Revise dynamic_add_media API to better accomodate future changes

builtin/game/misc.lua

@@ -266,3 +266,26 @@ end
 function core.cancel_shutdown_requests()
 	core.request_shutdown("", false, -1)
 end
+
+
+-- Callback handling for dynamic_add_media
+
+local dynamic_add_media_raw = core.dynamic_add_media_raw
+core.dynamic_add_media_raw = nil
+function core.dynamic_add_media(filepath, callback)
+	local ret = dynamic_add_media_raw(filepath)
+	if ret == false then
+		return ret
+	end
+	if callback == nil then
+		core.log("deprecated", "Calling minetest.dynamic_add_media without "..
+			"a callback is deprecated and will stop working in future versions.")
+	else
+		-- At the moment async loading is not actually implemented, so we
+		-- immediately call the callback ourselves
+		for _, name in ipairs(ret) do
+			callback(name)
+		end
+	end
+	return true
+end

doc/lua_api.txt

@@ -5446,20 +5446,22 @@ Server
     * Returns a code (0: successful, 1: no such player, 2: player is connected)
 * `minetest.remove_player_auth(name)`: remove player authentication data
     * Returns boolean indicating success (false if player nonexistant)
-* `minetest.dynamic_add_media(filepath)`
-    * Adds the file at the given path to the media sent to clients by the server
-      on startup and also pushes this file to already connected clients.
+* `minetest.dynamic_add_media(filepath, callback)`
+    * `filepath`: path to a media file on the filesystem
+    * `callback`: function with arguments `name`, where name is a player name
+      (previously there was no callback argument; omitting it is deprecated)
+    * Adds the file to the media sent to clients by the server on startup
+      and also pushes this file to already connected clients.
       The file must be a supported image, sound or model format. It must not be
       modified, deleted, moved or renamed after calling this function.
       The list of dynamically added media is not persisted.
-    * Returns boolean indicating success (duplicate files count as error)
-    * The media will be ready to use (in e.g. entity textures, sound_play)
-      immediately after calling this function.
+    * Returns false on error, true if the request was accepted
+    * The given callback will be called for every player as soon as the
+      media is available on the client.
       Old clients that lack support for this feature will not see the media
-      unless they reconnect to the server.
-    * Since media transferred this way does not use client caching or HTTP
-      transfers, dynamic media should not be used with big files or performance
-      will suffer.
+      unless they reconnect to the server. (callback won't be called)
+    * Since media transferred this way currently does not use client caching
+       or HTTP transfers, dynamic media should not be used with big files.
 
 Bans
 ----

src/script/lua_api/l_server.cpp

@@ -452,19 +452,30 @@ int ModApiServer::l_sound_fade(lua_State *L)
 }
 
 // dynamic_add_media(filepath)
-int ModApiServer::l_dynamic_add_media(lua_State *L)
+int ModApiServer::l_dynamic_add_media_raw(lua_State *L)
 {
 	NO_MAP_LOCK_REQUIRED;
 
-	// Reject adding media before the server has started up
 	if (!getEnv(L))
 		throw LuaError("Dynamic media cannot be added before server has started up");
 
 	std::string filepath = readParam<std::string>(L, 1);
 	CHECK_SECURE_PATH(L, filepath.c_str(), false);
 
-	bool ok = getServer(L)->dynamicAddMedia(filepath);
-	lua_pushboolean(L, ok);
+	std::vector<RemotePlayer*> sent_to;
+	bool ok = getServer(L)->dynamicAddMedia(filepath, sent_to);
+	if (ok) {
+		// (see wrapper code in builtin)
+		lua_createtable(L, sent_to.size(), 0);
+		int i = 0;
+		for (RemotePlayer *player : sent_to) {
+			lua_pushstring(L, player->getName());
+			lua_rawseti(L, -2, ++i);
+		}
+	} else {
+		lua_pushboolean(L, false);
+	}
+
 	return 1;
 }
 
@@ -532,7 +543,7 @@ void ModApiServer::Initialize(lua_State *L, int top)
 	API_FCT(sound_play);
 	API_FCT(sound_stop);
 	API_FCT(sound_fade);
-	API_FCT(dynamic_add_media);
+	API_FCT(dynamic_add_media_raw);
 
 	API_FCT(get_player_information);
 	API_FCT(get_player_privs);

src/script/lua_api/l_server.h

@@ -71,7 +71,7 @@ private:
 	static int l_sound_fade(lua_State *L);
 
 	// dynamic_add_media(filepath)
-	static int l_dynamic_add_media(lua_State *L);
+	static int l_dynamic_add_media_raw(lua_State *L);
 
 	// get_player_privs(name, text)
 	static int l_get_player_privs(lua_State *L);

src/server.cpp

@@ -3465,7 +3465,8 @@ void Server::deleteParticleSpawner(const std::string &playername, u32 id)
 	SendDeleteParticleSpawner(peer_id, id);
 }
 
-bool Server::dynamicAddMedia(const std::string &filepath)
+bool Server::dynamicAddMedia(const std::string &filepath,
+	std::vector<RemotePlayer*> &sent_to)
 {
 	std::string filename = fs::GetFilenameFromPath(filepath.c_str());
 	if (m_media.find(filename) != m_media.end()) {
@@ -3485,9 +3486,17 @@ bool Server::dynamicAddMedia(const std::string &filepath)
 	pkt << raw_hash << filename << (bool) true;
 	pkt.putLongString(filedata);
 
-	auto client_ids = m_clients.getClientIDs(CS_DefinitionsSent);
-	for (session_t client_id : client_ids) {
+	m_clients.lock();
+	for (auto &pair : m_clients.getClientList()) {
+		if (pair.second->getState() < CS_DefinitionsSent)
+			continue;
+		if (pair.second->net_proto_version < 39)
+			continue;
+
+		if (auto player = m_env->getPlayer(pair.second->peer_id))
+			sent_to.emplace_back(player);
 		/*
+			FIXME: this is a very awful hack
 			The network layer only guarantees ordered delivery inside a channel.
 			Since the very next packet could be one that uses the media, we have
 			to push the media over ALL channels to ensure it is processed before
@@ -3496,9 +3505,10 @@ bool Server::dynamicAddMedia(const std::string &filepath)
 			- channel 1 (HUD)
 			- channel 0 (everything else: e.g. play_sound, object messages)
 		*/
-		m_clients.send(client_id, 1, &pkt, true);
-		m_clients.send(client_id, 0, &pkt, true);
+		m_clients.send(pair.second->peer_id, 1, &pkt, true);
+		m_clients.send(pair.second->peer_id, 0, &pkt, true);
 	}
+	m_clients.unlock();
 
 	return true;
 }

src/server.h

@@ -257,7 +257,7 @@ public:
 
 	void deleteParticleSpawner(const std::string &playername, u32 id);
 
-	bool dynamicAddMedia(const std::string &filepath);
+	bool dynamicAddMedia(const std::string &filepath, std::vector<RemotePlayer*> &sent_to);
 
 	ServerInventoryManager *getInventoryMgr() const { return m_inventory_mgr.get(); }
 	void sendDetachedInventory(Inventory *inventory, const std::string &name, session_t peer_id);