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BUG/MAJOR: lua: some function are not yieldable, the forced yield causes errors

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The hook function called each nth Lua instructions just
do a yield. Sometimes this yield is not allowed, because
some functions are not compatible.

The Lua-5.3 permits to known if the yield is avalaible with
the function lua_isyieldable().

If the processing is interrupted in non yieldable state,
we try to execute a yield asap. The yield will be may
available at the end of the non-yieldable currently
executed function. So, we require interrupt at the end
of the current function.

But, Lua cannot yield when its returning from a function,
so, we can fix the interrupt hook to 1 instruction,
expecting that the function is finnished.

During this time, the execution timeout is always checked.
This commit is contained in:
Thierry FOURNIER 2015-03-06 14:05:24 +01:00 committed by Willy Tarreau
parent f90838b71a
commit cae49c9ee8
1 changed files with 30 additions and 1 deletions
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31
src/hlua.c
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@ -644,7 +644,36 @@ static int hlua_ctx_renew(struct hlua *lua, int keep_msg)
void hlua_hook(lua_State *L, lua_Debug *ar)
{
hlua_yieldk(L, 0, 0, NULL, TICK_ETERNITY, HLUA_CTRLYIELD);
struct hlua *hlua = hlua_gethlua(L);
/* Lua cannot yield when its returning from a function,
* so, we can fix the interrupt hook to 1 instruction,
* expecting that the function is finnished.
*/
if (lua_gethookmask(L) & LUA_MASKRET) {
lua_sethook(hlua->T, hlua_hook, LUA_MASKCOUNT, 1);
return;
}
/* restore the interrupt condition. */
lua_sethook(hlua->T, hlua_hook, LUA_MASKCOUNT, hlua_nb_instruction);
/* If we interrupt the Lua processing in yieldable state, we yield.
* If the state is not yieldable, trying yield causes an error.
*/
if (lua_isyieldable(L))
WILL_LJMP(hlua_yieldk(L, 0, 0, NULL, TICK_ETERNITY, HLUA_CTRLYIELD));
/* If we cannot yield, check the timeout. */
if (tick_is_expired(hlua->expire, now_ms)) {
lua_pushfstring(L, "execution timeout");
WILL_LJMP(lua_error(L));
}
/* Try to interrupt the process at the end of the current
* unyieldable function.
*/
lua_sethook(hlua->T, hlua_hook, LUA_MASKRET|LUA_MASKCOUNT, hlua_nb_instruction);
}
/* This function start or resumes the Lua stack execution. If the flag