Cache HTTP content using a custom Handler

Much much cleaner. Nothing comparable

README.md

@@ -119,7 +119,7 @@ Using cache and passing arguments:
 ```python
 >>> import morss
 >>> url = 'http://feeds.bbci.co.uk/news/rss.xml'
->>> cache = '/tmp/morss-cache' # cache folder, needs write permission
+>>> cache = '/tmp/morss-cache.db' # sqlite cache location
 >>> options = {'csv':True, 'md':True}
 >>> xml_string = morss.process(url, cache, options)
 >>> xml_string[:50]
@@ -130,16 +130,15 @@ Using cache and passing arguments:
 
 Doing it step-by-step:
 ```python
-import morss
+import morss, morss.crawler
 
 url = 'http://newspaper.example/feed.xml'
 options = morss.Options(csv=True, md=True) # arguments
-cache_path = '/tmp/morss-cache' # cache folder, needs write permission
+morss.crawler.sqlite_default = '/tmp/morss-cache.db' # sqlite cache location
 
-url, cache = morss.Init(url, cache_path, options) # properly create folders and objects
-rss = morss.Fetch(url, cache, options) # this only grabs the RSS feed
+rss = morss.Fetch(url, options) # this only grabs the RSS feed
 rss = morss.Before(rss, options) # applies first round of options
-rss = morss.Gather(rss, url, cache, options) # this fills the feed and cleans it up
+rss = morss.Gather(rss, url, options) # this fills the feed and cleans it up
 rss = morss.After(rss, options) # applies second round of options
 
 output = morss.Format(rss, options) # formats final feed

morss/crawler.py

@@ -1,20 +1,26 @@
+import sys
+
 import ssl
 import socket
 
 from gzip import GzipFile
-from io import BytesIO
+from io import BytesIO, StringIO
+import re
+import sqlite3
+import time
 
 try:
     from urllib2 import BaseHandler, addinfourl, parse_keqv_list, parse_http_list
+    import mimetools
 except ImportError:
     from urllib.request import BaseHandler, addinfourl, parse_keqv_list, parse_http_list
-
-import re
+    import email
 
 try:
     basestring
 except NameError:
-    basestring = str
+    basestring = unicode = str
+    buffer = memoryview
 
 
 MIMETYPE = {
@@ -186,27 +192,195 @@ class HTTPRefreshHandler(BaseHandler):
     https_response = http_response
 
 
-class EtagHandler(BaseHandler):
-    def __init__(self, cache="", etag=None, lastmodified=None):
-        self.cache = cache
-        self.etag = etag
-        self.lastmodified = lastmodified
+class NotInCache(IOError):
+    pass
+
+
+class BaseCacheHandler(BaseHandler):
+    " Cache based on etags/last-modified. Inherit from this to implement actual storage "
+
+    private_cache = False # False to behave like a CDN (or if you just don't care), True like a PC
+    handler_order = 499
+
+    def __init__(self, force_min=None):
+        self.force_min = force_min # force_min (seconds) to bypass http headers, -1 forever, 0 never, -2 do nothing if not in cache, -3 is like -2 but raises an error
+
+    def _load(self, url):
+        out = list(self.load(url))
+
+        if sys.version > '3':
+            out[2] = email.message_from_string(out[2] or unicode()) # headers
+        else:
+            out[2] = mimetools.Message(StringIO(out[2] or unicode()))
+
+        out[3] = out[3] or bytes() # data
+        out[4] = out[4] or 0 # timestamp
+
+        return out
+
+    def load(self, url):
+        " Return the basic vars (code, msg, headers, data, timestamp) "
+        return (None, None, None, None, None)
+
+    def _save(self, url, code, msg, headers, data, timestamp):
+        headers = unicode(headers)
+        self.save(url, code, msg, headers, data, timestamp)
+
+    def save(self, url, code, msg, headers, data, timestamp):
+        " Save values to disk "
+        pass
 
     def http_request(self, req):
-        if self.cache:
-            if self.etag:
-                req.add_unredirected_header('If-None-Match', self.etag)
-            if self.lastmodified:
-                req.add_unredirected_header('If-Modified-Since', self.lastmodified)
+        (code, msg, headers, data, timestamp) = self._load(req.get_full_url())
+
+        if 'etag' in headers:
+            req.add_unredirected_header('If-None-Match', headers['etag'])
+
+        if 'last-modified' in headers:
+            req.add_unredirected_header('If-Modified-Since', headers.get('last-modified'))
 
