Review Request 120420: [OS X] a more complete approach to prevent the crash after finishing a code-difference review or git/commit

[René J.V. Bertin]

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I don't know whether it's related to my proposed changes or to something else, but I am now experiencing another issue.

After submitting a patch to ReviewBoard, *most of the time* KDevelop enters what I can only describe as an "in-between" state. The actions in the Mac's global menubar remain functional, but when I try to open a context menu by right-clicking on an entry in the project toolview, a kind of UI freeze occurs. Again, the global menu items remain functional, and allow me to quit KDevelop (which is about the only sensible thing to do at this point).
Attaching a debugger and going over backtraces obtained after trying too hard to get back into a working state it would seem that the right-click context menu *did and remains open* but simply never got rendered. (In fact, there's a brief flicker, and a visual indication in the project tree where I right-clicked.) Hitting escape is no help, though.

This only happens after submitting a patch for review successfully.

Any ideas?

- René J.V. Bertin


On Dec. 19, 2014, 6:52 p.m., René J.V. Bertin wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://git.reviewboard.kde.org/r/120420/
> -----------------------------------------------------------
> 
> (Updated Dec. 19, 2014, 6:52 p.m.)
> 
> 
> Review request for KDE Software on Mac OS X and KDevelop.
> 
> 
> Repository: kdevplatform
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> 
> Description
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> 
> This RR replaces https://git.reviewboard.kde.org/r/120150/, itself a follow-up to RR https://reviewboard.kde.org/r/120081/ . In that RR I proposed an (accepted & submitted ) approach to prevent kdevelop from crashing after closing the patch review ("git/show differences") toolview.
> 
> This turned out to be insufficient, the most likely culprit being a nested event loop. In my most recent bug hunting I noticed that `closeReview` is called through Qt's mouse-eventh handling function when the "Finish Review" button (or "Commit", when doing a git->commit) is pressed. The crash I have been experiencing occurs in that function (or at least not far down the call stack from that function).
> I had already noticed that the crash never occurred when I closed all document views first (the patch file and all modified files), e.g. by using the "Close All" menu action.
> 
> So:
> - `closeReview` closes all open documents (minus the patchfile) via `qDeleteAll(m_highlighters)` or by calling `m_highlighters.erase(iterator)` repeatedly. Documents are thus closed by deleting the "content object" that represents them, letting that fact filter back to the UI
> - closing documents via the UI takes the opposite route, and is more in line with a modern GUI framework (at least OS X/Cocoa) where everything happens because of an event in the user interface. You receive an event (message) when the user closes a document, the framework handles most UI-related stuff for you, and if you have to dispose of document-related non-gui data you can do that for example just before the widget actually closes (`windowWillClose`, `menuWillClose`, `applicationWillClose` etc. messages in Cocoa).
> 
> This led to the current patch, which cycles through and closes the `Sublime::View`s associated with the window area, and then lets Qt send and process all events that are pending and/or result from closing those windows. Only then does it proceed the regular course of action (calling `removeHighLighting()` which ought to be no longer necessary).
> 
> The only change for the user is that the pinkish patch review plugin background (with the "back to code" button) is visible briefly before the toolview is closed.
> 
> I understand that this crash (or a closely related one) does not only occur on OS X but also on Linux, so I did not put the new code in a conditional block.
> 
> 
> Diffs
> -----
> 
>   plugins/grepview/grepviewplugin.cpp 7e3d933 
>   plugins/patchreview/patchreview.cpp 18b63db 
>   shell/sessioncontroller.cpp ae4e355 
>   vcs/vcspluginhelper.cpp 26ab57c 
>   vcs/widgets/vcsdiffpatchsources.cpp c3e2dae 
>   vcs/widgets/vcsdiffwidget.cpp 54787b9 
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> Diff: https://git.reviewboard.kde.org/r/120420/diff/
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> 
> Testing
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> kdevplatform git/kde4-legacy on KDE/MacPorts OS X 10.6.8 with kdelibs 4.14.1
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> 
> Thanks,
> 
> René J.V. Bertin
> 
>

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