GitHub - mwilliamson/locket.py: File-based locks for Python on Linux and Windows (original) (raw)

locket.py: File-based locks for Python on Linux and Windows

Locket implements a file-based lock that can be used by multiple processes provided they use the same path.

import locket

Wait for lock

with locket.lock_file("path/to/lock/file"): perform_action()

Raise LockError if lock cannot be acquired immediately

with locket.lock_file("path/to/lock/file", timeout=0): perform_action()

Raise LockError if lock cannot be acquired after thirty seconds

with locket.lock_file("path/to/lock/file", timeout=30): perform_action()

Without context managers:

lock = locket.lock_file("path/to/lock/file") try: lock.acquire() perform_action() finally: lock.release()

Locks largely behave as (non-reentrant) Lock instances from the threadingmodule in the standard library. Specifically, their behaviour is:

• Locks are uniquely identified by the file being locked, both in the same process and across different processes.
• Locks are either in a locked or unlocked state.
• When the lock is unlocked, calling acquire() returns immediately and changes the lock state to locked.
• When the lock is locked, calling acquire() will block until the lock state changes to unlocked, or until the timeout expires.
• If a process holds a lock, any thread in that process can call release() to change the state to unlocked.
• Calling release() on an unlocked lock raises LockError.
• Behaviour of locks after fork is undefined.

Installation