由于HTTP响应中的内容长度=0,有助于消除异步接收器中的循环

某些Web服务器在HTTP响应头中将内容长度设置为零。我想要一个确定性和性能的解决方案来接收这种情况下的所有数据。

显示此行为的已知URL(下面的其他URL):

http://www.washingtonpost.com/wp-dyn/content/article/2010/02/12/AR2010021204894.html?hpid=topnews

页眉:

Cache-control:no-cache
Connection:close
Content-Encoding:gzip
Content-type:text/html
Server:Web Server
Transfer-encoding:chunked

我当前的解决方案不能保证获得所有的数据,因为maxtries常量,并且由于thread.sleep()而变慢。

private bool MoreDataIsAvailable()
{
    int avail = _socket.Available;
    if (avail == 0 &&
        _contentLength != null && _contentLength == 0)
    {
        int tries = 0;
        while (avail == 0 && tries < MaxTries)
        {
            Thread.Sleep(5);
            _socket.Poll(1000, SelectMode.SelectRead);
            avail = _socket.Available;
            tries++;
            if (avail > 0)
            {
                Console.WriteLine(_socket.Handle + " avail = " + avail + " received = " + _bytes.Length + " && tries = " + tries);
            }
        }
    }
    return avail > 0;
}

上下文中的用法:

private void ReceiveCallback(object sender, SocketAsyncEventArgs e)
{
    if (ConnectionWasClosed(e) || HadSocketError(e))
    {
        _receiveDone.Set();
        return;
    }

    StoreReceivedBytes(e);

    if (AllBytesReceived())
    {
        _receiveDone.Set();
        return;
    }

    if (MoreDataIsExpected() || MoreDataIsAvailable())
    {
        WaitForBytes(e);
    }
    else
    {
        _receiveDone.Set();
    }
}

样品输出:

1436 avail = 3752 received = 1704 && tries = 9
1436 avail = 3752 received = 9208 && tries = 8
1436 avail = 3752 received = 12960 && tries = 9
1436 avail = 3752 received = 20464 && tries = 8
1436 avail = 3752 received = 27968 && tries = 7
1436 avail = 7504 received = 31720 && tries = 1
1436 avail = 3752 received = 39224 && tries = 6

编辑:

尼古拉观察到 传输编码:分块 头需要特殊处理,但其末端可以确定地检测到。

但是,除了分块的响应之外,还有其他URL最终出现在我的catch all方法中,例如:

http://www.biomedcentral.com/1471-2105/6/197

页眉:

Cache-control:private
Connection:close
Content-Type:text/html
P3P:policyref="/w3c/p3p.xml", CP="NOI DSP COR CURa ADMa DEVa TAIa OUR BUS PHY ONL UNI COM NAV INT DEM PRE"
Server:Microsoft-IIS/5.0
X-Powered-By:ASP.NET

http://slampp.abangadek.com/info/

页眉:

Connection:close
Content-Type:text/html
Server:Apache/2.2.8 (Ubuntu) DAV/2 PHP/5.2.4-2ubuntu5.3 with Suhosin-Patch mod_ruby/1.2.6 Ruby/1.8.6(2007-09-24) mod_ssl/2.2.8 OpenSSL/0.9.8g
X-Cache:MISS from server03.abangadek.com
X-Powered-By:PHP/5.2.4-2ubuntu5.3

http://video.forbes.com/embedvideo/?format=frame&height=515&width=336&mode=render&networklink=1

页眉:

Connection:close
Content-Language:en-US
Content-Type:text/html;charset=ISO-8859-1
Server:Apache-Coyote/1.1

我想知道我可以在这些响应中查找什么,就像第一个URL的传输编码头一样,它提供了一个线索,可以确定地读取整个响应,从而避免对我的方法的调用。