42 lines
1.4 KiB
Python
42 lines
1.4 KiB
Python
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from asyncio import sleep
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from time import monotonic, process_time
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SLEEP_GRANULARITY: float = 1 / 50
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SLEEP_IDLE: float = SLEEP_GRANULARITY / 20.0
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async def wait_for_idle(
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min_sleep: float = SLEEP_GRANULARITY, max_sleep: float = 1
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) -> None:
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"""Wait until the process isn't working very hard.
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This will compare wall clock time with process time. If the process time
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is not advancing at the same rate as wall clock time it means the process is
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idle (i.e. sleeping or waiting for input).
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When the process is idle it suggests that input has been processed and the state
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is predictable enough to test.
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Args:
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min_sleep: Minimum time to wait.
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max_sleep: Maximum time to wait.
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"""
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start_time = monotonic()
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while True:
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cpu_time = process_time()
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# Sleep for a predetermined amount of time
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await sleep(SLEEP_GRANULARITY)
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# Calculate the wall clock elapsed time and the process elapsed time
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cpu_elapsed = process_time() - cpu_time
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elapsed_time = monotonic() - start_time
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# If we have slept the maximum, we can break
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if elapsed_time >= max_sleep:
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break
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# If we have slept at least the minimum and the cpu elapsed is significantly less
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# than wall clock, then we can assume the process has finished working for now
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if elapsed_time > min_sleep and cpu_elapsed < SLEEP_IDLE:
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break
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