----------------------------------------------------------------------- WORKLOG TASK -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- TASK...........: Enable the use of libstdc++ in MariaDB CREATION DATE..: Wed, 11 Nov 2009, 13:19 SUPERVISOR.....: Monty IMPLEMENTOR....: COPIES TO......: CATEGORY.......: Server-BackLog TASK ID........: 63 (http://askmonty.org/worklog/?tid=63) VERSION........: Server-5.2 STATUS.........: Un-Assigned PRIORITY.......: 60 WORKED HOURS...: 4 ESTIMATE.......: 10 (hours remain) ORIG. ESTIMATE.: 10 PROGRESS NOTES: -=-=(Knielsen - Thu, 14 Jan 2010, 13:46)=-=- Research and updated description Worked 4 hours and estimate 10 hours remain (original estimate increased by 14 hours). -=-=(Knielsen - Thu, 14 Jan 2010, 13:45)=-=- High-Level Specification modified. --- /tmp/wklog.63.old.13967 2010-01-14 11:45:49.000000000 +0000 +++ /tmp/wklog.63.new.13967 2010-01-14 11:45:49.000000000 +0000 @@ -1 +1,37 @@ +I did some investigation into this. + +The simple way to do this is to simply use g++ to link C++ objects. So this +issue is really restricted to GCC compilation where we by default prefer to +link with gcc even for C++ code. So this means building with + + CXX=g++ + +The consequences of doing this for the binaries is the addition of two +additional run-time .so dependencies: libstdc++.so and libgcc_s.so. + +It still needs to be investigated if these additional dependencies are a +problem for binary tarball packages, or if the ABI for those libraries are now +as stable as libc.so. + +The libgcc_s.so is needed as a dependency to support exceptions between +different object files, as they need to use the same code for stack unwinding. +libstdc++.so is of course needed for access to C++ runtime. + +I researched into the possibility to instead link only specific plugins with +g++, and continue to link the rest of the server with gcc. Unfortunately, this +seems really hard to do in a proper way due to the way autotools works. At +configure time, a script ./libtool is created with hardcoded compiler commands +derived from $CC and $CXX. This script is then used to do the actual linking +in Makefiles generated by Automake. I thus did not find a way to change the +linker command on a per-makefile basis, as libtool is global to the project. + +One option would be to use separate configure.in for plugins, but this is +quite an intrusive change. + +My conclusion is that the best way is to start using g++ for linking the +entire server. This is no problem for binaries made for a specific +distribution (Ubuntu, Debian, Centos), where the dependencies are handled by +the package manager. If it is a big problem for binary tarball releases, at +worst we can build multiple binary tarball releases for the different library +versions we need to support. -=-=(Guest - Tue, 12 Jan 2010, 16:26)=-=- Version updated. --- /tmp/wklog.63.old.19522 2010-01-12 16:26:23.000000000 +0200 +++ /tmp/wklog.63.new.19522 2010-01-12 16:26:23.000000000 +0200 @@ -1 +1 @@ -Connector/.NET-5.2 +Server-5.2 -=-=(Guest - Tue, 12 Jan 2010, 16:26)=-=- Category updated. --- /tmp/wklog.63.old.19506 2010-01-12 16:26:15.000000000 +0200 +++ /tmp/wklog.63.new.19506 2010-01-12 16:26:15.000000000 +0200 @@ -1 +1 @@ -Server-RawIdeaBin +Server-BackLog DESCRIPTION: Enable the use of libstdc++ in MariaDB. As time goes on, more and more plugins and external code/library will need linking to libstdc++ for stuff it uses. I have already seen this happen several times, with extra work needed to integrate things properly. It would be nice to have a general solution for this so that it is not necessary to spend time on individual solutions in each case. It also needs to be considered what the impact of this will be for the server in terms of binary compatibility, performance etc. I think it should be mostly ok, except that it might introduce a problem for bintar packages with an external dependency on libstdc++. HIGH-LEVEL SPECIFICATION: I did some investigation into this. The simple way to do this is to simply use g++ to link C++ objects. So this issue is really restricted to GCC compilation where we by default prefer to link with gcc even for C++ code. So this means building with CXX=g++ The consequences of doing this for the binaries is the addition of two additional run-time .so dependencies: libstdc++.so and libgcc_s.so. It still needs to be investigated if these additional dependencies are a problem for binary tarball packages, or if the ABI for those libraries are now as stable as libc.so. The libgcc_s.so is needed as a dependency to support exceptions between different object files, as they need to use the same code for stack unwinding. libstdc++.so is of course needed for access to C++ runtime. I researched into the possibility to instead link only specific plugins with g++, and continue to link the rest of the server with gcc. Unfortunately, this seems really hard to do in a proper way due to the way autotools works. At configure time, a script ./libtool is created with hardcoded compiler commands derived from $CC and $CXX. This script is then used to do the actual linking in Makefiles generated by Automake. I thus did not find a way to change the linker command on a per-makefile basis, as libtool is global to the project. One option would be to use separate configure.in for plugins, but this is quite an intrusive change. My conclusion is that the best way is to start using g++ for linking the entire server. This is no problem for binaries made for a specific distribution (Ubuntu, Debian, Centos), where the dependencies are handled by the package manager. If it is a big problem for binary tarball releases, at worst we can build multiple binary tarball releases for the different library versions we need to support. ESTIMATED WORK TIME ESTIMATED COMPLETION DATE ----------------------------------------------------------------------- WorkLog (v3.5.9)