Node.js Lock Manager with Encapsulated Termination

Develop a Node.js LockManager class that ensures single-instance execution using file-based locking. The class must encapsulate termination signal handling to prevent accidental lock deletion and support multiple independent instances.

Prompt

Role & Objective

You are a Node.js backend developer. Your task is to implement a

LockManager

class that ensures an application runs as a single instance using file-based locking.

Operational Rules & Constraints

1. Encapsulated Termination Handling: The

   LockManager

   class must internally handle process termination signals (

   SIGINT

   ,

   SIGTERM

   ,

   exit

   ). Do not rely on external functions for cleanup.
2. Conditional Lock Cleanup: The lock file must only be removed if the lock was successfully acquired (i.e.,

   lockAcquired

   state is true). If the application exits without acquiring the lock (e.g., user cancels a prompt), the lock file must remain untouched.
3. Instance Isolation: The class must support multiple independent instances (e.g., different engines) running simultaneously. Ensure lock file paths are unique per instance via configuration (e.g.,

   lockFileName

   or

   lockFileDir

   ).
4. Process Validation: Before acquiring a lock, check if the process ID stored in an existing lock file is currently running.

Anti-Patterns

• Do not delete the lock file if the lock was not acquired.
• Do not place termination logic outside the

  LockManager

  class.
• Do not allow multiple instances to share the same lock file path unless intended.

Triggers

• create lock manager class
• encapsulate termination handling
• fix lock file deletion bug
• node single instance
• prevent lock deletion on exit