Python手写Request Handler Loop

类定义

class HandlerLoop(object):
    def __init__(self):
        self.thread = None
        self.queue = queue.Queue()
        self.running = True

• self.thread = None：持有线程对象的字段
• self.queue = queue.Queue()：请求队列
• self.running = True：反映“处理循环是否该继续执行”的标记字段

启动、停止处理循环

def start(self):
        self.thread = threading.Thread(target=self.serve_forever)
        self.thread.start()

    def stop(self):
        self.running = False

• start函数：创建任务执行线程，以serve_forever作为线程主函数
• stop函数：把running标记设置为False。serve_forever函数内部的while循环条件判断中会查看此字段以决定是否终止循环

向处理循环提交执行请求

def submit(self, work_func, work_args, work_kwargs):
        item = (work_func, work_args, work_kwargs)
        self.queue.put(item)

• 构造函数调用所必需的三元组，放入任务队列中

执行函数调用请求

def serve_forever(self):
        while self.running or self.queue.qsize():
            try:
                work_func, work_args, work_kwargs = self.queue.get(timeout=1)
                work_func(*work_args, **work_kwargs)
            except:
                continue

• while self.running or self.queue.qsize()：只要running标记为True，或者任务队列非空，处理循环都继续执行下去
• work_func, work_args, work_kwargs = self.queue.get(timeout=1)：从任务队列中获取函数调用的各个参数
• work_func(*work_args, **work_kwargs)：执行函数调用

完整代码如下

class HandlerLoop(object):

    def __init__(self):
        self.thread = None
        self.queue = queue.Queue()
        self.running = True

    def start(self):
        self.thread = threading.Thread(target=self.serve_forever)
        self.thread.start()

    def stop(self):
        self.running = False

    def submit(self, work_func, work_args, work_kwargs):
        item = (work_func, work_args, work_kwargs)
        self.queue.put(item)

    def serve_forever(self):
        while self.running or self.queue.qsize():
            try:
                work_func, work_args, work_kwargs = self.queue.get(timeout=1)
                work_func(*work_args, **work_kwargs)
            except:
                continue


def work_func(a, b, c):
    time.sleep(1)
    print('parameters: ', a, b, c)

    
if __name__ == '__main__':
    loop = HandlerLoop()
    loop.start()
    for i in range(6):
        loop.submit(work_func, (0, 6), {'c': 4})
    loop.stop()
    print('main thread exit')