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actions: Fix “Fix UserActivityInterval overlap bug” bug. 

Commit 1a7ddd9ea3 “Fix
UserActivityInterval overlap bug” introduced a mathematically
incorrect assertion about how intervals work.  There’s a third way two
intervals could overlap: both the start and end of the old interval
could be inside the new interval.  This probably can’t happen here
because the old interval should be at least as long as the new
interval.  However, a correct overlap test can be formulated in a
simpler way anyway.

Signed-off-by: Anders Kaseorg <anders@zulip.com>
This commit is contained in:
Anders Kaseorg 2021-05-24 18:00:00 -07:00
parent 8bcdbc720e
commit 276d95b58b
1 changed files with 4 additions and 7 deletions
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11
zerver/lib/actions.py
View File

@ -5053,13 +5053,10 @@ def do_update_user_activity_interval(
# often, and can be corrected for in post-processing
try:
last = UserActivityInterval.objects.filter(user_profile=user_profile).order_by("-end")[0]
# There are two ways our intervals could overlap:
# (1) The start of the new interval could be inside the old interval
# (2) The end of the new interval could be inside the old interval
# In either case, we just extend the old interval to include the new interval.
if (log_time <= last.end and log_time >= last.start) or (
effective_end <= last.end and effective_end >= last.start
):
# Two intervals overlap iff each interval ends after the other
# begins. In this case, we just extend the old interval to
# include the new interval.
if log_time <= last.end and effective_end >= last.start:
last.end = max(last.end, effective_end)
last.start = min(last.start, log_time)
last.save(update_fields=["start", "end"])