Add basic support for per-user session timeout

tailbone/beaker.py

@@ -0,0 +1,140 @@
+# -*- coding: utf-8 -*-
+################################################################################
+#
+#  Rattail -- Retail Software Framework
+#  Copyright © 2010-2017 Lance Edgar
+#
+#  This file is part of Rattail.
+#
+#  Rattail is free software: you can redistribute it and/or modify it under the
+#  terms of the GNU Affero General Public License as published by the Free
+#  Software Foundation, either version 3 of the License, or (at your option)
+#  any later version.
+#
+#  Rattail is distributed in the hope that it will be useful, but WITHOUT ANY
+#  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+#  FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for
+#  more details.
+#
+#  You should have received a copy of the GNU Affero General Public License
+#  along with Rattail.  If not, see <http://www.gnu.org/licenses/>.
+#
+################################################################################
+"""
+Custom sessions, based on Beaker
+
+Note that most of the code for this module was copied from the beaker and
+pyramid_beaker projects.
+"""
+
+from __future__ import unicode_literals, absolute_import
+
+import time
+
+from beaker.session import Session
+from beaker.util import coerce_session_params
+from pyramid.settings import asbool
+from pyramid_beaker import BeakerSessionFactoryConfig, set_cache_regions_from_settings
+
+
+class TailboneSession(Session):
+    """
+    Custom session class for Beaker, which overrides load() to add per-request
+    session timeout support.
+    """
+
+    def load(self):
+        "Loads the data from this session from persistent storage"
+        self.namespace = self.namespace_class(self.id,
+            data_dir=self.data_dir,
+            digest_filenames=False,
+            **self.namespace_args)
+        now = time.time()
+        if self.use_cookies:
+            self.request['set_cookie'] = True
+
+        self.namespace.acquire_read_lock()
+        timed_out = False
+        try:
+            self.clear()
+            try:
+                session_data = self.namespace['session']
+
+                if (session_data is not None and self.encrypt_key):
+                    session_data = self._decrypt_data(session_data)
+
+                # Memcached always returns a key, its None when its not
+                # present
+                if session_data is None:
+                    session_data = {
+                        '_creation_time': now,
+                        '_accessed_time': now
+                    }
+                    self.is_new = True
+            except (KeyError, TypeError):
+                session_data = {
+                    '_creation_time': now,
+                    '_accessed_time': now
+                }
+                self.is_new = True
+
+            if session_data is None or len(session_data) == 0:
+                session_data = {
+                    '_creation_time': now,
+                    '_accessed_time': now
+                }
+                self.is_new = True
+
+            # TODO: sure would be nice if we could get this little bit of logic
+            # into the upstream Beaker package, as that would avoid the need
+            # for this module entirely...
+            timeout = session_data.get('_timeout', self.timeout)
+            if timeout is not None and \
+               now - session_data['_accessed_time'] > timeout:
+                timed_out = True
+            else:
+                # Properly set the last_accessed time, which is different
+                # than the *currently* _accessed_time
+                if self.is_new or '_accessed_time' not in session_data:
+                    self.last_accessed = None
+                else:
+                    self.last_accessed = session_data['_accessed_time']
+
+                # Update the current _accessed_time
+                session_data['_accessed_time'] = now
+
+                # Set the path if applicable
+                if '_path' in session_data:
+                    self._path = session_data['_path']
+                self.update(session_data)
+                self.accessed_dict = session_data.copy()
+        finally:
+            self.namespace.release_read_lock()
+        if timed_out:
+            self.invalidate()
+
+
+def session_factory_from_settings(settings):
+    """ Return a Pyramid session factory using Beaker session settings
+    supplied from a Paste configuration file"""
+    prefixes = ('session.', 'beaker.session.')
+    options = {}
+
+    # Pull out any config args meant for beaker session. if there are any
+    for k, v in settings.items():
+        for prefix in prefixes:
+            if k.startswith(prefix):
+                option_name = k[len(prefix):]
+                if option_name == 'cookie_on_exception':
+                    v = asbool(v)
+                options[option_name] = v
+
+    options = coerce_session_params(options)
+    options['session_class'] = TailboneSession
+    return BeakerSessionFactoryConfig(**options)
+
+
+def includeme(config):
+    session_factory = session_factory_from_settings(config.registry.settings)
+    config.set_session_factory(session_factory)
+    set_cache_regions_from_settings(config.registry.settings)