Lenz Grimmer's blog

There has been a lot of buzz about the MySQL 5.5 GA release and its new features and other user-visible improvements. In this blog post, I'd like to touch on a less noticeable, but still important change.

CMake has already been used to build the MySQL Server on Windows for a long time, while the GNU autotools were used on all other platforms. Since MySQL 5.5, all builds on all platforms are now performed using the same tool chain. With the latest release of MySQL 5.5, we've made an important step to clean up and simplify the MySQL build system: the support for autoconf/automake has now been removed completely. We've been performing the release builds of MySQL 5.5 using CMake exclusively for quite some time already. It became obvious that maintaining two separate build systems simply had become too much of a burden for our engineers, especially since the autotools-based builds were no longer exhaustively tested. This change was outlined in WorkLog#5665 - Removal of the autotools-based build system. We've made this step in close cooperation with our community of packagers (e.g. the maintainers of MySQL packages on the various Linux distributions).

By moving to CMake, we are giving our developers one common build mechanism for all platforms and there is a lot of new useful functionality such as out-of-source builds or a GUI for configuring the build options. And they can now build MySQL in the very same way that we do it for our own binaries! I've covered the advantages in my previous blog post about Building MySQL Server with CMake on Linux/Unix already. We've also created a general article about CMake and MySQL as well as an Autotools to CMake Transition Guide on the MySQL Forge Wiki. The description of the source build process in the reference manual has also been updated to reflect this change.

A big “thank you” should to go to Vladislav Vaintroub and Davi Arnaut for implementing and pushing the transition to CMake forward, and to Paul DuBois for creating and improving the documentation! Wearing my former build and release engineer hat, I am very happy about this change.

Other CMake-related articles that are worth reading:

• Giuseppe Maxia: Building MySQL 5.5 with CMake
• Jonathan Perkin: How To Build MySQL Releases
• Santo Leto: Step by Step Guide on How to Compile MySQL 5.5 on Microsoft Windows

CMake is a cross-platform, open-source build system, maintained by Kitware, Inc.

From the CMake.org home page:

CMake is a family of tools designed to build, test and package software. CMake is used to control the software compilation process using simple platform and compiler independent configuration files. CMake generates native makefiles and workspaces that can be used in the compiler environment of your choice.

It has been used for building the MySQL Server on Windows since MySQL 5.0 – the initial CMake build support was added in August 2006.

For building MySQL on all other platforms, the GNU autotools (autoconf, automake and libtool) are currently being used.

CMake is used in some other MySQL projects as well, e.g.

• MySQL Connector/C
• MySQL Connector/C++
• MySQL Proxy

On February 22nd, Vladislav Vaintroub pushed the changes required to implement WorkLog#5161 "CMake-based unified build system" into the "mysql-next-mr" branch (aka the "Celosia" mile stone).

From this version on, CMake can also be used to build MySQL on Linux and other Unix platforms. For the time being, the autoconf/automake files are still available as well, but will be phased out once the CMake build enviroment has reached the desired level of maturity. The change was announced on February 28th on our "internals" developer discussion list.

The purpose of WL#5161 is to simplify the MySQL build system. It is much easier and less error-prone to maintain a unified build system for all platforms than two separate ones.

CMake has been chosen because of several reasons; the worklog description lists a few pro-CMake arguments (slightly rephrased):

• CMake works on Windows. The GNU buildsystem does not really work and likely never will work natively on Windows (Using Cygwin is not really an option).
• Traditionally, new MySQL features that required changes in the build environment (e.g. the plugin system, unit tests, most recently googletest integration) were always implemented on Unix first, leaving Windows behind (sometimes for years). This would not happen with a unified build system.
• MySQL already uses CMake since 2006 on Windows, so we do not need to start from scratch, only port what we have to Unix.
• CMake runs on every OS and compiler we support.
• It is simple to obtain and install on a wide range of platforms. It is available in all major Linux package repositories (e.g. Ubuntu, Fedora, OpenSUSE). It is also in the OpenSolaris repository, known as SUNWCmake. It's in FreeBSD ports and available for Mac OS X. It is also very simple to compile it from source, the single prerequisite is a working C++ compiler and make utility.
• CMake has support for features we need and might need, e.g. system checks or cross-compiling.
• CMake provides integrated support for packaging. It can handle both simple packages (tar.gz or zip archives) and more complex things like DEB and RPM without much extra coding.
• Good integration with the popular IDEs (Visual Studio, Xcode, Eclipse CDT, KDevelop). Developing in an IDE makes the development process more enjoyable, and potentially it lowers the barrier for external contributors. Of course, CMake can generate traditional Unix Makefiles, which appear to be are superior to the ones generated by GNU autotools (for example, they have progress indicators, colored output and working dependencies).
• The scripting language used by CMake is simpler than m4 used by autotools.
• CMake is a single small tool, not a bunch of different tools as in GNU system (autoconf, autoheader, automake, libtool)

I'd like to mention a few additional reasons:

• Out-of-source builds – CMake can separate the build directory from the source directory. This is convenient, as your working source tree is not cluttered with object files and other fragments of the build process.
• Build configuration using a GUI. The cmake-gui package (based on Nokia/TrollTech's Qt library) provides a convenient way of enabling and configuring the various available build options. This is much better than having to memorize all the required defines and configuration flags.
• Integrated support for creating a wide range of package formats.

The CMake Wiki lists a number of other "nice to have" features.

From a developer perspective, I hope that it will make it much easier to finally implement two things that many developers working with MySQL have been waiting for (now that the build code has been cleaned up):

• Compiling the embedded MySQL Server (libmysqld) as a shared library
• Better support for cross-compilation

Building MySQL with CMake is quite simple and straighforward – the process is outlined on the MySQL Forge Wiki. The document is still work in progress and we'd like to encourage you to take a look at it, try to follow the steps and update/improve the Wiki page, if needed! Your feedback on the build process is appreciated. Feel free to join our internals mailing list to discuss your impressions and observations or submit a bug report via the Bug Database. It's likely that the build still has a few rough edges that we'd like to fix quickly (e.g. BUG#51502 – a fix for this one is already commited to the mysql-next-mr-bugfixing source tree and will be merged into the mysql-next-mr trunk soon).

If you're new to CMake, you might want to take a look at the "Getting Started With CMake (An End-User's Perspective) For Cross-Platform Building" screencast or the "Running CMake" article.

Happy hacking!