How can I set time out for fread when access socket?

The following is my code. I wish fread can return when there don't have data to read after some seconds. I called stream_set_timeout. But it don't work. And I called stream_get_meta_data too. It don't give my need yet. I am connecting chat.facebook.com.

$fp = fsockopen($server, 8888, $errno, $errstr);

stream_socket_enable_crypto($fp, true, STREAM_CRYPTO_METHOD_TLS_CLIENT);

fwrite($fp, $xml);

stream_set_timeout($fp, 5);

$str = fread($fp,8192);//This code will hang when there don't have data to read.开发者_Python百科

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If you'd read the manual for stream_set_timeout() you'd know that the only thing stream_set_timeout() does in case of timeout is setting of 'timed_out' key of the array returned by stream_get_meta_data() to true.

stream_set_timeout($fp, 5);
// set stream into non-blocking mode
stream_set_blocking($fp, false);

$break_counter = 0;
$result = '';
$info = stream_get_meta_data($fp);

while (!$info['timed_out'] && !feof($fp)) {
    $str = @fgets($fp, 1160);
    if ($str) {
        $result .= $str;
    } else {
        $break_counter += 1;

        if ($break_counter > 100) {
            break;
        }

        // 10000*100 microseconds gives you one second
        usleep(10000);
    }
    $info = stream_get_meta_data($fp);
}