Minimal c interface

Summary

See https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/404

• Minimal C Interface
• Configuration via json files
• Renaming of many classes and functions (In order to comply with best-practices as formulated by https://google.github.io/styleguide/cppguide.html)

Integration tests are in caosdb-cppinttest!1 (merged)

Focus

• Please take a look at the c-interface functions:
  • I the naming consistent?
  • I see one problem regarding the destructors: When a client uses caosdb_connection_connection_manager_get_default_connection to get the default connection, the destructor caosdb_connection_delete_connection should not be called, because the connection object is actually owned by the ConnectionManager. Maybe, we should prevent the deletion of the wrapped connection somehow, when the connection is owned by the ConnectionManager?
• ConfigurationManager and ConnectionManager:
  • These two singletons are tightly coupled. When the ConfigurationManager is being reset, also the ConnectionManager resets. Is this a good behavior?
• There is currently no error/exception handling in the c-interface. I will add this in https://gitlab.indiscale.com/caosdb/customers/lfpb/management/-/issues/390

Test Environment

Please try and setup a client (e.g. the ccaosdbcli) with a json configuration file.

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related Issues
• Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there spezifications? Are they satisfied?

For further good practices have a look at our review guidelines.

CMakeLists.txt

@@ -20,12 +20,16 @@
 
 cmake_minimum_required(VERSION 3.14)
 
-set(libcaosdb_VERSION 0.0.4)
+set(libcaosdb_VERSION 0.0.5)
+set(libcaosdb_COMPATIBLE_SERVER_VERSION_MAJOR 0)
+set(libcaosdb_COMPATIBLE_SERVER_VERSION_MINOR 5)
+set(libcaosdb_COMPATIBLE_SERVER_VERSION_PATCH 0)
+set(libcaosdb_COMPATIBLE_SERVER_VERSION_PRE_RELEASE "GRPC${libcaosdb_VERSION}")
 
 project(libcaosdb
     VERSION ${libcaosdb_VERSION}
-    DESCRIPTION "C++ client libraries for CaosDB"
-    LANGUAGES CXX)
+    DESCRIPTION "C and C++ client libraries for CaosDB"
+    LANGUAGES CXX C)
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -100,7 +104,6 @@ foreach(i RANGE "${len_proto_files}")
         "${CMAKE_CURRENT_BINARY_DIR}/include/caosdb/${next_proto_module}.grpc.pb.h")
     list(APPEND GRPC_GENERATED_HEADERS "${next_proto_hdr}" "${next_grpc_hdr}")
     list(APPEND GRPC_GENERATED_SOURCES "${next_proto_src}" "${next_grpc_src}")
-
 endforeach()
 
 set(GRPC_GENERATED
@@ -116,28 +119,76 @@ add_custom_command(
         ${PROTO_FILES}
       DEPENDS ${PROTO_FILES})
 
+###############################################################################
+### Set up main targets
+### * [caosdb_grpc] - only in Debug builds. Otherwise this library is compiled
+###   into caosdb libraray
+### * caosdb (links to caosdb_grpc) - The main library.
+### * cxxcaosdbcli - A C++ test client.
+### * ccaosdb - A C-Wrapper of the C++ caosdb library.
+### * ccaosdbcli - A plain C test client.
+###############################################################################
 
 if("${CMAKE_BUILD_TYPE}" MATCHES "Debug")
-    add_library(caosdb_grpc STATIC ${GRPC_GENERATED})
-    add_library(caosdb STATIC ${libcaosdb_INCL} ${libcaosdb_SRC})
+  add_library(caosdb_grpc SHARED ${GRPC_GENERATED})
+  add_library(caosdb SHARED ${libcaosdb_INCL} ${libcaosdb_SRC})
     target_link_libraries(caosdb caosdb_grpc)
     set(LIBCAOSDB caosdb caosdb_grpc)
+
+    target_include_directories(caosdb_grpc PUBLIC
+        $<BUILD_INTERFACE:${libcaosdb_SOURCE_DIR}/include>
+        $<BUILD_INTERFACE:${libcaosdb_BINARY_DIR}/include>
+
+        $<INSTALL_INTERFACE:include>
+        ${CONAN_INCLUDE_DIRS}
+    )
 else()
     add_library(caosdb
-        STATIC ${libcaosdb_INCL} ${libcaosdb_SRC} ${GRPC_GENERATED})
+        SHARED ${libcaosdb_INCL} ${libcaosdb_SRC} ${GRPC_GENERATED})
     set(LIBCAOSDB caosdb)
 endif()
-add_executable(caosdbcli src/caosdbcli.cpp)
-
 target_link_libraries(caosdb
     ${CONAN_LIBS}
 )
+target_include_directories(caosdb PUBLIC
+    $<BUILD_INTERFACE:${libcaosdb_SOURCE_DIR}/include>
+    $<BUILD_INTERFACE:${libcaosdb_BINARY_DIR}/include>
+    $<INSTALL_INTERFACE:include>
+    ${CONAN_INCLUDE_DIRS}
+)
 
