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# MicroPython asyncio module
# MIT license; Copyright (c) 2019-2020 Damien P. George
from . import core
# Event class for primitive events that can be waited on, set, and cleared
class Event:
def __init__(self):
self.state = False # False=unset; True=set
self.waiting = core.TaskQueue() # Queue of Tasks waiting on completion of this event
def is_set(self):
return self.state
def set(self):
# Event becomes set, schedule any tasks waiting on it
# Note: This must not be called from anything except the thread running
# the asyncio loop (i.e. neither hard or soft IRQ, or a different thread).
while self.waiting.peek():
core._task_queue.push(self.waiting.pop())
self.state = True
def clear(self):
self.state = False
# async
def wait(self):
if not self.state:
# Event not set, put the calling task on the event's waiting queue
self.waiting.push(core.cur_task)
# Set calling task's data to the event's queue so it can be removed if needed
core.cur_task.data = self.waiting
yield
return True
# MicroPython-extension: This can be set from outside the asyncio event loop,
# such as other threads, IRQs or scheduler context. Implementation is a stream
# that asyncio will poll until a flag is set.
# Note: Unlike Event, this is self-clearing after a wait().
try:
import io
class ThreadSafeFlag(io.IOBase):
def __init__(self):
self.state = 0
def ioctl(self, req, flags):
if req == 3: # MP_STREAM_POLL
return self.state * flags
return -1 # Other requests are unsupported
def set(self):
self.state = 1
def clear(self):
self.state = 0
async def wait(self):
if not self.state:
yield core._io_queue.queue_read(self)
self.state = 0
except ImportError:
pass
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