Update app.py

app.py

@@ -27,7 +27,6 @@ lock = threading.Lock() # Non-reentrant lock
 # --- Helper Functions ---
 def save_data_to_json():
     # This function must be called with 'lock' acquired
-    # REMOVED 'with lock:' from here as callers already acquire it.
     serializable_data = {}
     for url_id, data in monitored_urls_store.items():
         s_data = data.copy()
@@ -37,9 +36,9 @@ def save_data_to_json():
     try:
         with open(DATA_FILE, 'w') as f:
             json.dump(serializable_data, f, indent=2)
-        print(f"Data saved to {DATA_FILE}")
+        print(f"Data saved to {DATA_FILE}", flush=True)
     except IOError as e:
-        print(f"Error saving data to {DATA_FILE}: {e}")
+        print(f"Error saving data to {DATA_FILE}: {e}", flush=True)
 
 def load_data_from_json():
     global monitored_urls_store
@@ -47,7 +46,7 @@ def load_data_from_json():
         try:
             with open(DATA_FILE, 'r') as f:
                 loaded_json_data = json.load(f)
-            print(f"Data loaded from {DATA_FILE}")
+            print(f"Data loaded from {DATA_FILE}", flush=True)
             
             temp_store = {}
             for url_id_key, data_item in loaded_json_data.items():
@@ -65,13 +64,13 @@ def load_data_from_json():
                 monitored_urls_store = temp_store
 
         except json.JSONDecodeError:
-            print(f"Warning: Could not decode {DATA_FILE}. Starting with an empty list.")
+            print(f"Warning: Could not decode {DATA_FILE}. Starting with an empty list.", flush=True)
             with lock: monitored_urls_store = {}
         except Exception as e:
-            print(f"Error loading data from {DATA_FILE}: {e}. Starting fresh.")
+            print(f"Error loading data from {DATA_FILE}: {e}. Starting fresh.", flush=True)
             with lock: monitored_urls_store = {}
     else:
-        print(f"{DATA_FILE} not found. Starting with an empty list.")
+        print(f"{DATA_FILE} not found. Starting with an empty list.", flush=True)
         with lock: monitored_urls_store = {}
     
     url_ids_to_start_monitoring = []
@@ -91,10 +90,10 @@ def get_host_ip_address(hostname_str):
             ip_address = socket.gethostbyname(hostname_str)
             return ip_address
         except socket.gaierror:
-            print(f"Could not resolve hostname: {hostname_str}")
+            print(f"Could not resolve hostname: {hostname_str}", flush=True)
             return 'N/A'
     except Exception as e:
-        print(f"Error processing hostname/IP for {hostname_str}: {e}")
+        print(f"Error processing hostname/IP for {hostname_str}: {e}", flush=True)
         return 'N/A'
 
 def prune_url_history(url_data_entry):
@@ -111,7 +110,7 @@ def execute_url_check(url_id_to_check):
         current_url_data = monitored_urls_store[url_id_to_check]
         if current_url_data.get('_stop_event') and current_url_data['_stop_event'].is_set(): return
         
-        print(f"Checking {current_url_data['url']} (ID: {url_id_to_check})...")
+        print(f"Checking {current_url_data['url']} (ID: {url_id_to_check})...", flush=True)
         current_url_data['status'] = 'checking'
         url_config_snapshot = current_url_data.copy()
 
@@ -128,11 +127,11 @@ def execute_url_check(url_id_to_check):
             if 200 <= head_response.status_code < 400:
                  final_check_status = 'ok'
             else:
-                print(f"HEAD for {url_config_snapshot['url']} returned {head_response.status_code}. Trying GET.")
+                print(f"HEAD for {url_config_snapshot['url']} returned {head_response.status_code}. Trying GET.", flush=True)
         except requests.exceptions.Timeout:
-            print(f"HEAD timeout for {url_config_snapshot['url']}. Trying GET...")
+            print(f"HEAD timeout for {url_config_snapshot['url']}. Trying GET...", flush=True)
         except requests.RequestException as e_head:
-            print(f"HEAD failed for {url_config_snapshot['url']}: {e_head}. Trying GET...")
+            print(f"HEAD failed for {url_config_snapshot['url']}: {e_head}. Trying GET...", flush=True)
 
