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"""
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 functools import wraps
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)})
future = 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'):
future = 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)
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