[Qt-interest] QNetworkDiskCache broken in 4.5

[Benjamin Meyer]

Sounds like you are using 4.5.1, I would recommend trying out 4.5.3

-Benjamin Meyer

On Oct 5, 2009, at 10:53 AM, Marcus Williams wrote:

> Hi -
>
> I'm trying to use the QNetworkDiskCache in qt 4.5 but it doesnt work  
> as
> expected. I've narrowed this down to a couple of reasons. The first is
> that the Cache doesnt work at all initially under windows because it
> creates a temporary file (its "prepared" file) for the contents of the
> cached file which it then tries to move to the cache directory using  
> the
> QTemporaryFile::rename - I suspect this fails because the file is  
> open.
>
> ---- From QNetworkDiskCache.cpp around line 249 ---
>     if (cacheItem->file
>         && cacheItem->file->isOpen()
>         && cacheItem->file->error() == QFile::NoError) {
>         cacheItem->file->setAutoRemove(false);
>         // ### use atomic rename rather then remove & rename
>         if (cacheItem->file->rename(fileName))
>             currentCacheSize += cacheItem->file->size();
>         else
>             cacheItem->file->setAutoRemove(true);
> ----------------------------------------------------
>
> If I "fix" this by changing the rename call to a copy call and then
> closing the file (to fix a bug that leaves open file handles around),
> this gets the file into the cache correctly.
>
> If I then construct a network request to the same url the cache is hit
> correctly and the data is fed into the reply from the cache. The bug  
> I'm
> hitting is that the finished() signal never gets emitted so my code  
> just
> sits there waiting for the file contents.
>
> Looking at the non-cached code route it appears that the finished  
> signal
> is called explicitly in
> QNetworkAccessHttpBackend::downstreamReadyWrite(), but this doesnt
> happen in the cached version as the cache contents is sent within
> QNetworkAccessHttpBackend::replyHeaderChanged() which then returns.
>
> QHttpNetworkConnectionPrivate::allDone queues up a finished signal  
> but I
> never see it so I'm wondering if its a threading issue (my download
> manager works in a separate thread) - all other (non-cached) download
> finished signals are working as expected, so I'm thinking its  
> something
> to do with the way it emits it via invokemethod, rather than  
> signalling
> via emit.
>
> Anyone got any ideas?
>
> Thanks
>
> Marcus
>
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