Review Request: Fix KIO listDir entries batching

[Mark Gaiser]

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This is an automatically generated e-mail. To reply, visit:
http://git.reviewboard.kde.org/r/107520/
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(Updated Dec. 5, 2012, 6:54 p.m.)


Review request for kdelibs and David Faure.


Changes
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Updated diff with comments from David.
Also added a comment block in file_unix.cpp explaining what details == 0 means and what the difference is between the else. I might know it now, but it's not _that_ obvious when you first see the code.


Description
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listDir is batching only in a vague manner. It required to have details set to something bigger then 0 and required to know the amount of files that where going to be send. Even then it was fixed to broadcast only the first 100 entries followed by _everything_ that comes after it. For more details, look at the diff. If you did happen to do a request with details set at 0 (thus only the filename and filetype are stored) then a different code path was taken where it wasn't even possible to batch.

I changed this to do time based batching. Now it broadcasts all the entries it currently has after 300ms have been passed. In normal situations on the local file system that means that you will never see batching. You will start to see them if you hit folders with 10.000+ entries in then (for a SSD that is). For the slower HDD drives you probably see more batching.

In the worst case scenario you could find yourself in the situation that 1 entry is broadcasted every 300ms. That is only on very slow external devices or internet places.

The advantage of batching (just repeating that here since it's currently not working in any KDE app) is that you can start showing results to the user without all the results being in. This gives the user a "feeling" that it's fast even though KIO might still be working hard to get all entries in. Dolphin is one app in particular that can really make use of this. Currently it doesn't do that. IT waits till all the results are in.

While working on this, i also updated the style of the FileProtocol::listDir function and greatly simplified how it lists the directory. Now the actual listing just follows one code path instead of one for details 0 and one for the rest.

I'd like to get this in kdelibs for KDE 4.10 because it is a bugfix even though there is no bug report.


Diffs (updated)
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  kio/kio/slavebase.h 0bdb146 
  kio/kio/slavebase.cpp 8f8ff03 
  kioslave/file/file_unix.cpp 2b47b7c 

Diff: http://git.reviewboard.kde.org/r/107520/diff/


Testing
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I tested this in various ways:
(SSD) 100.000 entries in a folder with details set to 0: 1 signal with all entries
(SSD) 100.000 entries in a folder without details set (all info): 2 or 3 signals each with between 20.000 - 50.000 entries
(slow ftp) ftp://ftp.mirror.aarnet.edu.au/pub/archlinux/extra/os/x86_64/ results start slowly with 20 - 50 per signal and quickly climb up.
Ran the kio test cases. Apparently i have a "failed" for kio-krununittest, a testcase that David Faure has fixed if i'm right.
Updated the documentation to not mention the total files anymore. KioSlaves can still set it, but it's just unused for the listDir now.
Last, running with this now and i haven't seen any issues so far.


Thanks,

Mark Gaiser

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