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List:       koffice-devel
Subject:    Re: Faster saving (Re: Global save method option)
From:       Nicolas Goutte <nicolasg () snafu ! de>
Date:       2004-02-15 15:56:04
Message-ID: 200402151656.04997.nicolasg () snafu ! de
[Download RAW message or body]

On Saturday 14 February 2004 11:53, David Faure wrote:
> On Saturday 14 February 2004 03:57, Nicolas Goutte wrote:
> > So for the maindoc.xml of the KWord demo flatland.kwd, I get:
> > 4.99 s by QCString
> > 13,44 s by QDomDocument::save (however that is then without indenting.)
> > 18.47 s by QTextStream::operator <<
>
> I see. When sending the data little by little to KZip, we end up doing much
> more I/O (and also triggering the zlib algorithms all the time, with very
> little data) and the result is much slower. That's not good. IMHO we need
> buffering at some level, either KZip or KoStore.... Hmm, this isn't going
> to require an intermediate QIODevice, like a QBuffer, which itself writes
> out the data in bigger chunks into KZip.

I think that if useful, the buffering can also be done in koStoreDevice.

>
> .... some time later ...
>
> I wrote KBufferedIODevice, see attachment. If it works, we could put it in
> kdelibs and use it transparently from KZip itself - but I don't have time
> to do that today.
>
> For now, could you try if it makes things faster, using it this way?

Well, it does, but it is still not as fast as using QCString.

I have used KoDocument:.saveToStream to test (see attached patch), again with 
flatland.kwd

It has taken (rounded values):
QCString: 19s
QTextStream: 55s
KBufferedIODevice( 8KB ): 41s
KBufferedIODevice( 64KB ): 35s
KBufferedIODevice( 128KB ): 34s

So something is still worng.

Meanwhile I have the feeling that we should wait on Qt4. If Qt4's speed is 
really optimized, the value that we would get could be very different.

>
> KBufferedIODevice bufdev( dev );
> <then write to bufdev instead of dev, e.g. using QTextStream and save()>
> bufdev.close();
>
> > It must be:
> > doc.save (s, 0)
> > but then there is not any indent.
>
> In fact it should be (s,1) like toString() does.

Have a nice day!

["test.diff" (text/x-diff)]

Index: koDocument.cc
===================================================================
RCS file: /home/kde/koffice/lib/kofficecore/koDocument.cc,v
retrieving revision 1.290
diff -u -p -r1.290 koDocument.cc
--- koDocument.cc	31 Jan 2004 10:26:33 -0000	1.290
+++ koDocument.cc	15 Feb 2004 15:42:44 -0000
@@ -975,6 +975,10 @@ bool KoDocument::saveNativeFormat( const
 
 bool KoDocument::saveToStream( QIODevice * dev )
 {
+    bool flag = false;
+    QTime time;
+    time.start();
+#if 0
     QDomDocument doc = saveXML();
     // Save to buffer
     QCString s = doc.toCString(); // utf8 already
@@ -983,7 +987,26 @@ bool KoDocument::saveToStream( QIODevice
     int nwritten = dev->writeBlock( s.data(), s.size()-1 );
     if ( nwritten != (int)s.size()-1 )
         kdWarning(30003) << "KoDocument::saveToStream wrote " << nwritten << "   - \
                expected " << s.size()-1 << endl;
-    return nwritten == (int)s.size()-1;
+    flag = nwritten == (int)s.size()-1;
+#elif 0
+    dev->resetStatus();
+    QTextStream stream( dev );
+    stream.setEncoding( QTextStream::UnicodeUTF8 );
+    stream << saveXML();
+    flag = ( dev->status() == IO_Ok );
+#else
+#include <kbufferediodevice.h>
+    KBufferedIODevice buf( dev, 64 * 1024 );
+    buf.open( IO_WriteOnly );
+    dev->resetStatus();
+    QTextStream stream( &buf );
+    stream.setEncoding( QTextStream::UnicodeUTF8 );
+    stream << saveXML();
+    buf.close();
+    flag = ( dev->status() == IO_Ok );
+#endif
+    kdDebug(30003) << "@@@ TIME: " << time.elapsed() << endl;
+    return flag;
 }
 
 bool KoDocument::saveToStore( KoStore* _store, const QString & _path )



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