[Tarantool-patches] [PATCH v2] refactoring: wrap lua_newthread using luaT_cpcall

[Tarantool-patches] [PATCH v2] refactoring: wrap lua_newthread using luaT_cpcall

[Ilya Kosarev]

Wrap throwing lua_newthread in luaT_newthread using luaT_cpcall
to process arising error properly.

Closes #4556
---
https://github.com/tarantool/tarantool/tree/i.kosarev/gh-4556-wrap-lua-newthread
https://github.com/tarantool/tarantool/issues/4556

Changes in v2:
- introduced luaT_newthread instead of repeated slocs
- renamed luaL_pushthread to luaT_pushthread due to namespaces agreement

 src/box/lua/call.c            | 12 +++++++---
 src/lua/fiber.c               |  4 +++-
 src/lua/trigger.c             | 12 ++++------
 src/lua/utils.h               | 41 +++++++++++++++++++++++++++++++++++
 third_party/lua-yaml/lyaml.cc |  5 ++++-
 5 files changed, 61 insertions(+), 13 deletions(-)

diff --git a/src/box/lua/call.c b/src/box/lua/call.c
index 631003c84..51cad286a 100644
--- a/src/box/lua/call.c
+++ b/src/box/lua/call.c
@@ -527,7 +527,9 @@ static inline int
 box_process_lua(lua_CFunction handler, struct execute_lua_ctx *ctx,
 		struct port *ret)
 {
-	lua_State *L = lua_newthread(tarantool_L);
+	lua_State *L = luaT_newthread(tarantool_L);
+	if (L == NULL)
+		return -1;
 	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
 	port_lua_create(ret, L);
 	((struct port_lua *) ret)->ref = coro_ref;
@@ -654,7 +656,9 @@ func_persistent_lua_load(struct func_lua *func)
 	 * an arbitrary user-defined code
 	 * (e.g. body = 'fiber.yield()').
 	 */
-	struct lua_State *coro_L = lua_newthread(tarantool_L);
+	lua_State *coro_L = luaT_newthread(tarantool_L);
+	if (coro_L == NULL)
+		return -1;
 	if (!func->base.def->is_sandboxed) {
 		/*
 		 * Keep the original env to apply to a non-sandboxed
@@ -811,7 +815,9 @@ lbox_func_call(struct lua_State *L)
 	 * before the function call to pass it into the
 	 * pcall-sandboxed tarantool_L handler.
 	 */
-	lua_State *args_L = lua_newthread(tarantool_L);
+	lua_State *args_L = luaT_newthread(tarantool_L);
+	if (args_L == NULL)
+		return luaT_error(L);
 	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
 	lua_xmove(L, args_L, lua_gettop(L) - 1);
 	struct port args;
diff --git a/src/lua/fiber.c b/src/lua/fiber.c
index 336be60a2..124908a05 100644
--- a/src/lua/fiber.c
+++ b/src/lua/fiber.c
@@ -388,7 +388,9 @@ lua_fiber_run_f(MAYBE_UNUSED va_list ap)
 static struct fiber *
 fiber_create(struct lua_State *L)
 {
-	struct lua_State *child_L = lua_newthread(L);
+	lua_State *child_L = luaT_newthread(L);
+	if (child_L == NULL)
+		luaT_error(L);
 	int coro_ref = luaL_ref(L, LUA_REGISTRYINDEX);
 
 	struct fiber *f = fiber_new("lua", lua_fiber_run_f);
diff --git a/src/lua/trigger.c b/src/lua/trigger.c
index 4803e85c5..6df048a8d 100644
--- a/src/lua/trigger.c
+++ b/src/lua/trigger.c
@@ -73,17 +73,13 @@ lbox_trigger_run(struct trigger *ptr, void *event)
 	 * trigger yields, so when it's time to clean
 	 * up the coro, we wouldn't know which stack position
 	 * it is on.
-	 *
-	 * XXX: lua_newthread() may throw if out of memory,
-	 * this needs to be wrapped with lua_pcall() as well.
-	 * Don't, since it's a stupid overhead on every trigger
-	 * invocation, and in future we plan to hack into Lua
-	 * C API to fix this.
 	 */
-	struct lua_State *L;
+	lua_State *L;
 	int coro_ref;
 	if (fiber()->storage.lua.stack == NULL) {
-		L = lua_newthread(tarantool_L);
+		L = luaT_newthread(tarantool_L);
+		if (L == NULL)
+			diag_raise();
 		coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
 	} else {
 		L = fiber()->storage.lua.stack;
diff --git a/src/lua/utils.h b/src/lua/utils.h
index f8c34545a..f82b30fbc 100644
--- a/src/lua/utils.h
+++ b/src/lua/utils.h
@@ -591,6 +591,47 @@ luaL_checkfinite(struct lua_State *L, struct luaL_serializer *cfg,
 		luaL_error(L, "number must not be NaN or Inf");
 }
 
