Decrease probability of missing important alerts

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.

src/base/bittorrent/session.cpp

@@ -1354,11 +1354,7 @@ void Session::configure(libtorrent::settings_pack &settingsPack)
     settingsPack.set_int(libt::settings_pack::active_tracker_limit, -1);
     settingsPack.set_int(libt::settings_pack::active_dht_limit, -1);
     settingsPack.set_int(libt::settings_pack::active_lsd_limit, -1);
-    // 1 active torrent force 2 connections. If you have more active torrents * 2 than connection limit,
-    // connection limit will get extended. Multiply max connections or active torrents by 10 for queue.
-    // Ignore -1 values because we don't want to set a max int message queue
-    settingsPack.set_int(libt::settings_pack::alert_queue_size, std::max(1000,
-        10 * std::max(maxActiveTorrents() * 2, maxConnections())));
+    settingsPack.set_int(libt::settings_pack::alert_queue_size, std::numeric_limits<int>::max() / 2);
 
     // Outgoing ports
     settingsPack.set_int(libt::settings_pack::outgoing_port, outgoingPortsMin());
@@ -1633,11 +1629,7 @@ void Session::configure(libtorrent::session_settings &sessionSettings)
     sessionSettings.active_tracker_limit = -1;
     sessionSettings.active_dht_limit = -1;
     sessionSettings.active_lsd_limit = -1;
-    // 1 active torrent force 2 connections. If you have more active torrents * 2 than connection limit,
-    // connection limit will get extended. Multiply max connections or active torrents by 10 for queue.
-    // Ignore -1 values because we don't want to set a max int message queue
-    sessionSettings.alert_queue_size = std::max(1000,
-        10 * std::max(maxActiveTorrents() * 2, maxConnections()));
+    sessionSettings.alert_queue_size = std::numeric_limits<int>::max() / 2;
 
     // Outgoing ports
     sessionSettings.outgoing_ports = std::make_pair(outgoingPortsMin(), outgoingPortsMax());

src/base/bittorrent/torrenthandle.cpp

@@ -1661,15 +1661,11 @@ void TorrentHandle::handleSaveResumeDataFailedAlert(const libtorrent::save_resum
 
 void TorrentHandle::handleFastResumeRejectedAlert(const libtorrent::fastresume_rejected_alert *p)
 {
-    qDebug("/!\\ Fast resume failed for %s, reason: %s", qUtf8Printable(name()), p->message().c_str());
-
-    updateStatus();
     if (p->error.value() == libt::errors::mismatching_file_size) {
         // Mismatching file size (files were probably moved)
-        LogMsg(tr("File sizes mismatch for torrent '%1', pausing it.").arg(name()), Log::CRITICAL);
+        pause();
         m_hasMissingFiles = true;
-        if (!isPaused())
-            pause();
+        LogMsg(tr("File sizes mismatch for torrent '%1', pausing it.").arg(name()), Log::CRITICAL);
     }
     else {
         LogMsg(tr("Fast resume data was rejected for torrent '%1'. Reason: %2. Checking again...")