Hi! Thanks for the patch.

Looks good to me.


> 6 дек. 2019 г., в 7:50, Alexander Tikhonov <avtikhon@tarantool.org> написал(а):
> 
> Alexander,
> 
> Thanks for the review, updated commit message as you suggested.
> 
> Четверг, 5 декабря 2019, 4:49 +03:00 от Alexander Turenko <alexander.turenko@tarantool.org>:
> 
> LGTM.
> 
> I'm okay with the approach I proposed, of course :) My review would be
> insufficient.
> 
> Serge, can you do the second review?
> 
> WBR, Alexander Turenko.
> 
> > build: fix unit tests build with lrt
> 
> Nit: librt or -ltr
> 
> Or just 'on CentOS 6'. All those details about librt are described in
> the commit message below, while the header would be better if it will
> give us an idea why the commit was made.
> Corrected commit message added 'on CentOS 6' add '-lrt', (use of 'librt' exceeded the limit of the commit message length)
> 
> > After the commit 77fa45bd05f8cdd4c0f9bad85185ef5b61528d49
> > ('lua: add fiber.top() listing fiber cpu consumption')
> > the unit tests builds failed like:
> > 
> > /opt/rh/devtoolset-6/root/usr/libexec/gcc/x86_64-redhat-linux/6.3.1/ld:
> > ../../src/lib/core/libcore.a(fiber.c.o): undefined reference to symbol
> > 'clock_gettime@@GLIBC_2.2.5'
> > //lib64/librt.so.1: error adding symbols: DSO missing from command line
> > collect2: error: ld returned 1 exit status
> > test/unit/CMakeFiles/cbus.test.dir/build.make:108: recipe for target
> > 'test/unit/cbus.test' failed
> > make[2]: *** [test/unit/cbus.test] Error 1
> > 
> > Found that fiber.cc is using now clock_gettime(), which requires -lrt
> > with glibc. To fix it added librt dependency for core library for glibc.
> > Due to glibc requires for -lrt for clock_gettime() only for some
> > versions, check 'man clock_gettime.2':
> > 'Link with -lrt (only for glibc versions before 2.17).'
> > the check whether is able to use clock_gettime() w/o librt library is
> > added.
> > 
> > Close #4639
> > ---
> > 
> > Github: https://github.com/tarantool/tarantool/tree/avtikhon/gh-4639-lrt-suggested-full-ci <https://github.com/tarantool/tarantool/tree/avtikhon/gh-4639-lrt-suggested-full-ci>
> > Issue: https://github.com/tarantool/tarantool/issues/4639 <https://github.com/tarantool/tarantool/issues/4639>
> > 
> > CMakeLists.txt | 6 ++++++
> > src/lib/core/CMakeLists.txt | 8 ++++++++
> > 2 files changed, 14 insertions(+)
> > 
> > diff --git a/CMakeLists.txt b/CMakeLists.txt
> > index 7d6c0846e..ca968eb8d 100644
> > --- a/CMakeLists.txt
> > +++ b/CMakeLists.txt
> > @@ -116,6 +116,12 @@ else ()
> > set(HAVE_CLOCK_GETTIME ${HAVE_CLOCK_GETTIME_DECL})
> > endif ()
> > set(CMAKE_REQUIRED_LIBRARIES "")
> > +# According to `man 2 clockgettime` the glibc wrapper requires
> > +# -lrt on glibc versions before 2.17. We need to check whether
> > +# the function is available without -lrt to set this linker option
> > +# conditionally.
> > +check_function_exists(clock_gettime HAVE_CLOCK_GETTIME_WITHOUT_RT)
> > +
> > check_symbol_exists(__get_cpuid cpuid.h HAVE_CPUID)
> > 
> > # Checks for libev
> > diff --git a/src/lib/core/CMakeLists.txt b/src/lib/core/CMakeLists.txt
> > index e60b5199e..8623aa0de 100644
> > --- a/src/lib/core/CMakeLists.txt
> > +++ b/src/lib/core/CMakeLists.txt
> > @@ -46,3 +46,11 @@ target_link_libraries(core salad small uri decNumber ${LIBEV_LIBRARIES}
> > if (ENABLE_BACKTRACE AND NOT TARGET_OS_DARWIN)
> > target_link_libraries(core gcc_s ${UNWIND_LIBRARIES})
> > endif()
> > +
> > +# Since fiber.top() introduction, fiber.cc, which is part of core
> > +# library, depends on clock_gettime() syscall, so we should set
> > +# -lrt when it is appropriate. See a comment for
> > +# HAVE_CLOCK_GETTIME_WITHOUT_RT in ${REPO}/CMakeLists.txt.
> > +if ("${HAVE_CLOCK_GETTIME}" AND NOT "${HAVE_CLOCK_GETTIME_WITHOUT_RT}")
> > + target_link_libraries(core rt)
> > +endif()
> > -- 
> > 2.17.1
> > 
> 
> 
> -- 
> Alexander Tikhonov


--
Serge Petrenko
sergepetrenko@tarantool.org