kopia lustrzana https://github.com/peterhinch/micropython-samples
69 wiersze
2.4 KiB
Python
69 wiersze
2.4 KiB
Python
try:
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import uasyncio as asyncio
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except ImportError:
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import asyncio
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from . import launch
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# A Barrier synchronises N coros. Each issues await barrier.
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# Execution pauses until all other participant coros are waiting on it.
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# At that point the callback is executed. Then the barrier is 'opened' and
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# execution of all participants resumes.
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# The nowait arg is to support task cancellation. It enables usage where one or
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# more coros can register that they have reached the barrier without waiting
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# for it. Any coros waiting normally on the barrier will pause until all
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# non-waiting coros have passed the barrier and all waiting ones have reached
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# it. The use of nowait promotes efficiency by enabling tasks which have been
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# cancelled to leave the task queue as soon as possible.
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class Barrier():
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def __init__(self, participants, func=None, args=()):
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self._participants = participants
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self._func = func
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self._args = args
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self._reset(True)
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def __await__(self):
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self._update()
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if self._at_limit(): # All other threads are also at limit
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if self._func is not None:
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launch(self._func, self._args)
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self._reset(not self._down) # Toggle direction to release others
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return
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direction = self._down
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while True: # Wait until last waiting thread changes the direction
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if direction != self._down:
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return
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await asyncio.sleep_ms(0)
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__iter__ = __await__
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def trigger(self):
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self._update()
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if self._at_limit(): # All other threads are also at limit
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if self._func is not None:
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launch(self._func, self._args)
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self._reset(not self._down) # Toggle direction to release others
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def _reset(self, down):
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self._down = down
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self._count = self._participants if down else 0
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def busy(self):
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if self._down:
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done = self._count == self._participants
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else:
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done = self._count == 0
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return not done
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def _at_limit(self): # Has count reached up or down limit?
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limit = 0 if self._down else self._participants
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return self._count == limit
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def _update(self):
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self._count += -1 if self._down else 1
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if self._count < 0 or self._count > self._participants:
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raise ValueError('Too many tasks accessing Barrier')
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