Merged in jaesivsm/pyaggr3g470r/evol/api (pull request #6)

Evolution Arch, API and new crawler

1 files changed, 257 insertions, 0 deletions

diff --git a/pyaggr3g470r/lib/crawler.py b/pyaggr3g470r/lib/crawler.py
new file mode 100644
index 00000000..64ef8b6d
--- /dev/null
+++ b/pyaggr3g470r/lib/crawler.py
@@ -0,0 +1,257 @@
+"""
+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 requests
+import feedparser
+import dateutil.parser
+from functools import wraps
+from datetime import datetime
+from concurrent.futures import ThreadPoolExecutor
+from requests_futures.sessions import FuturesSession
+from pyaggr3g470r.lib.utils import default_handler
+
+logger = logging.getLogger(__name__)
+API_ROOT = "api/v2.0/"
+
+
+def extract_id(entry, keys=[('link', 'link'),
+                            ('published', 'retrieved_date'),
+                            ('updated', 'retrieved_date')], force_id=False):
+    """For a given entry will return a dict that allows to identify it. The
+    dict will be constructed on the uid of the entry. if that identifier is
+    absent, the dict will be constructed upon the values of "keys".
+    """
+    entry_id = entry.get('entry_id') or entry.get('id')
+    if entry_id:
+        return {'entry_id': entry_id}
+    if not entry_id and force_id:
+        entry_id = hash("".join(entry[entry_key] for _, entry_key in keys
+                                if entry_key in entry))
+    else:
+        ids = {}
+        for entry_key, pyagg_key in keys:
+            if entry_key in entry and pyagg_key not in ids:
+                ids[pyagg_key] = entry[entry_key]
+                if 'date' in pyagg_key:
+                    ids[pyagg_key] = dateutil.parser.parse(ids[pyagg_key])\
+                                                    .isoformat()
+        return ids
+
+
+class AbstractCrawler:
+    __session__ = None
+    __counter__ = 0
+
+    def __init__(self, auth):
+        self.auth = auth
+        self.session = self.get_session()
+        self.url = conf.PLATFORM_URL
+
+    @classmethod
+    def get_session(cls):
+        """methods that allows us to treat session as a singleton"""
+        if cls.__session__ is None:
+            cls.__session__ = FuturesSession(
+                    executor=ThreadPoolExecutor(max_workers=conf.NB_WORKER))
+            cls.__session__.verify = False
+        return cls.__session__
+
+    @classmethod
+    def count_on_me(cls, func):
+        """A basic decorator which will count +1 at the begining of a call
+        and -1 at the end. It kinda allows us to wait for the __counter__ value
+        to be 0, meaning nothing is done anymore."""
+        @wraps(func)
+        def wrapper(*args, **kwargs):
+            cls.__counter__ += 1
+            result = func(*args, **kwargs)
+            cls.__counter__ -= 1
+            return result
+        return wrapper
+
+    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'})
+
+    @classmethod
+    def wait(cls):
+        "See count_on_me, that method will just wait for the counter to be 0"
+        time.sleep(1)
+        while cls.__counter__:
+            time.sleep(1)
+
+
+class PyAggUpdater(AbstractCrawler):
+
+    def __init__(self, feed, entries, headers, auth):
+        self.feed = feed
+        self.entries = entries
+        self.headers = headers
+        super(PyAggUpdater, self).__init__(auth)
+
+    def to_article(self, entry):
+        "Safe method to transorm a feedparser entry into an article"
+        date = datetime.now()
+
+        for date_key in ('published', 'updated'):
+            if entry.get(date_key):
+                try:
+                    date = dateutil.parser.parse(entry[date_key])
+                except Exception:
+                    pass
+                else:
+                    break
+        content = ''
+        if entry.get('content'):
+            content = entry['content'][0]['value']
+        elif entry.get('summary'):
+            content = entry['summary']
+
+        return {'feed_id': self.feed['id'],
+                'entry_id': extract_id(entry).get('entry_id', None),
+                'link': entry.get('link', self.feed['site_link']),
+                'title': entry.get('title', 'No title'),
+                'readed': False, 'like': False,
+                'content': content,
+                'retrieved_date': date.isoformat(),
+                'date': date.isoformat()}
+
+    @AbstractCrawler.count_on_me
+    def callback(self, response):
+        """Will process the result from the challenge, creating missing article
+        and updating the feed"""
+        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:
+            entry = self.to_article(
+                    self.entries[tuple(sorted(id_to_create.items()))])
+            logger.info('creating %r - %r', entry['title'], id_to_create)
+            self.query_pyagg('post', 'article', entry)
+
+        now = datetime.now()
+        logger.debug('%r %r - updating feed etag %r last_mod %r',
+                     self.feed['id'], self.feed['title'],
+                     self.headers.get('etag'), now)
+
+        self.query_pyagg('put', 'feed/%d' % self.feed['id'], {'error_count': 0,
+                     'etag': self.headers.get('etag', ''),
+                     'last_error': '',
+                     'last_modified': self.headers.get('last-modified', '')})
+
+
+class FeedCrawler(AbstractCrawler):
+
+    def __init__(self, feed, auth):
+        self.feed = feed
+        super(FeedCrawler, self).__init__(auth)
+
+    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': ''})
+
+    @AbstractCrawler.count_on_me
+    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.warn('%r %r - an error occured while fetching feed; bumping'
+                        ' error count to %r', self.feed['id'],
+                        self.feed['title'], error_count)
+            self.query_pyagg('put', 'feed/%d' % self.feed['id'],
+                             {'error_count': error_count,
+                              'last_error': str(error)})
+            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 self.feed['etag'] and response.headers.get('etag') \
+                and response.headers.get('etag') == self.feed['etag']:
+            logger.info("%r %r - feed responded with same etag (%d)",
+                         self.feed['id'], self.feed['title'],
+                         response.status_code)
+            self.clean_feed()
+            return
+        ids, entries = [], {}
+        parsed_response = feedparser.parse(response.text)
+        for entry in parsed_response['entries']:
+            entries[tuple(sorted(extract_id(entry).items()))] = entry
+            ids.append(extract_id(entry))
+        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, self.auth)
+        future.add_done_callback(updater.callback)
+
+
+class CrawlerScheduler(AbstractCrawler):
+
+    def __init__(self, username, password):
+        self.auth = (username, password)
+        super(CrawlerScheduler, self).__init__(self.auth)
+
+    def prepare_headers(self, feed):
+        """For a known feed, will construct some header dictionnary"""
+        headers = {}
+        if feed.get('etag', None):
+            headers['If-None-Match'] = feed['etag']
+        if feed.get('last_modified'):
+            headers['If-Modified-Since'] = feed['last_modified']
+        logger.debug('%r %r - calculated headers %r',
+                     feed['id'], feed['title'], headers)
+        return headers
+
+    @AbstractCrawler.count_on_me
+    def callback(self, response):
+        """processes feeds that need to be fetched"""
+        response = response.result()
+        response.raise_for_status()
+        feeds = response.json()
+        logger.debug('%d to fetch %r', len(feeds), feeds)
+        for feed in feeds:
+            logger.info('%r %r - fetching resources',
+                        feed['id'], feed['title'])
+            future = self.session.get(feed['link'],
+                                      headers=self.prepare_headers(feed))
+            future.add_done_callback(FeedCrawler(feed, self.auth).callback)
+
+    @AbstractCrawler.count_on_me
+    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)