = float(mem["value3"])  # Add the third value to the message
                     mem["finishflag"] = False  # Reset the finish flag
                     vals.append(msg)  # Append the message to the list of retrieved values