File size: 3,216 Bytes
63a63dd | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 | import os.path as osp
from threading import current_thread
from .utils import ThreadPool
class Feeder(ThreadPool):
"""Base class for feeder.
A thread pool of feeder threads, in charge of feeding urls to parsers.
Attributes:
thread_num (int): An integer indicating the number of threads.
global_signal (Signal): A :class:`Signal` object for communication
among all threads.
out_queue (Queue): A queue connected with parsers' inputs,
storing page urls.
session (Session): A session object.
logger (Logger): A logging.Logger object used for logging.
workers (list): A list storing all the threading.Thread objects
of the feeder.
lock (Lock): A :class:`Lock` instance shared by all feeder threads.
"""
def __init__(self, thread_num, signal, session):
"""Init Feeder with some shared variables."""
super().__init__(thread_num=thread_num, in_queue=None, name="feeder")
self.signal = signal
self.session = session
def feed(self, **kwargs):
"""Feed urls.
This method should be implemented by users.
"""
raise NotImplementedError
def worker_exec(self, **kwargs):
"""Target function of workers"""
self.feed(**kwargs)
self.logger.info(f"thread {current_thread().name} exit")
def __exit__(self):
self.logger.info("all feeder threads exited")
class UrlListFeeder(Feeder):
"""Url list feeder which feed a list of urls"""
def feed(self, url_list, offset=0, max_num=0):
if isinstance(url_list, str):
if osp.isfile(url_list):
with open(url_list) as fin:
url_list = [line.rstrip("\n") for line in fin]
else:
raise OSError(f"url list file {url_list} not found")
elif not isinstance(url_list, list):
raise TypeError('"url_list" can only be a filename or a str list')
if offset < 0 or offset >= len(url_list):
raise ValueError('"offset" exceed the list length')
else:
if max_num > 0:
end_idx = min(len(url_list), offset + max_num)
else:
end_idx = len(url_list)
for i in range(offset, end_idx):
url = url_list[i]
self.out_queue.put(url)
self.logger.debug(f"put url to url_queue: {url}")
class SimpleSEFeeder(Feeder):
"""Simple search engine like Feeder"""
def feed(self, url_template, keyword, offset, max_num, page_step):
"""Feed urls once
Args:
url_template: A string with parameters replaced with "{}".
keyword: A string indicating the searching keyword.
offset: An integer indicating the starting index.
max_num: An integer indicating the max number of images to be crawled.
page_step: An integer added to offset after each iteration.
"""
for i in range(offset, offset + max_num, page_step):
url = url_template.format(keyword, i)
self.out_queue.put(url)
self.logger.debug(f"put url to url_queue: {url}")
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