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authorDamien <damien.p.george@gmail.com>2013-12-29 18:21:02 +0000
committerDamien <damien.p.george@gmail.com>2013-12-29 18:21:02 +0000
commit2eda70874ef193c609207db2ba87324244afcf84 (patch)
tree5a570df6296c40f7774d6d25cd3cc4c38fc1e1ff /tests/bytecode/pylib-tests/sched.py
parentde690d128bbec4f53e8a7d6149738a6facae4382 (diff)
downloadmicropython-2eda70874ef193c609207db2ba87324244afcf84.tar.gz
micropython-2eda70874ef193c609207db2ba87324244afcf84.zip
Add tests to test compiler and emitted byte code.
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+"""A generally useful event scheduler class.
+
+Each instance of this class manages its own queue.
+No multi-threading is implied; you are supposed to hack that
+yourself, or use a single instance per application.
+
+Each instance is parametrized with two functions, one that is
+supposed to return the current time, one that is supposed to
+implement a delay. You can implement real-time scheduling by
+substituting time and sleep from built-in module time, or you can
+implement simulated time by writing your own functions. This can
+also be used to integrate scheduling with STDWIN events; the delay
+function is allowed to modify the queue. Time can be expressed as
+integers or floating point numbers, as long as it is consistent.
+
+Events are specified by tuples (time, priority, action, argument, kwargs).
+As in UNIX, lower priority numbers mean higher priority; in this
+way the queue can be maintained as a priority queue. Execution of the
+event means calling the action function, passing it the argument
+sequence in "argument" (remember that in Python, multiple function
+arguments are be packed in a sequence) and keyword parameters in "kwargs".
+The action function may be an instance method so it
+has another way to reference private data (besides global variables).
+"""
+
+# XXX The timefunc and delayfunc should have been defined as methods
+# XXX so you can define new kinds of schedulers using subclassing
+# XXX instead of having to define a module or class just to hold
+# XXX the global state of your particular time and delay functions.
+
+import time
+import heapq
+from collections import namedtuple
+try:
+ import threading
+except ImportError:
+ import dummy_threading as threading
+try:
+ from time import monotonic as _time
+except ImportError:
+ from time import time as _time
+
+__all__ = ["scheduler"]
+
+class Event(namedtuple('Event', 'time, priority, action, argument, kwargs')):
+ def __eq__(s, o): return (s.time, s.priority) == (o.time, o.priority)
+ def __ne__(s, o): return (s.time, s.priority) != (o.time, o.priority)
+ def __lt__(s, o): return (s.time, s.priority) < (o.time, o.priority)
+ def __le__(s, o): return (s.time, s.priority) <= (o.time, o.priority)
+ def __gt__(s, o): return (s.time, s.priority) > (o.time, o.priority)
+ def __ge__(s, o): return (s.time, s.priority) >= (o.time, o.priority)
+
+_sentinel = object()
+
+class scheduler:
+
+ def __init__(self, timefunc=_time, delayfunc=time.sleep):
+ """Initialize a new instance, passing the time and delay
+ functions"""
+ self._queue = []
+ self._lock = threading.RLock()
+ self.timefunc = timefunc
+ self.delayfunc = delayfunc
+
+ def enterabs(self, time, priority, action, argument=(), kwargs=_sentinel):
+ """Enter a new event in the queue at an absolute time.
+
+ Returns an ID for the event which can be used to remove it,
+ if necessary.
+
+ """
+ if kwargs is _sentinel:
+ kwargs = {}
+ with self._lock:
+ event = Event(time, priority, action, argument, kwargs)
+ heapq.heappush(self._queue, event)
+ return event # The ID
+
+ def enter(self, delay, priority, action, argument=(), kwargs=_sentinel):
+ """A variant that specifies the time as a relative time.
+
+ This is actually the more commonly used interface.
+
+ """
+ with self._lock:
+ time = self.timefunc() + delay
+ return self.enterabs(time, priority, action, argument, kwargs)
+
+ def cancel(self, event):
+ """Remove an event from the queue.
+
+ This must be presented the ID as returned by enter().
+ If the event is not in the queue, this raises ValueError.
+
+ """
+ with self._lock:
+ self._queue.remove(event)
+ heapq.heapify(self._queue)
+
+ def empty(self):
+ """Check whether the queue is empty."""
+ with self._lock:
+ return not self._queue
+
+ def run(self, blocking=True):
+ """Execute events until the queue is empty.
+ If blocking is False executes the scheduled events due to
+ expire soonest (if any) and then return the deadline of the
+ next scheduled call in the scheduler.
+
+ When there is a positive delay until the first event, the
+ delay function is called and the event is left in the queue;
+ otherwise, the event is removed from the queue and executed
+ (its action function is called, passing it the argument). If
+ the delay function returns prematurely, it is simply
+ restarted.
+
+ It is legal for both the delay function and the action
+ function to modify the queue or to raise an exception;
+ exceptions are not caught but the scheduler's state remains
+ well-defined so run() may be called again.
+
+ A questionable hack is added to allow other threads to run:
+ just after an event is executed, a delay of 0 is executed, to
+ avoid monopolizing the CPU when other threads are also
+ runnable.
+
+ """
+ # localize variable access to minimize overhead
+ # and to improve thread safety
+ lock = self._lock
+ q = self._queue
+ delayfunc = self.delayfunc
+ timefunc = self.timefunc
+ pop = heapq.heappop
+ while True:
+ with lock:
+ if not q:
+ break
+ time, priority, action, argument, kwargs = q[0]
+ now = timefunc()
+ if time > now:
+ delay = True
+ else:
+ delay = False
+ pop(q)
+ if delay:
+ if not blocking:
+ return time - now
+ delayfunc(time - now)
+ else:
+ action(*argument, **kwargs)
+ delayfunc(0) # Let other threads run
+
+ @property
+ def queue(self):
+ """An ordered list of upcoming events.
+
+ Events are named tuples with fields for:
+ time, priority, action, arguments, kwargs
+
+ """
+ # Use heapq to sort the queue rather than using 'sorted(self._queue)'.
+ # With heapq, two events scheduled at the same time will show in
+ # the actual order they would be retrieved.
+ with self._lock:
+ events = self._queue[:]
+ return map(heapq.heappop, [events]*len(events))