最近在分析untiy客户端lua的性能时发现， 真机上有的lua重复加载了2次策划数值表。
打印了一下当时package.loaded （按理require了之后这里会存一下，后面require就不会重复加载了），
发现了存在 data/xxxx data.xxxx 两个路径的。
那是项目里 require "data/xxxx" require "data.xxxx" 两种方式混用造成的。
在Unity编辑器里跑没问题，package.loaded里打印出来都是点.连接的。 但真机上却重复了。
再仔细分析源码问题，发现真机为了编译lua用了luajit （lib_package.c 有个版本 require实现没有 /替换成 .）， unity上用的是tolua编出来的dll（macnojit 的 loadlib.c 里 require实现做了/换成.）
简单解决方案，在第一个加载.lua文件开头把require函数重写一下：
Lua
-- 保存原始的 require 函数
local original_require = require
-- 新的 require 函数，重写路径处理
function require(modname)
-- 将路径中的斜杠替换为点
local modified_modname = modname:gsub("/", ".")
-- 调用原始的 require 函数加载模块
return original_require(modified_modname)
end
就能避免这个重复加载了的问题。
真机上跑了一下，运行内存竟然少了近几十M（项目里数值表占用太多吧= =）, 加载卡顿也少了一些。
放一下lua源码里的 require实现：
https://www.lua.org/source/5.4/loadlib.c.html
cpp
static int ll_require (lua_State *L) {
const char *name = luaL_checkstring(L, 1);
lua_settop(L, 1); /* LOADED table will be at index 2 */
lua_getfield(L, LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
lua_getfield(L, 2, name); /* LOADED[name] */
if (lua_toboolean(L, -1)) /* is it there? */
return 1; /* package is already loaded */
/* else must load package */
lua_pop(L, 1); /* remove 'getfield' result */
findloader(L, name);
lua_rotate(L, -2, 1); /* function <-> loader data */
lua_pushvalue(L, 1); /* name is 1st argument to module loader */
lua_pushvalue(L, -3); /* loader data is 2nd argument */
/* stack: ...; loader data; loader function; mod. name; loader data */
lua_call(L, 2, 1); /* run loader to load module */
/* stack: ...; loader data; result from loader */
if (!lua_isnil(L, -1)) /* non-nil return? */
lua_setfield(L, 2, name); /* LOADED[name] = returned value */
else
lua_pop(L, 1); /* pop nil */
if (lua_getfield(L, 2, name) == LUA_TNIL) { /* module set no value? */
lua_pushboolean(L, 1); /* use true as result */
lua_copy(L, -1, -2); /* replace loader result */
lua_setfield(L, 2, name); /* LOADED[name] = true */
}
lua_rotate(L, -2, 1); /* loader data <-> module result */
return 2; /* return module result and loader data */
}用lua翻译就是：
Lua
--require 函数的实现
function require(name)
if not package.loaded[name] then
local loader = findloader(name) //这一步演示在代码中以抽象函数findloader来表示
if loader == nil then
error("unable to load module" .. name)
end
package.loaded[name] = true
local res = loader(name)
if res ~= nil then
package.loaded[name] = res
end
end
return package.loaded[name]
endfrom Lua-require_lua require原理-CSDN博客
ToLua\macnojit\lua\loadlib.c里的实现 luaL_gsub(L, name, "/", ".");做了替换
cpp
static int ll_require (lua_State *L) {
const char *name = luaL_checkstring(L, 1);
int i;
lua_settop(L, 1); /* _LOADED table will be at index 2 */
const char* key = luaL_gsub(L, name, "/", ".");
lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
lua_getfield(L, 3, key);
if (lua_toboolean(L, -1)) { /* is it there? */
if (lua_touserdata(L, -1) == sentinel) /* check loops */
luaL_error(L, "loop or previous error loading module " LUA_QS, name);
return 1; /* package is already loaded */
}
/* else must load it; iterate over available loaders */
