kopia lustrzana https://github.com/peterhinch/micropython-samples
80 wiersze
2.8 KiB
Python
80 wiersze
2.8 KiB
Python
# barrier.py MicroPython optimised version
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# A Barrier synchronises N coros. In normal use 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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# .trigger enables a coro to signal it has passed the barrier without waiting.
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try:
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import asyncio
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raise RuntimeError('This version of barrier is MicroPython specific')
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except ImportError:
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import uasyncio
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async def _g():
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pass
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type_coro = type(_g())
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# If a callback is passed, run it and return.
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# If a coro is passed initiate it and return.
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# coros are passed by name i.e. not using function call syntax.
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def launch(func, tup_args):
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res = func(*tup_args)
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if isinstance(res, type_coro):
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uasyncio.create_task(res)
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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.waiting = uasyncio.TQueue() # Linked list of Tasks waiting on completion of barrier
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self._reset(True)
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def trigger(self):
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self._update()
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if self._at_limit(): # All other coros 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 and release others
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while self.waiting.next:
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uasyncio.tqueue.push_head(self.waiting.pop_head())
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def __iter__(self): # MicroPython
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self._update()
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if self._at_limit(): # All other coros 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 and release others
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while self.waiting.next:
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uasyncio.tqueue.push_head(self.waiting.pop_head())
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return
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direction = self._down
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# Other tasks have not reached barrier, put the calling task on the barrier's waiting queue
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self.waiting.push_head(uasyncio.cur_task)
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# Set calling task's data to this barrier that it waits on, to double-link it
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uasyncio.cur_task.data = self
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yield
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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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