金慶的專欄

C調用lua腳本的效率測試

以下代碼以C語言為基準，測試了C調用Lua循環和循環調用Lua的效率。結論是不要頻繁地穿越C/Lua邊界.

代碼整理自：http://blog.csdn.net/Tomorrow/archive/2008/06/11/2536884.aspx

#include <time.h>

extern "C"
{
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
}/* Lua解釋器指針 */

const char LUA_SCRIPT[] =
    "function loop_add(a, b)            "
    "   local sum = 0                   "
    "   for i = 1, 10000000 do          "
    "       sum = sum + a + b           "
    "   end                             "
    "   return sum                      "
    "end                                "
    "                                   "
    "function add(a, b)                 "
    "   return a + b                    "
    "end                                "
    ;

// lua 腳本里面的函數由C調用
int use_lua_add(lua_State *L, const char *func_name, int x, int y)
{
    int sum;                        /* 通過名字得到Lua函數 */
    lua_getglobal(L, func_name);    /* 第一個參數 */
    lua_pushnumber(L, x);           /* 第二個參數 */
    lua_pushnumber(L, y);           /* 調用函數，告知有兩個參數，一個返回值 */
    lua_call(L, 2, 1);              /* 得到結果 */
    sum = (int)lua_tointeger(L, -1);
    lua_pop(L, 1);
    return sum;
}

int main()
{
    int i, sum = 0;
    clock_t tStart, tStop;

    lua_State *L = lua_open();  /* opens Lua */
    luaL_openlibs(L);
    if (luaL_dostring(L, LUA_SCRIPT))  // Run lua script
    {
        printf("run script failed\n");
        lua_close(L);
        return -1;
    }

    sum = 0;
    tStart = clock();
    for (i = 0; i < 10000000; i++)
    {
        sum += 1 + 1;
    }
    tStop = clock();
    printf("C++: %dms.\nThe sum is %u.\n",
           (tStop - tStart) * 1000 / CLOCKS_PER_SEC, sum);

    sum = 0;
    tStart = clock();
    sum = use_lua_add(L, "loop_add", 1, 1);
    tStop = clock();
    printf("Lua loop_add: %dms.\nThe sum is %u.\n",
           (tStop - tStart) * 1000 / CLOCKS_PER_SEC, sum);

    sum = 0;
    tStart = clock();
    for (i = 0; i < 10000000; i++)
    {
        sum += use_lua_add(L, "add", 1, 1);
    }
    tStop = clock();
    printf("Loop lua add: %dms.\nThe sum is %u.\n",
           (tStop - tStart) * 1000 / CLOCKS_PER_SEC, sum);


    lua_close(L);
    return 0;
}

運行結果：

C++: 31ms.
The sum is 20000000.
Lua loop_add: 437ms.
The sum is 20000000.
Loop lua add: 2360ms.
The sum is 20000000.