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Diffstat (limited to 'src/crawler/http_crawler.py')
| -rw-r--r-- | src/crawler/http_crawler.py | 251 |
1 files changed, 251 insertions, 0 deletions
diff --git a/src/crawler/http_crawler.py b/src/crawler/http_crawler.py new file mode 100644 index 00000000..f480fe96 --- /dev/null +++ b/src/crawler/http_crawler.py @@ -0,0 +1,251 @@ +""" +Here's a sum up on how it works : + +CrawlerScheduler.run + will retreive a list of feeds to be refreshed and pass result to +CrawlerScheduler.callback + which will retreive each feed and treat result with +FeedCrawler.callback + which will interprete the result (status_code, etag) collect ids + and match them agaisnt pyagg which will cause +PyAggUpdater.callback + to create the missing entries +""" + +import time +import conf +import json +import logging +import feedparser +from datetime import datetime, timedelta +from time import strftime, gmtime +from concurrent.futures import ThreadPoolExecutor +from requests_futures.sessions import FuturesSession +from web.lib.utils import default_handler, to_hash +from web.lib.feed_utils import construct_feed_from +from web.lib.article_utils import extract_id, construct_article + +logger = logging.getLogger(__name__) +logging.captureWarnings(True) +API_ROOT = "api/v2.0/" + + +class AbstractCrawler: + + def __init__(self, auth, pool=None, session=None): + self.auth = auth + self.pool = pool or ThreadPoolExecutor(max_workers=conf.NB_WORKER) + self.session = session or FuturesSession(executor=self.pool) + self.session.verify = False + self.url = conf.PLATFORM_URL + + def query_pyagg(self, method, urn, data=None): + """A wrapper for internal call, method should be ones you can find + on requests (header, post, get, options, ...), urn the distant + resources you want to access on pyagg, and data, the data you wanna + transmit.""" + if data is None: + data = {} + method = getattr(self.session, method) + return method("%s%s%s" % (self.url, API_ROOT, urn), + auth=self.auth, data=json.dumps(data, + default=default_handler), + headers={'Content-Type': 'application/json', + 'User-Agent': conf.USER_AGENT}) + + def wait(self, max_wait=300, checks=5, wait_for=2): + checked, second_waited = 0, 0 + while True: + time.sleep(wait_for) + second_waited += wait_for + if second_waited > max_wait: + logger.warn('Exiting after %d seconds', second_waited) + break + if self.pool._work_queue.qsize(): + checked = 0 + continue + checked += 1 + if checked == checks: + break + + +class PyAggUpdater(AbstractCrawler): + + def __init__(self, feed, entries, headers, parsed_feed, + auth, pool=None, session=None): + self.feed = feed + self.entries = entries + self.headers = headers + self.parsed_feed = parsed_feed + super().__init__(auth, pool, session) + + def callback(self, response): + """Will process the result from the challenge, creating missing article + and updating the feed""" + article_created = False + if response.result().status_code != 204: + results = response.result().json() + logger.debug('%r %r - %d entries were not matched ' + 'and will be created', + self.feed['id'], self.feed['title'], len(results)) + for id_to_create in results: + article_created = True + entry = construct_article( + self.entries[tuple(sorted(id_to_create.items()))], + self.feed) + logger.info('%r %r - creating %r for %r - %r', self.feed['id'], + self.feed['title'], entry['title'], + entry['user_id'], id_to_create) + self.query_pyagg('post', 'article', entry) + + logger.debug('%r %r - updating feed etag %r last_mod %r', + self.feed['id'], self.feed['title'], + self.headers.get('etag', ''), + self.headers.get('last-modified', '')) + + up_feed = {'error_count': 0, 'last_error': None, + 'etag': self.headers.get('etag', ''), + 'last_modified': self.headers.get('last-modified', + strftime('%a, %d %b %Y %X %Z', gmtime()))} + fresh_feed = construct_feed_from(url=self.feed['link'], + fp_parsed=self.parsed_feed) + for key in ('description', 'site_link', 'icon_url'): + if fresh_feed.get(key) and fresh_feed[key] != self.feed.get(key): + up_feed[key] = fresh_feed[key] + if not self.feed.get('title'): + up_feed['title'] = fresh_feed.get('title', '') + up_feed['user_id'] = self.feed['user_id'] + # re-getting that feed earlier since new entries appeared + if article_created: + up_feed['last_retrieved'] \ + = (datetime.now() - timedelta(minutes=45)).isoformat() + + diff_keys = {key for key in up_feed + if up_feed[key] != self.feed.get(key)} + if not diff_keys: + return # no change in the feed, no update + if not article_created and diff_keys == {'last_modified', 'etag'}: + return # meaningless if no new article has been published + logger.info('%r %r - pushing feed attrs %r', + self.feed['id'], self.feed['title'], + {key: "%s -> %s" % (up_feed[key], self.feed.get(key)) + for key in up_feed if up_feed[key] != self.feed.get(key)}) + + self.query_pyagg('put', 'feed/%d' % self.feed['id'], up_feed) + + +class FeedCrawler(AbstractCrawler): + + def __init__(self, feed, auth, pool=None, session=None): + self.feed = feed + super().