如何检查连接套接字上的数据是否可用？

Question

When I send HTTP requests I want to use Connection: Keep-Alive when I need to send few requests one after the other. How can I check whether the socket contains data? my expected code:

    $soc = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
    $t = socket_connect($soc, gethostbyname('www.example.com'), 80);
    if (!$t) {
        die(socket_strerror(socket_last_error($soc)));
    }
    $request = "GET /index.php HTTP/1.1\r\n";
    $request .= "Host: www.example.com\r\n";
    $request .= "Connection: Keep-Alive\r\n";
    $request .= "\r\n";
    socket_write($soc, $request);
    $buffer = '';
    $html = '';
    while (socket_data_available($soc)/* THIS FUNCTION DOES NOT EXIST*/) {
        socket_recv($soc, $buffer, 2048, MSG_WAITALL);
        $html .= $buffer;
    }

Answer 1

It seems to me that you don't want to check whether the socket contains data (whatever that means), but to read the HTTP response and then continue. This can be accomplished by replacing the loop above:

while ($buffer = socket_read($soc, 2048, PHP_NORMAL_READ))
{
    $html .= $buffer;
    if ($buffer == "\r") break;
    if ($buffer == "\n") continue;
    list($key, $val) = explode(' ', $buffer, 2);
    if ($key == "Content-Length:") $length = $val;
}
$html .= socket_read($soc, 1+$length);