# Copyright (c) 2014 Boris Bera
#
# MIT License
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# Sourced from https://github.com/dotboris/reentrant_mutex

class ReentrantMutex < Mutex
  def initialize
    @count_mutex = Mutex.new
    @counts = Hash.new(0)

    super
  end

  def synchronize
    raise ThreadError, 'Must be called with a block' unless block_given?

    begin
      lock
      yield
    ensure
      unlock
    end
  end

  def lock
    c = increase_count Thread.current
    super if c <= 1
  end

  def unlock
    c = decrease_count Thread.current
    if c <= 0
      super
      delete_count Thread.current
    end
  end

  def count
    @count_mutex.synchronize { @counts[Thread.current] }
  end

  private

  def increase_count(thread)
    @count_mutex.synchronize { @counts[thread] += 1 }
  end

  def decrease_count(thread)
    @count_mutex.synchronize { @counts[thread] -= 1 }
  end

  def delete_count(thread)
    @count_mutex.synchronize { @counts.delete(thread) }
  end
end