延时队列

https://www.jianshu.com/p/a663e52e6488

import queue
import datetime
import threading
import functools


class DelayedTask(object):

    def __init__(self, plan_time, job_func):
        self.plan_time = plan_time  # 单位: datetime
        self.job_func = job_func  # 执行的方法,此处是简易版


def total_seconds(td):
    return (td.microseconds + (td.seconds + td.days * 24 * 3600) * 10 ** 6) / 10 ** 6


class DelayQueue(queue.PriorityQueue):
    def __init__(self, maxsize=100):
        self.can_done = threading.Condition()
        super(DelayQueue, self).__init__()

    def put_task(self, task):
        self.put((task.plan_time, task))

    def get_task(self):
        self.can_done.acquire()
        try:
            task = self._peek()
            delta = total_seconds(task.plan_time - datetime.datetime.now())
            while delta > 0:
                self.can_done.wait(delta) # 这里会挂起,挂delta秒
                task = self._peek()
                delta = total_seconds(task.plan_time - datetime.datetime.now())

            item = self.get()
            self.can_done.notify_all()
            return item[1]
        finally:
            self.can_done.release()

    def _peek(self):
        self.not_empty.acquire()
        try:
            while not self._qsize():
                self.not_empty.wait()

            return self.queue[0][1]
        finally:
            self.not_empty.release()


def hello_world(name):
    print("%s say hello world" %(name))


if __name__ == '__main__':
    task1_hello_world = functools.partial(hello_world, name="dsgdtc5秒")
    task2_hello_world = functools.partial(hello_world, name="dsgdtc1秒")
    task1 = DelayedTask(plan_time=datetime.datetime.now() + datetime.timedelta(seconds=5),
                        job_func=task1_hello_world)
    task2 = DelayedTask(plan_time=datetime.datetime.now() + datetime.timedelta(seconds=1),
                        job_func=task2_hello_world)
    delay_queue = DelayQueue()
    # 5秒的先入队列
    delay_queue.put_task(task1)
    res = delay_queue.get_task()
    res.job_func()
    # 1秒的后入队列,1秒任务需要等5秒的完成后才执行。
    # 可以根据业务场景做多个优先级队列解决，比如做3个队列
    # 分别存放1秒钟延迟任务；5秒钟延迟任务；10秒钟延迟任务。
    # 任意时间的解决方式。
    #  暂定利用redis的zset结构,(taskid, task， task_timestamp)用task_timestamp做score存入redis中，taskid是key
    #  taskid和task再放到一个bucket中
    #  然后加个轮询，只轮询score大于当前时间的key，拿到key后去bucket中找对应task
    delay_queue.put_task(task2)
    res = delay_queue.get_task()
    print(res)
    res.job_func()

---

https://blog.csdn.net/weixin_39900286/article/details/111750070

https://www.cnblogs.com/hellojesson/p/11547014.html

import sched,time
def func(a):
  print(time.time(),"Hello Sched!",a)

print(time.time())

s = sched.scheduler(time.time,time.sleep)
# 2为延后时间，1为优先级，func为函数名，("test1",)为函数参数

s.enter(1,1,func,("test1",))
s.enter(2,3,func,("test2",))
s.enter(2,0,func,("test3",))
s.enter(1,1,func,("test4",))
s.run()
print(time.time())

---

import threading,time
def func(a):
  print(time.time(),"Hello Sched!",a)

print(time.time())
s = threading.Timer(2,func,("test",))
s.start()
print(time.time())

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2022-04-01 22:00:54