Smarter Downloader::startDownload()

[veloman-yunkan]

This PR is an alternative to #1052. Similar to the latter it addresses the user-observable problems behind #1050 without fixing that issue the way it was formulated.

The shared property of #1052 and this PR is that they try to solve the bugs without enhancing the libkiwix API. The difference is that this PR tries to make Downloader::startDownload() smarter, whereas #1052 deprived it of the slightest smartness that it tried to exercise.

Now having tried both approaches I think that we better follow the dumb path. Although we can close the seemingly small gap in downloadCanBeReused() (marked with an XXX comment) my feeling is that trying to optimize for a theoretical situation that can hardly happen in practice is not justified.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 15 lines in your changes missing coverage. Please review.

Project coverage is 40.93%. Comparing base (922c138) to head (3733e50).
Report is 69 commits behind head on main.

Files with missing lines	Patch %	Lines
src/downloader.cpp	0.00%	15 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1066      +/-   ##
==========================================
- Coverage   41.07%   40.93%   -0.14%     
==========================================
  Files          58       58              
  Lines        4190     4204      +14     
  Branches     2304     2307       +3     
==========================================
  Hits         1721     1721              
- Misses       1001     1015      +14     
  Partials     1468     1468              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[mgautierfr]

It is a technical approval. Maybe we need a extra step of discussion if this is a better solution than #1052 (or not)

[mgautierfr]

@veloman-yunkan Do we agree to merge this solution ?

[veloman-yunkan]

@veloman-yunkan Do we agree to merge this solution ?

I think that it may be the best way to proceed. Although my intuition tells me that we may eventually run into other (more subtle) issues connected with this approach, I don't see why we should try to absolutely avoid them, since we can easily switch to the dumb solution at any time.

[mgautierfr]

Let's go with this solution then. If we face some bug with this, we will see then what to do.

[mgautierfr]

Fixes kiwix/kiwix-desktop#1022