[Qt-interest] QHttp upload won't stream?

[Info]

Hi,

Did you get anywhere with this? I'm having exactly the same problem  
with QNetworkAccessManager and have tracked it back to the same place  
you have QSslSocket::writeData, so it seems that you will still have  
the issue if you switch from QHttp to QNetworkAccessManager as they  
both use the same underlying socket.


On 30 Sep 2009, at 18:02, qt-interest-request at trolltech.com wrote:

> Hi All,
>
> (Note: also posted on Qt Centre.  Just trying to widen the net.)
>
> Using QT 4.5.2 on Windows XP.
>
> I have a file upload API which uses QHttp to send a PUT request to a  
> WebDav server.  It works fine except for one major problem:  it  
> loads the entire file into memory before it uploads the file.  This  
> is a problem with large files, a show stopper if the client runs out  
> of memory.  See code example below (of course, you need a dav server  
> for it to work).
>
> int QHttp::request ( const QHttpRequestHeader & header, QIODevice *  
> data = 0, QIODevice * to = 0 )
>
> I'm using QHttp::request to start the request.  I can't seem to come  
> up with a device or combination of devices which will stream or  
> otherwise buffer the file from the disk.
>
> My working code (which doesn't stream) just passes in the QFile:
>
> _httpId = _qHttp->request(header, sourceFile);
>
> I tried passing a QDataStream (or TextStream), which is not a  
> QIODevice.  Tried to come up with a combination of QBuffer, QFile,  
> just to see if something would work.  No luck.
>
> I took a look at the QT source.  Interestingly, it _is_ buffering  
> the file read in qhttp.cpp, QHttpPrivate::_q_slotBytesWritten().   
> The memory load looks to me like it's happening in qsslsocket.cpp,  
> QSslSocket::writeData() when the method memcpy's the buffer.
>
> - Can I use QHttp to do what I want?  It doesn't seem like it, but  
> maybe I'm missing something.  Is this a bug (I don't think so, yet)?
> - Is it worth trying QNetworkAccessManager, or am I going to run  
> into the same problem?  (I'm working on trying this now.  Looks to  
> me like QNetworkAccessManager is an entirely new impl.)
> - If I need to write custom code to support this, could someone  
> outline a basic approach?  Will I need to create multiple requests  
> for this kind of "chunked" transfer?
>
> Code snippet (builds, haven't tried to run.  my actual code has a  
> bunch of classes abstracting/wrapping a lot of this.)
>
>
>    QUrl destUrl(QString("http://www.someDAVserver.com/someFolder/someBigFile.dat 
> "));
>    QFile* sourceFile = new QFile("D:\\someLocalDir\\someBigFile.dat");
>
>    if (!sourceFile->open(QIODevice::ReadOnly)) {
>        //throw
>    }
>
>    QHttp::ConnectionMode mode = destUrl.scheme().toLower() ==  
> "https" ? QHttp::ConnectionModeHttps : QHttp::ConnectionModeHttp;
>
>    QHttp http;
>    http.setHost(destUrl.host(), mode, destUrl.port() == -1 ? 0 :  
> destUrl.port());
>
>    QHttpRequestHeader header("PUT", destUrl.toEncoded 
> (QUrl::RemoveScheme|QUrl::RemoveAuthority));
>    header.setValue("Host", destUrl.host());
>    header.setValue("Accept-Language", QLocale::system().name());
>    header.setValue("Content-Length", QString::number(sourceFile->size 
> ()));
>
>
>    http.request(header, sourceFile);
>
>
>
> Thanks in advance,
>
> Hawkeye Parker

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