find folly using its installed cmake config file

Summary:
Find folly using its installed CMake configuration file, and delete the
custom FindFolly.cmake file that was being used previously.  The
FindFolly.cmake file did not list all dependent libraries necessary to
link statically against folly.  Linking against folly as a shared
library is not recommended, as folly provides no binary compatibility
guarantees between changes.  folly's current CMake-based build only
builds it as a static library by default.

When building with RSOCKET_INSTALL_DEPS enabled, this also changes the
code to always build the latest version of folly (instead of pinning to
an older release), and to build folly using CMake rather than the older
autotools-based folly build which no longer exists in folly.  Note that
the build now happens as part of the `cmake` step, since folly must be
installed before we call `find_package()` to find folly.

Test Plan:
Tested building rsocket-cpp on an Ubuntu 18.04 host.  Confirmed it
worked both with an existing folly installation, as well as when using
`INSTALL_FOLLY` to have rsocket download and build folly as part of its
build steps.

.travis.yml

@@ -14,9 +14,6 @@ addons:
     packages: &common_deps
       - lcov
       # Folly dependencies
-      - autoconf
-      - autoconf-archive
-      - automake
       - binutils-dev
       - g++
       - libboost-all-dev
@@ -29,9 +26,7 @@ addons:
       - liblzma-dev
       - libsnappy-dev
       - libssl-dev
-      - libtool
       - make
-      - pkg-config
       - zlib1g-dev
 
 matrix:
@@ -82,10 +77,6 @@ env:
         eHz/lHAoLXWg/BhtgQbPmMYYKRrQaH7EKzBbqEHv6PhOk7vLMtdx5X7KmhVuFjpAMbaYoj
         zwxxH0u+VAnVB5iazzyjhySjvzkvx6pGzZtTnjLJHxKcp9633z4OU=
 
-cache:
-  directories:
-    - $HOME/folly
-
 before_script:
   # Install lcov to coveralls conversion + upload tool.
   - gem install coveralls-lcov

CMakeLists.txt

@@ -306,7 +306,9 @@ add_library(
   rsocket/transports/tcp/TcpDuplexConnection.cpp
   rsocket/transports/tcp/TcpDuplexConnection.h)
 
-target_link_libraries(ReactiveSocket yarpl ${GFLAGS_LIBRARY} ${GLOG_LIBRARY})
+target_link_libraries(ReactiveSocket
+    PUBLIC yarpl ${GFLAGS_LIBRARY} ${GLOG_LIBRARY}
+    INTERFACE ${EXTRA_LINK_FLAGS})
 
 target_compile_options(
   ReactiveSocket

cmake/InstallFolly.cmake

@@ -1,73 +1,19 @@
 if (NOT FOLLY_INSTALL_DIR)
-  set(FOLLY_INSTALL_DIR $ENV{HOME}/folly)
+  set(FOLLY_INSTALL_DIR ${CMAKE_BINARY_DIR}/folly-install)
 endif ()
 
-# Check if the correct version of folly is already installed.
-set(FOLLY_VERSION v2018.06.25.00)
-set(FOLLY_VERSION_FILE ${FOLLY_INSTALL_DIR}/${FOLLY_VERSION})
 if (RSOCKET_INSTALL_DEPS)
-  if (NOT EXISTS ${FOLLY_VERSION_FILE})
-    # Remove the old version of folly.
-    file(REMOVE_RECURSE ${FOLLY_INSTALL_DIR})
-    set(INSTALL_FOLLY True)
-  endif ()
-endif ()
-
-if (INSTALL_FOLLY)
-  # Build and install folly.
-  ExternalProject_Add(
-    folly-ext
-    GIT_REPOSITORY https://github.com/facebook/folly
-    GIT_TAG ${FOLLY_VERSION}
-    BINARY_DIR folly-ext-prefix/src/folly-ext/folly
-    CONFIGURE_COMMAND autoreconf -ivf
-      COMMAND ./configure CXX=${CMAKE_CXX_COMPILER}
-                          --prefix=${FOLLY_INSTALL_DIR}
-    BUILD_COMMAND make -j4
-    INSTALL_COMMAND make install
-      COMMAND cmake -E touch ${FOLLY_VERSION_FILE})
-
-  set(FOLLY_INCLUDE_DIR ${FOLLY_INSTALL_DIR}/include)
-  set(lib ${CMAKE_SHARED_LIBRARY_PREFIX}folly${CMAKE_SHARED_LIBRARY_SUFFIX})
-  set(benchlib ${CMAKE_SHARED_LIBRARY_PREFIX}follybenchmark${CMAKE_SHARED_LIBRARY_SUFFIX})
-  set(FOLLY_LIBRARY ${FOLLY_INSTALL_DIR}/lib/${lib})
-  set(FOLLY_BENCHMARK_LIBRARY ${FOLLY_INSTALL_DIR}/lib/${benchlib})
-
-  # CMake requires directories listed in INTERFACE_INCLUDE_DIRECTORIES to exist.
-  file(MAKE_DIRECTORY ${FOLLY_INCLUDE_DIR})
-else ()
-  # Use installed folly.
-  find_package(Folly REQUIRED)
+  execute_process(
+    COMMAND
+      ${CMAKE_SOURCE_DIR}/scripts/build_folly.sh
+      ${CMAKE_BINARY_DIR}/folly-src
+      ${FOLLY_INSTALL_DIR}
+    RESULT_VARIABLE folly_result
+  )
+  if (NOT "${folly_result}" STREQUAL "0")
+    message(FATAL_ERROR "failed to build folly")
+  endif()
 endif ()
 
 find_package(Threads)
-find_library(EVENT_LIBRARY event)
-
-add_library(folly SHARED IMPORTED)
-set_property(TARGET folly PROPERTY IMPORTED_LOCATION ${FOLLY_LIBRARY})
-set_property(TARGET folly
-  APPEND PROPERTY INTERFACE_LINK_LIBRARIES
-  ${EXTRA_LINK_FLAGS} ${EVENT_LIBRARY} ${CMAKE_THREAD_LIBS_INIT})
-if (TARGET folly-ext)
-  add_dependencies(folly folly-ext)
-endif ()
-
-add_library(folly-benchmark SHARED IMPORTED)
-set_property(TARGET folly-benchmark PROPERTY IMPORTED_LOCATION ${FOLLY_BENCHMARK_LIBRARY})
-set_property(TARGET folly-benchmark
-  APPEND PROPERTY INTERFACE_LINK_LIBRARIES
-  ${EXTRA_LINK_FLAGS} ${EVENT_LIBRARY} ${CMAKE_THREAD_LIBS_INIT})
-if (TARGET folly-ext)
-  add_dependencies(folly-benchmark folly-ext)
-endif ()
-
-# Folly includes are marked as system to prevent errors on non-standard
-# extensions when compiling with -pedantic and -Werror.
-set_property(TARGET folly
-  APPEND PROPERTY INTERFACE_SYSTEM_INCLUDE_DIRECTORIES ${FOLLY_INCLUDE_DIR})
-set_property(TARGET folly
-  APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${FOLLY_INCLUDE_DIR})
-set_property(TARGET folly-benchmark
-  APPEND PROPERTY INTERFACE_SYSTEM_INCLUDE_DIRECTORIES ${FOLLY_INCLUDE_DIR})
-set_property(TARGET folly-benchmark
-  APPEND PROPERTY INTERFACE_INCLUDE_DIRECTORIES ${FOLLY_INCLUDE_DIR})
+find_package(folly CONFIG REQUIRED PATHS ${FOLLY_INSTALL_DIR})

rsocket/benchmarks/CMakeLists.txt

@@ -1,13 +1,13 @@
 add_library(fixture Fixture.cpp Fixture.h)
-target_link_libraries(fixture ReactiveSocket folly)
+target_link_libraries(fixture ReactiveSocket Folly::folly)
 
 function(benchmark NAME FILE)
   add_executable(${NAME} ${FILE} Benchmarks.cpp)
   target_link_libraries(
     ${NAME}
     fixture
     ReactiveSocket
-    folly-benchmark
+    Folly::follybenchmark
     ${GFLAGS_LIBRARY}
     ${GLOG_LIBRARY})
 endfunction()

scripts/build_folly.sh

@@ -0,0 +1,34 @@
+#!/bin/bash
+#
+# Copyright 2004-present Facebook. All Rights Reserved.
+#
+CHECKOUT_DIR=$1
+INSTALL_DIR=$2
+if [[ -z $INSTALL_DIR ]]; then
+  echo "usage: $0 CHECKOUT_DIR INSTALL_DIR" >&2
+  exit 1
+fi
+
+# If folly was already installed, just return early
+INSTALL_MARKER_FILE="$INSTALL_DIR/folly.installed"
+if [[ -f $INSTALL_MARKER_FILE ]]; then
+  echo "folly was previously built"
+  exit 0
+fi
+
+set -e
+set -x
+
+if [[ -d "$CHECKOUT_DIR" ]]; then
+  git -C "$CHECKOUT_DIR" fetch
+  git -C "$CHECKOUT_DIR" checkout master
+else
+  git clone https://github.com/facebook/folly "$CHECKOUT_DIR"
+fi
+
+mkdir -p "$CHECKOUT_DIR/_build"
+cd "$CHECKOUT_DIR/_build"
+cmake "-DCMAKE_INSTALL_PREFIX=${INSTALL_DIR}" ..
+make -j4
+make install
+touch "$INSTALL_MARKER_FILE"

yarpl/CMakeLists.txt

@@ -119,8 +119,8 @@ message("yarpl source dir: ${CMAKE_CURRENT_SOURCE_DIR}")
 
 target_link_libraries(
   yarpl
-  folly
-  ${GLOG_LIBRARY})
+  PUBLIC Folly::folly ${GLOG_LIBRARY}
+  INTERFACE ${EXTRA_LINK_FLAGS})
 
 install(TARGETS yarpl DESTINATION lib)
 install(DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR} DESTINATION include FILES_MATCHING PATTERN "*.h")