+/**
+ * @brief A wrapper for lua_newthread() to pass it into luaT_cpcall
+ * @param L is a Lua State
+ * @sa lua_newthread()
+ */
+static inline int
+lua_newthread_wrapper(lua_State *L)
+{
+	*(lua_State **)lua_touserdata(L, 1) = lua_newthread(L);
+	return 0;
+}
+
+/**
+ * @brief Push L1 thread onto the L stack
+ * @param L is a Lua State whose stack we are pushing onto
+ * @param L1 is a Lua State whose thread we are pushing
+ */
+static inline void
+luaT_pushthread(lua_State *L, lua_State *L1)
+{
+	setthreadV(L, L->top, L1);
+	incr_top(L);
+}
+
+/**
+ * @brief Safe wrapper for lua_newthread()
+ * @param L is a Lua State
+ * @sa lua_newthread()
+ */
+static inline lua_State *
+luaT_newthread(lua_State *L)
+{
+	lua_State *L1 = NULL;
+	if (luaT_cpcall(L, lua_newthread_wrapper, &L1) != 0) {
+		return NULL;
+	}
+	assert(L1 != NULL);
+	luaT_pushthread(L, L1);
+	return L1;
+}
+
 /**
  * Check if a value on @a L stack by index @a idx is an ibuf
  * object. Both 'struct ibuf' and 'struct ibuf *' are accepted.
diff --git a/third_party/lua-yaml/lyaml.cc b/third_party/lua-yaml/lyaml.cc
index 7485341fa..af4f2f5d5 100644
--- a/third_party/lua-yaml/lyaml.cc
+++ b/third_party/lua-yaml/lyaml.cc
@@ -789,7 +789,10 @@ lua_yaml_encode(lua_State *L, struct luaL_serializer *serializer,
    dumper.cfg = serializer;
    dumper.error = 0;
    /* create thread to use for YAML buffer */
-   dumper.outputL = lua_newthread(L);
+   dumper.outputL = luaT_newthread(L);
+   if (dumper.outputL == NULL) {
+      return luaL_error(L, OOM_ERRMSG);
+   }
    luaL_buffinit(dumper.outputL, &dumper.yamlbuf);
 
    if (!yaml_emitter_initialize(&dumper.emitter))
-- 
2.17.1

Re: [Tarantool-patches] [PATCH v2] refactoring: wrap lua_newthread using luaT_cpcall

[Igor Munkin]

Ilya,

Thanks, the patch LGTM, however please consider my minor comments.

