Add/restore all torrents in "paused" state and then resume those
that need to be really "resumed" (added/restored in "resumed" state).
Keep torrents with missing files paused.
Force recheck torrent with missing files when it's resumed by the user.
During startup we can get above 1000 alerts at each pop even with only
30 torrents in the queue. This is because libtorrent will post
piece_finished_alert and file_completed_alert for each torrent. These
alerts push out of the way the ones we care about.
The alert queue will be grown to max only if needed. So we don't use
more memory. It will greatly depend on how many torrents a user has in
their session.
When getting fastresume_rejected_alert we need to act as fast as
possible in pausing it, otherwise there's a chance it will begin
downloading and writing to disk before we pause it.
"Active torrents" is a somewhat unintuitive concept as a basis for
preventing sleep, as torrents can become active or inactive on the
network at any time. This brings some predictability to the inhibit
sleep option, and will inhibit sleep as long as there are unpaused
downloads or uploads, regardless of network activity.
Closes#1696, #4592, #4655, #7019, #7159, #7452
`QIODevice::read(qint64 maxSize)` will allocate full `maxSize` of memory no matter
what the real file size was, this caused users to experience out-of-memory
exception on 32-bit qbt.
Also handle the OOM execption if it still fails.
Closes#9064, #9075, #9130, #9239, #9246, #9279.
Updating file priorities is an async operation in libtorrent, when we
just updated it and immediately query it, we might get the
old/wrong values, so we rely on `updatedFilePrio` in this case.
Don't post "torrent resumed" event when torrent starts in "resumed"
state.
Fix confusing names. Now "resumed torrent" means "unpaused torrent"
only. When we load previously added torrent it is called "restored
torrent".
