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Thread: [Qt bug?] QNetworkReply::setReadBufferSize() and data loss

  1. #1
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    Unhappy [Qt bug?] QNetworkReply::setReadBufferSize() and data loss

    I'm having trouble using QNetworkReply::setReadBufferSize().

    When I try to limit the buffer size to throttle down download speed, I get random data loss.
    It always happens at the end of the transmitted content. The first big part of the content is always valid.


    Is it safe to call QNetworkReply::setReadBufferSize() DURING the download?

    I also use multiple QNetworkAccessManagers, but I guess this should not be the cause of the problem.


    I checked the network traffic with Wireshark, and the missing part is there.

    QNetworkReply::bytesAvailable() returns 0, so it looks like I'm reading all available data.


    I don't exclude the possibility that it's just my mistake, but I cannot find it in my code.


    Qt 4.6.3, Debian GNU/Linux 7.0 Wheezy


    EDIT:
    It seems to be a Qt bug.
    The problem occurs when using QNetworkReply::setReadBufferSize() with downloads with unknown content length, i.e. no Content-Length header and downloadProgress()'s bytesTotal == 0.
    On random occasions Qt does not provide the ending part in such cases.
    Last edited by ultr; 7th March 2011 at 21:14.

  2. #2
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    Default Re: [Qt bug?] QNetworkReply::setReadBufferSize() and data loss


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