Function luaCreateFunction

app/redis-6.2.6/src/scripting.c:1405–1457

Define a Lua function with the specified body. * The function name will be generated in the following form: * * f_ * * The function increments the reference count of the 'body' object as a * side effect of a successful call. * * On success a pointer to an SDS string representing the function SHA1 of the * just added function is returned (and will be valid until the next ca

 * If 'c' is not NULL, on error the client is informed with an appropriate
 * error describing the nature of the problem and the Lua interpreter error. */
sds luaCreateFunction(client *c, lua_State *lua, robj *body) {
    char funcname[43];
    dictEntry *de;

    funcname[0] = 'f';
    funcname[1] = '_';
    sha1hex(funcname+2,body->ptr,sdslen(body->ptr));

    sds sha = sdsnewlen(funcname+2,40);
    if ((de = dictFind(server.lua_scripts,sha)) != NULL) {
        sdsfree(sha);
        return dictGetKey(de);
    }

    sds funcdef = sdsempty();
    funcdef = sdscat(funcdef,"function ");
    funcdef = sdscatlen(funcdef,funcname,42);
    funcdef = sdscatlen(funcdef,"() ",3);
    funcdef = sdscatlen(funcdef,body->ptr,sdslen(body->ptr));
    funcdef = sdscatlen(funcdef,"\nend",4);

    if (luaL_loadbuffer(lua,funcdef,sdslen(funcdef),"@user_script")) {
        if (c != NULL) {
            addReplyErrorFormat(c,
                "Error compiling script (new function): %s\n",
                lua_tostring(lua,-1));
        }
        lua_pop(lua,1);
        sdsfree(sha);
        sdsfree(funcdef);
        return NULL;
    }
    sdsfree(funcdef);

    if (lua_pcall(lua,0,0,0)) {
        if (c != NULL) {
            addReplyErrorFormat(c,"Error running script (new function): %s\n",
                lua_tostring(lua,-1));
        }
        lua_pop(lua,1);
        sdsfree(sha);
        return NULL;
    }

    /* We also save a SHA1 -> Original script map in a dictionary
     * so that we can replicate / write in the AOF all the
     * EVALSHA commands as EVAL using the original script. */
    int retval = dictAdd(server.lua_scripts,sha,body);
    serverAssertWithInfo(c ? c : server.lua_client,NULL,retval == DICT_OK);
    server.lua_scripts_mem += sdsZmallocSize(sha) + getStringObjectSdsUsedMemory(body);
    incrRefCount(body);
    return sha;
}

/* This is the Lua script "count" hook that we use to detect scripts timeout. */
void luaMaskCountHook(lua_State *lua, lua_Debug *ar) {