89 lines
2.5 KiB
Python
89 lines
2.5 KiB
Python
import trio
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import tractor
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async def cancellable_pause_loop(
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task_status: trio.TaskStatus[trio.CancelScope] = trio.TASK_STATUS_IGNORED
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):
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with trio.CancelScope() as cs:
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task_status.started(cs)
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for _ in range(3):
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try:
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# ON first entry, there is no level triggered
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# cancellation yet, so this cp does a parent task
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# ctx-switch so that this scope raises for the NEXT
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# checkpoint we hit.
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await trio.lowlevel.checkpoint()
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await tractor.pause()
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cs.cancel()
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# parent should have called `cs.cancel()` by now
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await trio.lowlevel.checkpoint()
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except trio.Cancelled:
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print('INSIDE SHIELDED PAUSE')
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await tractor.pause(shield=True)
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else:
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# should raise it again, bubbling up to parent
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print('BUBBLING trio.Cancelled to parent task-nursery')
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await trio.lowlevel.checkpoint()
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async def pm_on_cancelled():
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async with trio.open_nursery() as tn:
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tn.cancel_scope.cancel()
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try:
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await trio.sleep_forever()
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except trio.Cancelled:
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# should also raise `Cancelled` since
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# we didn't pass `shield=True`.
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try:
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await tractor.post_mortem(hide_tb=False)
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except trio.Cancelled as taskc:
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# should enter just fine, in fact it should
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# be debugging the internals of the previous
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# sin-shield call above Bo
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await tractor.post_mortem(
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hide_tb=False,
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shield=True,
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)
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raise taskc
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else:
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raise RuntimeError('Dint cancel as expected!?')
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async def cancelled_before_pause(
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):
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'''
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Verify that using a shielded pause works despite surrounding
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cancellation called state in the calling task.
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'''
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async with trio.open_nursery() as tn:
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cs: trio.CancelScope = await tn.start(cancellable_pause_loop)
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await trio.sleep(0.1)
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assert cs.cancelled_caught
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await pm_on_cancelled()
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async def main():
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async with tractor.open_nursery(
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debug_mode=True,
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) as n:
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portal: tractor.Portal = await n.run_in_actor(
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cancelled_before_pause,
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)
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await portal.result()
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# ensure the same works in the root actor!
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await pm_on_cancelled()
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if __name__ == '__main__':
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trio.run(main)
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