From a73a964e51247ed169d322c725a3a18859f109a3 Mon Sep 17 00:00:00 2001 From: Ori Bernstein Date: Mon, 14 Jun 2021 00:00:37 +0000 Subject: python, hg: tow outside the environment. they've served us well, and can ride off into the sunset. --- sys/lib/python/mutex.py | 52 ------------------------------------------------- 1 file changed, 52 deletions(-) delete mode 100644 sys/lib/python/mutex.py (limited to 'sys/lib/python/mutex.py') diff --git a/sys/lib/python/mutex.py b/sys/lib/python/mutex.py deleted file mode 100644 index 5d35bdf6a..000000000 --- a/sys/lib/python/mutex.py +++ /dev/null @@ -1,52 +0,0 @@ -"""Mutual exclusion -- for use with module sched - -A mutex has two pieces of state -- a 'locked' bit and a queue. -When the mutex is not locked, the queue is empty. -Otherwise, the queue contains 0 or more (function, argument) pairs -representing functions (or methods) waiting to acquire the lock. -When the mutex is unlocked while the queue is not empty, -the first queue entry is removed and its function(argument) pair called, -implying it now has the lock. - -Of course, no multi-threading is implied -- hence the funny interface -for lock, where a function is called once the lock is aquired. -""" - -from collections import deque - -class mutex: - def __init__(self): - """Create a new mutex -- initially unlocked.""" - self.locked = 0 - self.queue = deque() - - def test(self): - """Test the locked bit of the mutex.""" - return self.locked - - def testandset(self): - """Atomic test-and-set -- grab the lock if it is not set, - return True if it succeeded.""" - if not self.locked: - self.locked = 1 - return True - else: - return False - - def lock(self, function, argument): - """Lock a mutex, call the function with supplied argument - when it is acquired. If the mutex is already locked, place - function and argument in the queue.""" - if self.testandset(): - function(argument) - else: - self.queue.append((function, argument)) - - def unlock(self): - """Unlock a mutex. If the queue is not empty, call the next - function with its argument.""" - if self.queue: - function, argument = self.queue.popleft() - function(argument) - else: - self.locked = 0 -- cgit v1.2.3