Bitcoin should shut itself down or cancel system shutdown if system is shutdown while running #4036

If a user shutdowns their system while bitcoin-qt is running, they receive the pop-up window that says, "Bitcoin Core is shutting down..." "Do not shut down the computer until this window disappears."

However, by the time the pop-up shows, the user has already shutdown the system and is thinking that that they may have caused a problem.

Should the second line say, "Do not power off the computer until this window disappears." Or should there be a warning to never shutdown your computer while bitcoin-qt is running?

shutdown message here: https://github.com/bitcoin/bitcoin/blob/master/src/qt/utilitydialog.cpp#L126

The message is accurate. Shutting down your computer while bitcoin is running can be dangerous. If it is not shut down properly, the database (or even wallet) may be left in a corrupted state.

Maybe you could use QtCloseEvent to prevent windows program termination during important tasks. This way when program close is requested it can prevent termination during the bitcoin shutdown tasks, then release control.

Thanks - yes, it's more than just the message. The problem is that a user hits shutdown, then the user sees the message that they should not have done it. Like @drak said, can we make bitcoin stall shutdown so it can finish? See: QSessionManager::cancel () https://qt-project.org/doc/qt-4.7/qsessionmanager.html#id-df0f5c47-b430-4fdb-8ef2-d1214a82b61f "Tells the session manager to cancel the shutdown process. Applications should not call this function without asking the user first. See also allowsInteraction() and allowsErrorInteraction()."

I'd suggest popping up a window with "Shutdown bitcoin or cancel system log off?" with an "ok" and "cancel" button if allowsInteraction() is true. "ok" triggers normal bitcoin close, "cancel" triggers QSessionManager:cancel(). It won't prevent remote shutdowns, but if allowsInteraction() is true, it will stop users from shutting down accidentally.

EDIT: an example of catching the shutdown signal and cancelling it is here: http://qt.developpez.com/doc/4.7/qsessionmanager/#allowsinteraction

I have got working code for this at least for Windows, I'll create a patch tomorrow for review :).

For *nix implement callback signal(SIGINT, sigint_callback) via signal.h & errno.h would work does Windows use this? then you are already done? :-)

On Wed, Apr 9, 2014 at 4:49 PM, P. Kaufmann notifications@github.comwrote:

I have got working code for this at least for Windows, I'll create a patch tomorrow for review :).

Reply to this email directly or view it on GitHubhttps://github.com/bitcoin/bitcoin/issues/4036#issuecomment-40014486 .

Jourdain Casale Lead Computer Scientist | Advanced Research Projects | CASCORP Direct: +1 (647) 505-5919

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If it's possible to hold the windows shutdown it should be done in a non-QT specific way because the gui-less daemon also needs to close itself completely. I'm unsure if we have any more remaining issues where shutdown will take more than a few seconds— we probably do.

@gmaxwell Several, at least these I know of:

#3966 Client keeps updating tip after Shutdown requested #2954 Opencon thread massively slows down client shutdown

It could be frustrating to hold up shutdown in this case, though it's certainly better than forcing shutting down and possibly breaking something.