22 lines
871 B
ReStructuredText
22 lines
871 B
ReStructuredText
.. SPDX-License-Identifier: GPL-3.0-or-later
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.. _mod-detect_time_jump:
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Detect discontinuous jumps in the system time
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=============================================
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This module detect discontinuous jumps in the system time when resolver
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is running. It clears cache when a significant backward time jumps occurs.
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Time jumps are usually created by NTP time change or by admin intervention.
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These change can affect cache records as they store timestamp and TTL in real
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time.
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If you want to preserve cache during time travel you should disable
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this module by ``modules.unload('detect_time_jump')``.
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Due to the way monotonic system time works on typical systems,
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suspend-resume cycles will be perceived as forward time jumps,
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but this direction of shift does not have the risk of using records
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beyond their intended TTL, so forward jumps do not cause erasing the cache.
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