Staging
v0.8.1
v0.8.1
Revision 93e938440213c9e032b4c4e1af6bb20a1ce644a1 authored by Neal Norwitz on 01 April 2007, 18:29:47 UTC, committed by Neal Norwitz on 01 April 2007, 18:29:47 UTC
SF #1685563, MSVCCompiler creates redundant and long PATH strings If MSVCCompiler.initialize() was called multiple times, the path would get duplicated. On Windows, this is a problem because the path is limited to 4k. There's no benefit in adding a path multiple times, so prevent that from occuring. We also normalize the path before checking for duplicates so things like /a and /a/ won't both be stored.
1 parent 5306982
mutex.py
"""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
Computing file changes ...