         return req
 
+    def http_open(self, req):
+        (code, msg, headers, data, timestamp) = self._load(req.get_full_url())
+
+        # some info needed to process everything
+        cache_control = parse_http_list(headers.get('cache-control', ()))
+        cache_control += parse_http_list(headers.get('pragma', ()))
+
+        cc_list = [x for x in cache_control if '=' not in x]
+        cc_values = parse_keqv_list([x for x in cache_control if '=' in x])
+
+        cache_age = time.time() - timestamp
+
+        # list in a simple way what to do when
+        if self.force_min in (-2, -3):
+            if code is not None:
+                # already in cache, perfect, use cache
+                pass
+
+            else:
+                # ok then...
+                if self.force_min == -2:
+                    headers['morss'] = 'from_cache'
+                    resp = addinfourl(BytesIO(), headers, req.get_full_url(), 409)
+                    resp.msg = 'Conflict'
+                    return resp
+
+                elif self.force_min == -3:
+                    raise NotInCache()
+
+        elif code is None:
+            # cache empty, refresh
+            return None
+
+        elif self.force_min == -1:
+            # force use cache
+            pass
+
+        elif self.force_min == 0:
+            # force refresh
+            return None
+
+        elif  self.force_min is None and ('no-cache' in cc_list
+                                        or 'no-store' in cc_list
+                                        or ('private' in cc_list and not self.private)):
+            # kindly follow web servers indications, refresh
+            return None
+
+        elif 'max-age' in cc_values and int(cc_values['max-age']) > cache_age:
+            # server says it's still fine (and we trust him, if not, use force_min=0), use cache
+            pass
+
+        elif self.force_min is not None and self.force_min > cache_age:
+            # still recent enough for us, use cache
+            pass
+
+        else:
+            # according to the www, we have to refresh when nothing is said
+            return None
+
+        # return the cache as a response
+        headers['morss'] = 'from_cache' # TODO delete the morss header from incoming pages, to avoid websites messing up with us
+        resp = addinfourl(BytesIO(data), headers, req.get_full_url(), code)
+        resp.msg = msg
+
+        return resp
+
+    def http_response(self, req, resp):
+        # code for after-fetch, to know whether to save to hard-drive (if stiking to http headers' will)
+
+        if resp.code == 304:
+            return resp
+
+        if ('cache-control' in resp.headers or 'pragma' in resp.headers) and self.force_min is None:
+            cache_control = parse_http_list(resp.headers.get('cache-control', ()))
+            cache_control += parse_http_list(resp.headers.get('pragma', ()))
+
+            cc_list = [x for x in cache_control if '=' not in x]
+
+            if 'no-cache' in cc_list or 'no-store' in cc_list or ('private' in cc_list and not self.private):
+                # kindly follow web servers indications
+                return resp
+
+        if resp.headers.get('morss') == 'from_cache':
+            # it comes from cache, so no need to save it again
+            return resp
+
+        # save to disk
+        data = resp.read()
+        self._save(req.get_full_url(), resp.code, resp.msg, resp.headers, data, time.time())
+
+        fp = BytesIO(data)
+        old_resp = resp
+        resp = addinfourl(fp, old_resp.headers, old_resp.url, old_resp.code)
+        resp.msg = old_resp.msg
+
+        return resp
+
     def http_error_304(self, req, fp, code, msg, headers):
-        if self.etag:
-            headers.addheader('etag', self.etag)
-        if self.lastmodified:
-            headers.addheader('last-modified', self.lastmodified)
-        resp = addinfourl(BytesIO(self.cache), headers, req.get_full_url(), 200)
+        (code, msg, headers, data, timestamp) = self._load(req.get_full_url())
+
+        resp = addinfourl(BytesIO(data), headers, req.get_full_url(), code)
+        resp.msg = msg
+
         return resp
 
     https_request = http_request
+    https_open = http_open
+    https_response = http_response
+
+
+sqlite_default = ':memory'
+
+
+class SQliteCacheHandler(BaseCacheHandler):
+    def __init__(self, force_min=-1, filename=None):
+        BaseCacheHandler.__init__(self, force_min)
+
+        self.con = sqlite3.connect(filename or sqlite_default, detect_types=sqlite3.PARSE_DECLTYPES, check_same_thread=False)
+        self.con.execute('create table if not exists data (url unicode PRIMARY KEY, code int, msg unicode, headers unicode, data bytes, timestamp int)')
+        self.con.commit()
+
+    def __del__(self):
+        self.con.close()
+
+    def load(self, url):
+        row = self.con.execute('select * from data where url=?', (url,)).fetchone()
+
+        if not row:
+            return (None, None, None, None, None)
+
+        return row[1:]
+
+    def save(self, url, code, msg, headers, data, timestamp):
+        data = buffer(data)
+
+        if self.con.execute('select code from data where url=?', (url,)).fetchone():
+            self.con.execute('update data set code=?, msg=?, headers=?, data=?, timestamp=? where url=?',
+                (code, msg, headers, data, timestamp, url))
+
+        else:
+            self.con.execute('insert into data values (?,?,?,?,?,?)', (url, code, msg, headers, data, timestamp))
+
+        self.con.commit()

morss/feedify.py

@@ -94,20 +94,20 @@ def format_string(string, getter, error=False):
         return out
 
