cmake: add cmake Find<package>.cmake for thrift

In some cases, when using jaeger-cpp-client, we use thrift provided from
distro packages, these does not contain thriftConfig.cmake.
For such scenarios, we pivot to do not make find_package CONFIG mode as
default, instead we use basic signature[0]. We make use of
`CMAKE_MODULE_PATH` to search for FindThrift.cmake, which will find and
set all thrift::thrift's target properties.

This appends cmake/modules dir to CMAKE_MODULE_PATH, which is used
as all modules requiring find_package mode with basic_signature.

[0] https://cmake.org/cmake/help/latest/command/find_package.html
The command arguments determine which of the above modes is used. When
the basic signature is used, the command searches in Module mode first.
If the package is not found, the search falls back to Config mode.

Signed-off-by: Deepika Upadhyay <[email protected]>

CMakeLists.txt

@@ -15,6 +15,8 @@ project(opentelemetry-cpp)
 # Mark variables as used so cmake doesn't complain about them
 mark_as_advanced(CMAKE_TOOLCHAIN_FILE)
 
+list(APPEND CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake/modules/")
+
 if(DEFINED ENV{ARCH})
   # Architecture may be specified via ARCH environment variable
   set(ARCH $ENV{ARCH})
@@ -219,7 +221,7 @@ function(install_windows_deps)
 endfunction()
 
 if(WITH_JAEGER)
-  find_package(Thrift QUIET CONFIG)
+  find_package(Thrift QUIET)
   if(NOT Thrift_FOUND)
     # Install Thrift and propagate via vcpkg toolchain file
     if(WIN32 AND (NOT DEFINED CMAKE_TOOLCHAIN_FILE))

cmake/modules/FindThrift.cmake

@@ -0,0 +1,31 @@
+# This module defines Thrift_LIBRARIES, libraries to link Thrift_INCLUDE_DIR,
+# Thrift_FOUND, If false, do not try to use it.
+
+# prefer the Thrift version supplied in Thrift_HOME (cmake -DThrift_HOME then
+# environment)
+find_path(
+  Thrift_INCLUDE_DIR
+  NAMES thrift/Thrift.h
+  HINTS ${Thrift_HOME} ENV Thrift_HOME /usr/local /opt/local
+  PATH_SUFFIXES include)
+
+# prefer the Thrift version supplied in Thrift_HOME
+find_library(
+  Thrift_LIBRARIES
+  NAMES thrift libthrift
+  HINTS ${Thrift_HOME} ENV Thrift_HOME /usr/local /opt/local
+  PATH_SUFFIXES lib lib64)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Thrift DEFAULT_MSG Thrift_LIBRARIES
+                                  Thrift_INCLUDE_DIR)
+mark_as_advanced(Thrift_LIBRARIES Thrift_INCLUDE_DIR)
+
+
+if(Thrift_FOUND AND NOT (TARGET thrift::thrift))
+  add_library(thrift::thrift UNKNOWN IMPORTED)
+  set_target_properties(
+    thrift::thrift
+    PROPERTIES IMPORTED_LOCATION ${Thrift_LIBRARIES}
+	       INTERFACE_INCLUDE_DIRECTORIES ${Thrift_INCLUDE_DIR})
+endif()