LuaSocket性能猜测

int socket_waitfd(p_socket ps, int sw, p_timeout tm) {
    int ret;
    struct pollfd pfd;
    pfd.fd = *ps;
    pfd.events = sw;
    pfd.revents = 0;
    if (timeout_iszero(tm)) return IO_TIMEOUT;  /* optimize timeout == 0 case */
    do {
        int t = (int)(timeout_getretry(tm)*1e3);
        ret = poll(&pfd, 1, t >= 0? t: -1);
    } while (ret == -1 && errno == EINTR);
    if (ret == -1) return errno;
    if (ret == 0) return IO_TIMEOUT;
    if (sw == WAITFD_C && (pfd.revents & (POLLIN|POLLERR))) return IO_CLOSED;
    return IO_DONE;
}

/*-------------------------------------------------------------------------** Send with timeout
\*-------------------------------------------------------------------------*/
int socket_send(p_socket ps, const char *data, size_t count, 
        size_t *sent, p_timeout tm)
{
    int err;
    *sent = 0;
    /* avoid making system calls on closed sockets */
    if (*ps == SOCKET_INVALID) return IO_CLOSED;
    /* loop until we send something or we give up on error */
    for ( ;; ) {
        long put = (long) send(*ps, data, count, 0);
        /* if we sent anything, we are done */
        if (put >= 0) {
            *sent = put;
            return IO_DONE;
        }
        err = errno;
        /* EPIPE means the connection was closed */
        if (err == EPIPE) return IO_CLOSED;
        /* we call was interrupted, just try again */
        if (err == EINTR) continue;
        /* if failed fatal reason, report error */
        if (err != EAGAIN) return err;
        /* wait until we can send something or we timeout */
        if ((err = socket_waitfd(ps, WAITFD_W, tm)) != IO_DONE) return err;
    }
    /* can‘t reach here */
    return IO_UNKNOWN;
}

/*-------------------------------------------------------------------------** Receive with timeout
\*-------------------------------------------------------------------------*/
int socket_recv(p_socket ps, char *data, size_t count, size_t *got, p_timeout tm) {
    int err;
    *got = 0;
    if (*ps == SOCKET_INVALID) return IO_CLOSED;
    for ( ;; ) {
        long taken = (long) recv(*ps, data, count, 0);
        if (taken > 0) {
            *got = taken;
            return IO_DONE;
        }
        err = errno;
        if (taken == 0) return IO_CLOSED;
        if (err == EINTR) continue;
        if (err != EAGAIN) return err; 
        if ((err = socket_waitfd(ps, WAITFD_R, tm)) != IO_DONE) return err; 
    }
    return IO_UNKNOWN;
}

/*-------------------------------------------------------------------------** Sets timeout values for IO operations
* Lua Input: base, time [, mode]
*   time: time out value in seconds
*   mode: "b" for block timeout, "t" for total timeout. (default: b)
\*-------------------------------------------------------------------------*/
int timeout_meth_settimeout(lua_State *L, p_timeout tm) {
    double t = luaL_optnumber(L, 2, -1);
    const char *mode = luaL_optstring(L, 3, "b");
    switch (*mode) {
        case ‘b‘:
            tm->block = t; 
            break;
        case ‘r‘: case ‘t‘:
            tm->total = t;
            break;
        default:
            luaL_argcheck(L, 0, 3, "invalid timeout mode");
            break;
    }
    lua_pushnumber(L, 1);
    return 1;
}