WL#5161: CMake-based unified build system
Affects: Server-5.5 — Status: Complete — Priority: Medium
Currently, there are 2 build do different toolsets used to build MySQL Server - GNU (autoconf, automake, libtool) is used on Unixes. - CMake is used on Windows. The purpose of this worklog is to unify the build system .After evaluation period, switch from using 2 different systems to a single one CMake The main reasons for choosing CMake is that it is obviously simpler to maintain a unified build system than two disparate systems. Here are some pro-CMake arguments: - It works on Window. GNU buildsystem does not appear to be enough “cross- platform”, that is it does not work and likely never will work natively on Windows. - Traditionally, new MySQL features that required changes in build (plugin yystem, unit tests, most recently googletest integration) were always implemented on Unixes first, leaving Windows behind, sometimes for years. This would not happen with unified build system. - We already use 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 get. It is available in all major Linux repositories (checked Ubuntu, Fedora, OpenSUSE). It is also in OpenSolaris repository, known as SUNWCmake. It in FreeBSD ports. The It is also very simple to compile it from source, the single prerequisite is a working C++ compiler and make utility. - CMake has support features we need and might need: system checks, 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 IDE makes 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 autotools generated ones (for example they have progress indicators, color and working dependencies). - Scripting language used by CMake is simpler m4 used by autotools. - CMake is a single small tool, not a bunch of different tools as in GNU system (autoconf,autoheader,automake,libtool)
=====Quick start==== Using cmake for developer is simple, to compile and test MySQL server, the minimalistic instructions to compile on Unix are bzr branch <repo> cd repo cmake . make make test-force Of course we will support build options, so the above cmake command could look a bit more complicated with cmake . –DWITH_INNOBASE_STORAGE_ENGINE=1 –DWITH_SSL=bundled – DWITH_EXTRA_CHARSETS=all ========Which build options are supported======== We will support all important options and platform specialities (like DTrace) . We’ll cut support for some obsolete things (like –with-named-thread- library). Likely there won’t be support for non-thread safe client libraries, but we’ll generate symlinks such that user’s build does not break. Translation from the currently known autotools configure script options will work like this : leading – is omitted, option name is translated to upper case, dash is replaced with underscore.- - “boolean” options (on/off), are translated like this ./configure --with-innobase-storage-engine => cmake - DWITH_INNOBASE_STORAGE_ENGINE=1 - “textual” options will are translated like this ./configure –with-ssl=bundled => cmake –DWITH_SSL=bundled This is compatible with what we use on Windows currently, at least KDE folks and other CMake users seem to follow the same schema. cmake –LH will list the really important options, cmake –LAH will list all options, including exotic ones. cmake –LH or cmake-gui can be seen as replacement for ./configure –help ======How to compile for debugging=============== By default, unless explicit options are given in CFLAGS or CXXFLAGS environment variables, we will use Relwithdebinfo configuration (release with debug information) which typically equates to –O2 -g compile flags. We also add –DDBUG_OFF in all but Dbug configurations. To compile debug, one can use following options cmake –DCMAKE_BUILD_TYPE=Debug (native cmake syntax) cmake –DWITH_DEBUG (added for compatibity with autotools) cmake –DWITH_DEBUG_FULL (uses safemalloc, slow) ======Platform checks============= System checks in configure.in ( availabity of header files, functions etc) will be ported. Restricted subset of checks will also run on Windows, which means Windows will config-win.h will be ditched and Windows will use the same mechanism for config.h generation as every other platform. Why not to run all checks on Windows, but just a restricted subset? Platform checks generally run slower on Windows , because cmake needs to generate a VS solution for every test and since most of the tests do not apply to Windows anyway (pthread_ is not known to exist on every current or future version of windows, nor there will ever be a posix_fallocate on Windows), we’ll restrict the number of tests to minimum – it is a pure performance tweak. ======Out-of-source (aka out-of-place) builds======== We will support both in-source builds, as it is how people are used to work. We will also support and encourage out-of-sourc e builds, which are recommended by CMake folks because it is cleaner build- the source tree is not polluted with binaries and objects. The main advantage of an out-of-source build is the possibility to have multiple build tree of the same source. One can build example building with different options , or debug and release, or even put the source tree on the network share and build on different OSes with different compilers. An out of source build is done with simple cmake <config-options> <path-to-source-tree> We’ll also support running tests in an out-of-source builds, which will require some modifications in MTR (as it currently assumes sources and binaries are under same directory) ======Packaging (binary) =========== cmake-built projects will break existing scripts used for tarball packaging – existing scripts rely on build that is done with libtool, for example on existence of .libs directories. Also, existing scripts will not work for Xcode projects – the paths used there are different from what make_bnary_distribution expects , they rather resemble structure that is used for Visual Studio projects (binaries are different Debug and Relwithdebinfo subdirectories). Therefore we’ll use builtin support for packaging via cmake’s INSTALL command (we need to use it anyway to generate “make install”) . First, we’ll support tar.gz and zip packages - potentially it can be expanded to DEBs and RPMs with minimal overhead Creating a binary package with CMake2.6 : make package (Unix Makefiles generator) devenv mysql.sln /build relwithdebinfo /project package (VS generator) xcodebuild -target=package–config=Relwithdebinfo (Xcode generator) ======Packaging(source) =========== This is different to autotools and “make dist” is not provided by default. CMake-generated Makefiles provide package_source target, but it just packs everything in source directory. In an in-source build, this will packs binaries as well. We will implement “make dist” ourselves, using “bzr export” functionality or, if bzr is not available, “make package_source” ( for in-source build we’ll need to issue “make clean” prior to avoid packing the binaries). We’ll pack some extra files into the tarball, that are there traditionally packed – that is bison output files. For some period of time (as long as we continue supporting both autotools in addition to cmake) we’ll generate and package the traditional configure script too. It is worth noting that “make dist” less important for cmake and can possibly can be completely replaced with “bzr export” or out-of-source “make package_source” in the future. =======Backward compatibility with autotools system======= At least for the start and time required for transition, autotools build will be supported. Existing scripts (BUILD/autorun.sh && configure) will continue to work. configure script will be changed to call cmake with relevant parameters , if cmake is found on the machine, otherwise it will fall back to autotools build. There will be a possibility to disable CMake build and force autotools via environment variable HAVE_CMAKE=no. Plugging cmake into existing systems like described above has the benefit that all scripts in the BUILD directory continue to work. ======Backward compatibility with existing cmake usage on Windows ======= For the time required for transition, configure.js and win\build-foo.bat scripts will continue to work. We should encourage users though to use cmake directly. New versions of CMake (2.8, currently release candidate) will find existing Visual Studio so there is no need to specify generator with a long commands like cmake . –G “Visual Studio 9 2008”. Instead, one could just use cmake . as on Unix.
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