         if final_check_status != 'ok':
             try:
@@ -140,20 +139,20 @@ def execute_url_check(url_id_to_check):
                 if get_response.ok:
                     final_check_status = 'ok'
                 else:
-                    print(f"GET for {url_config_snapshot['url']} status: {get_response.status_code}")
+                    print(f"GET for {url_config_snapshot['url']} status: {get_response.status_code}", flush=True)
                     final_check_status = 'error' 
             except requests.exceptions.Timeout:
-                print(f"GET timeout for {url_config_snapshot['url']}")
+                print(f"GET timeout for {url_config_snapshot['url']}", flush=True)
                 final_check_status = 'error'
             except requests.RequestException as e_get:
-                print(f"GET failed for {url_config_snapshot['url']}: {e_get}")
+                print(f"GET failed for {url_config_snapshot['url']}: {e_get}", flush=True)
                 final_check_status = 'error'
         
         if final_check_status == 'ok':
             http_response_time_ms = (time.perf_counter() - check_start_time) * 1000
 
     except Exception as e: 
-        print(f"Outer check exception for {url_config_snapshot['url']}: {e}")
+        print(f"Outer check exception for {url_config_snapshot['url']}: {e}", flush=True)
         final_check_status = 'error'
 
     with lock:
@@ -170,7 +169,7 @@ def execute_url_check(url_id_to_check):
         prune_url_history(live_url_data)
         
         save_data_to_json() # Called while lock is held
-        print(f"Finished check for {live_url_data['url']}: {final_check_status}, {http_response_time_ms} ms")
+        print(f"Finished check for {live_url_data['url']}: {final_check_status}, {http_response_time_ms} ms", flush=True)
 
 def pinger_thread_function(url_id_param, stop_event_param):
     while not stop_event_param.is_set():
@@ -178,18 +177,18 @@ def pinger_thread_function(url_id_param, stop_event_param):
         for _ in range(PING_INTERVAL_SECONDS): 
             if stop_event_param.is_set(): break
             time.sleep(1)
-    print(f"PingerThread for {url_id_param} stopped.")
+    print(f"PingerThread for {url_id_param} stopped.", flush=True)
 
 def start_url_monitoring_thread(target_url_id):
     with lock:
         if target_url_id not in monitored_urls_store:
-            print(f"Cannot start monitoring: URL ID {target_url_id} not found.")
+            print(f"Cannot start monitoring: URL ID {target_url_id} not found.", flush=True)
             return
 
         url_data_entry = monitored_urls_store[target_url_id]
 
         if "_thread" in url_data_entry and url_data_entry["_thread"].is_alive():
-            print(f"Monitor for URL ID {target_url_id} already running. Attempting to restart.")
+            print(f"Monitor for URL ID {target_url_id} already running. Attempting to restart.", flush=True)
             if "_stop_event" in url_data_entry and url_data_entry["_stop_event"]:
                 url_data_entry["_stop_event"].set()
             url_data_entry["_thread"].join(timeout=3)
@@ -201,14 +200,14 @@ def start_url_monitoring_thread(target_url_id):
         url_data_entry["_stop_event"] = new_stop_event
         
         new_thread.start()
-        print(f"Started/Restarted monitoring for URL ID {target_url_id}: {url_data_entry['url']}")
+        print(f"Started/Restarted monitoring for URL ID {target_url_id}: {url_data_entry['url']}", flush=True)
 
 def stop_url_monitoring_thread(target_url_id):
     # This function must be called with 'lock' acquired
     if target_url_id in monitored_urls_store:
         url_data_entry = monitored_urls_store[target_url_id]
         if "_thread" in url_data_entry and url_data_entry["_thread"].is_alive():
-            print(f"Signaling stop for monitor thread of URL ID {target_url_id}")
+            print(f"Signaling stop for monitor thread of URL ID {target_url_id}", flush=True)
             if "_stop_event" in url_data_entry and url_data_entry["_stop_event"]:
                 url_data_entry["_stop_event"].set()
         url_data_entry.pop("_thread", None)
@@ -302,7 +301,7 @@ def delete_existing_url_for_user(target_url_id):
             response_data = removed_url_entry.copy()
             response_data.pop("_thread", None)
             response_data.pop("_stop_event", None)
-            print(f"Deleted URL ID {target_url_id} for user {user_id}")
+            print(f"Deleted URL ID {target_url_id} for user {user_id}", flush=True)
             return jsonify({"message": "URL removed", "url": response_data}), 200
         else:
             return jsonify({"error": "URL not found"}), 404