[sr-dev] git:master: modules_k/presence: Use database row/ table locking where supported in DB only mode

[Peter Dunkley]

Module: sip-router
Branch: master
Commit: 34cd2acb5370f36238f8765765cee6d97fd18209
URL:    http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commit;h=34cd2acb5370f36238f8765765cee6d97fd18209

Author: Peter Dunkley <peter.dunkley at crocodile-rcs.com>
Committer: Peter Dunkley <peter.dunkley at crocodile-rcs.com>
Date:   Tue Aug 21 15:36:34 2012 +0100

modules_k/presence: Use database row/table locking where supported in DB only mode

- Under load there are lots of DB deadlocks when using
  (start|end)_transaction() with multiple presence processes and/or
  servers.
- Without using (start|end)_transaction() multiple processes/servers
  overwrite each others changes.
- Using row locking (where possible) and table locking (where
  required) fixes these problems.
- IMPORTANT NOTE: DB only, multi-process/multi-server, presence will
  only work properly under high-load when using a database driver that
  supports transactions and locking (currently just db_postgres).

---

 modules_k/presence/notify.c     |   47 +++++++++++++++++++----
 modules_k/presence/presentity.c |   53 +++++++++++++++++++++++++-
 modules_k/presence/subscribe.c  |   81 +++++++++++++++++++++++++++++++++++---
 3 files changed, 165 insertions(+), 16 deletions(-)

Diff:   http://git.sip-router.org/cgi-bin/gitweb.cgi/sip-router/?a=commitdiff;h=34cd2acb5370f36238f8765765cee6d97fd18209