-target_link_libraries(caosdbcli
+add_library(ccaosdb SHARED src/ccaosdb.cpp)
+target_link_libraries(ccaosdb
     ${LIBCAOSDB}
     ${CONAN_LIBS}
 )
 
+add_executable(ccaosdbcli src/ccaosdbcli.c)
+target_include_directories(ccaosdbcli PUBLIC
+    $<BUILD_INTERFACE:${libcaosdb_SOURCE_DIR}/include>
+    $<BUILD_INTERFACE:${libcaosdb_BINARY_DIR}/include>
+    $<INSTALL_INTERFACE:include>
+    ${CONAN_INCLUDE_DIRS}
+)
+target_link_libraries(ccaosdbcli
+    ccaosdb
+    ${CONAN_LIBS}
+)
+
+add_executable(cxxcaosdbcli src/cxxcaosdbcli.cpp)
+target_include_directories(cxxcaosdbcli PUBLIC
+    $<BUILD_INTERFACE:${libcaosdb_SOURCE_DIR}/include>
+    $<BUILD_INTERFACE:${libcaosdb_BINARY_DIR}/include>
+    $<INSTALL_INTERFACE:include>
+    ${CONAN_INCLUDE_DIRS}
+)
+target_link_libraries(cxxcaosdbcli
+    ${LIBCAOSDB}
+    ${CONAN_LIBS}
+)
+
+
+
 #######################################################
 ### LINTING with CLANG-TIDY and INCLUDE-WHAT-YOU-USE
 #######################################################
@@ -165,9 +216,12 @@ if(_LINTING)
         set_target_properties(caosdb PROPERTIES
             CXX_INCLUDE_WHAT_YOU_USE "${_CMAKE_CXX_INCLUDE_WHAT_YOU_USE}"
             )
-        set_target_properties(caosdbcli PROPERTIES
+        set_target_properties(cxxcaosdbcli PROPERTIES
             CXX_INCLUDE_WHAT_YOU_USE "${_CMAKE_CXX_INCLUDE_WHAT_YOU_USE}"
             )
+        set_target_properties(ccaosdbcli PROPERTIES
+            C_INCLUDE_WHAT_YOU_USE "${_CMAKE_CXX_INCLUDE_WHAT_YOU_USE}"
+            )
     endif()
 
     find_program(clang_tidy NAMES clang-tidy clang-tidy-11)
@@ -176,7 +230,7 @@ if(_LINTING)
     else()
         message(STATUS "clang-tidy: ${clang_tidy}")
         set(_CMAKE_CXX_CLANG_TIDY_CHECKS
-            "--checks=*,-fuchsia-*,-llvm-include-order,-llvmlibc-*")
+            "--checks=*,-fuchsia-*,-llvm-include-order,-llvmlibc-*,-readability-convert-member-functions-to-static,-cppcoreguidelines-pro-bounds-array-to-pointer-decay,-hicpp-no-array-decay,-llvm-else-after-return,-readability-else-after-return")
         set(_CMAKE_CXX_CLANG_TIDY "${clang_tidy}"
             "--header-filter=caosdb/.*[^\(\.pb\.h\)]$"
             "--warnings-as-errors=*")
@@ -189,9 +243,12 @@ if(_LINTING)
         set_target_properties(caosdb PROPERTIES
             CXX_CLANG_TIDY "${_CMAKE_CXX_CLANG_TIDY};${_CMAKE_CXX_CLANG_TIDY_CHECKS}"
             )
-        set_target_properties(caosdbcli PROPERTIES
+        set_target_properties(cxxcaosdbcli PROPERTIES
             CXX_CLANG_TIDY "${_CMAKE_CXX_CLANG_TIDY};${_CMAKE_CXX_CLANG_TIDY_CHECKS}"
             )
+        set_target_properties(ccaosdbcli PROPERTIES
+            C_CLANG_TIDY "${_CMAKE_CXX_CLANG_TIDY};${_CMAKE_CXX_CLANG_TIDY_CHECKS}"
+            )
     endif()
 endif()
 
