v8.2.1: Add a utility for managing file locks to prevent concurrent executions

Introduced `lock_utils.py` to manage file-based locks. Includes functions to acquire and release locks, ensuring the safety of processes by detecting stale or live locks with PID validation.

app/modules/common/lock_utils.py

@@ -0,0 +1,58 @@
+import os
+import time
+import atexit
+import psutil
+
+LOCK_FILE = "/tmp/roxy-wi.lock"
+
+
+def acquire_file_lock() -> bool:
+    if os.path.exists(LOCK_FILE):
+        try:
+            with open(LOCK_FILE, "r") as f:
+                pid_str, ts_str = f.read().strip().split(",")
+                old_pid = int(pid_str)
+                old_time = float(ts_str)
+        except Exception as e:
+            print(f"[LOCK] Corrupt lock file. Removing. ({e})")
+            os.remove(LOCK_FILE)
+            _create_lock()
+            return False
+
+        if psutil.pid_exists(old_pid):
+            print( f"[LOCK] Lock held by live process PID {old_pid} (started {time.ctime(old_time)}).")
+            return True
+        else:
+            print( f"[LOCK] Detected dead PID {old_pid}. Lock is stale. Taking ownership.")
+            os.remove(LOCK_FILE)
+            _create_lock()
+            return False
+    else:
+        _create_lock()
+        return False
+
+
+def _create_lock():
+    try:
+        with open(LOCK_FILE, "w") as f:
+            f.write(f"{os.getpid()},{time.time()}")
+        print( f"[LOCK] Lock acquired by PID {os.getpid()}")
+    except Exception as e:
+        print( f"error: [LOCK] Failed to write lock file: {e}")
+        raise e
+
+    # Register cleanup on normal exit
+    atexit.register(release_file_lock)
+
+
+def release_file_lock():
+    if not os.path.exists(LOCK_FILE):
+        return
+    try:
+        with open(LOCK_FILE, "r") as f:
+            pid_str, _ = f.read().strip().split(",")
+        if int(pid_str) == os.getpid():
+            os.remove(LOCK_FILE)
+            print( f"[LOCK] Lock released by PID {os.getpid()}")
+    except Exception as e:
+        print( f"[LOCK] Error releasing lock: {e}")