On 17.10.19, Ilya Kosarev wrote:
> Wrap throwing lua_newthread in luaT_newthread using luaT_cpcall
> to process arising error properly.
> 
> Closes #4556
> ---
> https://github.com/tarantool/tarantool/tree/i.kosarev/gh-4556-wrap-lua-newthread
> https://github.com/tarantool/tarantool/issues/4556
> 
> Changes in v2:
> - introduced luaT_newthread instead of repeated slocs
> - renamed luaL_pushthread to luaT_pushthread due to namespaces agreement
> 
>  src/box/lua/call.c            | 12 +++++++---
>  src/lua/fiber.c               |  4 +++-
>  src/lua/trigger.c             | 12 ++++------
>  src/lua/utils.h               | 41 +++++++++++++++++++++++++++++++++++
>  third_party/lua-yaml/lyaml.cc |  5 ++++-
>  5 files changed, 61 insertions(+), 13 deletions(-)
> 
> diff --git a/src/box/lua/call.c b/src/box/lua/call.c
> index 631003c84..51cad286a 100644
> --- a/src/box/lua/call.c
> +++ b/src/box/lua/call.c
> @@ -527,7 +527,9 @@ static inline int
>  box_process_lua(lua_CFunction handler, struct execute_lua_ctx *ctx,
>  		struct port *ret)
>  {
> -	lua_State *L = lua_newthread(tarantool_L);
> +	lua_State *L = luaT_newthread(tarantool_L);
> +	if (L == NULL)
> +		return -1;
>  	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
>  	port_lua_create(ret, L);
>  	((struct port_lua *) ret)->ref = coro_ref;
> @@ -654,7 +656,9 @@ func_persistent_lua_load(struct func_lua *func)
>  	 * an arbitrary user-defined code
>  	 * (e.g. body = 'fiber.yield()').
>  	 */
> -	struct lua_State *coro_L = lua_newthread(tarantool_L);
> +	lua_State *coro_L = luaT_newthread(tarantool_L);
> +	if (coro_L == NULL)
> +		return -1;
>  	if (!func->base.def->is_sandboxed) {
>  		/*
>  		 * Keep the original env to apply to a non-sandboxed
> @@ -811,7 +815,9 @@ lbox_func_call(struct lua_State *L)
>  	 * before the function call to pass it into the
>  	 * pcall-sandboxed tarantool_L handler.
>  	 */
> -	lua_State *args_L = lua_newthread(tarantool_L);
> +	lua_State *args_L = luaT_newthread(tarantool_L);
> +	if (args_L == NULL)
> +		return luaT_error(L);
>  	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
>  	lua_xmove(L, args_L, lua_gettop(L) - 1);
>  	struct port args;
> diff --git a/src/lua/fiber.c b/src/lua/fiber.c
> index 336be60a2..124908a05 100644
> --- a/src/lua/fiber.c
> +++ b/src/lua/fiber.c
> @@ -388,7 +388,9 @@ lua_fiber_run_f(MAYBE_UNUSED va_list ap)
>  static struct fiber *
>  fiber_create(struct lua_State *L)
>  {
> -	struct lua_State *child_L = lua_newthread(L);
> +	lua_State *child_L = luaT_newthread(L);
> +	if (child_L == NULL)
> +		luaT_error(L);
>  	int coro_ref = luaL_ref(L, LUA_REGISTRYINDEX);
>  
>  	struct fiber *f = fiber_new("lua", lua_fiber_run_f);
> diff --git a/src/lua/trigger.c b/src/lua/trigger.c
> index 4803e85c5..6df048a8d 100644
> --- a/src/lua/trigger.c
> +++ b/src/lua/trigger.c
> @@ -73,17 +73,13 @@ lbox_trigger_run(struct trigger *ptr, void *event)
>  	 * trigger yields, so when it's time to clean
>  	 * up the coro, we wouldn't know which stack position
>  	 * it is on.
> -	 *
> -	 * XXX: lua_newthread() may throw if out of memory,
> -	 * this needs to be wrapped with lua_pcall() as well.
> -	 * Don't, since it's a stupid overhead on every trigger
> -	 * invocation, and in future we plan to hack into Lua
> -	 * C API to fix this.
>  	 */
> -	struct lua_State *L;
> +	lua_State *L;
>  	int coro_ref;
>  	if (fiber()->storage.lua.stack == NULL) {
> -		L = lua_newthread(tarantool_L);
> +		L = luaT_newthread(tarantool_L);
> +		if (L == NULL)
> +			diag_raise();
>  		coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
>  	} else {
>  		L = fiber()->storage.lua.stack;
> diff --git a/src/lua/utils.h b/src/lua/utils.h
> index f8c34545a..f82b30fbc 100644
> --- a/src/lua/utils.h
> +++ b/src/lua/utils.h
> @@ -591,6 +591,47 @@ luaL_checkfinite(struct lua_State *L, struct luaL_serializer *cfg,
>  		luaL_error(L, "number must not be NaN or Inf");
>  }
>  

Note: the comment about lua_* namespace also relates to the wrapper
below. I guess we need some follow-up activity for it.

