Add callback on_mapblocks_changed

builtin/game/misc_s.lua

@@ -8,10 +8,9 @@
 -- Misc. API functions
 --
 
+-- This must match the implementation in src/script/common/c_converter.h
 function core.hash_node_position(pos)
-	return (pos.z + 32768) * 65536 * 65536
-		 + (pos.y + 32768) * 65536
-		 +  pos.x + 32768
+	return (pos.z + 0x8000) * 0x100000000 + (pos.y + 0x8000) * 0x10000 + (pos.x + 0x8000)
 end
 
 

builtin/game/register.lua

@@ -633,6 +633,17 @@ core.registered_on_player_inventory_actions, core.register_on_player_inventory_a
 core.registered_allow_player_inventory_actions, core.register_allow_player_inventory_action = make_registration()
 core.registered_on_rightclickplayers, core.register_on_rightclickplayer = make_registration()
 core.registered_on_liquid_transformed, core.register_on_liquid_transformed = make_registration()
+core.registered_on_mapblocks_changed, core.register_on_mapblocks_changed = make_registration()
+
+core.register_on_mods_loaded(function()
+	core.after(0, function()
+		setmetatable(core.registered_on_mapblocks_changed, {
+			__newindex = function()
+				error("on_mapblocks_changed callbacks must be registered at load time")
+			end,
+		})
+	end)
+end)
 
 --
 -- Compatibility for on_mapgen_init()

builtin/profiler/instrumentation.lua

@@ -43,6 +43,7 @@ local register_functions = {
 	register_on_item_eat = 0,
 	register_on_punchplayer = 0,
 	register_on_player_hpchange = 0,
+	register_on_mapblocks_changed = 0,
 }
 
 ---

doc/lua_api.txt

@@ -5372,6 +5372,16 @@ Call these functions only at load time!
     * `pos_list` is an array of all modified positions.
     * `node_list` is an array of the old node that was previously at the position
       with the corresponding index in pos_list.
+* `minetest.register_on_mapblocks_changed(function(modified_blocks, modified_block_count))`
+    * Called soon after any nodes or node metadata have been modified. No
+      modifications will be missed, but there may be false positives.
+    * Will never be called more than once per server step.
+    * `modified_blocks` is the set of modified mapblock position hashes. These
+      are in the same format as those produced by `minetest.hash_node_position`,
+      and can be converted to positions with `minetest.get_position_from_hash`.
+      The set is a table where the keys are hashes and the values are `true`.
+    * `modified_block_count` is the number of entries in the set.
+    * Note: callbacks must be registered at mod load time.
 
 Setting-related
 ---------------

games/devtest/mods/unittests/misc.lua

@@ -147,3 +147,33 @@ local function test_mapgen_edges(cb)
 	minetest.emerge_area(max_edge, max_edge:add(1), emerge_block, max_finished)
 end
 unittests.register("test_mapgen_edges", test_mapgen_edges, {map=true, async=true})
+
+local finish_test_on_mapblocks_changed
+minetest.register_on_mapblocks_changed(function(modified_blocks, modified_block_count)
+	if finish_test_on_mapblocks_changed then
+		finish_test_on_mapblocks_changed(modified_blocks, modified_block_count)
+		finish_test_on_mapblocks_changed = nil
+	end
+end)
+local function test_on_mapblocks_changed(cb, player, pos)
+	local bp1 = (pos / minetest.MAP_BLOCKSIZE):floor()
+	local bp2 = bp1:add(1)
+	for _, bp in ipairs({bp1, bp2}) do
+		-- Make a modification in the block.
+		local p = bp * minetest.MAP_BLOCKSIZE
+		minetest.load_area(p)
+		local meta = minetest.get_meta(p)
+		meta:set_int("test_on_mapblocks_changed", meta:get_int("test_on_mapblocks_changed") + 1)
+	end
+	finish_test_on_mapblocks_changed = function(modified_blocks, modified_block_count)
+		if modified_block_count < 2 then
+			return cb("Expected at least two mapblocks to be recorded as modified")
+		end
+		if not modified_blocks[minetest.hash_node_position(bp1)] or
+				not modified_blocks[minetest.hash_node_position(bp2)] then
+			return cb("The expected mapblocks were not recorded as modified")
+		end
+		cb()
+	end
+end
+unittests.register("test_on_mapblocks_changed", test_on_mapblocks_changed, {map=true, async=true})

src/script/common/c_converter.h

@@ -121,3 +121,12 @@ void                warn_if_field_exists(lua_State *L, int table,
 
 size_t write_array_slice_float(lua_State *L, int table_index, float *data,
 	v3u16 data_size, v3u16 slice_offset, v3u16 slice_size);
+
+// This must match the implementation in builtin/game/misc_s.lua
+// Note that this returns a floating point result as Lua integers are 32-bit
+inline lua_Number hash_node_position(v3s16 pos)
+{
+	return (((s64)pos.Z + 0x8000L) << 32)
+			| (((s64)pos.Y + 0x8000L) << 16)
+			| ((s64)pos.X + 0x8000L);
+}

