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- mutex
class mutex |
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# 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.
#
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- __init__(self)
- #
- # Create a new mutex -- initially unlocked
#
- 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.
#
- test(self)
- #
- # Test the locked bit of the mutex
#
- testandset(self)
- #
- # Atomic test-and-set -- grab the lock if it is not set,
- # return true if it succeeded
#
- unlock(self)
- #
- # Unlock a mutex. If the queue is not empty, call the next
- # function with its argument.
#
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