ARROW-2416: [C++] Support system libprotobuf

Author: Kouhei Sutou <kou@clear-code.com>

Closes #1854 from kou/cpp-system-protobuf and squashes the following commits:

25d3d34 <Kouhei Sutou>  Support system libprotobuf

Author: kou

cpp/CMakeLists.txt

@@ -139,6 +139,10 @@ if("${CMAKE_SOURCE_DIR}" STREQUAL "${CMAKE_CURRENT_SOURCE_DIR}")
     "Use vendored Boost instead of existing Boost"
     OFF)
 
+  option(ARROW_PROTOBUF_USE_SHARED
+    "Rely on Protocol Buffers shared libraries where relevant"
+    OFF)
+
   option(ARROW_PYTHON
     "Build the Arrow CPython extensions"
     OFF)
@@ -531,6 +535,7 @@ endif(UNIX)
 # Linker and Dependencies
 ############################################################
 
+set(ARROW_LINK_LIBS)
 set(ARROW_STATIC_LINK_LIBS)
 
 if (ARROW_WITH_BROTLI)
@@ -568,8 +573,16 @@ endif()
 if (ARROW_ORC)
   SET(ARROW_STATIC_LINK_LIBS
     orc
-    protobuf
     ${ARROW_STATIC_LINK_LIBS})
+  if (ARROW_PROTOBUF_USE_SHARED)
+    SET(ARROW_LINK_LIBS
+      protobuf
+      ${ARROW_LINK_LIBS})
+  else()
+    SET(ARROW_STATIC_LINK_LIBS
+      protobuf
+      ${ARROW_STATIC_LINK_LIBS})
+  endif()
 endif()
 
 if (ARROW_STATIC_LINK_LIBS)
@@ -583,7 +596,8 @@ set(ARROW_BENCHMARK_LINK_LIBS
   ${ARROW_STATIC_LINK_LIBS})
 
 set(ARROW_LINK_LIBS
-  ${ARROW_STATIC_LINK_LIBS})
+  ${ARROW_STATIC_LINK_LIBS}
+  ${ARROW_LINK_LIBS})
 
 set(ARROW_SHARED_PRIVATE_LINK_LIBS
   ${BOOST_SYSTEM_LIBRARY}

cpp/cmake_modules/FindProtobuf.cmake

@@ -36,15 +36,23 @@ find_path (PROTOBUF_INCLUDE_DIR google/protobuf/io/coded_stream.h HINTS
   NO_DEFAULT_PATH
   PATH_SUFFIXES "include")
 
+set (lib_dirs "lib")
+if (EXISTS "${_protobuf_path}/lib64")
+  set (lib_dirs "lib64" ${lib_dirs})
+endif ()
+if (EXISTS "${_protobuf_path}/lib/${CMAKE_LIBRARY_ARCHITECTURE}")
+  set (lib_dirs "lib/${CMAKE_LIBRARY_ARCHITECTURE}" ${lib_dirs})
+endif ()
+
 find_library (PROTOBUF_LIBRARY NAMES protobuf PATHS
   ${_protobuf_path}
   NO_DEFAULT_PATH
-  PATH_SUFFIXES "lib")
+  PATH_SUFFIXES ${lib_dirs})
 
 find_library (PROTOC_LIBRARY NAMES protoc PATHS
   ${_protobuf_path}
   NO_DEFAULT_PATH
-  PATH_SUFFIXES "lib")
+  PATH_SUFFIXES ${lib_dirs})
 
 find_program(PROTOBUF_EXECUTABLE protoc HINTS
   ${_protobuf_path}
@@ -53,6 +61,8 @@ find_program(PROTOBUF_EXECUTABLE protoc HINTS
 
 if (PROTOBUF_INCLUDE_DIR AND PROTOBUF_LIBRARY AND PROTOC_LIBRARY AND PROTOBUF_EXECUTABLE)
   set (PROTOBUF_FOUND TRUE)
+  set (PROTOBUF_SHARED_LIB ${PROTOBUF_LIBRARY})
+  set (PROTOC_SHARED_LIB ${PROTOC_LIBRARY})
   get_filename_component (PROTOBUF_LIBS ${PROTOBUF_LIBRARY} PATH)
   set (PROTOBUF_LIB_NAME protobuf)
   set (PROTOC_LIB_NAME protoc)
@@ -64,7 +74,9 @@ endif ()
 
 if (PROTOBUF_FOUND)
   message (STATUS "Found the Protobuf headers: ${PROTOBUF_INCLUDE_DIR}")
+  message (STATUS "Found the Protobuf shared library: ${PROTOBUF_SHARED_LIB}")
   message (STATUS "Found the Protobuf library: ${PROTOBUF_STATIC_LIB}")
+  message (STATUS "Found the Protoc shared library: ${PROTOC_SHARED_LIB}")
   message (STATUS "Found the Protoc library: ${PROTOC_STATIC_LIB}")
   message (STATUS "Found the Protoc executable: ${PROTOBUF_EXECUTABLE}")
 else()

cpp/cmake_modules/ThirdpartyToolchain.cmake

@@ -915,8 +915,13 @@ if (ARROW_ORC)
   endif ()
 
   include_directories (SYSTEM ${PROTOBUF_INCLUDE_DIR})
-  ADD_THIRDPARTY_LIB(protobuf
-    STATIC_LIB ${PROTOBUF_STATIC_LIB})
+  if (ARROW_PROTOBUF_USE_SHARED)
+    ADD_THIRDPARTY_LIB(protobuf
+      SHARED_LIB ${PROTOBUF_LIBRARY})
+  else ()
+    ADD_THIRDPARTY_LIB(protobuf
+      STATIC_LIB ${PROTOBUF_STATIC_LIB})
+  endif ()
 
   if (PROTOBUF_VENDORED)
     add_dependencies (protobuf protobuf_ep)