__init__(auth, pool, session) + + def clean_feed(self): + """Will reset the errors counters on a feed that have known errors""" + if self.feed.get('error_count') or self.feed.get('last_error'): + self.query_pyagg('put', 'feed/%d' % self.feed['id'], + {'error_count': 0, 'last_error': ''}) + + def callback(self, response): + """will fetch the feed and interprete results (304, etag) or will + challenge pyagg to compare gotten entries with existing ones""" + try: + response = response.result() + response.raise_for_status() + except Exception as error: + error_count = self.feed['error_count'] + 1 + logger.exception('%r %r - an error occured while fetching ' + 'feed; bumping error count to %r', + self.feed['id'], self.feed['title'], error_count) + future = self.query_pyagg('put', 'feed/%d' % self.feed['id'], + {'error_count': error_count, + 'last_error': str(error), + 'user_id': self.feed['user_id']}) + return + + if response.status_code == 304: + logger.info("%r %r - feed responded with 304", + self.feed['id'], self.feed['title']) + self.clean_feed() + return + if 'etag' not in response.headers: + logger.debug('%r %r - manually generating etag', + self.feed['id'], self.feed['title']) + response.headers['etag'] = 'pyagg/"%s"' % to_hash(response.text) + if response.headers['etag'] and self.feed['etag'] \ + and response.headers['etag'] == self.feed['etag']: + if 'pyagg' in self.feed['etag']: + logger.info("%r %r - calculated hash matches (%d)", + self.feed['id'], self.feed['title'], + response.status_code) + else: + logger.info("%r %r - feed responded with same etag (%d)", + self.feed['id'], self.feed['title'], + response.status_code) + self.clean_feed() + return + else: + logger.debug('%r %r - etag mismatch %r != %r', + self.feed['id'], self.feed['title'], + response.headers['etag'], self.feed['etag']) + logger.info('%r %r - cache validation failed, challenging entries', + self.feed['id'], self.feed['title']) + + ids, entries = [], {} + parsed_response = feedparser.parse(response.content) + for entry in parsed_response['entries']: + entry_ids = extract_id(entry) + entry_ids['feed_id'] = self.feed['id'] + entry_ids['user_id'] = self.feed['user_id'] + entries[tuple(sorted(entry_ids.items()))] = entry + ids.append(entry_ids) + logger.debug('%r %r - found %d entries %r', + self.feed['id'], self.feed['title'], len(ids), ids) + future = self.query_pyagg('get', 'articles/challenge', {'ids': ids}) + updater = PyAggUpdater(self.feed, entries, response.headers, + parsed_response, + self.auth, self.pool, self.session) + future.add_done_callback(updater.callback) + + +class CrawlerScheduler(AbstractCrawler): + + def __init__(self, username, password, pool=None, session=None): + self.auth = (username, password) + super(CrawlerScheduler, self).__init__(self.auth, pool, session) + + def prepare_headers(self, feed): + """For a known feed, will construct some header dictionnary""" + headers = {'User-Agent': conf.USER_AGENT} + if feed.get('last_modified'): + headers['If-Modified-Since'] = feed['last_modified'] + if feed.get('etag') and 'pyagg' not in feed['etag']: + headers['If-None-Match'] = feed['etag'] + logger.debug('%r %r - calculated headers %r', + feed['id'], feed['title'], headers) + return headers + + def callback(self, response): + """processes feeds that need to be fetched""" + response = response.result() + response.raise_for_status() + if response.status_code == 204: + logger.debug("No feed to fetch") + return + feeds = response.json() + logger.debug('%d to fetch %r', len(feeds), feeds) + for feed in feeds: + logger.debug('%r %r - fetching resources', + feed['id'], feed['title']) + future = self.session.get(feed['link'], + headers=self.prepare_headers(feed)) + + feed_crwlr = FeedCrawler(feed, self.auth, self.pool, self.session) + future.add_done_callback(feed_crwlr.callback) + + def run(self, **kwargs): + """entry point, will retreive feeds to be fetch + and launch the whole thing""" + logger.debug('retreving fetchable feed') + future = self.query_pyagg('get', 'feeds/fetchable', kwargs) + future.add_done_callback(self.callback) |