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+# - ProcessorCount(var)
+# Determine the number of processors/cores and save value in ${var}
+#
+# Sets the variable named ${var} to the number of physical cores available on
+# the machine if the information can be determined. Otherwise it is set to 0.
+# Currently this functionality is implemented for AIX, cygwin, FreeBSD, HPUX,
+# IRIX, Linux, Mac OS X, QNX, Sun and Windows.
+#
+# This function is guaranteed to return a positive integer (>=1) if it
+# succeeds. It returns 0 if there's a problem determining the processor count.
+#
+# Example use, in a ctest -S dashboard script:
+#
+# include(ProcessorCount)
+# ProcessorCount(N)
+# if(NOT N EQUAL 0)
+# set(CTEST_BUILD_FLAGS -j${N})
+# set(ctest_test_args ${ctest_test_args} PARALLEL_LEVEL ${N})
+# endif()
+#
+# This function is intended to offer an approximation of the value of the
+# number of compute cores available on the current machine, such that you
+# may use that value for parallel building and parallel testing. It is meant
+# to help utilize as much of the machine as seems reasonable. Of course,
+# knowledge of what else might be running on the machine simultaneously
+# should be used when deciding whether to request a machine's full capacity
+# all for yourself.
+
+# A more reliable way might be to compile a small C program that uses the CPUID
+# instruction, but that again requires compiler support or compiling assembler
+# code.
+
+#=============================================================================
+# Copyright 2010-2011 Kitware, Inc.
+#
+# Distributed under the OSI-approved BSD License (the "License");
+# see accompanying file Copyright.txt for details.
+#
+# This software is distributed WITHOUT ANY WARRANTY; without even the
+# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the License for more information.
+#=============================================================================
+# (To distribute this file outside of CMake, substitute the full
+# License text for the above reference.)
+
+function(ProcessorCount var)
+ # Unknown:
+ set(count 0)
+
+ if(WIN32)
+ # Windows:
+ set(count "$ENV{NUMBER_OF_PROCESSORS}")
+ #message("ProcessorCount: WIN32, trying environment variable")
+ endif()
+
+ if(NOT count)
+ # Mac, FreeBSD, OpenBSD (systems with sysctl):
+ find_program(ProcessorCount_cmd_sysctl sysctl
+ PATHS /usr/sbin /sbin)
+ if(ProcessorCount_cmd_sysctl)
+ execute_process(COMMAND ${ProcessorCount_cmd_sysctl} -n hw.ncpu
+ ERROR_QUIET
+ OUTPUT_STRIP_TRAILING_WHITESPACE
+ OUTPUT_VARIABLE count)
+ #message("ProcessorCount: trying sysctl '${ProcessorCount_cmd_sysctl}'")
+ endif()
+ endif()
+
+ if(NOT count)
+ # Linux (systems with getconf):
+ find_program(ProcessorCount_cmd_getconf getconf)
+ if(ProcessorCount_cmd_getconf)
+ execute_process(COMMAND ${ProcessorCount_cmd_getconf} _NPROCESSORS_ONLN
+ ERROR_QUIET
+ OUTPUT_STRIP_TRAILING_WHITESPACE
+ OUTPUT_VARIABLE count)
+ #message("ProcessorCount: trying getconf '${ProcessorCount_cmd_getconf}'")
+ endif()
+ endif()
+
+ if(NOT count)
+ # HPUX (systems with machinfo):
+ find_program(ProcessorCount_cmd_machinfo machinfo
+ PATHS /usr/contrib/bin)
+ if(ProcessorCount_cmd_machinfo)
