If we're passing file handles to libcurl to write the data into, the
game may crash under Windows due to incompatible C runtimes between cURL
and quake2. This is even mentioned in the official cURL doku.
Since the moment I took a very first look at the download code I wasn't
a friend of parallel downloads. There're several reasons for that:
- Parallel downloading needs some ugly hacks. For example downloading a
pak file has a high chance to make asset downloads running in parallel
unnecessary.
- Parallel downloads are hard to debug.
- There's just no need for them. I've tested several connection, 1
GBit/s LAN, 50 MBit/s DSL, 6 MBit/s DSL, and there wasn't a
significant difference between 1, 4 or even 16 parallel downloads.
I'm leaving the parallel download code in place. I someone really wants
parallel downloads he can bump the MAX_HTTP_HANDLES define.
Until now download queues entries were created for each file, but only
removed in the unlikely event of changed download server. This leaked
about 4200 byte per file. Fix this by:
- Create a new function CL_RemoveFromQueue() that removes a queue entry
and call it everytime when a download either finished, failed or
aborted.
- Retire the 'download done' state, just the queue entries associated
with a download handle to NULL to communicate that the handle is
unused.
- Cleanup the full queue at shutdown.
Loading libcurl at runtime instead of linking it at compile time makes
things a lot easier and more reliable on Windows. On other platform
libcurl can be installed as optional dependency instead as an hard one.
