LTTng » LTTng-UST

Hi Ricardo,

Can you try with this patch:

https://github.com/sebhtml/lttng-ust/commit/70b1330de854adf544fcdf8b61f644d3af79e052.patch

From my branch

https://github.com/sebhtml/lttng-ust/commits/lttng-ust-issue-1042.v1

The fix could be implemented 100% in FindLTTngUST.cmake such that it looks in the lttng-ust source distribution for the header file and for the shared library.

I don't think that we would really want that.

So...

The 3 solutions that I can see are:

1. The patch that I provided (or a variant thereof).

2. Implement a solution strictly in FindLTTngUST.cmake.

3. Don't build this example if if LTTngUST is not found on the system.

On another machine (without LTTng), using the repository/branch mentioned by Sébastien, the build completed without errors:

(...)
make[4]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/gen-tp'
if [ x"cmake-multiple-shared-libraries" != x"" ]; then \
    for subdir in cmake-multiple-shared-libraries; do \
        (cd cmake-multiple-shared-libraries && mkdir -p build && cd build && cmake .. && make && cd ..) || exit 1; \
    done; \
fi;
-- The C compiler identification is GNU 5.3.0
-- The CXX compiler identification is GNU 5.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Could NOT find LTTngUST (missing:  LTTNGUST_LIBRARIES LTTNGUST_INCLUDE_DIRS) 
-- Configuring done
-- Generating done
-- Build files have been written to: /home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build
make[4]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[5]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
Scanning dependencies of target tracepoint-provider
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 10%] Building CXX object CMakeFiles/tracepoint-provider.dir/tracepoint-provider.cpp.o
[ 20%] Linking CXX shared library libtracepoint-provider.so
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 20%] Built target tracepoint-provider
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
Scanning dependencies of target aligner-lib
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 30%] Building CXX object CMakeFiles/aligner-lib.dir/aligner-lib.cpp.o
[ 40%] Linking CXX shared library libaligner-lib.so
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 40%] Built target aligner-lib
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
Scanning dependencies of target tester-lib
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 50%] Building CXX object CMakeFiles/tester-lib.dir/tester-lib.cpp.o
[ 60%] Linking CXX shared library libtester-lib.so
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 60%] Built target tester-lib
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
Scanning dependencies of target tester
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 70%] Building CXX object CMakeFiles/tester.dir/tester.cpp.o
[ 80%] Linking CXX executable tester
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 80%] Built target tester
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
Scanning dependencies of target aligner
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[6]: Entering directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[ 90%] Building CXX object CMakeFiles/aligner.dir/aligner.cpp.o
[100%] Linking CXX executable aligner
make[6]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
[100%] Built target aligner
make[5]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[4]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples/cmake-multiple-shared-libraries/build'
make[3]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc/examples'
make[2]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml/doc'
make[1]: Leaving directory '/home/rnsanchez/apps/lttng/lttng-ust-sebhtml'

I would think that there might be a way to FindLTTngUST.cmake to look in additional spots ?

So it would itself not have to know whether it is invoked from src tree or not, but would rather receive environment variables telling it where to look.

Solution (1) looks weird because there appears to be an error in the configure output (cannot find...), but then it succeeds afterward.

find_path() and find_library() need to know where to find the include and library files beyond the system directories.

One of the many ways to achieve this is by using the standard CMake definitions CMAKE_INCLUDE_PATH and CMAKE_LIBRARY_PATH.

This is fixed in this GH pull request.

Confirmed:

(...)
-- Found LTTngUST: /home/rnsanchez/apps/lttng/lttng-ust/liblttng-ust/.libs/liblttng-ust.so;dl (found version "2.9.0") 
-- Configuring done
-- Generating done
-- Build files have been written to: /home/rnsanchez/apps/lttng/lttng-ust/doc/examples/cmake-multiple-shared-libraries/build
(...)