topic_spider/find_source/crawler/task_queue.py

import json
import re
import time
from datetime import datetime, date
from itertools import chain

from crawler.constants import REDIS


class ExpandJsonEncoder(json.JSONEncoder):
    """
    采用json方式序列化传入的任务参数，而原生的json.dumps()方法不支持datetime、date，这里做了扩展
    """

    def default(self, obj):
        if isinstance(obj, datetime):
            return obj.strftime('%Y-%m-%d %H:%M:%S')
        elif isinstance(obj, date):
            return obj.strftime('%Y-%m-%d')
        else:
            return json.JSONEncoder.default(self, obj)


class RedisQueue:

    def __init__(self):
        self.redis = REDIS

    def get_len(self, key):
        keys = self.get_keys(key)
        # 每个键的任务数量
        key_len = [(k, self.redis.llen(k)) for k in keys]
        # 所有键的任务数量
        task_len = sum(dict(key_len).values())
        return task_len, key_len

    def get_keys(self, key):
        # Redis的键支持模式匹配
        keys = [key.decode() for key in self.redis.keys(key + '-[0-9]*')]
        # 按优先级将键降序排序
        keys = sorted(keys, key=lambda x: x.split('-')[-1], reverse=True)
        return keys

    def push_task(self, key, tasks, level=1):
        """
        双端队列，左边推进任务
        :param key: 任务队列名称
        :param tasks: 任务
        :param level: 优先级(int类型)，数值越大优先级越高，默认1
        :return: 任务队列任务数量
        """
        # 重新定义优先队列的key
        new_key = key + '-' + str(level)
        # 序列化任务参数
        tasks = [json.dumps(t, cls=ExpandJsonEncoder) for t in tasks]
        print('RedisQueue info > the number of push tasks:', len(tasks))

        if not tasks:
            return self.get_len(key)

        self.redis.lpush(new_key, *tasks)
        return self.get_len(key)

    def pop_task(self, keys=None, priority=False):
        """
        双端队列 右边弹出任务
        :param keys: 键列表，默认为None（将获取所有任务的keys）
        :param priority: 优先级
        :return:
        """
        while True:
            # 避免在while循环中修改参数，将keys参数赋值到临时变量
            temp_keys = keys

            # 不指定keys，将获取所有任务
            if not keys:
                temp_keys = self.redis.keys()
                temp_keys = list(set([re.sub('-\d+$', '', k) for k in temp_keys if re.findall('\w+-\d+$', k)]))

            # 根据key作为关键字获取所有的键
            all_keys = list(chain(*[self.get_keys(k) for k in temp_keys]))

            # 屏蔽任务差异性，只按优先级高到低弹出任务
            if priority:
                all_keys = sorted(all_keys, key=lambda x: x.split('-')[-1], reverse=True)

            if all_keys:
                _task_key, _task = self.redis.brpop(all_keys)
                return _task_key.decode(), json.loads(_task.decode())
            time.sleep(2)


# if __name__ == '__main__':
#     mrq = RedisQueue()
#
#     # 把任务推入redis 队列
#     lst = [i for i in range(0, 40)]
#     print(mrq.push_task('C', lst, level=3))
#
#     # 从redis queue取出任务
#     while True:
#         redis_key, task = mrq.pop_task(keys=['A', 'B', 'C', 'D', 'E'], priority=True)
#         print(redis_key, task)
#         time.sleep(1)
#
#     # 查看任务数量以及优先级情况
#     count, key_len = mrq.get_len('task')
#     print(key_len)