 
-def pre_worker(url, cache):
+def pre_worker(url):
     if urlparse(url).netloc == 'itunes.apple.com':
         match = re.search('/id([0-9]+)(\?.*)?$', url)
         if match:
             iid = match.groups()[0]
             redirect = 'https://itunes.apple.com/lookup?id={id}'.format(id=iid)
-            cache.set('redirect', redirect)
+            return redirect
+
+    return None
 
 
 class Builder(object):
-    def __init__(self, link, data=None, cache=False):
+    def __init__(self, link, data=None):
         self.link = link
-        self.cache = cache
-
         self.data = data
 
         if self.data is None:

morss/morss.py

@@ -140,112 +140,16 @@ def parseOptions(options):
     return out
 
 
-class Cache:
-    """ Light, error-prone caching system. """
-
-    def __init__(self, folder=None, key='cache', lifespan=10 * 24 * 3600):
-        self._key = key
-        self._dir = folder
-        self._lifespan = lifespan
-
-        self._cache = {}
-
-        if self._dir is None:
-            self._hash = "NO CACHE"
-            return
-
-        maxsize = os.statvfs('./').f_namemax - len(self._dir) - 1 - 4  # ".tmp"
-        self._hash = quote_plus(self._key)[:maxsize]
-
-        self._file = self._dir + '/' + self._hash
-        self._file_tmp = self._file + '.tmp'
-
-        try:
-            data = open(self._file).read()
-            if data:
-                self._cache = json.loads(data)
-        except IOError:
-            pass
-        except ValueError:
-            log('JSON cache parse fail')
-
-    def __del__(self):
-        self.save()
-
-    def __contains__(self, key):
-        return key in self._cache
-
-    def get(self, key):
-        if key in self._cache:
-            self._cache[key]['last'] = time.time()
-            return self._cache[key]['value']
-        else:
-            return None
-
-    def set(self, key, content):
-        if sys.version > '3' and isinstance(content, bytes):
-            content = content.decode('utf-8')
-
-        self._cache[key] = {'last': time.time(), 'value': content}
-
-    __getitem__ = get
-    __setitem__ = set
-
-    def save(self):
-        if len(self._cache) == 0 or self._dir is None:
-            return
-
-        if not os.path.exists(self._dir):
-            os.makedirs(self._dir)
-
-        for i in list(self._cache.keys()):
-            if time.time() - self._cache[i]['last'] > self._lifespan > -1:
-                del self._cache[i]
-
-        out = json.dumps(self._cache, indent=4)
-
-        try:
-            open(self._file_tmp, 'w+').write(out)
-            os.rename(self._file_tmp, self._file)
-        except IOError:
-            log('failed to write cache to tmp file')
-        except OSError:
-            log('failed to move cache to file')
-
-    def last(self, key):
-        if key not in self._cache:
-            return -1
-
-        return self._cache[key]['last']
-
-    def age(self, key):
-        if key not in self._cache:
-            return -1
-
-        return time.time() - self.last(key)
-
-    def new(self, *arg, **karg):
-        """ Returns a Cache object in the same directory """
-        if arg[0] != self._key:
-            return Cache(self._dir, *arg, **karg)
-        else:
-            return self
-
-
 default_handlers = [crawler.GZIPHandler(), crawler.UAHandler(DEFAULT_UA),
                     crawler.AutoRefererHandler(), crawler.HTTPEquivHandler(),
                     crawler.HTTPRefreshHandler(), crawler.EncodingFixHandler()]
 
-def accept_handler(*kargs):
+def custom_handler(accept, delay=DELAY):
     handlers = default_handlers[:]
-    handlers.append(crawler.ContentNegociationHandler(*kargs))
-    return handlers
+    handlers.append(crawler.ContentNegociationHandler(accept))
+    handlers.append(crawler.SQliteCacheHandler(delay))
 
-def etag_handler(accept, strict, cache, etag, lastmodified):
-    handlers = default_handlers[:]
-    handlers.append(crawler.ContentNegociationHandler(accept, strict))
-    handlers.append(crawler.EtagHandler(cache, etag, lastmodified))
-    return handlers
+    return build_opener(*handlers)
 
 
 def Fix(item, feedurl='/'):
@@ -315,7 +219,7 @@ def Fix(item, feedurl='/'):
     return item
 
