libferris and ego meet google earth. The new release 1.1.96 will allow nice integration with ge letting you do desktop searches from within google earth aswell as show where a file is located by clicking on it in ego.

See the top of this page for a screen animation.

Desktop search?

I noticed on planet KDE this post on desktop search. It mentioned not using xattr for metadata because some filesystems don't support it. I'd say that most filesystems don't, iso filesystems, NFS (depending on setup), http, ftp and xemacs don't. The simple solution to all this in libferris is to virtualise xattr just like the filesytem itself is virtual. So you store xattr in RDF when the underlying filesystem doesn't allow it.

I should also highlight that the tagging mentioned in the post referenced by the above post is already available and usable with libferris :) You can attach arbitrary metadata to virtual filesystem objects, index them and search based on that metadata. Indexing can be done in many formats, lucene, postgresql, RDF using redland (db4, sqlite, postgresql) or on an LDAP server.

For indexing see here. For EA stuff here.

FUSE.sf.net meets libferris

Yes folks, its true, you can now mount libferris through the kernel using fuse. The goodness of your xemacs session becoming a kernel filesystem, mounting firefox through ferris and fuse... mmm, filesystems ease the pain.

Still trying to get some more advanced article about libferris usage out there. Things are starting to get rather interesting now because of the stacked filesystems in libferris and ultimate exposure through fuse lets you do some rather funky things with data that comes from (and returns to) many and varied places.

Fighto time.

Recently a question was posed to me in which I tended to offer a reasonably off the cuff response for. This led to an interesting debate about if set<string> was going to be hugely slower than hash_set<string> for the exact case where hash_set<> should whip an AVL tree's butt: direct lookups.

So without going into that conversation I decided to benchmark the two std::collections from both stdc++ and stlport 4.x. This is using gcc 4.0.2 which is shameful as I should have a more recent gcc. I'll likely rereun it on icc and 4.1.x as well.

The core of the code is to read strings from cin and shove them into a std::list. During the set<> parts I create a set with the list (which will have dups) and then iterate the list 50 times looking for each entry (including dups again) in the built set<> or hash_set<>.

There is of course some cruft there to select the right container from stdc++ and stlport because hash_set is non standard.

    if( use_hash )
    {
        l_t::iterator e = l.end();
        for( l_t::iterator iter = l.begin(); iter != e; ++iter )
            hstrset.insert( *iter );
        for( int i=0; i<LOOKUPS; ++i )
            for( l_t::iterator iter = l.begin(); iter != e; ++iter )
                hstrset.find( *iter );
    }
    else
    {
        l_t::iterator e = l.end();
        for( l_t::iterator iter = l.begin(); iter != e; ++iter )
            strset.insert( *iter );
        for( int i=0; i<LOOKUPS; ++i )
            for( l_t::iterator iter = l.begin(); iter != e; ++iter )
                strset.find( *iter );
    }

So the benchmarks, all compiled with -O9. Other gcc options don't seem to make any real effect. I created input from Gutenberg files, l.size is the number of words read. The hash_set methods are quicker for the completely degenerate case of only doing direct lookups and doing each of them at least 50 times per uniq word in the input.

Perhaps the most interesting point is the difference in speed between stlport and libstdc++ for this. I am now very interested to see how stlport5.x compares.

 # Using stdc++::set<>
 foo$ time cat /tmp/largetxt.txt | ./string_xset
l.size:273435
use_hash:0

 real    0m16.980s
user    0m16.493s
sys     0m0.028s

 # Using stlport::set<>
 foo$ time cat /tmp/largetxt.txt | ./string_xset_stlport
l.size:273435
use_hash:0

 real    0m10.184s
user    0m9.821s
sys     0m0.084s

 # Using stdc++::hash_set<>
 foo$ time cat /tmp/largetxt.txt | ./string_xset 1
l.size:273435
use_hash:1

 real    0m4.061s
user    0m3.868s
sys     0m0.024s

 # Using stlport::hash_set<>
 foo$ time cat /tmp/largetxt.txt | ./string_xset_stlport 1
l.size:273435
use_hash:1

 real    0m2.430s
user    0m2.328s
sys     0m0.012s

 

Moving back to blogging here for a while... Seems using university equipment for this is not so much an optimal thing. Loss of control over the network environment etc.