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# -*- coding: utf-8 -*- |
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# |
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# This file is part of Glances. |
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# |
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# SPDX-FileCopyrightText: 2022 Nicolas Hennion <[email protected]> |
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# |
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# SPDX-License-Identifier: LGPL-3.0-only |
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import threading |
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import time |
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from glances.logger import logger |
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class StatsStreamer: |
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""" |
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Utility class to stream an iterable using a background / daemon Thread |
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Use `StatsStreamer.stats` to access the latest streamed results |
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""" |
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def __init__(self, iterable, initial_stream_value=None, sleep_duration=0.1): |
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""" |
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iterable: an Iterable instance that needs to be streamed |
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""" |
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self._iterable = iterable |
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# Iterable results are stored here |
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self._raw_result = initial_stream_value |
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# Use a Thread to stream iterable (daemon=True to automatically kill thread when main process dies) |
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self._thread = threading.Thread(target=self._stream_results, daemon=True) |
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# Event needed to stop the thread manually |
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self._stopper = threading.Event() |
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# Lock to avoid the daemon thread updating stats when main thread reads the stats |
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self.result_lock = threading.Lock() |
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# Last result streamed time (initial val 0) |
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self._last_update_time = 0 |
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# Time to sleep before next iteration |
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self._sleep_duration = sleep_duration |
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self._thread.start() |
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def stop(self): |
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"""Stop the thread.""" |
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self._stopper.set() |
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def stopped(self): |
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"""Return True is the thread is stopped.""" |
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return self._stopper.is_set() |
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def _stream_results(self): |
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"""Grab the stats. |
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Infinite loop, should be stopped by calling the stop() method |
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""" |
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try: |
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for res in self._iterable: |
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self._pre_update_hook() |
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self._raw_result = res |
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self._post_update_hook() |
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time.sleep(self._sleep_duration) |
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if self.stopped(): |
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break |
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except Exception as e: |
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logger.debug("docker plugin - Exception thrown during run ({})".format(e)) |
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self.stop() |
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def _pre_update_hook(self): |
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"""Hook that runs before worker thread updates the raw_stats""" |
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self.result_lock.acquire() |
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def _post_update_hook(self): |
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"""Hook that runs after worker thread updates the raw_stats""" |
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self._last_update_time = time.time() |
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self.result_lock.release() |
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@property |
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def stats(self): |
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"""Raw Stats getter.""" |
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return self._raw_result |
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@property |
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def last_update_time(self): |
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"""Raw Stats getter.""" |
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return self._last_update_time |
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nicolargo /
glances
