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- Subject: Re: zero-copy read() into Lua string?
- From: starwing <weasley.wx@...>
- Date: Mon, 10 Jan 2011 11:38:48 +0800
I think Lua need some mutable string like mechanism. LuaL_Buffer is To simple. maybe lua std-lib will support something like e.g. stringbuffer.
2011/1/10 Josh Haberman <email@example.com>
There doesn't seem to be a way to construct a Lua string by writing
directly into Lua's internal buffer. For example, read_chars() in
iolib uses the luaL_Buffer abstraction which uses an intermediate
Is there any reason Lua couldn't support a function like:
/* Pushes a string of length "len" whose contents are uninitialized.
* The caller must initialize the string by writing to the returned
* buffer and call lua_finalizewstring() before calling any other Lua
* function on "L"; after this call, the client may no longer write
* into the returned buffer. */
char *lua_pushwstring(lua_State *L, size_t len);
void lua_finalizewstring(lua_State *L);
(lua_finalizewstring() is there in case Lua wants to internally
precompute a hash of the string or anything like that.)
In some cases (like read()/fread()) this could save a memory copy for
string data that is flowing from C->Lua, which seems like a big
benefit. Though I haven't implemented this idea to perform benchmarks,
avoiding memory copies can improve efficiency significantly in my