> +/**
> + * @brief A wrapper for lua_newthread() to pass it into luaT_cpcall
> + * @param L is a Lua State
> + * @sa lua_newthread()
> + */
> +static inline int
> +lua_newthread_wrapper(lua_State *L)
> +{
> +	*(lua_State **)lua_touserdata(L, 1) = lua_newthread(L);
> +	return 0;
> +}
> +

Minor: I see no reason to create a separate function for pushing one
lua_State onto the anothers' stack. Feel free to ignore or to discuss it
with the next reviewer.

> +/**
> + * @brief Push L1 thread onto the L stack
> + * @param L is a Lua State whose stack we are pushing onto
> + * @param L1 is a Lua State whose thread we are pushing
> + */
> +static inline void
> +luaT_pushthread(lua_State *L, lua_State *L1)
> +{
> +	setthreadV(L, L->top, L1);
> +	incr_top(L);
> +}
> +
> +/**
> + * @brief Safe wrapper for lua_newthread()
> + * @param L is a Lua State
> + * @sa lua_newthread()
> + */
> +static inline lua_State *
> +luaT_newthread(lua_State *L)
> +{
> +	lua_State *L1 = NULL;
> +	if (luaT_cpcall(L, lua_newthread_wrapper, &L1) != 0) {
> +		return NULL;
> +	}
> +	assert(L1 != NULL);
> +	luaT_pushthread(L, L1);
> +	return L1;
> +}
> +
>  /**
>   * Check if a value on @a L stack by index @a idx is an ibuf
>   * object. Both 'struct ibuf' and 'struct ibuf *' are accepted.
> diff --git a/third_party/lua-yaml/lyaml.cc b/third_party/lua-yaml/lyaml.cc
> index 7485341fa..af4f2f5d5 100644
> --- a/third_party/lua-yaml/lyaml.cc
> +++ b/third_party/lua-yaml/lyaml.cc
> @@ -789,7 +789,10 @@ lua_yaml_encode(lua_State *L, struct luaL_serializer *serializer,
>     dumper.cfg = serializer;
>     dumper.error = 0;
>     /* create thread to use for YAML buffer */
> -   dumper.outputL = lua_newthread(L);
> +   dumper.outputL = luaT_newthread(L);
> +   if (dumper.outputL == NULL) {
> +      return luaL_error(L, OOM_ERRMSG);
> +   }
>     luaL_buffinit(dumper.outputL, &dumper.yamlbuf);
>  
>     if (!yaml_emitter_initialize(&dumper.emitter))
> -- 
> 2.17.1
> 

-- 
Best regards,
IM

Re: [Tarantool-patches] [PATCH v2] refactoring: wrap lua_newthread using luaT_cpcall

[Igor Munkin]

CCed Sergos for proceeding with the review.

