D28181: [contacts/ContactModifyJob] Avoid race condition

[Igor Poboiko]

poboiko created this revision.
poboiko added a reviewer: dvratil.
Herald added a project: KDE PIM.
poboiko requested review of this revision.

REVISION SUMMARY
  This patch is similar to D28178: [contacts] Fix ContactCreateJob with a photo <https://phabricator.kde.org/D28178>. Although `uid` is populated, and we can
  freely dispatch both contact and photo modify requests in parallel, the
  following race condition still sometimes happens:
  
  1. Contact modify request dispatched
  2. Contact photo modify request dispatched
  3. Photo reply arrives
  
  At this point, `d->lastContact` is not yet populated, and we call
  `processNextContact()`, which repeats steps 1 and 2 for the very same contact.
  Which could happen again and again, if photo reply arrives first again.
  
  Instead, I suggest to fire photo modify request only after we receive reply
  for contact modify request, ensuring everything happens in the following order:
  
  1. Contact modify request dispatched
  2. Contact modify reply received
  3. Contact photo modify request dispatched
  4. Contact photo reply received

TEST PLAN
  1. Modify a contact via KAddressBook
  2. Check logs 3.1) (without patch) Bunch of modify requests somtimes gets fired 3.2) (with patch) Only one modify request gets fired

REPOSITORY
  R477 KGAPI Library

BRANCH
  no-race-modify (branched from master)

REVISION DETAIL
  https://phabricator.kde.org/D28181

AFFECTED FILES
  src/contacts/contactmodifyjob.cpp

To: poboiko, dvratil
Cc: kde-pim, fbampaloukas, dcaliste, dvasin, rodsevich, winterz, vkrause, mlaurent, knauss, dvratil
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