Function setup_first_sqlite_step

lua/sp.c:3372–3407

** NOTE: The "profile" (logical boolean) argument is used here to indicate ** whether or not the caller has its own BEGIN / ANOTHER / END loop ** (i.e. using the lua_*_step() functions). When zero, it means the ** caller does have its own SQL statement stepping loop and this ** function must not call lua_begin_step() on the callers behalf when ** performing first-tim

**       setup for the result set.
*/
static inline void setup_first_sqlite_step(SP sp, dbstmt_t *dbstmt, int profile)
{
    if (dbstmt->fetched) {
        // tbls already locked by previous step()
        return;
    }
    run_stmt_setup(sp->clnt, dbstmt->stmt);
    if (profile) lua_begin_step(sp->clnt, sp, dbstmt->stmt);
    dbstmt->fetched = 1;
    if (dbstmt->rec == NULL) {
        // Not a prepared-stmt.
        // tbls locked by get_prepared_stmt_try_lock()
        return;
    }
    if (dbstmt->initial) {
        // Initial run of prepared-stmt.
        // tbls locked by get_prepared_stmt_try_lock()
        dbstmt->initial = 0;
        return;
    }
    // Need to lock tbls. We may be holding some other tbl locks and locking
    // schema can cause deadlock; trylock instead.
    if (tryrdlock_schema_lk() != 0) {
        luaL_error(sp->lua, sqlite3ErrStr(SQLITE_SCHEMA));
        return;
    }
    int rc = sqlengine_prepare_engine(sp->thd, sp->clnt, 0);
    if (rc == 0) {
        sqlite3LockStmtTables(dbstmt->stmt);
        unlock_schema_lk();
    } else {
        unlock_schema_lk();
        luaL_error(sp->lua, sqlite3ErrStr(rc));
        return;
    }
}

static int dbstmt_exec(Lua lua)
{