# Copyright (c) 2007-2015, Evan Phoenix 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:
#
# * Redistributions of source code must retain the above copyright notice, this
#   list of conditions and the following disclaimer.
# * 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.
# * Neither the name of Rubinius nor the names of its contributors
#   may be used to endorse or promote products derived from this software
#   without specific prior written permission.
#
# 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.

#--
# Be very careful about calling raise in here! Thread has its own
# raise which, if you're calling raise, you probably don't want. Use
# Kernel.raise to call the proper raise.
#++

class Thread
  MUTEX_FOR_THREAD_EXCLUSIVE = Mutex.new

  def self.exclusive
    MUTEX_FOR_THREAD_EXCLUSIVE.synchronize { yield }
  end

  Truffle.omit("Not currently used") do
    attr_reader :recursive_objects
    attr_reader :pid

    # Implementation note: ideally, the recursive_objects
    # lookup table would be different per method call.
    # Currently it doesn't cause problems, but if ever
    # a method :foo calls a method :bar which could
    # recurse back to :foo, it could require making
    # the tables independant.

    def self.recursion_guard(obj)
      id = obj.object_id
      objects = current.recursive_objects
      objects[id] = true

      begin
        yield
      ensure
        objects.delete id
      end
    end

    def self.guarding?(obj)
      current.recursive_objects[obj.object_id]
    end

    # detect_recursion will return if there's a recursion
    # on obj (or the pair obj+paired_obj).
    # If there is one, it returns true.
    # Otherwise, it will yield once and return false.

    def self.detect_recursion(obj, paired_obj=undefined)
      id = obj.object_id
      pair_id = paired_obj.object_id
      objects = current.recursive_objects

      case objects[id]

        # Default case, we haven't seen +obj+ yet, so we add it and run the block.
      when nil
        objects[id] = pair_id
        begin
          yield
        ensure
          objects.delete id
        end

        # We've seen +obj+ before and it's got multiple paired objects associated
        # with it, so check the pair and yield if there is no recursion.
      when Rubinius::LookupTable
        return true if objects[id][pair_id]
        objects[id][pair_id] = true

        begin
          yield
        ensure
          objects[id].delete pair_id
        end

        # We've seen +obj+ with one paired object, so check the stored one for
        # recursion.
        #
        # This promotes the value to a LookupTable since there is another new paired
        # object.
      else
        previous = objects[id]
        return true if previous == pair_id

        objects[id] = Rubinius::LookupTable.new(previous => true, pair_id => true)

        begin
          yield
        ensure
          objects[id] = previous
        end
      end

      false
    end

    # Similar to detect_recursion, but will short circuit all inner recursion
    # levels (using a throw)

    class InnerRecursionDetected < Exception; end

    def self.detect_outermost_recursion(obj, paired_obj=undefined, &block)
      rec = current.recursive_objects

      if rec[:__detect_outermost_recursion__]
        if detect_recursion(obj, paired_obj, &block)
          raise InnerRecursionDetected
        end
        false
      else
        begin
          rec[:__detect_outermost_recursion__] = true

          begin
            detect_recursion(obj, paired_obj, &block)
          rescue InnerRecursionDetected
            return true
          end

          return nil
        ensure
          rec.delete :__detect_outermost_recursion__
        end
      end
    end
  end

  def randomizer
    @randomizer ||= Rubinius::Randomizer.new
  end

  Truffle.omit("Not currently used") do
    def backtrace
      mri_backtrace.map do |tup|
        code = tup[0]
        line = tup[1]
        is_block = tup[2]
        name = tup[3]

        "#{code.active_path}:#{line}:in `#{name}'"
      end
    end

    # This is a class in MRI, although you can't initialize it.
    class Backtrace
      # Stores location of a single call frame, available since Ruby 2.0.
      class Location
        attr_reader :label
        attr_reader :path
        attr_reader :absolute_path
        attr_reader :lineno

        def initialize(label, absolute_path, path, lineno)
          @label         = label
          @absolute_path = absolute_path
          @path          = path
          @lineno        = lineno
        end

        alias_method :base_label, :label

        def to_s
          "#{absolute_path}:#{lineno}:in `#{label}'"
        end

        def inspect
          to_s
        end
      end
    end
  end
end