On 17.10.19, Igor Munkin wrote:
> Ilya,
> 
> Thanks, the patch LGTM, however please consider my minor comments.
> 
> On 17.10.19, Ilya Kosarev wrote:
> > Wrap throwing lua_newthread in luaT_newthread using luaT_cpcall
> > to process arising error properly.
> > 
> > Closes #4556
> > ---
> > https://github.com/tarantool/tarantool/tree/i.kosarev/gh-4556-wrap-lua-newthread
> > https://github.com/tarantool/tarantool/issues/4556
> > 
> > Changes in v2:
> > - introduced luaT_newthread instead of repeated slocs
> > - renamed luaL_pushthread to luaT_pushthread due to namespaces agreement
> > 
> >  src/box/lua/call.c            | 12 +++++++---
> >  src/lua/fiber.c               |  4 +++-
> >  src/lua/trigger.c             | 12 ++++------
> >  src/lua/utils.h               | 41 +++++++++++++++++++++++++++++++++++
> >  third_party/lua-yaml/lyaml.cc |  5 ++++-
> >  5 files changed, 61 insertions(+), 13 deletions(-)
> > 
> > diff --git a/src/box/lua/call.c b/src/box/lua/call.c
> > index 631003c84..51cad286a 100644
> > --- a/src/box/lua/call.c
> > +++ b/src/box/lua/call.c
> > @@ -527,7 +527,9 @@ static inline int
> >  box_process_lua(lua_CFunction handler, struct execute_lua_ctx *ctx,
> >  		struct port *ret)
> >  {
> > -	lua_State *L = lua_newthread(tarantool_L);
> > +	lua_State *L = luaT_newthread(tarantool_L);
> > +	if (L == NULL)
> > +		return -1;
> >  	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
> >  	port_lua_create(ret, L);
> >  	((struct port_lua *) ret)->ref = coro_ref;
> > @@ -654,7 +656,9 @@ func_persistent_lua_load(struct func_lua *func)
> >  	 * an arbitrary user-defined code
> >  	 * (e.g. body = 'fiber.yield()').
> >  	 */
> > -	struct lua_State *coro_L = lua_newthread(tarantool_L);
> > +	lua_State *coro_L = luaT_newthread(tarantool_L);
> > +	if (coro_L == NULL)
> > +		return -1;
> >  	if (!func->base.def->is_sandboxed) {
> >  		/*
> >  		 * Keep the original env to apply to a non-sandboxed
> > @@ -811,7 +815,9 @@ lbox_func_call(struct lua_State *L)
> >  	 * before the function call to pass it into the
> >  	 * pcall-sandboxed tarantool_L handler.
> >  	 */
> > -	lua_State *args_L = lua_newthread(tarantool_L);
> > +	lua_State *args_L = luaT_newthread(tarantool_L);
> > +	if (args_L == NULL)
> > +		return luaT_error(L);
> >  	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
> >  	lua_xmove(L, args_L, lua_gettop(L) - 1);
> >  	struct port args;
> > diff --git a/src/lua/fiber.c b/src/lua/fiber.c
> > index 336be60a2..124908a05 100644
> > --- a/src/lua/fiber.c
> > +++ b/src/lua/fiber.c
> > @@ -388,7 +388,9 @@ lua_fiber_run_f(MAYBE_UNUSED va_list ap)
> >  static struct fiber *
> >  fiber_create(struct lua_State *L)
> >  {
> > -	struct lua_State *child_L = lua_newthread(L);
> > +	lua_State *child_L = luaT_newthread(L);
> > +	if (child_L == NULL)
> > +		luaT_error(L);
> >  	int coro_ref = luaL_ref(L, LUA_REGISTRYINDEX);
> >  
> >  	struct fiber *f = fiber_new("lua", lua_fiber_run_f);
> > diff --git a/src/lua/trigger.c b/src/lua/trigger.c
> > index 4803e85c5..6df048a8d 100644
> > --- a/src/lua/trigger.c
> > +++ b/src/lua/trigger.c
> > @@ -73,17 +73,13 @@ lbox_trigger_run(struct trigger *ptr, void *event)
> >  	 * trigger yields, so when it's time to clean
