kopia lustrzana https://github.com/peterhinch/micropython-samples
46 wiersze
1.3 KiB
Python
46 wiersze
1.3 KiB
Python
# semaphore.py
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import uasyncio
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class Semaphore():
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def __init__(self, value=1):
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self._count = value
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self.waiting = uasyncio.TQueue() # Linked list of Tasks waiting on completion of this event
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async def __aenter__(self):
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await self.acquire()
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return self
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async def __aexit__(self, exc_type, exc, tb):
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self.release()
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async def acquire(self):
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if self._count == 0:
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# Semaphore unavailable, put the calling Task on the waiting queue
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self.waiting.push_head(uasyncio.cur_task)
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# Set calling task's data to double-link it
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uasyncio.cur_task.data = self
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yield
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self._count -= 1
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def release(self):
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self._count += 1
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if self.waiting.next:
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# Task(s) waiting on semaphore, schedule first Task
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uasyncio.tqueue.push_head(self.waiting.pop_head())
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class BoundedSemaphore(Semaphore):
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def __init__(self, value=1):
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super().__init__(value)
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self._initial_value = value
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def release(self):
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if self._count < self._initial_value:
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super().release()
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else:
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raise ValueError('Semaphore released more than acquired')
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uasyncio.Semaphore = Semaphore
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uasyncio.BoundedSemaphore = BoundedSemaphore
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