Recalling the lambda notation…

“All changes, even the most longed for, have their melancholy; for what we leave behind us is a part of ourselves; we must die to one life before we can enter another.” ~ Anatole France

Finally I did it. I changed the long name of my blog, from “Developing, programming and computer science” to “Recalling the lambda notation”, with the subtitle “I was a student of computer science in Pisa”.

Most of you do not understand, but some of you will do.

Why I chose this name? Because sometimes, when I am working, I think at that time, when I was a simple student of computer science.

The anxiety caused from the waiting to read the text of the exam, the trepidation during the passage of the list of results, the crucial moment passing through the door thinking “the die has been cast”, the last night before graduation…

But it was an experience that has changed me forever.

Still today, occasionally it happens to me to relive those moments. Often I and my friend jokingly talk about this (words like “I saw the ghost of <theacher name>” or “I like the exercise of the thumb” [1]).

More to come…

[1] Yes, that is the infamous “Hall effect”

I made a new TRAC macro, BackLinksMenu. This macro is similar to BackLinks, because it shows a menu as in the figure below. Read the rest of this entry »

Check out these sites:

• http://trac-hacks.org/wiki/BackLinksMacro (it contains a ticket/bugzilla system, too!)
• http://trac.edgewall.org/wiki/MacroBazaar (from the official Trac website)

Here I’ll describe how to install BackLinks.5.py for Trac. I’ve tested it on Trac 0.10.4 and it works fine.
Read the rest of this entry »

Hi, I’ve released and modified the original BackLinks v4 plugin with these modifications:
Read the rest of this entry »

Happy new year to everybody.

After several months of absence (11!), finally I am writing a post on my blog!

Many things have happened during this time. I’ll write some of them. Read the rest of this entry »

Finally I made the last code modifications to SquidLook installer.  The upgrade from MySAR is to do, yet. But it’s not too difficult, I think to use ‘ALTER TABLE’ commands.

SquidLook 1.0 beta1 is approaching soon…

 I’ve drawn the squidLook logo. The big one:

and the small one:

Squidlook-importer.php is the script that do the big work: importing the Squid log files.
It is based from the old mysar-importer.php.
The original author, Giannis Stollis, pointed me about the slowness of the importer. He was working on Mysar 3.0 with an entirelly C compiled importer to get things faster, but he dropped out.
I saw the code and optimized it a bit. I've taken some simple but powerful tactics.
Given that the importer uses many, many, many SQL queries, so the bottleneck is those Mysql calls.
So:

• Cache all small tables: for example, users table, can be entirelly cached into memory: it is good for organizations up to 80.000 employers.
• Buffered inserts: multiple inserts done in one time is much, much, much faster than multiple single inserts. Simple do this:

Sorry for the code not indented: I must discover how to enable this in wordpress...

I found the plugin for the code at http://blog.igeek.info/wp-plugins/igsyntax-hiliter/ ! It's awesome

Finally I uploaded first sources of SquidLook in Google Code SVN repositories.
I except to release the first 1.0 package soon.

Stay tuned.

...I'm back.
And I upgraded my Wordpress to 2.1. Seems that all is working!

A prerelease build of Flash Player 9 Update for the Linux platform is now available. Flash Player 9 Update for Linux currently does not include full-screen mode and complete SSL support (SSL support is currently available in the Linux Plugin but not the Linux Standalone Player). Full-screen mode and SSL support will be available in the final release. The current Linux build is 9.0.21.55.

Go get it!!!

My friend has an old Apple eMac PowerPC G4 running at 700 Mhz, which he acquired in 2000.

He tried Ubuntu Breezy 5.10 and Dapper Drake 6.06 but with no luck running it on Xserver/X.org: when he goes into X11 mode after the boot, the screeen is absolutely black. He can go to console clicking CTRL+F1.

Here is the solution of the problem:

1. Wait until the X11 is started (black screen)
2. Press CTRL+F1
3. At login, do (write this in a single line!):
   

   sudo mv /etc/X11/xorg.conf /etc/X11/xorg.bak

4. Download this xorg.conf and put it into /etc/X11:
   

   sudo mv xorg.conf /etc/X11/xorg.conf

5. Restart X11 with:
   

   sudo /etc/init.d/gdm restart

6. All done! Now you can enjoy Ubuntu with your eMac G4

The fourth implementation of ext file system is pushed into 2.6.19 development tree.

Ext4 is backward compatible with Ext3, so systems without Ext4 support can mount Ext4 partitions.

The main new feature of Ext4 is the support of Extents:

An extent is a contiguous area of storage in a computer file system, reserved for a file. When starting to write to a file, a whole extent is allocated. When writing to the file again, possibly after doing other write operations, the data continues where the previous write left off. This reduces or eliminates file fragmentation.

From wikipedia

The Extents are disabled for default, to guarantee the backward compatibility.

Read more here!

Performance Gain of Factor 15 to 40
I knew the headline would draw your attention

I'd love it (and you'd love us) if these numbers were for the entire application suite, but totally unspectacular they're for the import of huge formula loaded MS-Excel documents into Calc, which is nice enough to be delighted anyway.. Down on the floor and back to the facts: when loading a quite big Excel document, I'm referring to 25 MB of size, more than 100 sheets, a million cells and hundredthousand formulas, formula cells unnecessarily broadcasted their initial recalculation state to all dependents. Building up this dirty tree took most of the time and by replacing it with a document wide simple chain mechanism for this case, loading times went down to a fraction. The metrics from two different machines for that document are:

Small one processor system:
model name      : Intel(R) Pentium(R) 4 CPU 1.80GHz
cpu MHz         : 1816.213
cache size      : 256 KB
bogomips        : 3617.58
Mem free        : 386488 kB (or somewhere near that)
old performance : 39:08 minutes
new performance :  2:37 minutes
performance gain: factor 15

Two dual core processors system:
model name      : Dual Core AMD Opteron(tm) Processor 275
cpu MHz         : 2194.038
cache size      : 1024 KB
bogomips        : 4393.64
Mem free        : 3388412 kB
old performance : 27:58 minutes
new performance :  0:43 minutes
performance gain: factor 39

This is from issue 68960, targeted to OOo2.1

Taken from this blog post.