class Concurrent::Utility::ProcessorCounter

def compute_physical_processor_count: () -> Integer

def compute_physical_processor_count
  ppc = case RbConfig::CONFIG["target_os"]
        when /darwin\d\d/
          IO.popen("/usr/sbin/sysctl -n hw.physicalcpu", &:read).to_i
        when /linux/
          cores = {} # unique physical ID / core ID combinations
          phy   = 0
          IO.read("/proc/cpuinfo").scan(/^physical id.*|^core id.*/) do |ln|
            if ln.start_with?("physical")
              phy = ln[/\d+/]
            elsif ln.start_with?("core")
              cid        = phy + ":" + ln[/\d+/]
              cores[cid] = true if not cores[cid]
            end
          end
          cores.count
        when /mswin|mingw/
          require 'win32ole'
          result_set = WIN32OLE.connect("winmgmts://").ExecQuery(
            "select NumberOfCores from Win32_Processor")
          result_set.to_enum.collect(&:NumberOfCores).reduce(:+)
        else
          processor_count
        end
  # fall back to logical count if physical info is invalid
  ppc > 0 ? ppc : processor_count
rescue
  return 1
end

def compute_processor_count
  if Concurrent.on_jruby?
    java.lang.Runtime.getRuntime.availableProcessors
  else
    Etc.nprocessors
  end
end

def initialize
  @processor_count          = Delay.new { compute_processor_count }
  @physical_processor_count = Delay.new { compute_physical_processor_count }
end

def physical_processor_count: () -> Integer

def physical_processor_count
  @physical_processor_count.value
end

def processor_count
  @processor_count.value
end