#!/usr/bin/env python3
# -*- coding:utf-8 -*-

def consumer():
  r = ''
  while True:
    n = yield r
    print("[Consumer] n = %d" %n)
    if not n:
      return
    print("[Consumer] consuming %s..." %n)
    r = '200 OK'

def produce(c):
  c.send(None)
  h = 0
  while h < 5:
    h = h + 1
    print("[Producer] producing %d..." %h)
    s = c.send(h)
    print("[Producer] consumer return: %s" %s)
  c.close()

c = consumer() #创建一个生成器
produce(c) #在该函数中，调用生成器的send()方法

"""
  1.yield 挂起当前函数.
  2.使用调度器循环
  3.使用next唤醒此函数继续执行
"""
def f1():
  for i in range(3):
    print('f1 %d'%i)
    yield
def f2():
  for i in range(5):
    print('f2 %d' %i)
    yield
def f3():
  for i in range(10):
    print('f3 %d'%i)
    yield
#模拟一个调度器
task_q = collections.deque((f1(),f2(),f3()))
#让调度器调度这些生成器们
while task_q:
  task = task_q.popleft() #弹出首个生成器
  try:
    next(task)     #执行,如果没有异常证明此生成器还没执行完成,可以继续放入队列中
    task_q.append(task) #执行完成后,把任务继续添加到队列中.
    time.sleep(0.5)
  except StopIteration as ex:
    pass