# encoding: utf-8

# Copyright (c) 2012, HipByte SPRL and contributors
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# 1. Redistributions of source code must retain the above copyright notice, this
#    list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright notice,
#    this list of conditions and the following disclaimer in the documentation
#    and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

require 'thread'

class ParallelBuilder
  attr_accessor :files

  def initialize(objs_build_dir, builder)
    @builders_count = begin
      if jobs = ENV['jobs']
        jobs.to_i
      else
        `/usr/sbin/sysctl -n machdep.cpu.thread_count`.strip.to_i
      end
    end
    @builders_count = 1 if @builders_count < 1

    @builders = []
    @builders_count.times do
      queue = []
      th = Thread.new do
        sleep
        objs = []
        while path = queue.shift
          objs << builder.call(objs_build_dir, path)
        end
        queue.concat(objs)
      end
      @builders << [queue, th]
    end
  end

  def run
    builder_i = 0
    @files.each do |path|
      @builders[builder_i][0] << path
      builder_i += 1
      builder_i = 0 if builder_i == @builders_count
    end

    # Start build.
    @builders.each do |queue, th|
      sleep 0.01 while th.status != 'sleep'
      th.wakeup
    end
    @builders.each { |queue, th| th.join }
    @builders
  end

  def objects
    objs = []
    builder_i = 0
    @files.each do |path|
      objs << @builders[builder_i][0].shift
      builder_i += 1
      builder_i = 0 if builder_i == @builders_count
    end
    objs
  end
end