Threaded HTTP downloader

Composite of the work of:
- Hacinef (SRB2 repository, https://git.do.srb2.org/STJr/SRB2/-/merge_requests/2322 )
- alufolie91 (SRB2Kart-Saturn repository, 84bfb3991e )
This advancement made possible by Indev in the KKD discord

Untested because I don't know how to set up a HTTP download server

src/d_clisrv.c

@@ -2067,8 +2067,10 @@ static boolean CL_ServerConnectionTicker(const char *tmpsave, tic_t *oldtic, tic
 					break;
 				}
 
+#ifndef HAVE_THREADS
 			if (curl_running)
 				CURLGetFile();
+#endif
 
 			if (waitmore)
 				break; // exit the case

src/d_main.cpp

@@ -1205,6 +1205,7 @@ void D_ClearState(void)
 
 	// okay, stop now
 	// (otherwise the game still thinks we're playing!)
+	CURLAbortFile();
 	SV_StopServer();
 	SV_ResetServer();
 	serverlistultimatecount = 0;

src/d_netfil.c

@@ -101,6 +101,9 @@ static filetran_t transfer[MAXNETNODES];
 INT32 fileneedednum; // Number of files needed to join the server
 fileneeded_t fileneeded[MAX_WADFILES]; // List of needed files
 static tic_t lasttimeackpacketsent = 0;
+#ifdef HAVE_THREADS
+static I_mutex downloadmutex;
+#endif
 
 // For resuming failed downloads
 typedef struct
@@ -1829,10 +1832,13 @@ void CURLPrepareFile(const char* url, int dfilenum)
 		I_Error("Attempted to download files in -nodownload mode");
 #endif
 
+	if (!multi_handle)
+	{
 		curl_global_init(CURL_GLOBAL_ALL);
+		multi_handle = curl_multi_init();
+	}
 
 	http_handle = curl_easy_init();
-	multi_handle = curl_multi_init();
 
 	if (http_handle && multi_handle)
 	{
@@ -1883,34 +1889,54 @@ void CURLPrepareFile(const char* url, int dfilenum)
 		curl_multi_add_handle(multi_handle, http_handle);
 
 		curl_multi_perform(multi_handle, &curl_runninghandles);
+
 		curl_starttime = time(NULL);
 		curl_running = true;
+
+#ifdef HAVE_THREADS
+		I_spawn_thread("http-download", (I_thread_fn)CURLGetFile, NULL);
+#endif
 	}
 }
 
+void CURLAbortFile(void)
+{
+	curl_running = false;
+
+#ifdef HAVE_THREADS
+	// lock and unlock to wait for the download thread to exit
+	I_lock_mutex(&downloadmutex);
+	I_unlock_mutex(downloadmutex);
+#endif
+}
+
 void CURLGetFile(void)
 {
 	CURLMcode mc; /* return code used by curl_multi_wait() */
 	CURLcode easyres; /* Return from easy interface */
-	int numfds;
 	CURLMsg *m; /* for picking up messages with the transfer status */
 	CURL *e;
 	int msgs_left; /* how many messages are left */
 	const char *easy_handle_error;
-	long response_code = 0;
-	static char *filename;
 
+#ifdef HAVE_THREADS
+	boolean running = true;
+
+	I_lock_mutex(&downloadmutex);
+	while (running && curl_running)
+#endif
+	{
 		if (curl_runninghandles)
 		{
 			curl_multi_perform(multi_handle, &curl_runninghandles);
 
 			/* wait for activity, timeout or "nothing" */
-		mc = curl_multi_wait(multi_handle, NULL, 0, 1000, &numfds);
+			mc = curl_multi_wait(multi_handle, NULL, 0, 1000, NULL);
 
 			if (mc != CURLM_OK)
 			{
 				CONS_Alert(CONS_WARNING, "curl_multi_wait() failed, code %d.\n", mc);
-			return;
+				continue;
 			}
 			curl_curfile->currentsize = curl_dlnow;
 			curl_curfile->totalsize = curl_dltotal;
@@ -1921,16 +1947,23 @@ void CURLGetFile(void)
 		{
 			if (m && (m->msg == CURLMSG_DONE))
 			{
+#ifdef HAVE_THREADS
+				running = false;
+#endif
 				e = m->easy_handle;
 				easyres = m->data.result;
-			filename = Z_StrDup(curl_realname);
+
+				char *filename = Z_StrDup(curl_realname);
 				nameonly(filename);
+
 				if (easyres != CURLE_OK)
 				{
+					long response_code = 0;
+
 					if (easyres == CURLE_HTTP_RETURNED_ERROR)
 						curl_easy_getinfo(e, CURLINFO_RESPONSE_CODE, &response_code);
 
-				easy_handle_error = (response_code) ? va("HTTP reponse code %ld", response_code) : curl_easy_strerror(easyres);
+					easy_handle_error = (response_code) ? va("HTTP response code %ld", response_code) : curl_easy_strerror(easyres);
 					curl_curfile->status = FS_FALLBACK;
 					curl_curfile->currentsize = curl_origfilesize;
 					curl_curfile->totalsize = curl_origtotalfilesize;
@@ -1958,10 +1991,11 @@ void CURLGetFile(void)
 					}
 				}
 
-
 				Z_Free(filename);
 				curl_curfile->file = NULL;
+#ifndef HAVE_THREADS
 				curl_running = false;
+#endif
 				curl_transfers--;
 				curl_multi_remove_handle(multi_handle, e);
 				curl_easy_cleanup(e);
@@ -1970,12 +2004,19 @@ void CURLGetFile(void)
 					break;
 			}
 		}
+	}
 
-    if (!curl_transfers)
+    if (!curl_transfers || !curl_running)
     {
 		curl_multi_cleanup(multi_handle);
 		curl_global_cleanup();
+		multi_handle = NULL;
     }
+
+#ifdef HAVE_THREADS
+	curl_running = false;
+	I_unlock_mutex(downloadmutex);
+#endif
 }
 
 HTTP_login *

src/d_netfil.h

@@ -166,6 +166,7 @@ size_t nameonlylength(const char *s);
 
 #ifdef HAVE_CURL
 void CURLPrepareFile(const char* url, int dfilenum);
+void CURLAbortFile(void);
 void CURLGetFile(void);
 HTTP_login * CURLGetLogin (const char *url, HTTP_login ***return_prev_next);
 #endif