src/script/cpp_api/s_env.cpp

@@ -299,3 +299,36 @@ void ScriptApiEnv::on_liquid_transformed(
 
 	runCallbacks(2, RUN_CALLBACKS_MODE_FIRST);
 }
+
+void ScriptApiEnv::on_mapblocks_changed(const std::unordered_set<v3s16> &set)
+{
+	SCRIPTAPI_PRECHECKHEADER
+
+	// Get core.registered_on_mapblocks_changed
+	lua_getglobal(L, "core");
+	lua_getfield(L, -1, "registered_on_mapblocks_changed");
+	luaL_checktype(L, -1, LUA_TTABLE);
+	lua_remove(L, -2);
+
+	// Convert the set to a set of position hashes
+	lua_createtable(L, 0, set.size());
+	for(const v3s16 &p : set) {
+		lua_pushnumber(L, hash_node_position(p));
+		lua_pushboolean(L, true);
+		lua_rawset(L, -3);
+	}
+	lua_pushinteger(L, set.size());
+
+	runCallbacks(2, RUN_CALLBACKS_MODE_FIRST);
+}
+
+bool ScriptApiEnv::has_on_mapblocks_changed()
+{
+	SCRIPTAPI_PRECHECKHEADER
+
+	// Get core.registered_on_mapblocks_changed
+	lua_getglobal(L, "core");
+	lua_getfield(L, -1, "registered_on_mapblocks_changed");
+	luaL_checktype(L, -1, LUA_TTABLE);
+	return lua_objlen(L, -1) > 0;
+}

src/script/cpp_api/s_env.h

@@ -22,6 +22,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "cpp_api/s_base.h"
 #include "irr_v3d.h"
 #include "mapnode.h"
+#include <unordered_set>
 #include <vector>
 
 class ServerEnvironment;
@@ -48,5 +49,11 @@ public:
 	// Called after liquid transform changes
 	void on_liquid_transformed(const std::vector<std::pair<v3s16, MapNode>> &list);
 
+	// Called after mapblock changes
+	void on_mapblocks_changed(const std::unordered_set<v3s16> &set);
+
+	// Determines whether there are any on_mapblocks_changed callbacks
+	bool has_on_mapblocks_changed();
+
 	void initializeEnvironment(ServerEnvironment *env);
 };

src/serverenvironment.cpp

@@ -381,6 +381,18 @@ void ActiveBlockList::update(std::vector<PlayerSAO*> &active_players,
 	m_list = std::move(newlist);
 }
 
+/*
+	OnMapblocksChangedReceiver
+*/
+
+void OnMapblocksChangedReceiver::onMapEditEvent(const MapEditEvent &event)
+{
+	assert(receiving);
+	for (const v3s16 &p : event.modified_blocks) {
+		modified_blocks.insert(p);
+	}
+}
+
 /*
 	ServerEnvironment
 */
@@ -476,6 +488,11 @@ void ServerEnvironment::init()
 
 	m_player_database = openPlayerDatabase(player_backend_name, m_path_world, conf);
 	m_auth_database = openAuthDatabase(auth_backend_name, m_path_world, conf);
+
+	if (m_map && m_script->has_on_mapblocks_changed()) {
+		m_map->addEventReceiver(&m_on_mapblocks_changed_receiver);
+		m_on_mapblocks_changed_receiver.receiving = true;
+	}
 }
 
 ServerEnvironment::~ServerEnvironment()
@@ -1570,6 +1587,14 @@ void ServerEnvironment::step(float dtime)
 	// Send outdated detached inventories
 	m_server->sendDetachedInventories(PEER_ID_INEXISTENT, true);
 
+	// Notify mods of modified mapblocks
+	if (m_on_mapblocks_changed_receiver.receiving &&
+			!m_on_mapblocks_changed_receiver.modified_blocks.empty()) {
+		std::unordered_set<v3s16> modified_blocks;
+		std::swap(modified_blocks, m_on_mapblocks_changed_receiver.modified_blocks);
+		m_script->on_mapblocks_changed(modified_blocks);
+	}
+
 	const auto end_time = porting::getTimeUs();
 	m_step_time_counter->increment(end_time - start_time);
 }

src/serverenvironment.h

@@ -21,7 +21,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include "activeobject.h"
 #include "environment.h"
-#include "mapnode.h"
+#include "map.h"
 #include "settings.h"
 #include "server/activeobjectmgr.h"
 #include "util/numeric.h"
@@ -30,9 +30,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include <random>
 
 class IGameDef;
-class ServerMap;
 struct GameParams;
-class MapBlock;
 class RemotePlayer;
 class PlayerDatabase;
 class AuthDatabase;
@@ -193,6 +191,16 @@ public:
 	std::set<v3s16> m_forceloaded_list;
 };
 
+/*
+	ServerEnvironment::m_on_mapblocks_changed_receiver
+*/
+struct OnMapblocksChangedReceiver : public MapEventReceiver {
+	std::unordered_set<v3s16> modified_blocks;
+	bool receiving = false;
+
+	void onMapEditEvent(const MapEditEvent &event) override;
+};
+
 /*
 	Operation mode for ServerEnvironment::clearObjects()
 */
@@ -455,6 +463,8 @@ private:
 	Server *m_server;
 	// Active Object Manager
 	server::ActiveObjectMgr m_ao_manager;
+	// on_mapblocks_changed map event receiver
+	OnMapblocksChangedReceiver m_on_mapblocks_changed_receiver;
 	// World path
 	const std::string m_path_world;
 	// Outgoing network message buffer for active objects