[tarantool-patches] Re: [PATCH 2/2] box: introduce on_shutdown triggers to lua

[Konstantin Osipov]

* Serge Petrenko <sergepetrenko at tarantool.org> [18/11/22 20:21]:
> Make it possible to register on_shutdown triggers from lua via
> box.ctl.on_shutdown()

OK, this is a nice step forward, can we add shutdown reason to the
event and marshal it to Lua? 

Why are you calling the trigger only in case box is configured?
Why should it matter?

The ticket is missing a docbot plea.

What if on_shutdown trigger yields? We either should document that
it can't yield or test that it can yield. Besides, it can do some
very nasty things, like use 'box', or sockets, or seep. We should
(if possible) test and document what it can and cannot do.

> 
> Part of #1607
> ---
>  src/box/lua/ctl.c      | 21 +++++++++++++++++++++
>  test/box/misc.result   | 34 ++++++++++++++++++++++++++++++++++
>  test/box/misc.test.lua | 14 ++++++++++++++
>  3 files changed, 69 insertions(+)
> 
> diff --git a/src/box/lua/ctl.c b/src/box/lua/ctl.c
> index 9a105ed5c..dad39515c 100644
> --- a/src/box/lua/ctl.c
> +++ b/src/box/lua/ctl.c
> @@ -37,6 +37,7 @@
>  #include <lualib.h>
>  
>  #include "lua/utils.h"
> +#include "lua/trigger.h"
>  
>  #include "box/box.h"
>  
> @@ -64,9 +65,29 @@ lbox_ctl_wait_rw(struct lua_State *L)
>  	return 0;
>  }
>  
> +/*
> + * This is a placeholder. It will be used when we decide to pass
> + * a signal which caused termination to the trigger.
> + */
> +static int
> +lbox_push_on_shutdown(struct lua_State *L, void *event)
> +{
> +	(void)L;
> +	(void)event;
> +	return 0;
> +}
> +
> +static int
> +lbox_ctl_on_shutdown(struct lua_State *L)
> +{
> +	return lbox_trigger_reset(L, 2, &on_shutdown, lbox_push_on_shutdown,
> +				  NULL);
> +}
> +
>  static const struct luaL_Reg lbox_ctl_lib[] = {
>  	{"wait_ro", lbox_ctl_wait_ro},
>  	{"wait_rw", lbox_ctl_wait_rw},
> +	{"on_shutdown", lbox_ctl_on_shutdown},
>  	{NULL, NULL}
>  };
>  
> diff --git a/test/box/misc.result b/test/box/misc.result
> index 4ee4797d0..fd55b8cf1 100644
> --- a/test/box/misc.result
> +++ b/test/box/misc.result
> @@ -1205,3 +1205,37 @@ box.cfg{too_long_threshold = too_long_threshold}
>  s:drop()
>  ---
>  ...
> +--
> +-- gh-1607: on_shutdown triggers.
> +--
> +f = function() print('on_shutdown 1') end
> +---
> +...
> +g = function() print('on_shutdown 2') end
> +---
> +...
> +h = function() print('on_shutdown 3') end
> +---
> +...
> +_ = box.ctl.on_shutdown(f)
> +---
> +...
> +_ = box.ctl.on_shutdown(g)
> +---
> +...
> +_ = box.ctl.on_shutdown(h, g)
> +---
> +...
> +test_run:cmd('restart server default')
> +test_run:grep_log('default', 'on_shutdown 1', nil, {noreset=true})
> +---
> +- on_shutdown 1
> +...
> +test_run:grep_log('default', 'on_shutdown 2', nil, {noreset=true})
> +---
> +- null
> +...
> +test_run:grep_log('default', 'on_shutdown 3', nil, {noreset=true})
> +---
> +- on_shutdown 3
> +...
> diff --git a/test/box/misc.test.lua b/test/box/misc.test.lua
> index ee81c7be1..a4b38b403 100644
> --- a/test/box/misc.test.lua
> +++ b/test/box/misc.test.lua
> @@ -342,3 +342,17 @@ rows == expected_rows
>  lsn == expected_lsn
>  box.cfg{too_long_threshold = too_long_threshold}
>  s:drop()
> +
> +--
> +-- gh-1607: on_shutdown triggers.
> +--
> +f = function() print('on_shutdown 1') end
> +g = function() print('on_shutdown 2') end
> +h = function() print('on_shutdown 3') end
> +_ = box.ctl.on_shutdown(f)
> +_ = box.ctl.on_shutdown(g)
> +_ = box.ctl.on_shutdown(h, g)
> +test_run:cmd('restart server default')
> +test_run:grep_log('default', 'on_shutdown 1', nil, {noreset=true})
> +test_run:grep_log('default', 'on_shutdown 2', nil, {noreset=true})
> +test_run:grep_log('default', 'on_shutdown 3', nil, {noreset=true})
> -- 
> 2.17.2 (Apple Git-113)
> 

-- 
Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov