Build gflags and glog through CMake if not found in the system

This adds functionality to fetch gflags and glog from GitHub and build
them during the Caffe build. This happens only if a system-wide
installed version is not found (i.e., when find_package() fails).

If built as part of the Caffe build, gflags and glog are compiled as
position-independent static libraries. This avoids doing a system-wide
install of these libraries during the Caffe install target.

CMakeLists.txt

@@ -6,6 +6,8 @@ project(Caffe C CXX)
 # ---[ Using cmake scripts and modules
 list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake/Modules)
 
+include(ExternalProject)
+
 include(cmake/Utils.cmake)
 include(cmake/Targets.cmake)
 include(cmake/Misc.cmake)

cmake/Dependencies.cmake

@@ -11,12 +11,12 @@ find_package(Threads REQUIRED)
 list(APPEND Caffe_LINKER_LIBS ${CMAKE_THREAD_LIBS_INIT})
 
 # ---[ Google-glog
-find_package(Glog REQUIRED)
+include("cmake/External/glog.cmake")
 include_directories(SYSTEM ${GLOG_INCLUDE_DIRS})
 list(APPEND Caffe_LINKER_LIBS ${GLOG_LIBRARIES})
 
 # ---[ Google-gflags
-find_package(GFlags REQUIRED)
+include("cmake/External/gflags.cmake")
 include_directories(SYSTEM ${GFLAGS_INCLUDE_DIRS})
 list(APPEND Caffe_LINKER_LIBS ${GFLAGS_LIBRARIES})
 

cmake/External/gflags.cmake

@@ -0,0 +1,56 @@
+if (NOT __GFLAGS_INCLUDED) # guard against multiple includes
+  set(__GFLAGS_INCLUDED TRUE)
+
+  # use the system-wide gflags if present
+  find_package(GFlags)
+  if (GFLAGS_FOUND)
+    set(GFLAGS_EXTERNAL FALSE)
+  else()
+    # gflags will use pthreads if it's available in the system, so we must link with it
+    find_package(Threads)
+
+    # build directory
+    set(gflags_PREFIX ${CMAKE_BINARY_DIR}/external/gflags-prefix)
+    # install directory
+    set(gflags_INSTALL ${CMAKE_BINARY_DIR}/external/gflags-install)
+
+    # we build gflags statically, but want to link it into the caffe shared library
+    # this requires position-independent code
+    if (UNIX)
+        set(GFLAGS_EXTRA_COMPILER_FLAGS "-fPIC")
+    endif()
+
+    set(GFLAGS_CXX_FLAGS ${CMAKE_CXX_FLAGS} ${GFLAGS_EXTRA_COMPILER_FLAGS})
+    set(GFLAGS_C_FLAGS ${CMAKE_C_FLAGS} ${GFLAGS_EXTRA_COMPILER_FLAGS})
+
+    ExternalProject_Add(gflags
+      PREFIX ${gflags_PREFIX}
+      GIT_REPOSITORY "https://github.com/gflags/gflags.git"
+      GIT_TAG "v2.1.2"
+      UPDATE_COMMAND ""
+      INSTALL_DIR ${gflags_INSTALL}
+      CMAKE_ARGS -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                 -DCMAKE_INSTALL_PREFIX=${gflags_INSTALL}
+                 -DBUILD_SHARED_LIBS=OFF
+                 -DBUILD_STATIC_LIBS=ON
+                 -DBUILD_PACKAGING=OFF
+                 -DBUILD_TESTING=OFF
+                 -DBUILD_NC_TESTS=OFF
+                 -BUILD_CONFIG_TESTS=OFF
+                 -DINSTALL_HEADERS=ON
+                 -DCMAKE_C_FLAGS=${GFLAGS_C_FLAGS}
+                 -DCMAKE_CXX_FLAGS=${GFLAGS_CXX_FLAGS}
+      LOG_DOWNLOAD 1
+      LOG_INSTALL 1
+      )
+  
+    set(GFLAGS_FOUND TRUE)
+    set(GFLAGS_INCLUDE_DIRS ${gflags_INSTALL}/include)
+    set(GFLAGS_LIBRARIES ${gflags_INSTALL}/lib/libgflags.a ${CMAKE_THREAD_LIBS_INIT})    
+    set(GFLAGS_LIBRARY_DIRS ${gflags_INSTALL}/lib)
+    set(GFLAGS_EXTERNAL TRUE)
+
+    list(APPEND external_project_dependencies gflags)
+  endif()
+
+endif()

cmake/External/glog.cmake

@@ -0,0 +1,56 @@
+# glog depends on gflags
+include("cmake/External/gflags.cmake")
+
+if (NOT __GLOG_INCLUDED)
+  set(__GLOG_INCLUDED TRUE)
+
+  # try the system-wide glog first
+  find_package(Glog)
+  if (GLOG_FOUND)
+      set(GLOG_EXTERNAL FALSE)
+  else()
+    # fetch and build glog from github
+
+    # build directory
+    set(glog_PREFIX ${CMAKE_BINARY_DIR}/external/glog-prefix)
+    # install directory
+    set(glog_INSTALL ${CMAKE_BINARY_DIR}/external/glog-install)
+
+    # we build glog statically, but want to link it into the caffe shared library
+    # this requires position-independent code
+    if (UNIX)
+      set(GLOG_EXTRA_COMPILER_FLAGS "-fPIC")
+    endif()
+
+    set(GLOG_CXX_FLAGS ${CMAKE_CXX_FLAGS} ${GLOG_EXTRA_COMPILER_FLAGS})
+    set(GLOG_C_FLAGS ${CMAKE_C_FLAGS} ${GLOG_EXTRA_COMPILER_FLAGS})
+
+    # depend on gflags if we're also building it
+    if (GFLAGS_EXTERNAL)
+      set(GLOG_DEPENDS gflags)
+    endif()
+    
+    ExternalProject_Add(glog
+      DEPENDS ${GLOG_DEPENDS}
+      PREFIX ${glog_PREFIX}
+      GIT_REPOSITORY "https://github.com/google/glog"
+      GIT_TAG "v0.3.4"
+      UPDATE_COMMAND ""
+      INSTALL_DIR ${gflags_INSTALL}
+      CONFIGURE_COMMAND env "CFLAGS=${GLOG_C_FLAGS}" "CXXFLAGS=${GLOG_CXX_FLAGS}" ${glog_PREFIX}/src/glog/configure --prefix=${glog_INSTALL} --enable-shared=no --enable-static=yes --with-gflags=${GFLAGS_LIBRARY_DIRS}/..
+      LOG_DOWNLOAD 1
+      LOG_CONFIGURE 1
+      LOG_INSTALL 1
+      )
+
+    set(GLOG_FOUND TRUE)
+    set(GLOG_INCLUDE_DIRS ${glog_INSTALL}/include)
+    set(GLOG_LIBRARIES ${GFLAGS_LIBRARIES} ${glog_INSTALL}/lib/libglog.a)
+    set(GLOG_LIBRARY_DIRS ${glog_INSTALL}/lib)
+    set(GLOG_EXTERNAL TRUE)
+
+    list(APPEND external_project_dependencies glog)
+  endif()
+
+endif()
+

cmake/Targets.cmake

@@ -110,6 +110,10 @@ function(caffe_default_properties target)
     ARCHIVE_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib"
     LIBRARY_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/lib"
     RUNTIME_OUTPUT_DIRECTORY "${PROJECT_BINARY_DIR}/bin")
+  # make sure we build all external depepdencies first
+  if (DEFINED external_project_dependencies)
+    add_dependencies(${target} ${external_project_dependencies})
+  endif()
 endfunction()
 
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