Faster checking of userdata
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- Subject: Faster checking of userdata
- From: Shannon Stewman <stew@...>
- Date: 2004年8月26日 16:23:57 -0500
Hello all,
After profiling some C extensions I had written, I noticed that many
of my fast routines spent an enormous percentage of time (60% or more)
calling luaL_checkudata, and most of that was spent in its strcmp call.
I wrote a faster routine that works on pointers, and should work for
both userdata and tables.
Is there are problem using this technique, assuming the metatables I'm
comparing are allocated in a library's luaopen_XXX function and only
freed on a lua_close() call?
void* fastcheckudata( lua_State* L, int index, const char* id)
{
lua_getmetatable(L,index);
const void* p1 = lua_topointer(L,-1);
luaL_getmetatable(L,id);
const void* p2 = lua_topointer(L,-1);
lua_pop(L,2);
return p1 == p2 ? lua_touserdata(L, index) : NULL;
}
Best,
--
Shannon Stewman | Let us walk through the waning night,
Caught in a whirlpool, | As dawn-rays tickle our toes, the dew soothes
A quartering act: | Our blistered soles, and damp bones stir
Solitude or society? | As crimson cracks under the blue-grey sky.