+ execute_process(COMMAND ${ProcessorCount_cmd_machinfo}
+ ERROR_QUIET
+ OUTPUT_STRIP_TRAILING_WHITESPACE
+ OUTPUT_VARIABLE machinfo_output)
+ string(REGEX MATCHALL "Number of CPUs = ([0-9]+)" procs "${machinfo_output}")
+ set(count "${CMAKE_MATCH_1}")
+ #message("ProcessorCount: trying machinfo '${ProcessorCount_cmd_machinfo}'")
+ endif()
+ endif()
+
+ if(NOT count)
+ # IRIX (systems with hinv):
+ find_program(ProcessorCount_cmd_hinv hinv
+ PATHS /sbin)
+ if(ProcessorCount_cmd_hinv)
+ execute_process(COMMAND ${ProcessorCount_cmd_hinv}
+ ERROR_QUIET
+ OUTPUT_STRIP_TRAILING_WHITESPACE
+ OUTPUT_VARIABLE hinv_output)
+ string(REGEX MATCHALL "([0-9]+) .* Processors" procs "${hinv_output}")
+ set(count "${CMAKE_MATCH_1}")
+ #message("ProcessorCount: trying hinv '${ProcessorCount_cmd_hinv}'")
+ endif()
+ endif()
+
+ if(NOT count)
+ # AIX (systems with lsconf):
+ find_program(ProcessorCount_cmd_lsconf lsconf
+ PATHS /usr/sbin)
+ if(ProcessorCount_cmd_lsconf)
+ execute_process(COMMAND ${ProcessorCount_cmd_lsconf}
+ ERROR_QUIET
+ OUTPUT_STRIP_TRAILING_WHITESPACE
+ OUTPUT_VARIABLE lsconf_output)
+ string(REGEX MATCHALL "Number Of Processors: ([0-9]+)" procs "${lsconf_output}")
+ set(count "${CMAKE_MATCH_1}")
+ #message("ProcessorCount: trying lsconf '${ProcessorCount_cmd_lsconf}'")
+ endif()
+ endif()
+
+ if(NOT count)
+ # QNX (systems with pidin):
+ find_program(ProcessorCount_cmd_pidin pidin)
+ if(ProcessorCount_cmd_pidin)
+ execute_process(COMMAND ${ProcessorCount_cmd_pidin} info
+ ERROR_QUIET
+ OUTPUT_STRIP_TRAILING_WHITESPACE
+ OUTPUT_VARIABLE pidin_output)
+ string(REGEX MATCHALL "Processor[0-9]+: " procs "${pidin_output}")
+ list(LENGTH procs count)
+ #message("ProcessorCount: trying pidin '${ProcessorCount_cmd_pidin}'")
+ endif()
+ endif()
+
+ if(NOT count)
+ # Sun (systems where uname -X emits "NumCPU" in its output):
+ find_program(ProcessorCount_cmd_uname uname)
+ if(ProcessorCount_cmd_uname)
+ execute_process(COMMAND ${ProcessorCount_cmd_uname} -X
+ ERROR_QUIET
+ OUTPUT_STRIP_TRAILING_WHITESPACE
+ OUTPUT_VARIABLE uname_X_output)
+ string(REGEX MATCHALL "NumCPU = ([0-9]+)" procs "${uname_X_output}")
+ set(count "${CMAKE_MATCH_1}")
+ #message("ProcessorCount: trying uname -X '${ProcessorCount_cmd_uname}'")
+ endif()
+ endif()
+
+ # Execute this code when all previously attempted methods return empty
+ # output:
+ #
+ if(NOT count)
+ # Systems with /proc/cpuinfo:
+ set(cpuinfo_file /proc/cpuinfo)
+ if(EXISTS "${cpuinfo_file}")
+ file(STRINGS "${cpuinfo_file}" procs REGEX "^processor.: [0-9]+$")
+ list(LENGTH procs count)
+ #message("ProcessorCount: trying cpuinfo '${cpuinfo_file}'")
+ endif()
+ endif()
+
+ # Since cygwin builds of CMake do not define WIN32 anymore, but they still
+ # run on Windows, and will still have this env var defined:
+ #
+ if(NOT count)
+ set(count "$ENV{NUMBER_OF_PROCESSORS}")
+ #message("ProcessorCount: last fallback, trying environment variable")
+ endif()
+
+ # Ensure an integer return (avoid inadvertently returning an empty string
+ # or an error string)... If it's not a decimal integer, return 0:
+ #
+ if(NOT count MATCHES "^[0-9]+$")
+ set(count 0)
+ endif()
+
+ set(${var} ${count} PARENT_SCOPE)
+endfunction()