#Submitter线程类实现，主要是`task_generator`调用
class SubmitterThread(threading.Thread):
  _DEFAULT_WAIT_TIMEOUT = 2 #seconds
  def __init__(self, queue, task_gen, timeout=2):
    super(SubmitterThread, self).__init__()
    self.queue = queue
    if not isinstance(timeout, int):
      _logger.error('Thread wait timeout value error: %s, '
             'use default instead.' % timeout)
      self.timeout = self._DEFAULT_WAIT_TIMEOUT
    self.timeout = timeout
    self.task_generator = task_gen

  def run(self):
    while True:
      try:
        task = self.task_generator.next()
        self.queue.put(task, True, self.timeout)
      except Queue.Full:
        _logger.debug('Task queue is full. %s wait %d second%s timeout' %
               (self.name, self.timeout, 's' if (self.timeout > 1) else ''))
        break
      except (StopIteration, ValueError) as e:
        _logger.debug('Task finished')
        break

#Worker线程实现，主要就是try块内的func调用
class WorkerThread(threading.Thread):
  _DEFAULT_WAIT_TIMEOUT = 2 #seconds
  def __init__(self, queue, timeout=2):
    super(WorkerThread, self).__init__()
    self.queue = queue
    if not isinstance(timeout, int):
      _logger.error('Thread wait timeout value error: %s, '
             'use default instead.' % timeout)
      self.timeout = self._DEFAULT_WAIT_TIMEOUT
    self.timeout = timeout

  def run(self):
    while True:
      try:
        func = self.queue.get(True, self.timeout)
      except Queue.Empty:
        _logger.debug('Task queue is empty. %s wait %d second%s timeout' %
               (self.name, self.timeout, 's' if (self.timeout > 1) else ''))
        break

      if not callable(func):
        time.sleep(1)
      try:
        func()
      except Exception as e:
        _logger.error('Thread %s running occurs error: %s' %
               (self.name, e))
        print('Thread running error: %s' % e)

class Executor(object):
  """
  The really place to execute executor
  """
  thread_list = []
  submitters = 0
  workers = 0
  queue = None
  task_generator = None
  timeout = 0
  def __init__(self, task_gen, submitters=1, workers=1 , timeout=2):
    if len(self.thread_list) != 0:
      raise RuntimeError('Executor can only instance once.')
    self.queue = Queue.Queue(maxsize=submitters * 2 + workers * 2)
    self.submitters = submitters
    self.workers = workers
    self.task_generator = task_gen
    self.timeout = timeout

  def start(self):
    for i in range(self.submitters):
      submitter = SubmitterThread(self.queue, self.task_generator, self.timeout)
      self.thread_list.append(submitter)
      submitter.setName('Submitter-%d' % i)
      submitter.setDaemon(True)
      submitter.start()
    for i in range(self.workers):
      worker = WorkerThread(self.queue, self.timeout)
      self.thread_list.append(worker)
      worker.setName('Worker-%d' % i)
      worker.setDaemon(True)
      worker.start()

  def is_alive(self):
    alive = False
    for t in self.thread_list:
      if t.isAlive():
        alive = True
        break
    return alive

  def wait_to_shutdown(self):
    _logger.debug('Start to wait to shutdown')
    for t in self.thread_list:
      t.join()
      _logger.debug('Shutdown thread : %s' % t.name)