 
-def Fill(item, cache, options, feedurl='/', fast=False):
+def Fill(item, options, feedurl='/', fast=False):
     """ Returns True when it has done its best """
 
     if not item.link:
@@ -364,58 +268,44 @@ def Fill(item, cache, options, feedurl='/', fast=False):
         log('no used link')
         return True
 
-    # check cache and previous errors
-    if link in cache:
-        content = cache.get(link)
-        match = re.search(r'^error-([a-z]{2,10})$', content)
-        if match:
-            if cache.age(link) < DELAY and not options.theforce:
-                log('cached error: %s' % match.groups()[0])
-                return True
-            else:
-                log('ignored old error: %s' % match.groups()[0])
-        else:
-            log('cached')
-            item.push_content(cache.get(link))
-            return True
+    # download
+    delay = -1
 
-    # super-fast mode
     if fast:
+        # super-fast mode
+        delay = -3
+
+    try:
+        con = custom_handler(('html', 'text/*'), delay).open(link, timeout=TIMEOUT)
+        data = con.read()
+
+    except crawler.NotInCache:
         log('skipped')
         return False
 
-    # download
-    try:
-        con = build_opener(*accept_handler(('html', 'text/*'), True)).open(link, timeout=TIMEOUT)
-        data = con.read()
     except (IOError, HTTPException) as e:
-        log('http error:  %s' % e.message)
-        cache.set(link, 'error-http')
+        log('http error')
         return True
 
     contenttype = con.info().get('Content-Type', '').split(';')[0]
     if contenttype not in MIMETYPE['html'] and contenttype != 'text/plain':
         log('non-text page')
-        cache.set(link, 'error-type')
         return True
 
     out = breadability.readable.Article(data, url=con.url).readable
 
     if options.hungry or count_words(out) > max(count_content, count_desc):
         item.push_content(out)
-        cache.set(link, out)
+
     else:
         log('link not bigger enough')
-        cache.set(link, 'error-length')
         return True
 
     return True
 
 
-def Init(url, cache_path, options):
-    # url clean up
-    log(url)
-
+def Fetch(url, options):
+    # basic url clean-up
     if url is None:
         raise MorssException('No url provided')
 
@@ -428,91 +318,66 @@ def Init(url, cache_path, options):
     if isinstance(url, bytes):
         url = url.decode()
 
-    # cache
-    cache = Cache(cache_path, url)
-    log(cache._hash)
-
-    return (url, cache)
-
-
-def Fetch(url, cache, options):
     # do some useful facebook work
-    feedify.pre_worker(url, cache)
-
-    if 'redirect' in cache:
-        url = cache.get('redirect')
+    pre = feedify.pre_worker(url)
+    if pre:
+        url = pre
         log('url redirect')
         log(url)
 
     # fetch feed
-    if not options.theforce and 'xml' in cache and cache.age('xml') < DELAY and 'style' in cache:
-        log('xml cached')
-        xml = cache.get('xml')
-        style = cache.get('style')
-    else:
-        try:
-            opener = etag_handler(('xml', 'html'), False, cache.get(url), cache.get('etag'), cache.get('lastmodified'))
-            con = build_opener(*opener).open(url, timeout=TIMEOUT * 2)
-            xml = con.read()
-        except (HTTPError) as e:
-            raise MorssException('Error downloading feed (HTTP Error %s)' % e.code)
-        except (crawler.InvalidCertificateException) as e:
-            raise MorssException('Error downloading feed (Invalid SSL Certificate)')
-        except (IOError, HTTPException):
-            raise MorssException('Error downloading feed')
+    delay = DELAY
 
-        cache.set('xml', xml)
-        cache.set('etag', con.info().get('etag'))
-        cache.set('lastmodified', con.info().get('last-modified'))
+    if options.theforce:
+        delay = 0
 
-        contenttype = con.info().get('Content-Type', '').split(';')[0]
+    try:
+        con = custom_handler(('xml', 'html'), delay).open(url, timeout=TIMEOUT * 2)
+        xml = con.read()
 
-        if url.startswith('https://itunes.apple.com/lookup?id='):
-            style = 'itunes'
-        elif xml.startswith(b'<?xml') or contenttype in MIMETYPE['xml']:
-            style = 'normal'
-        elif feedify.supported(url):
-            style = 'feedify'
-        elif contenttype in MIMETYPE['html']:
-            style = 'html'
-        else:
-            style = 'none'
-            log(contenttype)
+    except (HTTPError) as e:
+        raise MorssException('Error downloading feed (HTTP Error %s)' % e.code)
 
