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# Copyright 2010 Canonical Ltd. This software is licensed under the
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# GNU Affero General Public License version 3 (see the file LICENSE).
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"""Coordinate a sequence of non overlapping TimedActionss."""
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from pytz import utc as UTC
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from timedaction import TimedAction
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from nestingtimedaction import NestingTimedAction
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class OverlappingActionError(Exception):
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"""A new action was attempted without finishing the prior one."""
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# To make analysis easy we do not permit overlapping actions by default:
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# each action that is being timed and accrued must complete before the next
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# is started. This means, for instance, that sending mail cannot do SQL
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# queries, as both are timed and accrued. OTOH it makes analysis and
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# serialisation of timelines simpler, and for the current use cases in
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# Launchpad this is sufficient. This constraint should not be considered
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# sacrosanct - if, in future, we desire timelines with overlapping actions,
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# as long as the OOPS analysis code is extended to generate sensible
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# reports in those situations, this can be changed. In the interim, actions
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# can be explicitly setup to permit nesting by passing allow_nested=True
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# which will cause the action to be recorded with 0 duration and a -start
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# and -stop suffix added to its category. This is potentially lossy but
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# good enough to get nested metrics and can be iterated on in the future to
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# do an actual stacked/tree model of actions - if needed.
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"""A sequence of TimedActions.
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This is used for collecting expensive/external actions inside Launchpad
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:ivar actions: The actions.
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:ivar baseline: The point the timeline starts at.
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def __init__(self, actions=None):
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:param actions: An optional object to use to store the timeline. This
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must implement the list protocol.
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self.actions = actions
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self.baseline = datetime.datetime.now(UTC)
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def start(self, category, detail, allow_nested=False):
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"""Create a new TimedAction at the end of the timeline.
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:param category: the category for the action.
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:param detail: The detail for the action.
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:param allow_nested: If True treat this action as a nested action -
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record it twice with 0 duration, once at the start and once at the
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:return: A TimedAction for that category and detail.
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result = NestingTimedAction(category, detail, self)
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result = TimedAction(category, detail, self)
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if self.actions and self.actions[-1].duration is None:
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raise OverlappingActionError(self.actions[-1], result)
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self.actions.append(result)
added
removed
lib/lp/services/timeline/timeline.py
