gnu: Add pthreadpool.

* gnu/packages/parallel.scm (pthreadpool): New variable.
* gnu/packages/patches/pthreadpool-system-libraries.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.

gnu/local.mk

@@ -1537,6 +1537,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/pciutils-hurd-fix.patch			\
   %D%/packages/patches/plasma-framework-fix-KF5PlasmaMacros.cmake.patch \
   %D%/packages/patches/ppsspp-disable-upgrade-and-gold.patch		\
+  %D%/packages/patches/pthreadpool-system-libraries.patch	\
   %D%/packages/patches/samba-fix-fcntl-hint-detection.patch		\
   %D%/packages/patches/sdcc-disable-non-free-code.patch		\
   %D%/packages/patches/sdl-pango-api_additions.patch		\

gnu/packages/parallel.scm

@@ -9,7 +9,7 @@
 ;;; Copyright © 2017, 2018 Rutger Helling <rhelling@mykolab.com>
 ;;; Copyright © 2018–2021 Tobias Geerinckx-Rice <me@tobias.gr>
 ;;; Copyright © 2018 Clément Lassieur <clement@lassieur.org>
-;;; Copyright © 2019, 2020 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2019, 2020, 2021 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2020 Roel Janssen <roel@gnu.org>
 ;;; Copyright © 2021 Stefan Reichör <stefan@xsteve.at>
 ;;;
@@ -44,6 +44,7 @@
   #:use-module (gnu packages flex)
   #:use-module (gnu packages freeipmi)
   #:use-module (gnu packages linux)
+  #:use-module (gnu packages maths)
   #:use-module (gnu packages mpi)
   #:use-module (gnu packages perl)
   #:use-module (gnu packages pkg-config)
@@ -378,3 +379,35 @@ and output captured in the notebook.  Whatever arguments are accepted by a
 SLURM command line executable are also accepted by the corresponding magic
 command---e.g., @code{%salloc}, @code{%sbatch}, etc.")
       (license license:bsd-3))))
+
+(define-public pthreadpool
+  ;; This repository has only one tag, 0.1, which is older than what users
+  ;; such as XNNPACK expect.
+  (let ((commit "1787867f6183f056420e532eec640cba25efafea")
+        (version "0.1")
+        (revision "1"))
+    (package
+      (name "pthreadpool")
+      (version (git-version version revision commit))
+      (home-page "https://github.com/Maratyszcza/pthreadpool")
+      (source (origin
+                (method git-fetch)
+                (uri (git-reference (url home-page) (commit commit)))
+                (file-name (git-file-name name version))
+                (sha256
+                 (base32
+                  "02hdvxfn5krw8zivkgjx3b4rk9p02yr4mpdjlp75lsv6z1xf5yrx"))
+                (patches (search-patches "pthreadpool-system-libraries.patch"))))
+      (build-system cmake-build-system)
+      (arguments '(#:configure-flags '("-DBUILD_SHARED_LIBS=ON")))
+      (inputs
+       `(("googletest" ,googletest)
+         ("googlebenchmark" ,googlebenchmark)
+         ("fxdiv" ,fxdiv)))
+      (synopsis "Efficient thread pool implementation")
+      (description
+       "The pthreadpool library implements an efficient and portable thread
+pool, similar to those implemented by OpenMP run-time support libraries for
+constructs such as @code{#pragma omp parallel for}, with additional
+features.")
+      (license license:bsd-2))))

