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4e16098ce7
Added runcall(func, *args) interfaces to profile.py, bdb.py, pdb.py, wdb.py Added new module bisect.py and used it in sched.py. Mostly cosmetic changes to profile.py (changed output format).
101 lines
3.6 KiB
Python
101 lines
3.6 KiB
Python
# Module sched -- a generally useful event scheduler class
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# Each instance of this class manages its own queue.
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# No multi-threading is implied; you are supposed to hack that
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# yourself, or use a single instance per application.
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#
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# Each instance is parametrized with two functions, one that is
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# supposed to return the current time, one that is supposed to
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# implement a delay. You can implement fine- or course-grained
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# real-time scheduling by substituting time and sleep or millitimer
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# and millisleep from the built-in module time, or you can implement
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# simulated time by writing your own functions. This can also be
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# used to integrate scheduling with STDWIN events; the delay function
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# is allowed to modify the queue. Time can be expressed as
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# integers or floating point numbers, as long as it is consistent.
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# Events are specified by tuples (time, priority, action, argument).
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# As in UNIX, lower priority numbers mean higher priority; in this
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# way the queue can be maintained fully sorted. Execution of the
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# event means calling the action function, passing it the argument.
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# Remember that in Python, multiple function arguments can be packed
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# in a tuple. The action function may be an instance method so it
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# has another way to reference private data (besides global variables).
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# Parameterless functions or methods cannot be used, however.
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# XXX The timefunc and delayfunc should have been defined as methods
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# XXX so you can define new kinds of schedulers using subclassing
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# XXX instead of having to define a module or class just to hold
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# XXX the global state of your particular time and delay functtions.
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import bisect
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class scheduler:
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#
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# Initialize a new instance, passing the time and delay functions
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#
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def init(self, (timefunc, delayfunc)):
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self.queue = []
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self.timefunc = timefunc
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self.delayfunc = delayfunc
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return self
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#
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# Enter a new event in the queue at an absolute time.
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# Returns an ID for the event which can be used
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# to remove it, if necessary.
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#
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def enterabs(self, event):
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bisect.insort(self.queue, event)
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return event # The ID
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#
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# A variant that specifies the time as a relative time.
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# This is actually the more commonly used interface.
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#
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def enter(self, (delay, priority, action, argument)):
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time = self.timefunc() + delay
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return self.enterabs(time, priority, action, argument)
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#
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# Remove an event from the queue.
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# This must be presented the ID as returned by enter().
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# If the event is not in the queue, this raises RuntimeError.
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#
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def cancel(self, event):
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self.queue.remove(event)
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#
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# Check whether the queue is empty.
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#
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def empty(self):
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return len(self.queue) == 0
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#
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# Run: execute events until the queue is empty.
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#
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# When there is a positive delay until the first event, the
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# delay function is called and the event is left in the queue;
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# otherwise, the event is removed from the queue and executed
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# (its action function is called, passing it the argument).
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# If the delay function returns prematurely, it is simply
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# restarted.
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#
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# It is legal for both the delay function and the action
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# function to to modify the queue or to raise an exception;
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# exceptions are not caught but the scheduler's state
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# remains well-defined so run() may be called again.
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#
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# A questionably hack is added to allow other threads to run:
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# just after an event is executed, a delay of 0 is executed,
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# to avoid monopolizing the CPU when other threads are also
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# runnable.
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#
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def run(self):
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q = self.queue
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while q:
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time, priority, action, argument = q[0]
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now = self.timefunc()
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if now < time:
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self.delayfunc(time - now)
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else:
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del q[0]
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void = action(argument)
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self.delayfunc(0) # Let other threads run
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#
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