taskrambler / libtrbase

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libtrbase

Class system and tools for the taskrambler framework.

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passed 3b021f65 fix libtool version · by Georg Hopp

Libtrbase

As the very basic building block of taskrambler this library provides a system to create basic classes and interfaces in ANSI C, some common macro definitions (always useful) and an optimized memory management system.

Synopsis

All prototypes can be included with:

#include <trbase.h>

...

Link your code against the library: gcc -ltrbase ....

Description

The class system

The class system is not what you know from "real" object oriented languages. It only provides these few OOP features:

  • code and data encapsulation
  • late binding through interfaces
  • inheritance

I created it with the idea that at least for me the most useful part of object orientation is the ability to create interfaces and bind them to a specific data structure. This binding in turn enables injection which for me is by far the most important type of object combination.

The second important thing, mostly to reduce code duplication, is inheritance.

The class system combines C structures with one or more interfaces. Each of these interfaces consists of one ore more pointers to functions which must be set during the class creation. These functions are then called via selector functions which have to be defined for the specific interface.

The interface of the class system consists of Preprocessor definitions which provide an easy way to create the neccessary data structures and definitions. There are also definitions for calling the correct interface implementation for a given class instance. If no implementation can be found in the class of the current object it will be looked for in the parent class if there is one and so forth.

The ideas for this are partly derived from the Book "Object Oriented Programming in ANSI C" from Axel-Tobias Schreiner.

In the examples I will show how libtrbase supports you in creating these structures.

The optimized memory management

Allocating and freeing memory on the heap is an expensive action. And because of fragmentation effects it might become even more expensive if the process runs really long.

To overcome this issue I implemented a memory management which never really free's a given memory region, instead it stores the address in a ballanced btree indexed by the size of the memory segment. Multiple adresses for memory of the same size are simply listed. The next allocation first looks in this btree if there is a fitting segment (same size or larger as the requested segment) and returns it if available.

For the ballanced btree I use red-black trees. Thanks to the authors of the Wikipedia article. This implementation is more or less taken from there, with only some small changes here and there.

The idea is based on an idea found on this page of the The Joseph M. Newcomer Co. The concrete idea was first described by Charles B. Weinstock in his Ph.D. dissertation on storage allocation.

Installation

This can be installed via the usual configure, make, make install cycle. For gentoo users am ebuild is added under docs.

Documentation

  • The API doc can be found here.
  • See the latest coverage report here.
  • You may have a look in our WIKI here.

Requirements

Buildtime

required

  • A C compiler & Tools.

optional

  • lcov: To generate test coverage reports.
  • doxygen: For API doc creation.
  • valgrind: For memory checks.

Contributing

I would really like to see some people possibly interested in this stuff. I think it contains some really interesting ideas.

If you like to contribute, contact me via email. You are free to clone and play with this code.

License

GNU General Public License (Version 3)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Author

Georg Hopp <georg@steffers.org>