> >  	 * up the coro, we wouldn't know which stack position
> >  	 * it is on.
> > -	 *
> > -	 * XXX: lua_newthread() may throw if out of memory,
> > -	 * this needs to be wrapped with lua_pcall() as well.
> > -	 * Don't, since it's a stupid overhead on every trigger
> > -	 * invocation, and in future we plan to hack into Lua
> > -	 * C API to fix this.
> >  	 */
> > -	struct lua_State *L;
> > +	lua_State *L;
> >  	int coro_ref;
> >  	if (fiber()->storage.lua.stack == NULL) {
> > -		L = lua_newthread(tarantool_L);
> > +		L = luaT_newthread(tarantool_L);
> > +		if (L == NULL)
> > +			diag_raise();
> >  		coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
> >  	} else {
> >  		L = fiber()->storage.lua.stack;
> > diff --git a/src/lua/utils.h b/src/lua/utils.h
> > index f8c34545a..f82b30fbc 100644
> > --- a/src/lua/utils.h
> > +++ b/src/lua/utils.h
> > @@ -591,6 +591,47 @@ luaL_checkfinite(struct lua_State *L, struct luaL_serializer *cfg,
> >  		luaL_error(L, "number must not be NaN or Inf");
> >  }
> >  
> 
> Note: the comment about lua_* namespace also relates to the wrapper
> below. I guess we need some follow-up activity for it.
> 
> > +/**
> > + * @brief A wrapper for lua_newthread() to pass it into luaT_cpcall
> > + * @param L is a Lua State
> > + * @sa lua_newthread()
> > + */
> > +static inline int
> > +lua_newthread_wrapper(lua_State *L)
> > +{
> > +	*(lua_State **)lua_touserdata(L, 1) = lua_newthread(L);
> > +	return 0;
> > +}
> > +
> 
> Minor: I see no reason to create a separate function for pushing one
> lua_State onto the anothers' stack. Feel free to ignore or to discuss it
> with the next reviewer.
> 
> > +/**
> > + * @brief Push L1 thread onto the L stack
> > + * @param L is a Lua State whose stack we are pushing onto
> > + * @param L1 is a Lua State whose thread we are pushing
> > + */
> > +static inline void
> > +luaT_pushthread(lua_State *L, lua_State *L1)
> > +{
> > +	setthreadV(L, L->top, L1);
> > +	incr_top(L);
> > +}
> > +
> > +/**
> > + * @brief Safe wrapper for lua_newthread()
> > + * @param L is a Lua State
> > + * @sa lua_newthread()
> > + */
> > +static inline lua_State *
> > +luaT_newthread(lua_State *L)
> > +{
> > +	lua_State *L1 = NULL;
> > +	if (luaT_cpcall(L, lua_newthread_wrapper, &L1) != 0) {
> > +		return NULL;
> > +	}
> > +	assert(L1 != NULL);
> > +	luaT_pushthread(L, L1);
> > +	return L1;
> > +}
> > +
> >  /**
> >   * Check if a value on @a L stack by index @a idx is an ibuf
> >   * object. Both 'struct ibuf' and 'struct ibuf *' are accepted.
> > diff --git a/third_party/lua-yaml/lyaml.cc b/third_party/lua-yaml/lyaml.cc
> > index 7485341fa..af4f2f5d5 100644
> > --- a/third_party/lua-yaml/lyaml.cc
> > +++ b/third_party/lua-yaml/lyaml.cc
> > @@ -789,7 +789,10 @@ lua_yaml_encode(lua_State *L, struct luaL_serializer *serializer,
> >     dumper.cfg = serializer;
> >     dumper.error = 0;
> >     /* create thread to use for YAML buffer */
> > -   dumper.outputL = lua_newthread(L);
> > +   dumper.outputL = luaT_newthread(L);
> > +   if (dumper.outputL == NULL) {
> > +      return luaL_error(L, OOM_ERRMSG);
> > +   }
> >     luaL_buffinit(dumper.outputL, &dumper.yamlbuf);
> >  
> >     if (!yaml_emitter_initialize(&dumper.emitter))
> > -- 
> > 2.17.1
> > 
> 
> -- 
> Best regards,
> IM

