mirror of
https://github.com/donnemartin/system-design-primer.git
synced 2024-03-22 13:11:35 +08:00
73 lines
2.1 KiB
Python
73 lines
2.1 KiB
Python
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# -*- coding: utf-8 -*-
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class PagesDataStore(object):
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def __init__(self, db);
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self.db = db
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...
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def add_link_to_crawl(self, url):
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"""Add the given link to `links_to_crawl`."""
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...
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def remove_link_to_crawl(self, url):
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"""Remove the given link from `links_to_crawl`."""
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...
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def reduce_priority_link_to_crawl(self, url)
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"""Reduce the priority of a link in `links_to_crawl` to avoid cycles."""
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...
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def extract_max_priority_page(self):
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"""Return the highest priority link in `links_to_crawl`."""
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...
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def insert_crawled_link(self, url, signature):
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"""Add the given link to `crawled_links`."""
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...
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def crawled_similar(self, signature):
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"""Determine if we've already crawled a page matching the given signature"""
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...
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class Page(object):
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def __init__(self, url, contents, child_urls):
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self.url = url
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self.contents = contents
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self.child_urls = child_urls
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self.signature = self.create_signature()
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def create_signature(self):
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# Create signature based on url and contents
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...
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class Crawler(object):
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def __init__(self, pages, data_store, reverse_index_queue, doc_index_queue):
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self.pages = pages
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self.data_store = data_store
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self.reverse_index_queue = reverse_index_queue
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self.doc_index_queue = doc_index_queue
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def crawl_page(self, page):
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for url in page.child_urls:
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self.data_store.add_link_to_crawl(url)
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self.reverse_index_queue.generate(page)
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self.doc_index_queue.generate(page)
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self.data_store.remove_link_to_crawl(page.url)
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self.data_store.insert_crawled_link(page.url, page.signature)
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def crawl(self):
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while True:
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page = self.data_store.extract_max_priority_page()
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if page is None:
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break
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if self.data_store.crawled_similar(page.signature):
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self.data_store.reduce_priority_link_to_crawl(page.url)
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else:
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self.crawl_page(page)
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page = self.data_store.extract_max_priority_page()
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