5 files changed, 105 insertions, 17 deletions

diff --git a/src/script/cpp_api/s_env.cpp b/src/script/cpp_api/s_env.cpp
index b8717597a..a1b11bfe1 100644
--- a/src/script/cpp_api/s_env.cpp
+++ b/src/script/cpp_api/s_env.cpp
@@ -157,3 +157,42 @@ void ScriptApiEnv::initializeEnvironment(ServerEnvironment *env)
 	}
 	lua_pop(L, 1);
 }
+
+void ScriptApiEnv::on_emerge_area_completion(
+	v3s16 blockpos, int action, ScriptCallbackState *state)
+{
+	Server *server = getServer();
+
+	// Note that the order of these locks is important!  Envlock must *ALWAYS*
+	// be acquired before attempting to acquire scriptlock, or else ServerThread
+	// will try to acquire scriptlock after it already owns envlock, thus
+	// deadlocking EmergeThread and ServerThread
+	MutexAutoLock envlock(server->m_env_mutex);
+
+	SCRIPTAPI_PRECHECKHEADER
+
+	int error_handler = PUSH_ERROR_HANDLER(L);
+
+	lua_rawgeti(L, LUA_REGISTRYINDEX, state->callback_ref);
+	luaL_checktype(L, -1, LUA_TFUNCTION);
+
+	push_v3s16(L, blockpos);
+	lua_pushinteger(L, action);
+	lua_pushinteger(L, state->refcount);
+	lua_rawgeti(L, LUA_REGISTRYINDEX, state->args_ref);
+
+	setOriginDirect(state->origin.c_str());
+
+	try {
+		PCALL_RES(lua_pcall(L, 4, 0, error_handler));
+	} catch (LuaError &e) {
+		server->setAsyncFatalError(e.what());
+	}
+
+	lua_pop(L, 1); // Pop error handler
+
+	if (state->refcount == 0) {
+		luaL_unref(L, LUA_REGISTRYINDEX, state->callback_ref);
+		luaL_unref(L, LUA_REGISTRYINDEX, state->args_ref);
+	}
+}
diff --git a/src/script/cpp_api/s_env.h b/src/script/cpp_api/s_env.h
index 180cfabd0..0d98e627f 100644
--- a/src/script/cpp_api/s_env.h
+++ b/src/script/cpp_api/s_env.h
@@ -24,19 +24,22 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "irr_v3d.h"
 
 class ServerEnvironment;
-struct MapgenParams;
+struct ScriptCallbackState;
 
-class ScriptApiEnv
-		: virtual public ScriptApiBase
-{
+class ScriptApiEnv : virtual public ScriptApiBase {
 public:
-	// On environment step
+	// Called on environment step
 	void environment_Step(float dtime);
-	// After generating a piece of map
-	void environment_OnGenerated(v3s16 minp, v3s16 maxp,u32 blockseed);
 
-	//called on player event
-	void player_event(ServerActiveObject* player, std::string type);
+	// Called after generating a piece of map
+	void environment_OnGenerated(v3s16 minp, v3s16 maxp, u32 blockseed);
+
+	// Called on player event
+	void player_event(ServerActiveObject *player, std::string type);
+
+	// Called after emerge of a block queued from core.emerge_area()
+	void on_emerge_area_completion(v3s16 blockpos, int action,
+		ScriptCallbackState *state);
 
 	void initializeEnvironment(ServerEnvironment *env);
 };
diff --git a/src/script/lua_api/l_env.cpp b/src/script/lua_api/l_env.cpp
index 6ffca6f0f..084b1b440 100644
--- a/src/script/lua_api/l_env.cpp
+++ b/src/script/lua_api/l_env.cpp
@@ -83,6 +83,21 @@ void LuaABM::trigger(ServerEnvironment *env, v3s16 p, MapNode n,
 	lua_pop(L, 1); // Pop error handler
 }
 
