feat(WriteDB): Added file lock, prevented race condition

WriteDB.py

@@ -1,10 +1,12 @@
 import pandas as pd
 import json
 from openpyxl import load_workbook
-from send_email import send_email
+#from send_email import send_email
+from filelock import FileLock 
 
-# Define the path to the Excel file
+# Define the path to the Excel file and the lock file
 file_path = "./interview_database.xlsx"
+lock_path = "./interview_database.xlsx.lock"  # Lock file for synchronization
 
 def ReadDatabase():
     """ 
@@ -18,6 +20,8 @@ def ReadDatabase():
 
     ``Contact``: ahmad.ahmad1@ucalgary.ca
     """
+    # Use a file-based lock for thread-safe and process-safe access
+    with FileLock(lock_path):
         # Load the Excel file into a pandas DataFrame with specific columns
         df = pd.read_excel(file_path, usecols=['Date', 'Start Time', 'Slot', 'Interviewee Name', 'Interviewee Email', 'Meeting Duration'])
 
@@ -63,6 +67,7 @@ def AppendAppointment(date, start_time, interviewee_name, interviewee_email):
     
     # Check if the requested slot is available in the `available_slots` structure
     if date in available_slots and start_time in available_slots[date]:
+        with FileLock(lock_path):  # Ensure process-safe access to the file
             # Load workbook and select "Sheet1" for updating appointments
             workbook = load_workbook(file_path)
             sheet = workbook["Sheet1"]
@@ -88,12 +93,13 @@ def AppendAppointment(date, start_time, interviewee_name, interviewee_email):
                     email_cell.value = updated_emails
 
                     workbook.save(file_path)
-                send_email(interviewee_email, interviewee_name, date, start_time)
+                    #send_email(interviewee_email, interviewee_name, date, start_time)
                     return True
 
     # If no slots available, return that the slot is unavailable
     return False
 
+
 def run_tests():
     """ 
     Executes test cases to verify appointment scheduling and slot availability.