-- 
Best regards,
IM

Re: [Tarantool-patches] [tarantool-patches] Re: [PATCH v2] refactoring: wrap lua_newthread using luaT_cpcall

[Sergey Ostanevich]

Hi!

Please, create a GH for follow-ups:

- Rename lua_ and luaL_ interfaces in tarantool code base (utils.h,
  etc..) so that we will not interfere with luajit code base

I also agree with Igor that there's no need in luaT_pushthread() since
it has only one use and provides no more functionality than 2 lines of
code. 

With above fixed this patch is LGTM.

Regards,
Sergos


On 17 Oct 15:57, Igor Munkin wrote:
> CCed Sergos for proceeding with the review.
> 
> On 17.10.19, Igor Munkin wrote:
> > Ilya,
> > 
> > Thanks, the patch LGTM, however please consider my minor comments.
> > 
> > On 17.10.19, Ilya Kosarev wrote:
> > > Wrap throwing lua_newthread in luaT_newthread using luaT_cpcall
> > > to process arising error properly.
> > > 
> > > Closes #4556
> > > ---
> > > https://github.com/tarantool/tarantool/tree/i.kosarev/gh-4556-wrap-lua-newthread
> > > https://github.com/tarantool/tarantool/issues/4556
> > > 
> > > Changes in v2:
> > > - introduced luaT_newthread instead of repeated slocs
> > > - renamed luaL_pushthread to luaT_pushthread due to namespaces agreement
> > > 
> > >  src/box/lua/call.c            | 12 +++++++---
> > >  src/lua/fiber.c               |  4 +++-
> > >  src/lua/trigger.c             | 12 ++++------
> > >  src/lua/utils.h               | 41 +++++++++++++++++++++++++++++++++++
> > >  third_party/lua-yaml/lyaml.cc |  5 ++++-
> > >  5 files changed, 61 insertions(+), 13 deletions(-)
> > > 
> > > diff --git a/src/box/lua/call.c b/src/box/lua/call.c
> > > index 631003c84..51cad286a 100644
> > > --- a/src/box/lua/call.c
> > > +++ b/src/box/lua/call.c
> > > @@ -527,7 +527,9 @@ static inline int
> > >  box_process_lua(lua_CFunction handler, struct execute_lua_ctx *ctx,
> > >  		struct port *ret)
> > >  {
> > > -	lua_State *L = lua_newthread(tarantool_L);
> > > +	lua_State *L = luaT_newthread(tarantool_L);
> > > +	if (L == NULL)
> > > +		return -1;
> > >  	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
> > >  	port_lua_create(ret, L);
> > >  	((struct port_lua *) ret)->ref = coro_ref;
> > > @@ -654,7 +656,9 @@ func_persistent_lua_load(struct func_lua *func)
> > >  	 * an arbitrary user-defined code
> > >  	 * (e.g. body = 'fiber.yield()').
> > >  	 */
> > > -	struct lua_State *coro_L = lua_newthread(tarantool_L);
> > > +	lua_State *coro_L = luaT_newthread(tarantool_L);
> > > +	if (coro_L == NULL)
> > > +		return -1;
> > >  	if (!func->base.def->is_sandboxed) {
> > >  		/*
> > >  		 * Keep the original env to apply to a non-sandboxed
> > > @@ -811,7 +815,9 @@ lbox_func_call(struct lua_State *L)
> > >  	 * before the function call to pass it into the
> > >  	 * pcall-sandboxed tarantool_L handler.
> > >  	 */
> > > -	lua_State *args_L = lua_newthread(tarantool_L);
> > > +	lua_State *args_L = luaT_newthread(tarantool_L);
> > > +	if (args_L == NULL)
> > > +		return luaT_error(L);
> > >  	int coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
> > >  	lua_xmove(L, args_L, lua_gettop(L) - 1);
> > >  	struct port args;
> > > diff --git a/src/lua/fiber.c b/src/lua/fiber.c
> > > index 336be60a2..124908a05 100644
> > > --- a/src/lua/fiber.c
> > > +++ b/src/lua/fiber.c
> > > @@ -388,7 +388,9 @@ lua_fiber_run_f(MAYBE_UNUSED va_list ap)
> > >  static struct fiber *
> > >  fiber_create(struct lua_State *L)
> > >  {
> > > -	struct lua_State *child_L = lua_newthread(L);
> > > +	lua_State *child_L = luaT_newthread(L);
> > > +	if (child_L == NULL)
> > > +		luaT_error(L);
> > >  	int coro_ref = luaL_ref(L, LUA_REGISTRYINDEX);
> > >  
> > >  	struct fiber *f = fiber_new("lua", lua_fiber_run_f);
> > > diff --git a/src/lua/trigger.c b/src/lua/trigger.c
