This fixes a bug whereby reconnections would be out of sync due to the
flip state of the server and client being different. The server now
resets its flip state on disconnect.
This changes netplay host mode's behavior in net (normal) mode from
immediately blocking to waiting for a connection while allowing the game
to run, like spectator mode.
Spectate mode is now far more similar to net (normal) mode, and, more
importantly, it works. In addition, spectate mode will not fast-forward
to catch up with the server if it lags too far behind.
The receiving side of a player-flip request now does a forced rewind to
assure that any already-computed frames are computed with the players on
the right side.
Every frame (soon to be configurable), the server does a CRC-32 hash and
sends it to the client. If the client finds that its own hash is
different from the server's, it requests a fresh savestate.
This is a last-ditch effort to sync if all else fails, and it's a
best-effort situation. The size of the buffer should assure that we
always still have the frame around to CRC, but I imagine there are edge
cases where we don't. If you're in an edge case, the CRC is ignored.
Assuming the core supports saving/loading states, and (crucially)
assuming the states are portable across the architectures on both sides
of the connection, Netplay now supports the transmission of savestates.
Right now the frontend doesn't actually send any such requests, as it's
not clear exactly where the code for that should be.
This works in either direction, although I'll admit I have no idea what
happens if they both load at the same time.
Support for remote pausing, and with it, support for Netplay pausing the
frontend correctly. With this patch alone this doesn't work, since
there's no clean way for the frontend to tell Netplay that it's paused.
Rather than counting on the complexicon of used_real calculations, set
used_real when... real is used. (Problem: If the core doesn't read input
at all, used_real won't be set; todo: test with handhelds.) Minor
resilience fixes.
working":
(1) Fixups to the stall logic to make sure it always receives frames
while stalling :)
(2) Disused the used_real field. It was misconfigured and would
frequently claim to be using real data when real data hadn't been
used... this means more replays for now, but used_real will be readded.
(TODO)
(3) Stall duration is now related to sync frames, and thus configurable.
(4) Delta frames were having the good ol' initialization problem, as
frame==0 was indistinguishable from unused. Quickfixed by adding a
"used" field, but maybe there's a better way.
(5) If serialization fails, switch immediately to blocking mode
(stall_frames = 0). Blocking mode barely works, but if serialization
fails, no mode will work!
(6) I'm not sure which bug my replaying-from-previous-frame was trying
to fix, but the correct behavior is to replay from the last frame we had
vital information, not the frame prior. Notionally this should just be
an efficiency thing, but unsigned arithmetic at 0 made this a "just
ignore all input from now on" thing.
for this, and in particular, it now sometimes stalls in a way that makes
it very difficult to actually input anything (whoops :) ). Simply
setting the sync frames higher avoids that. With supported cores, this
is incredibly risilient, but when it fails, it mostly fails to freezing,
which is less than ideal.
TODO: Stall frames should be configurable. All the UDP code is still
there but commented out, should be gutted. The original fast-forward
code is now commented out, but really both fast-forward and stalling
should be options; the only complication is that it needs to send
simulated self-input for fast-forward.
