Snap! Websites Journal

libQtCassandra 0.5.22 fixing a bug in the QCassandraLock implementation

Posted on 01/14/2016

WARNING: This implementation of an inter-process, inter-computer lock works with Cassandra only if you know that you are directly dealing with a single Cassandra node at a time. The Cassandra C++ driver (probably all the drivers) makes use of a set of threads to connect to several Cassandra nodes and if the load of the current thread/node pair becomes too large, it will automatically switch to another thread/node pair. This means your messages may not be received in the order you sent them to the database cluster. As a result, the lock mechanism described below will not function as ...

csspp 1.0.9 published

Posted on 01/10/2016

I pusblished a new version of CSS Preprocessor (csspp) because 1.0.8 had one fix from Coverity when there were 4 such bugs total. 1.0.9 includes the other 3 fixes. It was a missused & operator (the parenthesis were missing.)

Version 1.0.9 is otherwise pretty much the same as 1.0.8, I applied a few other clean ups and updated the copyright notice to 2016. The library will soon be 1 year old!

Download right here: https://sourceforge.net/projects/csspp/files/

Project here: CSS Preprocessor tool and library

libQtCassandra potential problem

Posted on 12/31/2015

As I was working on the antihammering plugin for Snap!, I wanted to use the count() feature to quickly know how many hits there are for a given amount of time.

Only as I did that, I noticed that the count() was blocked at 100. The problem was that the predicate used at the lower layer in libQtCassandra would actually set the count maximum to 100 by default.

I think that since the count function only counts the columns of interest, that it goes really fast no matter what the counter maximum is and whether you have a predicate or not. So I changed the lower layer implementation to force the ...

csspp 1.0.8 published

Posted on 12/12/2015

The csspp compiler was updated after being scanned for potential problems by Coverity.

Coverity found one potential buffer overflow in the lexer. This was certainly not possible to reach because that specific function is private and only used for a very few characters. But it is always worth fixing such bugs.

There are two other small issues: a compiler was created with 'this' as parameter instead of 'true' and a test misused the & operator.

So, as an end user you will probably not see any difference between 1.0.7 and 1.0.8.

Download right here: ...

Zipios++ version 2.1.1 published

Posted on 12/12/2015

The Zipios library was scanned using Coverity and we found a couple of variable members that were not initialized. Version 2.1.1 fixes these problems.

There were a few other fixes along the road that were really not major but are included in this version of the library. There is the changelog information:

Fixed a couple of class initializations that were missing.
Fixed a few system() call of which return values were not checked.
Added a BUILD_ZIPIOS_TESTS cmake option flag.
Fixed reference to README as README.md as it is called now.
Allow for ZIPIOS_WINDOWS to ...

Why do we read just 100 rows at a time?

Posted on 11/16/2015

Sample Code:

QtCassandra::QCassandraRowPredicate row_predicate;
row_predicate.setCount(100);
...

QtCassandra::QCassandraColumnRangePredicate column_predicate;
column_predicate.setCount(100);
...

The Cassandra system allows you to read an array of rows or columns. This is done by a special query command sent to the database system.

The libQtCassandra library offers predicate classes giving you the ability to read a set of rows or columns all at once (see example above.) In general, reading more at once is better because it gives you a faster transfer rate to get one large block ...

csspp 1.0.7 published

Posted on 10/07/2015

The CSS specification clearly says that the CSS language itself is case insensitive. Unfortunately, it will be applied to data representing things such as the name of a class which is case sensitive. For this reason, it is important for csspp to keep input identifiers in the same case as it is found in the input file.

Version 1.0.7 includes that fix with tests used to verify that the code matches as expected.

Note that csspp still transforms function names to lowercase. This can cause problems with CSS used for Internet Explorer older versions (6 and earlier, versions that are not supported ...

libtld 1.5.0 and 1.5.1 published

Posted on 08/22/2015

I just added version 1.5.0 to SourceForge.net. This newer version includes a new function that one can use to convert a URI to lowercase. This is important to call tld() because the URI is going to be compared to top level domain names that are all in lowercase.

The new function is called tld_domain_to_lowercase(). It takes a string as input and returns a copy in lowercase. The function understands encoded URIs and UTF-8 as expected by the standard.

The project also includes a new test to make sure I get all the versions bumped each time I do a new update.

P.S. I published 1.5.1 today ...

csspp 1.0.6 published

Posted on 08/11/2015

Got CSS Preprocessor version 1.0.6 published.

This fixes a crashing problem with the minus operator (the following: "field: -;" crashes version 1.0.5 and earlier.) But that was not the point, just a side effect of writing many more tests.

The new system supports the @return at-command which means user defined functions work.

I wrote the necessary tests to check the system defined external functions. They all get checked. The result is that a couple were moved to internal functions so they would work (unique_id() and percentage() which cannot otherwise be implemented) and I added ...

The if() and conditional operator (?:) in CSS Preprocessor

Posted on 08/10/2015

The CSS Preprocessor adds the capability to write complex expressions and functions to use in your CSS files.

One of the functions you can use is a system function named if. It is used to select one of two expressions as shown here:

if($color = white, 33px, 145px)

This says if $color represents the color white, then use 33px, otherwise use 145px.

This works great in all cases where the true and false expressions are both calculable. If one of the expressions is to generate an error, then the if() function cannot be used. In this case, you want to use the ?: operator instead.

In the ...