@@ -212,36 +269,10 @@ endif()
 set(libcaosdb_INCLUDE_DEST "include/caosdb")
 set(libcaosdb_LIB_DEST "lib")
 
-target_include_directories(caosdb PUBLIC
-    # headers to include when building from source
-    $<BUILD_INTERFACE:${libcaosdb_SOURCE_DIR}/include>
-    $<BUILD_INTERFACE:${libcaosdb_BINARY_DIR}/include>
-
-    # headers to include when installing  (implicitly prefixes with ${CMAKE_INSTALL_PREFIX}).
-    $<INSTALL_INTERFACE:include>
-)
-
-if("${CMAKE_BUILD_TYPE}" MATCHES "Debug")
-    target_include_directories(caosdb_grpc PUBLIC
-        # headers to include when building from source
-        $<BUILD_INTERFACE:${libcaosdb_SOURCE_DIR}/include>
-        $<BUILD_INTERFACE:${libcaosdb_BINARY_DIR}/include>
-
-        # headers to include when installing  (implicitly prefixes with ${CMAKE_INSTALL_PREFIX}).
-        $<INSTALL_INTERFACE:include>
-     )
-endif()
-
-target_include_directories(caosdbcli PUBLIC
-   ${libcaosdb_SOURCE_DIR}/include>
-   ${libcaosdb_BINARY_DIR}/include>
-   ${CONAN_INCLUDE_DIRS}
-)
-
 set(CMAKE_INSTALL_PREFIX "$ENV{HOME}/.local/")
 install(
     # targets to install
-    TARGETS ${LIBCAOSDB}
+    TARGETS ${LIBCAOSDB} ccaosdb
     # name of the CMake "export group" containing the targets we want to install
     EXPORT caosdbTargets
     # Dynamic, static library and include destination locations after running
@@ -266,9 +297,29 @@ install(
     DESTINATION ${libcaosdb_CMAKE_DEST}
 )
 
-install(FILES ${libcaosdb_INCL} DESTINATION ${libcaosdb_INCLUDE_DEST})
-install(FILES ${GRPC_GENERATED_HEADERS}
-    DESTINATION ${libcaosdb_INCLUDE_DEST}/${hw_hdrs_path})
+install(FILES ${libcaosdb_INCL} ${PROJECT_SOURCE_DIR}/include/ccaosdb.h DESTINATION ${libcaosdb_INCLUDE_DEST})
+foreach(i RANGE "${len_proto_files}")
+    list(GET PROTO_FILES ${i} next_proto_file)
+
+    # strip away the prefix path and the ".proto" suffix
+    string(REPLACE
+        "${PROJECT_SOURCE_DIR}/proto/proto/caosdb/"
+        ""
+        next_proto_module
+        "${next_proto_file}")
+    string(REPLACE
+        "/main.proto"
+        ""
+        next_proto_module
+        "${next_proto_module}")
+    set(next_proto_hdr
+        "${CMAKE_CURRENT_BINARY_DIR}/include/caosdb/${next_proto_module}/main.pb.h")
+    set(next_grpc_hdr
+        "${CMAKE_CURRENT_BINARY_DIR}/include/caosdb/${next_proto_module}/main.grpc.pb.h")
+    install(FILES ${next_proto_hdr} ${next_grpc_hdr} DESTINATION
+        ${libcaosdb_INCLUDE_DEST}/${next_proto_module})
+endforeach()
+
 install(FILES ${PROJECT_SOURCE_DIR}/caosdbConfig.cmake
     DESTINATION ${libcaosdb_CMAKE_DEST})
 
@@ -287,10 +338,13 @@ install(FILES ${PROJECT_SOURCE_DIR}/caosdbConfigVersion.cmake
 #######################################################
 option(AUTOFORMATTING "call clang-format at configure time" ON)
 if(AUTOFORMATTING)
-    file(GLOB format_test_sources test/*.cpp test/*.h)
+    file(GLOB format_test_sources test/*.cpp test/*.h test/*.h.in)
     execute_process(COMMAND clang-format -i --verbose ${libcaosdb_INCL}
         ${libcaosdb_SRC} ${libcaosdb_TEST_SRC}
-        ${PROJECT_SOURCE_DIR}/src/caosdbcli.cpp
+        ${PROJECT_SOURCE_DIR}/src/cxxcaosdbcli.cpp
+        ${PROJECT_SOURCE_DIR}/src/ccaosdbcli.c
+        ${PROJECT_SOURCE_DIR}/src/ccaosdb.cpp
+        ${PROJECT_SOURCE_DIR}/include/ccaosdb.h
         ${format_test_sources}
         WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
 endif()