-        cache.set('style', style)
+    except (crawler.InvalidCertificateException) as e:
+        raise MorssException('Error downloading feed (Invalid SSL Certificate)')
 
-    # decide what to do
-    log(style)
+    except (IOError, HTTPException):
+        raise MorssException('Error downloading feed')
 
-    if style == 'itunes':
-        link = json.loads(xml)['results'][0]['feedUrl']
+    contenttype = con.info().get('Content-Type', '').split(';')[0]
+
+    if url.startswith('https://itunes.apple.com/lookup?id='):
+        link = json.loads(xml.decode('utf-8', 'replace'))['results'][0]['feedUrl']
         log('itunes redirect: %s' % link)
-        return Fetch(link, cache.new(link), options)
-    elif style == 'normal':
+        return Fetch(link, options)
+
+    elif xml.startswith(b'<?xml') or contenttype in MIMETYPE['xml']:
         rss = feeds.parse(xml)
-    elif style == 'feedify':
-        feed = feedify.Builder(url, xml, cache)
+
+    elif feedify.supported(url):
+        feed = feedify.Builder(url, xml)
         feed.build()
         rss = feed.feed
-    elif style == 'html':
+
+    elif contenttype in MIMETYPE['html']:
         match = lxml.html.fromstring(xml).xpath(
             "//link[@rel='alternate'][@type='application/rss+xml' or @type='application/atom+xml']/@href")
         if len(match):
             link = urljoin(url, match[0])
             log('rss redirect: %s' % link)
-            return Fetch(link, cache.new(link), options)
+            return Fetch(link, options)
         else:
             log('no-link html')
             raise MorssException('Link provided is an HTML page, which doesn\'t link to a feed')
     else:
         log('random page')
+        log(contenttype)
         raise MorssException('Link provided is not a valid feed')
 
-    cache.save()
     return rss
 
 
-def Gather(rss, url, cache, options):
+def Gather(rss, url, options):
     size = len(rss.items)
     start_time = time.time()
 
@@ -549,12 +414,12 @@ def Gather(rss, url, cache, options):
 
         if time.time() - start_time > max_time >= 0 or i + 1 > max_item >= 0:
             if not options.proxy:
-                if Fill(item, cache, options, url, True) is False:
+                if Fill(item, options, url, True) is False:
                     item.remove()
                     return
         else:
             if not options.proxy:
-                Fill(item, cache, options, url)
+                Fill(item, options, url)
 
     queue = Queue()
 
@@ -567,7 +432,6 @@ def Gather(rss, url, cache, options):
         queue.put([i, item])
 
     queue.join()
-    cache.save()
 
     if options.ad:
         new = rss.items.append()
@@ -663,10 +527,10 @@ def process(url, cache=None, options=None):
         options = []
 
     options = Options(options)
-    url, cache = Init(url, cache, options)
-    rss = Fetch(url, cache, options)
+    if cache: crawler.sqlite_default = cache
+    rss = Fetch(url, options)
     rss = Before(rss, options)
-    rss = Gather(rss, url, cache, options)
+    rss = Gather(rss, url, options)
     rss = After(rss, options)
 
     return Format(rss, options)
@@ -728,10 +592,10 @@ def cgi_app(environ, start_response):
     else:
         headers['content-type'] = 'text/xml'
 
-    url, cache = Init(url, os.getcwd() + '/cache', options)
+    crawler.sqlite_default = os.getcwd() + '/morss-cache.db'
 
     # get the work done
-    rss = Fetch(url, cache, options)
+    rss = Fetch(url, options)
 
     if headers['content-type'] == 'text/xml':
         headers['content-type'] = rss.mimetype
@@ -739,7 +603,7 @@ def cgi_app(environ, start_response):
     start_response(headers['status'], list(headers.items()))
 
     rss = Before(rss, options)
-    rss = Gather(rss, url, cache, options)
+    rss = Gather(rss, url, options)
     rss = After(rss, options)
     out = Format(rss, options)
 
@@ -795,10 +659,11 @@ def cli_app():
     global DEBUG
     DEBUG = options.debug
 
-    url, cache = Init(url, os.path.expanduser('~/.cache/morss'), options)
-    rss = Fetch(url, cache, options)
+    crawler.sqlite_default = os.path.expanduser('~/.cache/morss-cache.db')
+
+    rss = Fetch(url, options)
     rss = Before(rss, options)
-    rss = Gather(rss, url, cache, options)
+    rss = Gather(rss, url, options)
     rss = After(rss, options)
     out = Format(rss, options)