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List:       kde-pim
Subject:    Re: [Kde-pim] Review Request 109186: work around a file descriptor leak when using QFileSystemWatche
From:       "Andras Mantia" <amantia () kde ! org>
Date:       2013-02-27 11:10:34
Message-ID: 20130227111034.15518.38122 () vidsolbach ! de
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> On Feb. 27, 2013, 9:56 a.m., Andras Mantia wrote:
> > resources/maildir/maildirresource.cpp, line 841
> > <http://git.reviewboard.kde.org/r/109186/diff/1/?file=116066#file116066line841>
> > 
> > I prefer caching the path here( like it was in the places you have replaced), \
> > although probably the difference is not too big.
> 
> Wolfgang Rohdewald wrote:
> dir.path() does not do much. Only "return d->path". Since everything is const, the \
> compiler should be able to cache it automatically. Allocating a local QString also \
> needs time, I suppose. And for full caching as it was, I would not be able to pass \
> dir to the new methods, I would have to pass the path. So I would always have to \
> cache path before calling stopDirScan. Too much additional code, IMHO

Calling dir.path() is a call to a function (dir.path()), a pointer indirection \
(d->path) to get the path. You do this twice. If you cache, you have an extra QString \
copy constructor calling (const QString path = dir.path();), while you save the call \
to function and the pointer indirection (d->path). I'm not sure how much the compiler \
optimizes this automatically, but the caching is what I like better, anytime the same \
method needs to be called more than one time. It also makes debugging easier, as you \
see the path variable in the debugger, you don't have to jump into the path() method.


- Andras


-----------------------------------------------------------
This is an automatically generated e-mail. To reply, visit:
http://git.reviewboard.kde.org/r/109186/#review28192
-----------------------------------------------------------


On Feb. 27, 2013, 9:32 a.m., Wolfgang Rohdewald wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://git.reviewboard.kde.org/r/109186/
> -----------------------------------------------------------
> 
> (Updated Feb. 27, 2013, 9:32 a.m.)
> 
> 
> Review request for KDEPIM.
> 
> 
> Description
> -------
> 
> this cleans up some code and avoids warnings from QFileSystemWatcher when many \
> mails are moved between folders. QFileSystemWatcher leaks four file descriptors for \
> every moved mail because removeDir does not close the fd (as can be seen in \
> /proc/X/fd where X is the process id of akonadi_agent_launcher \
> akonadi_maildir_resource). On my system (kubuntu 12.10) warnings start when 1024 \
> file descriptors are open. 
> I did not yet investigate which notifying method QFileSystemWatcher actually uses.
> 
> This has 3 commits:
> 
> 1. factor out common code
> 2. add a missing restore command in an error path
> 3. do not use removeDir/addDir but stopDirScan/restartDirScan
> 
> 
> Diffs
> -----
> 
> resources/maildir/maildirresource.h f792b23f49cd493f128602649384d2a790ec3b47 
> resources/maildir/maildirresource.cpp 6485f99d8f81cc46913cc473978ace818cbd114d 
> 
> Diff: http://git.reviewboard.kde.org/r/109186/diff/
> 
> 
> Testing
> -------
> 
> moving mails between folders. Needed time is about the same as before (like 50 \
> seconds for 900 mails) 
> 
> Thanks,
> 
> Wolfgang Rohdewald
> 
> 

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