| 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}") |
|
|
