Adding upstream version 5.6.0.upstream/5.6.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 22 insertions, 0 deletions

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