lua_getfield(L, LUA_ENVIRONINDEX, "loaders");
if (!lua_istable(L, -1))
luaL_error(L, LUA_QL("package.loaders") " must be a table");
lua_pushliteral(L, ""); /* error message accumulator */
for (i=1; ; i++) {
lua_rawgeti(L, -2, i); /* get a loader */
if (lua_isnil(L, -1))
luaL_error(L, "module " LUA_QS " not found:%s",
name, lua_tostring(L, -2));
lua_pushstring(L, name);
lua_call(L, 1, 1); /* call it */
if (lua_isfunction(L, -1)) /* did it find module? */
break; /* module loaded successfully */
else if (lua_isstring(L, -1)) /* loader returned error message? */
lua_concat(L, 2); /* accumulate it */
else
lua_pop(L, 1);
}
lua_pushlightuserdata(L, sentinel);
lua_setfield(L, 3, key); /* _LOADED[name] = sentinel */
lua_pushstring(L, name); /* pass name as argument to module */
lua_call(L, 1, 1); /* run loaded module */
if (!lua_isnil(L, -1)) /* non-nil return? */
lua_setfield(L, 3, key); /* _LOADED[name] = returned value */
lua_getfield(L, 3, key);
if (lua_touserdata(L, -1) == sentinel) { /* module did not set a value? */
lua_pushboolean(L, 1); /* use true as result */
lua_pushvalue(L, -1); /* extra copy to be returned */
lua_setfield(L, 3, key); /* _LOADED[name] = true */
}
return 1;
}https://github.com/LuaJIT/LuaJIT/blob/v2.1/src/lib_package.c 里没有实现替换，这边项目里本来改过的，后来升级一次不小心又改掉这个修改了：
cpp
#define KEY_SENTINEL (U64x(80000000,00000000)|'s')
static int lj_cf_package_require(lua_State *L)
{
const char *name = luaL_checkstring(L, 1);
int i;
lua_settop(L, 1); /* _LOADED table will be at index 2 */
lua_getfield(L, LUA_REGISTRYINDEX, "_LOADED");
lua_getfield(L, 2, name);
if (lua_toboolean(L, -1)) { /* is it there? */
if ((L->top-1)->u64 == KEY_SENTINEL) /* check loops */
luaL_error(L, "loop or previous error loading module " LUA_QS, name);
return 1; /* package is already loaded */
}
/* else must load it; iterate over available loaders */
lua_getfield(L, LUA_ENVIRONINDEX, "loaders");
if (!lua_istable(L, -1))
luaL_error(L, LUA_QL("package.loaders") " must be a table");
lua_pushliteral(L, ""); /* error message accumulator */
for (i = 1; ; i++) {
lua_rawgeti(L, -2, i); /* get a loader */
if (lua_isnil(L, -1))
luaL_error(L, "module " LUA_QS " not found:%s",
name, lua_tostring(L, -2));
lua_pushstring(L, name);
lua_call(L, 1, 1); /* call it */
if (lua_isfunction(L, -1)) /* did it find module? */
break; /* module loaded successfully */
else if (lua_isstring(L, -1)) /* loader returned error message? */
lua_concat(L, 2); /* accumulate it */
else
lua_pop(L, 1);
}
(L->top++)->u64 = KEY_SENTINEL;
lua_setfield(L, 2, name); /* _LOADED[name] = sentinel */
lua_pushstring(L, name); /* pass name as argument to module */
lua_call(L, 1, 1); /* run loaded module */
if (!lua_isnil(L, -1)) /* non-nil return? */
lua_setfield(L, 2, name); /* _LOADED[name] = returned value */
lua_getfield(L, 2, name);
if ((L->top-1)->u64 == KEY_SENTINEL) { /* module did not set a value? */
lua_pushboolean(L, 1); /* use true as result */
lua_pushvalue(L, -1); /* extra copy to be returned */
lua_setfield(L, 2, name); /* _LOADED[name] = true */
}
lj_lib_checkfpu(L);
return 1;
}