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Three issues in the existing Stats/Event_Data/Frames/Events delete
sequence:
- On any zmDbDo error inside the transaction the code called
dbh->commit() instead of dbh->rollback(). The server-side
transaction was already rolled back when InnoDB picked us as the
deadlock victim, so the commit() was effectively against a fresh
auto-started TX, but the bug pattern leaked through as confusing
state and prevented any retry.
- There was no retry. errno 1213 is expected under contention with
zmstats and zma touching the same Event_Summaries[MonitorId] row,
and the loser is supposed to re-run.
- At REPEATABLE READ, two concurrent filter workers deleting events
with adjacent EventIds take next-key/gap locks on each other's
rows in the bucket tables.
Rewrite the delete block as a retry loop: SET TRANSACTION ISOLATION
LEVEL READ COMMITTED, begin_work, run the four DELETEs, commit on
success. On any error rollback (was: commit). On errno 1213 retry up
to 5 times with backoff. Skip both the isolation switch and the
rollback-then-retry when the caller is managing their own transaction
(in_transaction); they would be the wrong scope to act in.
Falls through to the storage DiskSpace adjustment only on commit, so
a deadlocked delete leaves the event for the next filter pass instead
of orphaning the row with stale storage accounting.
Note: do NOT pre-lock Event_Summaries[MonitorId] FOR UPDATE here, even
though the trigger touches it last. Pre-locking puts ES before
buckets[Id] in the lock acquisition order, which inverts against zma's
event_update_trigger path (Events[A] -> buckets[A] -> ES[N]) and
re-introduces the cycle the rest of this work is removing.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
ZoneMinder version 0.01 ======================= The README is used to introduce the module and provide instructions on how to install the module, any machine dependencies it may have (for example C compilers and installed libraries) and any other information that should be provided before the module is installed. A README file is required for CPAN modules since CPAN extracts the README file from a module distribution so that people browsing the archive can use it get an idea of the modules uses. It is usually a good idea to provide version information here so that people can decide whether fixes for the module are worth downloading. INSTALLATION To install this module type the following: perl Makefile.PL make make test make install DEPENDENCIES This module requires these other modules and libraries: blah blah blah COPYRIGHT AND LICENCE Put the correct copyright and licence information here. Copyright (C) 2005 by Philip Coombes This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.3 or, at your option, any later version of Perl 5 you may have available.