server: handle dropped gamestate after UDP download

Adds an extra check for dropped gamestate for clients that just finished a UDP download, based on detecting missing move commands. Fixes potential "awaiting gamestate" freeze after UDP download completes.
ec- · Jun 1, 2024 · a875f25 · a875f25
1 parent 38c37ea
commit a875f25
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diff --git a/code/server/server.h b/code/server/server.h
@@ -181,6 +181,8 @@ typedef struct client_s {
 	int				downloadBlockSize[MAX_DOWNLOAD_WINDOW];
 	qboolean		downloadEOF;		// We have sent the EOF block
 	int				downloadSendTime;	// time we last got an ack from the client
+	qboolean		downloadGamestateDropCheck;		// perform extra dropped gamestate check after downloads
+	int				downloadGamestateDropTime;		// wait for 2nd client message ~750ms later
 
 	int				deltaMessage;		// frame last client usercmd message
 	int				lastPacketTime;		// svs.time when packet was last received

diff --git a/code/server/sv_client.c b/code/server/sv_client.c
@@ -1202,6 +1202,10 @@ static void SV_DoneDownload_f( client_t *cl ) {
 
 	// resend the game state to update any clients that entered during the download
 	SV_SendClientGameState( cl );
+
+	// activate protection to resend gamestate if previous one was dropped
+	cl->downloadGamestateDropCheck = qtrue;
+	cl->downloadGamestateDropTime = 0;
 }
 
 
@@ -2297,4 +2301,35 @@ void SV_ExecuteClientMessage( client_t *cl, msg_t *msg ) {
 //	if ( msg->readcount != msg->cursize ) {
 //		Com_Printf( "WARNING: Junk at end of packet for client %i\n", cl - svs.clients );
 //	}
+
+	// following UDP downloads, the client expects a new gamestate, but the usual check to
+	// detect if it was dropped may not work because the client has the correct serverid,
+	// so do an extra check based on missing move commands
+	if ( cl->downloadGamestateDropCheck && !*cl->downloadName ) {
+		if ( cl->state == CS_ACTIVE ) {
+			// this means client sent a move command, which means they have gamestate
+			Com_Printf( "%s: clearing gamestate drop check\n", cl->name );
+			cl->downloadGamestateDropCheck = qfalse;
+		} else if ( cl->state == CS_PRIMED && cl->messageAcknowledge - cl->gamestateMessageNum > 0 ) {
+			// likely dropped gamestate, but wait for 2 messages at least 750ms apart to be safer
+			// for client compatibility (client should send messages 1s apart without gamestate)
+			int time = Sys_Milliseconds();
+			if ( !cl->downloadGamestateDropTime ) {
+				Com_DPrintf( "%s: potential dropped post-download gamestate (ack=%i)\n",
+						cl->name, cl->messageAcknowledge - cl->gamestateMessageNum );
+				cl->downloadGamestateDropTime = time;
+			} else if ( time - cl->downloadGamestateDropTime < 750 ) {
+				Com_DPrintf( "%s: potential dropped post-download gamestate bad time (time=%i, ack=%i)\n",
+						cl->name, time - cl->downloadGamestateDropTime,
+						cl->messageAcknowledge - cl->gamestateMessageNum );
+				cl->downloadGamestateDropTime = time;
+			} else {
+				Com_DPrintf( "%s: resending post-download gamestate (time=%i, ack=%i)\n",
+						cl->name, time - cl->downloadGamestateDropTime,
+						cl->messageAcknowledge - cl->gamestateMessageNum );
+				SV_SendClientGameState( cl );
+				cl->downloadGamestateDropTime = 0;
+			}
+		}
+	}
 }