cmake: use the old plugin infra and add support for *_FUNC registrati…

…on (#80)

The new Customizable plugin infra in CMake relies on regex parsing of
Makefiles, which is very brittle and clunky, as well as being unintuitive
for CMake users.

The only thing missing from the old infra is plugin `*_FUNC` registration,
so just add support for that to the old infra, and remove the Makefile
parsing logic.

CMakeLists.txt

@@ -909,26 +909,62 @@ list(APPEND SOURCES
   utilities/transactions/lock/range/range_tree/lib/util/dbt.cc
   utilities/transactions/lock/range/range_tree/lib/util/memarena.cc)
 
+set(ROCKSDB_PLUGIN_EXTERNS "")
+set(ROCKSDB_PLUGIN_BUILTINS "")
 message(STATUS "ROCKSDB_PLUGINS: ${ROCKSDB_PLUGINS}")
 if ( ROCKSDB_PLUGINS )
   string(REPLACE " " ";" PLUGINS ${ROCKSDB_PLUGINS})
   foreach (plugin ${PLUGINS})
-    add_subdirectory("plugin/${plugin}")
+    set(plugin_root "plugin/${plugin}/")
+    add_subdirectory(${plugin_root})
+    # Use get_directory_property() to avoid having to declare the variables
+    # with PARENT_SCOPE in the plugin CMakeLists.txt
+    # TODO: Change the plugin support here so that a plugin would simply define
+    # a target that we'll link to.
+    get_directory_property(${plugin}_SOURCES
+      DIRECTORY ${plugin_root}
+      DEFINITION ${plugin}_SOURCES)
+    get_directory_property(${plugin}_COMPILE_FLAGS
+      DIRECTORY ${plugin_root}
+      DEFINITION ${plugin}_COMPILE_FLAGS)
     foreach (src ${${plugin}_SOURCES})
-      list(APPEND SOURCES plugin/${plugin}/${src})
+      list(APPEND SOURCES ${plugin_root}/${src})
       set_source_files_properties(
-        plugin/${plugin}/${src}
+        ${plugin_root}/${src}
         PROPERTIES COMPILE_FLAGS "${${plugin}_COMPILE_FLAGS}")
     endforeach()
+    get_directory_property(${plugin}_INCLUDE_PATHS
+      DIRECTORY ${plugin_root}
+      DEFINITION ${plugin}_INCLUDE_PATHS)
     foreach (path ${${plugin}_INCLUDE_PATHS})
       include_directories(${path})
     endforeach()
+    get_directory_property(${plugin}_LIBS
+      DIRECTORY ${plugin_root}
+      DEFINITION ${plugin}_LIBS)
     foreach (lib ${${plugin}_LIBS})
       list(APPEND THIRDPARTY_LIBS ${lib})
     endforeach()
+    get_directory_property(${plugin}_LINK_PATHS
+      DIRECTORY ${plugin_root}
+      DEFINITION ${plugin}_LINK_PATHS)
     foreach (link_path ${${plugin}_LINK_PATHS})
       link_directories(AFTER ${link_path})
     endforeach()
+    get_directory_property(${plugin}_FUNC
+      DIRECTORY ${plugin_root}
+      DEFINITION ${plugin}_FUNC)
+    string(STRIP "${${plugin}_FUNC}" ${plugin}_FUNC)
+    if (NOT "${plugin}_FUNC" STREQUAL "")
+      string(APPEND ROCKSDB_PLUGIN_BUILTINS "{\"${plugin}\", ${${plugin}_FUNC} },")
+      string(APPEND ROCKSDB_PLUGIN_EXTERNS "int ${${plugin}_FUNC} (ROCKSDB_NAMESPACE::ObjectLibrary&, const std::string&); ")
+    endif()
+    get_directory_property(${plugin}_CMAKE_SHARED_LINKER_FLAGS
+      DIRECTORY ${plugin_root}
+      DEFINITION ${plugin}_CMAKE_SHARED_LINKER_FLAGS)
+    get_directory_property(${plugin}_CMAKE_EXE_LINKER_FLAGS
+      DIRECTORY ${plugin_root}
+      DEFINITION ${plugin}_CMAKE_EXE_LINKER_FLAGS)
     set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} ${${plugin}_CMAKE_SHARED_LINKER_FLAGS}")
     set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} ${${plugin}_CMAKE_EXE_LINKER_FLAGS}")
   endforeach()
@@ -997,37 +1033,6 @@ else()
   set(SYSTEM_LIBS ${CMAKE_THREAD_LIBS_INIT})
 endif()
 
-set(ROCKSDB_PLUGIN_EXTERNS "")
-set(ROCKSDB_PLUGIN_BUILTINS "")
-message(STATUS "ROCKSDB PLUGINS TO BUILD ${ROCKSDB_PLUGINS}")
-list(APPEND PLUGINS ${ROCKSDB_PLUGINS})
-foreach(PLUGIN IN LISTS PLUGINS)
-  set(PLUGIN_ROOT "${CMAKE_SOURCE_DIR}/plugin/${PLUGIN}/")
-  message("including rocksb plugin ${PLUGIN_ROOT}")
-  set(PLUGINMKFILE "${PLUGIN_ROOT}${PLUGIN}.mk")
-  if (NOT EXISTS ${PLUGINMKFILE})
-    message(FATAL_ERROR "Missing plugin makefile: ${PLUGINMKFILE}")
-  endif()
-  file(READ ${PLUGINMKFILE} PLUGINMK)
-  string(REGEX MATCH "SOURCES = ([^\n]*)" FOO ${PLUGINMK})
-  set(MK_SOURCES ${CMAKE_MATCH_1})
-  separate_arguments(MK_SOURCES)
-  foreach(MK_FILE IN LISTS MK_SOURCES)
-    list(APPEND SOURCES "${PLUGIN_ROOT}${MK_FILE}")
-  endforeach()
-  string(REGEX MATCH "_FUNC = ([^\n]*)" FOO ${PLUGINMK})
-  if (NOT ${CMAKE_MATCH_1} STREQUAL "")
-    string(APPEND ROCKSDB_PLUGIN_BUILTINS "{\"${PLUGIN}\", " ${CMAKE_MATCH_1} "},")
-    string(APPEND ROCKSDB_PLUGIN_EXTERNS "int " ${CMAKE_MATCH_1} "(ROCKSDB_NAMESPACE::ObjectLibrary&, const std::string&); ")
-  endif()
-  string(REGEX MATCH "_LIBS = ([^\n]*)" FOO ${PLUGINMK})
-  if (NOT ${CMAKE_MATCH_1} STREQUAL "")
-    list(APPEND THIRDPARTY_LIBS "${CMAKE_MATCH_1}")
-  endif()
-  message("THIRDPARTY_LIBS=${THIRDPARTY_LIBS}")
-  #TODO: We need to set any compile/link-time flags and add any link libraries
-endforeach()
-
 string(TIMESTAMP TS "%Y-%m-%d %H:%M:%S" UTC)
 set(BUILD_DATE "${TS}" CACHE STRING "the time we first built rocksdb")