> > > index 4803e85c5..6df048a8d 100644
> > > --- a/src/lua/trigger.c
> > > +++ b/src/lua/trigger.c
> > > @@ -73,17 +73,13 @@ lbox_trigger_run(struct trigger *ptr, void *event)
> > >  	 * trigger yields, so when it's time to clean
> > >  	 * up the coro, we wouldn't know which stack position
> > >  	 * it is on.
> > > -	 *
> > > -	 * XXX: lua_newthread() may throw if out of memory,
> > > -	 * this needs to be wrapped with lua_pcall() as well.
> > > -	 * Don't, since it's a stupid overhead on every trigger
> > > -	 * invocation, and in future we plan to hack into Lua
> > > -	 * C API to fix this.
> > >  	 */
> > > -	struct lua_State *L;
> > > +	lua_State *L;
> > >  	int coro_ref;
> > >  	if (fiber()->storage.lua.stack == NULL) {
> > > -		L = lua_newthread(tarantool_L);
> > > +		L = luaT_newthread(tarantool_L);
> > > +		if (L == NULL)
> > > +			diag_raise();
> > >  		coro_ref = luaL_ref(tarantool_L, LUA_REGISTRYINDEX);
> > >  	} else {
> > >  		L = fiber()->storage.lua.stack;
> > > diff --git a/src/lua/utils.h b/src/lua/utils.h
> > > index f8c34545a..f82b30fbc 100644
> > > --- a/src/lua/utils.h
> > > +++ b/src/lua/utils.h
> > > @@ -591,6 +591,47 @@ luaL_checkfinite(struct lua_State *L, struct luaL_serializer *cfg,
> > >  		luaL_error(L, "number must not be NaN or Inf");
> > >  }
> > >  
> > 
> > Note: the comment about lua_* namespace also relates to the wrapper
> > below. I guess we need some follow-up activity for it.
> > 
> > > +/**
> > > + * @brief A wrapper for lua_newthread() to pass it into luaT_cpcall
> > > + * @param L is a Lua State
> > > + * @sa lua_newthread()
> > > + */
> > > +static inline int
> > > +lua_newthread_wrapper(lua_State *L)
> > > +{
> > > +	*(lua_State **)lua_touserdata(L, 1) = lua_newthread(L);
> > > +	return 0;
> > > +}
> > > +
> > 
> > Minor: I see no reason to create a separate function for pushing one
> > lua_State onto the anothers' stack. Feel free to ignore or to discuss it
> > with the next reviewer.
> > 
> > > +/**
> > > + * @brief Push L1 thread onto the L stack
> > > + * @param L is a Lua State whose stack we are pushing onto
> > > + * @param L1 is a Lua State whose thread we are pushing
> > > + */
> > > +static inline void
> > > +luaT_pushthread(lua_State *L, lua_State *L1)
> > > +{
> > > +	setthreadV(L, L->top, L1);
> > > +	incr_top(L);
> > > +}
> > > +
> > > +/**
> > > + * @brief Safe wrapper for lua_newthread()
> > > + * @param L is a Lua State
> > > + * @sa lua_newthread()
> > > + */
> > > +static inline lua_State *
> > > +luaT_newthread(lua_State *L)
> > > +{
> > > +	lua_State *L1 = NULL;
> > > +	if (luaT_cpcall(L, lua_newthread_wrapper, &L1) != 0) {
> > > +		return NULL;
> > > +	}
> > > +	assert(L1 != NULL);
> > > +	luaT_pushthread(L, L1);
> > > +	return L1;
> > > +}
> > > +
> > >  /**
> > >   * Check if a value on @a L stack by index @a idx is an ibuf
> > >   * object. Both 'struct ibuf' and 'struct ibuf *' are accepted.
> > > diff --git a/third_party/lua-yaml/lyaml.cc b/third_party/lua-yaml/lyaml.cc
> > > index 7485341fa..af4f2f5d5 100644
> > > --- a/third_party/lua-yaml/lyaml.cc
> > > +++ b/third_party/lua-yaml/lyaml.cc
> > > @@ -789,7 +789,10 @@ lua_yaml_encode(lua_State *L, struct luaL_serializer *serializer,
> > >     dumper.cfg = serializer;
> > >     dumper.error = 0;
> > >     /* create thread to use for YAML buffer */
> > > -   dumper.outputL = lua_newthread(L);
> > > +   dumper.outputL = luaT_newthread(L);
> > > +   if (dumper.outputL == NULL) {
> > > +      return luaL_error(L, OOM_ERRMSG);
> > > +   }
> > >     luaL_buffinit(dumper.outputL, &dumper.yamlbuf);
> > >  
> > >     if (!yaml_emitter_initialize(&dumper.emitter))
> > > -- 
> > > 2.17.1
> > > 
> > 
> > -- 
> > Best regards,
> > IM
> 
> -- 
> Best regards,
> IM
>