+void LuaEmergeAreaCallback(v3s16 blockpos, EmergeAction action, void *param)
+{
+	ScriptCallbackState *state = (ScriptCallbackState *)param;
+	assert(state != NULL);
+	assert(state->script != NULL);
+	assert(state->refcount > 0);
+
+	state->refcount--;
+
+	state->script->on_emerge_area_completion(blockpos, action, state);
+
+	if (state->refcount == 0)
+		delete state;
+}
+
 // Exported functions
 
 // set_node(pos, node)
@@ -748,24 +763,46 @@ int ModApiEnvMod::l_line_of_sight(lua_State *L)
 	return 1;
 }
 
-
-// emerge_area(p1, p2)
-// emerge mapblocks in area p1..p2
+// emerge_area(p1, p2, [callback, context])
+// emerge mapblocks in area p1..p2, calls callback with context upon completion
 int ModApiEnvMod::l_emerge_area(lua_State *L)
 {
 	GET_ENV_PTR;
 
+	EmergeCompletionCallback callback = NULL;
+	ScriptCallbackState *state = NULL;
+
 	EmergeManager *emerge = getServer(L)->getEmergeManager();
 
 	v3s16 bpmin = getNodeBlockPos(read_v3s16(L, 1));
 	v3s16 bpmax = getNodeBlockPos(read_v3s16(L, 2));
 	sortBoxVerticies(bpmin, bpmax);
 
+	size_t num_blocks = VoxelArea(bpmin, bpmax).getVolume();
+	assert(num_blocks != 0);
+
+	if (lua_isfunction(L, 3)) {
+		callback = LuaEmergeAreaCallback;
+
+		lua_pushvalue(L, 3);
+		int callback_ref = luaL_ref(L, LUA_REGISTRYINDEX);
+
+		lua_pushvalue(L, 4);
+		int args_ref = luaL_ref(L, LUA_REGISTRYINDEX);
+
+		state = new ScriptCallbackState;
+		state->script       = getServer(L)->getScriptIface();
+		state->callback_ref = callback_ref;
+		state->args_ref     = args_ref;
+		state->refcount     = num_blocks;
+		state->origin       = getScriptApiBase(L)->getOrigin();
+	}
+
 	for (s16 z = bpmin.Z; z <= bpmax.Z; z++)
 	for (s16 y = bpmin.Y; y <= bpmax.Y; y++)
 	for (s16 x = bpmin.X; x <= bpmax.X; x++) {
-		v3s16 chunkpos(x, y, z);
-		emerge->enqueueBlockEmerge(PEER_ID_INEXISTENT, chunkpos, false, true);
+		emerge->enqueueBlockEmergeEx(v3s16(x, y, z), PEER_ID_INEXISTENT,
+			BLOCK_EMERGE_ALLOW_GEN | BLOCK_EMERGE_FORCE_QUEUE, callback, state);
 	}
 
 	return 0;
diff --git a/src/script/lua_api/l_env.h b/src/script/lua_api/l_env.h
index 8354379f3..424556d4b 100644
--- a/src/script/lua_api/l_env.h
+++ b/src/script/lua_api/l_env.h
@@ -172,8 +172,7 @@ public:
 	static void Initialize(lua_State *L, int top);
 };
 
-class LuaABM : public ActiveBlockModifier
-{
+class LuaABM : public ActiveBlockModifier {
 private:
 	int m_id;
 
@@ -219,4 +218,12 @@ public:
 			u32 active_object_count, u32 active_object_count_wider);
 };
 
+struct ScriptCallbackState {
+	GameScripting *script;
+	int callback_ref;
+	int args_ref;
+	unsigned int refcount;
+	std::string origin;
+};
+
 #endif /* L_ENV_H_ */
diff --git a/src/server.h b/src/server.h
index a4be7d3fb..3ec889971 100644
--- a/src/server.h
+++ b/src/server.h
@@ -378,6 +378,9 @@ public:
 	// Bind address
 	Address m_bind_addr;
 
+	// Environment mutex (envlock)
+	Mutex m_env_mutex;
+
 private:
 
 	friend class EmergeThread;
@@ -518,7 +521,6 @@ private:
 
 	// Environment
 	ServerEnvironment *m_env;
-	Mutex m_env_mutex;
 
 	// server connection
 	con::Connection m_con;