# coding:utf-8
 
import Queue
import threading
import sys
import time
import math
 
 
class WorkThread(threading.Thread):
 
  def __init__(self, task_queue):
    threading.Thread.__init__(self)
    self.setDaemon(True)
    self.task_queue = task_queue
    self.start()
    self.idle = True
 
  def run(self):
    sleep_time = 0.01 # 第1次無任務可做時休息10毫秒
    multiply = 0
    while True:
      try:
        # 從隊列中取一個任務
        func, args, kwargs = self.task_queue.get(block=False)
        self.idle = False
        multiply = 0
        # 執行之
        func(*args, **kwargs)
      except Queue.Empty:
        time.sleep(sleep_time * math.pow(2, multiply))
        self.idle = True
        multiply += 1
        continue
      except:
        print sys.exc_info()
        raise
 
 
class ThreadPool:
 
  def __init__(self, thread_num=10, max_queue_len=1000):
    self.max_queue_len = max_queue_len
    self.task_queue = Queue.Queue(max_queue_len) # 任務等待隊列
    self.threads = []
    self.__create_pool(thread_num)
 
  def __create_pool(self, thread_num):
    for i in xrange(thread_num):
      thread = WorkThread(self.task_queue)
      self.threads.append(thread)
 
  def add_task(self, func, *args, **kwargs):
    '''添加一個任務，返回任務等待隊列的長度
      調用該方法前最后先調用isSafe()判斷一下等待的任務是不是很多，以防止提交的任務被拒絕
    '''
    try:
      self.task_queue.put((func, args, kwargs))
    except Queue.Full:
      raise # 隊列已滿時直接拋出異常，不給執行
    return self.task_queue.qsize()
 
  def isSafe(self):
    '''等待的任務數量離警界線還比較遠
    '''
    return self.task_queue.qsize() < 0.9 * self.max_queue_len
 
  def wait_for_complete(self):
    '''等待提交到線程池的所有任務都執行完畢
    '''
    #首先任務等待隊列要變成空
    while not self.task_queue.empty():
      time.sleep(1)
    # 其次，所以計算線程要變成idle狀態
    while True:
      all_idle = True
      for th in self.threads:
        if not th.idle:
          all_idle = False
          break
      if all_idle:
        break
      else:
        time.sleep(1)
 
 
if __name__ == '__main__':
  def foo(a, b):
    print a + b
    time.sleep(0.01)
  thread_pool = ThreadPool(10, 100)
  '''在Windows上測試不通過，Windows上Queue.Queue不是線程安全的'''
  size = 0
  for i in xrange(10000):
    try:
      size = thread_pool.add_task(foo, i, 2 * i)
    except Queue.Full:
      print 'queue full, queue size is ', size
  time.sleep(2)