class Concurrent::Utility::ProcessorCounter

def compute_processor_count
  if Concurrent.on_jruby?
    java.lang.Runtime.getRuntime.availableProcessors
  else
    os_name = RbConfig::CONFIG["target_os"]
    if os_name =~ /mingw|mswin/
      require 'win32ole'
      result = WIN32OLE.connect("winmgmts://").ExecQuery(
        "select NumberOfLogicalProcessors from Win32_Processor")
      result.to_enum.collect(&:NumberOfLogicalProcessors).reduce(:+)
    elsif File.readable?("/proc/cpuinfo") && (cpuinfo_count = IO.read("/proc/cpuinfo").scan(/^processor/).size) > 0
      cpuinfo_count
    elsif File.executable?("/usr/bin/nproc")
      IO.popen("/usr/bin/nproc --all", &:read).to_i
    elsif File.executable?("/usr/bin/hwprefs")
      IO.popen("/usr/bin/hwprefs thread_count", &:read).to_i
    elsif File.executable?("/usr/sbin/psrinfo")
      IO.popen("/usr/sbin/psrinfo", &:read).scan(/^.*on-*line/).size
    elsif File.executable?("/usr/sbin/ioscan")
      IO.popen("/usr/sbin/ioscan -kC processor", &:read).scan(/^.*processor/).size
    elsif File.executable?("/usr/sbin/pmcycles")
      IO.popen("/usr/sbin/pmcycles -m", &:read).count("\n")
    elsif File.executable?("/usr/sbin/lsdev")
      IO.popen("/usr/sbin/lsdev -Cc processor -S 1", &:read).count("\n")
    elsif File.executable?("/usr/sbin/sysconf") and os_name =~ /irix/i
      IO.popen("/usr/sbin/sysconf NPROC_ONLN", &:read).to_i
    elsif File.executable?("/usr/sbin/sysctl")
      IO.popen("/usr/sbin/sysctl -n hw.ncpu", &:read).to_i
    elsif File.executable?("/sbin/sysctl")
      IO.popen("/sbin/sysctl -n hw.ncpu", &:read).to_i
    else
      # TODO (pitr-ch 05-Nov-2016): warn about failures
      1
    end
  end
rescue
  return 1
end