CMake/Modules/FindOpenThreads.cmake

# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
# file Copyright.txt or https://cmake.org/licensing for details.

#[=======================================================================[.rst:
FindOpenThreads
---------------

OpenThreads is a C++ based threading library.  Its largest userbase
seems to OpenSceneGraph so you might notice I accept OSGDIR as an
environment path.  I consider this part of the ``Findosg*`` suite used to
find OpenSceneGraph components.  Each component is separate and you
must opt in to each module.

This module defines:

``OPENTHREADS_LIBRARY``

``OPENTHREADS_FOUND``
  if false, do not try to link to OpenThreads
``OPENTHREADS_INCLUDE_DIR``
  where to find the headers

``$OPENTHREADS_DIR`` is an environment variable that would correspond to the::

  ./configure --prefix=$OPENTHREADS_DIR

used in building osg.

.. versionadded:: 2.8.10

  The CMake variables ``OPENTHREADS_DIR`` or ``OSG_DIR`` can now
  be used as well to influence detection, instead of needing to specify
  an environment variable.
#]=======================================================================]

# Header files are presumed to be included like
# #include <OpenThreads/Thread>

# To make it easier for one-step automated configuration/builds,
# we leverage environmental paths. This is preferable
# to the -DVAR=value switches because it insulates the
# users from changes we may make in this script.
# It also offers a little more flexibility than setting
# the CMAKE_*_PATH since we can target specific components.
# However, the default CMake behavior will search system paths
# before anything else. This is problematic in the cases
# where you have an older (stable) version installed, but
# are trying to build a newer version.
# CMake doesn't offer a nice way to globally control this behavior
# so we have to do a nasty "double FIND_" in this module.
# The first FIND disables the CMAKE_ search paths and only checks
# the environmental paths.
# If nothing is found, then the second find will search the
# standard install paths.
# Explicit -DVAR=value arguments should still be able to override everything.

include(${CMAKE_CURRENT_LIST_DIR}/SelectLibraryConfigurations.cmake)

find_path(OPENTHREADS_INCLUDE_DIR OpenThreads/Thread
    HINTS
        ENV OPENTHREADS_INCLUDE_DIR
        ENV OPENTHREADS_DIR
        ENV OSG_INCLUDE_DIR
        ENV OSG_DIR
        ENV OSGDIR
        ENV OpenThreads_ROOT
        ENV OSG_ROOT
        ${OPENTHREADS_DIR}
        ${OSG_DIR}
    PATH_SUFFIXES include
)


find_library(OPENTHREADS_LIBRARY_RELEASE
    NAMES OpenThreads OpenThreadsWin32
    HINTS
        ENV OPENTHREADS_LIBRARY_DIR
        ENV OPENTHREADS_DIR
        ENV OSG_LIBRARY_DIR
        ENV OSG_DIR
        ENV OSGDIR
        ENV OpenThreads_ROOT
        ENV OSG_ROOT
        ${OPENTHREADS_DIR}
        ${OSG_DIR}
    PATH_SUFFIXES lib
)

find_library(OPENTHREADS_LIBRARY_DEBUG
    NAMES OpenThreadsd OpenThreadsWin32d
    HINTS
        ENV OPENTHREADS_DEBUG_LIBRARY_DIR
        ENV OPENTHREADS_LIBRARY_DIR
        ENV OPENTHREADS_DIR
        ENV OSG_LIBRARY_DIR
        ENV OSG_DIR
        ENV OSGDIR
        ENV OpenThreads_ROOT
        ENV OSG_ROOT
        ${OPENTHREADS_DIR}
        ${OSG_DIR}
    PATH_SUFFIXES lib
)

select_library_configurations(OPENTHREADS)

include(${CMAKE_CURRENT_LIST_DIR}/FindPackageHandleStandardArgs.cmake)
find_package_handle_standard_args(OpenThreads DEFAULT_MSG
    OPENTHREADS_LIBRARY OPENTHREADS_INCLUDE_DIR)