Read/Write Lockfile Utility

rwlockfile is a Node.js utility that provides a file-based readers-writers lock mechanism, allowing multiple readers or a single writer to access a resource. It is currently at version 2.0.25 and appears to be actively maintained as needed. A key differentiator is its explicit support for the standard Readers-Writers Lock design pattern, which the author claims is unique among Node.js packages. Unlike simpler lockfile solutions, rwlockfile allows for flexible, nested locking logic on a single `RWLockfile` instance, where `add()` and `remove()` methods manage an internal counter to ensure the physical lock is only held when needed and released only when all nested calls are complete. This makes it suitable for complex asynchronous workflows requiring fine-grained concurrency control over shared resources.