D15638: force-finish canberra notifications on close()

[Harald Sitter]

sitter created this revision.
sitter added a reviewer: broulik.
Herald added a project: Frameworks.
Herald added a subscriber: kde-frameworks-devel.
sitter requested review of this revision.

REVISION SUMMARY
  `KNotification::close()` causes the manager to close the plugin for the
  notification and after that KNotification will call deleteLater() on
  itself. In the canberra variant of NotifyByAudio we handled this by calling
  ca_context_cancel to abort playback of the audio. This ultimately would
  still cause a finishCallback once the playback actually cancelled. The
  callback does arrive in an undefined amount of loop cycles later though.
  Put together this allowed for timing issues where deleteLater would run
  before the finishCallback arrived, giving finishCallback the risk of
  accessing a KNotification object past its lifetime and segfaulting.
  
  To prevent this from happening we'll finishNotification in the plugin's
  close(). This drops the notification out of the mapping hashes and tells
  the manager that we are done. finishCallback now returns immediately if it
  cannot find a mapping for a notification (i.e. it was close()d already).
  
  CHANGELOG: Fixed a crash caused by bad lifetime management of canberra-based audio notification
  BUG: 398695

TEST PLAN
  added qdebugs. without patch close() and thus deleteLater() happens before finishCallback() but the callback still does its thing. with patch finishCallback is noop.

REPOSITORY
  R289 KNotifications

BRANCH
  master

REVISION DETAIL
  https://phabricator.kde.org/D15638

AFFECTED FILES
  src/notifybyaudio_canberra.cpp

To: sitter, broulik
Cc: kde-frameworks-devel, jtamate, michaelh, ngraham, bruns
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.kde.org/pipermail/kde-frameworks-devel/attachments/20180921/aebbe7ac/attachment-0001.html>