# encoding: UTF-8
#
# Author:    Stefano Harding <riddopic@gmail.com>
# License:   Apache License, Version 2.0
# Copyright: (C) 2014-2015 Stefano Harding
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

require_relative 'event'
require_relative 'executor'

module Garcon

  # An executor service which runs all operations on the current thread,
  # blocking as necessary. Operations are performed in the order they are
  # received and no two operations can be performed simultaneously.
  #
  # This executor service exists mainly for testing an debugging. When used
  # it immediately runs every `#post` operation on the current thread, blocking
  # that thread until the operation is complete. This can be very beneficial
  # during testing because it makes all operations deterministic.
  #
  # @note Intended for use primarily in testing and debugging.
  class ImmediateExecutor
    include SerialExecutor

    # Creates a new executor
    def initialize
      @stopped = Garcon::Event.new
    end

    # @!macro executor_method_post
    def post(*args, &task)
      raise ArgumentError, 'no block given' unless block_given?
      return false unless running?
      task.call(*args)
      true
    end

    # @!macro executor_method_left_shift
    def <<(task)
      post(&task)
      self
    end

    # @!macro executor_method_running_question
    def running?
      ! shutdown?
    end

    # @!macro executor_method_shuttingdown_question
    def shuttingdown?
      false
    end

    # @!macro executor_method_shutdown_question
    def shutdown?
      @stopped.set?
    end

    # @!macro executor_method_shutdown
    def shutdown
      @stopped.set
      true
    end
    alias_method :kill, :shutdown

    # @!macro executor_method_wait_for_termination
    def wait_for_termination(timeout = nil)
      @stopped.wait(timeout)
    end
  end
end