Refine CMake scirpt and add doc

bolt/CMakeLists.txt

@@ -93,12 +93,21 @@ function(bolt_add_library target_name)
 
   set(SHUFFLE_COMP_LIST "shuffle")
 
-  set(EXTENSIONS_COMP_LIST "torch" "cudf" "python")
+  set(BOLT_EXTENSION_COMP_LIST "cudf" "torch" "python")
 
   if (BOLT_INTERFACE)
     add_library(${target_name} INTERFACE ${ARGN})
     return()
   endif()
+  if (BOLT_OBJECT)
+    add_library(${target_name} OBJECT ${ARGN})
+    return()
+  endif()
+
+  if(FIRST_LEVEL_DIR IN_LIST BOLT_EXTENSION_COMP_LIST)
+    add_library(${target_name} ${ARGN})
+    return()
+  endif()
 
   # OBJECT libraries are used to aggregate source files without creating a library file.
   add_library(${target_name} OBJECT ${ARGN})
@@ -148,12 +157,6 @@ function(bolt_add_library target_name)
     return()
   endif()
 
-  if(FIRST_LEVEL_DIR IN_LIST EXTENSIONS_COMP_LIST)
-    list(APPEND EXTENSIONS_OBJECT_TARGETS $<TARGET_OBJECTS:${target_name}>)
-    set(EXTENSIONS_OBJECT_TARGETS ${EXTENSIONS_OBJECT_TARGETS} CACHE INTERNAL "")
-    return()
-  endif()
-
   message(FATAL_ERROR "New component ${target_name} in ${CURRENT_RELATIVE_PATH}?")
 endfunction()
 

bolt/connectors/fuzzer/CMakeLists.txt

@@ -25,7 +25,7 @@
 # This modified file is released under the same license.
 # --------------------------------------------------------------------------
 
-bolt_add_library(bolt_fuzzer_connector OBJECT FuzzerConnector.cpp)
+bolt_add_library(bolt_fuzzer_connector FuzzerConnector.cpp)
 
 target_link_libraries(bolt_fuzzer_connector bolt_connector bolt_vector_fuzzer)
 

bolt/core/CMakeLists.txt

@@ -30,7 +30,7 @@ if(${BOLT_BUILD_TESTING})
 endif()
 
 bolt_add_library(bolt_config Config.cpp Context.cpp)
-target_link_libraries(bolt_config bolt_exception Folly::folly)
+target_link_libraries(bolt_config  Folly::folly)
 
 bolt_add_library(
   bolt_core Expressions.cpp PlanFragment.cpp PlanNode.cpp QueryConfig.cpp QueryCtx.cpp

bolt/cudf/exec/CMakeLists.txt

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-add_library(bolt_cudf_exec HashAggregation.cpp InterOp.cpp OrderBy.cpp)
+bolt_add_library(bolt_cudf_exec HashAggregation.cpp InterOp.cpp OrderBy.cpp)
 
 target_include_directories(bolt_cudf_exec PRIVATE ${cudf_INCLUDE_DIRS})
 

bolt/torch/CMakeLists.txt

@@ -13,7 +13,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-add_library(bolt_torch Compatibility.cpp Operator.cpp PlanNode.cpp Tensor.cpp Utils.cpp)
+bolt_add_library(bolt_torch Compatibility.cpp Operator.cpp PlanNode.cpp Tensor.cpp Utils.cpp)
 
 target_include_directories(
   bolt_torch

doc/do-cmake-right.md

@@ -0,0 +1,23 @@
+## Do CMake Right
+
+Please write CMake scripts in a modern style, and follow the best practices in [Effective Modern CMake](https://gist.github.com/mbinna/c61dbb39bca0e4fb7d1f73b0d66a4fd1).
+
+## Adding a new CMake target in Bolt
+
+### Adding a CMake target into Bolt engine,
+Use the `bolt_add_library` command to add CMake target. It is a wrapper of the `add_library` command(see [here](https://github.com/bytedance/bolt/issues/139).
+It will turn this target into an `OBJECT` target, and categorize and assemble it into the correct Bolt's sub-components.
+
+Take this CMake target `bolt_config` for example:
+```
+# Step 1: turn bolt_config into an OBJECT target.
+# Step 2: add bolt_config into bolt_engine sub-component according to its directory hierarchy.
+bolt_add_library(bolt_config Config.cpp Context.cpp)
+
+target_link_libraries(bolt_config PUBLIC Folly::folly)
+```
+
+## References
+- [Effective Modern CMake](https://gist.github.com/mbinna/c61dbb39bca0e4fb7d1f73b0d66a4fd1)
+- [Advanced Dependencies Model in Conan 2.0](https://www.youtube.com/watch?v=kKGglzm5ous)
+- [CMake: Public VS Private VS Interface](https://leimao.github.io/blog/CMake-Public-Private-Interface/)