gnu/packages/patches/pthreadpool-system-libraries.patch

@@ -0,0 +1,79 @@
+This patch allows the build process to use the provided dependencies instead
+of adding their source as CMake sub-directories (in which case "make install"
+would install googletest's and googlebenchmark's libraries and headers).
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index c1cba55..627550f 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -36,7 +36,7 @@ MACRO(PTHREADPOOL_TARGET_ENABLE_CXX11 target)
+ ENDMACRO()
+ 
+ # ---[ Download deps
+-IF(NOT DEFINED FXDIV_SOURCE_DIR)
++IF(FALSE)
+   MESSAGE(STATUS "Downloading FXdiv to ${CMAKE_BINARY_DIR}/FXdiv-source (define FXDIV_SOURCE_DIR to avoid it)")
+   CONFIGURE_FILE(cmake/DownloadFXdiv.cmake "${CMAKE_BINARY_DIR}/FXdiv-download/CMakeLists.txt")
+   EXECUTE_PROCESS(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
+@@ -46,7 +46,7 @@ IF(NOT DEFINED FXDIV_SOURCE_DIR)
+   SET(FXDIV_SOURCE_DIR "${CMAKE_BINARY_DIR}/FXdiv-source" CACHE STRING "FXdiv source directory")
+ ENDIF()
+ 
+-IF(PTHREADPOOL_BUILD_TESTS AND NOT DEFINED GOOGLETEST_SOURCE_DIR)
++IF(FALSE)
+   MESSAGE(STATUS "Downloading Google Test to ${CMAKE_BINARY_DIR}/googletest-source (define GOOGLETEST_SOURCE_DIR to avoid it)")
+   CONFIGURE_FILE(cmake/DownloadGoogleTest.cmake "${CMAKE_BINARY_DIR}/googletest-download/CMakeLists.txt")
+   EXECUTE_PROCESS(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
+@@ -56,7 +56,7 @@ IF(PTHREADPOOL_BUILD_TESTS AND NOT DEFINED GOOGLETEST_SOURCE_DIR)
+   SET(GOOGLETEST_SOURCE_DIR "${CMAKE_BINARY_DIR}/googletest-source" CACHE STRING "Google Test source directory")
+ ENDIF()
+ 
+-IF(PTHREADPOOL_BUILD_BENCHMARKS AND NOT DEFINED GOOGLEBENCHMARK_SOURCE_DIR)
++IF(FALSE)
+   MESSAGE(STATUS "Downloading Google Benchmark to ${CMAKE_BINARY_DIR}/googlebenchmark-source (define GOOGLEBENCHMARK_SOURCE_DIR to avoid it)")
+   CONFIGURE_FILE(cmake/DownloadGoogleBenchmark.cmake "${CMAKE_BINARY_DIR}/googlebenchmark-download/CMakeLists.txt")
+   EXECUTE_PROCESS(COMMAND "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
+@@ -150,27 +150,18 @@ IF(CMAKE_SYSTEM_NAME STREQUAL "Linux")
+ ENDIF()
+ 
+ # ---[ Configure FXdiv
+-IF(NOT TARGET fxdiv)
++IF(FALSE)
+   SET(FXDIV_BUILD_TESTS OFF CACHE BOOL "")
+   SET(FXDIV_BUILD_BENCHMARKS OFF CACHE BOOL "")
+   ADD_SUBDIRECTORY(
+     "${FXDIV_SOURCE_DIR}"
+     "${CMAKE_BINARY_DIR}/FXdiv")
+ ENDIF()
+-TARGET_LINK_LIBRARIES(pthreadpool PRIVATE fxdiv)
+-
+ INSTALL(TARGETS pthreadpool
+   LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+   ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
+ 
+ IF(PTHREADPOOL_BUILD_TESTS)
+-  # ---[ Build google test
+-  IF(NOT TARGET gtest)
+-    SET(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+-    ADD_SUBDIRECTORY(
+-      "${GOOGLETEST_SOURCE_DIR}"
+-      "${CMAKE_BINARY_DIR}/googletest")
+-  ENDIF()
+ 
+   ADD_EXECUTABLE(pthreadpool-test test/pthreadpool.cc)
+   SET_TARGET_PROPERTIES(pthreadpool-test PROPERTIES
+@@ -188,14 +179,6 @@ IF(PTHREADPOOL_BUILD_TESTS)
+ ENDIF()
+ 
+ IF(PTHREADPOOL_BUILD_BENCHMARKS)
+-  # ---[ Build google benchmark
+-  IF(NOT TARGET benchmark)
+-    SET(BENCHMARK_ENABLE_TESTING OFF CACHE BOOL "")
+-    ADD_SUBDIRECTORY(
+-      "${GOOGLEBENCHMARK_SOURCE_DIR}"
+-      "${CMAKE_BINARY_DIR}/googlebenchmark")
+-  ENDIF()
+-
+   ADD_EXECUTABLE(latency-bench bench/latency.cc)
+   SET_TARGET_PROPERTIES(latency-bench PROPERTIES
+     CXX_STANDARD 11