NSIS installer takes a long time to install if previous version was not uninstalled

[Patrick Storz]

When the previous Inkscape version was not uninstalled, the installer takes a very long time to finish (i.e. some minutes on my machine instead of few seconds.)

The behavior seems to depend on the presence of the file "Uninstall.dat":
a) if present the installation is slow
b) if deleted the installation is fast

Installation is also fast if "Uninstall.dat" is present but emptied out (all lines deleted), but it seems we really need to avoid this case as NSIS seems not to add any files to the file in this case (probably detecting them as already present) and consequently won't uninstall them either in future.

This issue seems not to be unheard of in the NSIS community:
- http://forums.winamp.com/showthread.php?s=&threadid=302976
- http://forums.winamp.com/showthread.php?s=&threadid=182845
/further investigation - also regarding a solution - necessary, though.

Educated guess:
NSIS might try to compare previously installed files to the new files which are to be installed in scenario a) above which might take a lot of time.

[Patrick Storz (ede123)]

See bug #1718176 for initial report.

[Patrick Storz (ede123)]

I created an upstream report, maybe someone can check what's wrong here...

Either way this should probably never happen for Inkscape (we should not install into a non-empty directory), so maybe we should prevent that actively.

[Patrick Storz (ede123)]

Seems I forgot the link:
https://sourceforge.net/p/nsis/bugs/1192/

[larsch (larsch)]

Upstream bug has been closed as 'invalid' without any comment. Inkscape is still extremely slow when upgrading an existing installation. I gave up upgrading from 0.92.2 to 0.92.4. It basically takes hours, even on an SSD.

[Patrick Storz (ede123)]

Well, there was a comment upstream - it's possible the slowness is caused by "Advanced Uninstall Log".

Until somebody with some NSIS experience finds the time to investigate this, it's unlikely to change, especially as updating installations is usually not a good idea anyway and should be avoided. Actually I've considered to drop this functionality altogether and always recommend to the user to install into an empty folder (i.e. warn if there are still files in the chosen installation directory).

[Patrick Storz (ede123)]

Closing in favor of https://gitlab.com/inkscape/inkscape/issues/300