Changed tweets, added eca

eca/sessions.py

@@ -0,0 +1,128 @@
+from http.cookies import SimpleCookie
+from collections import namedtuple
+from collections.abc import Mapping
+from itertools import product, chain
+import time
+import random
+
+from . import httpd
+from . import Context, context_activate
+
+
+# Name generation for contexts and sessions
+def name_parts():
+    """
+    This generator will create an endless list of steadily increasing
+    name part lists.
+    """
+    # name parts
+    letters = ['alpha', 'beta', 'gamma', 'delta', 'epsilon', 'zeta', 'eta',
+               'theta', 'iota', 'kappa', 'lambda', 'mu', 'nu', 'xi', 'omicron',
+               'pi', 'rho', 'sigma', 'tau', 'upsilon', 'phi', 'chi', 'psi',
+               'omega']
+    colours = ['red', 'orange', 'yellow', 'green', 'blue', 'violet']
+
+    # randomize order
+    random.shuffle(letters)
+    random.shuffle(colours)
+
+    # yield initial sequence (letter-colour)
+    parts = [letters, colours]
+    yield parts
+
+    # forever generate longer sequences by appending the letter list
+    # over and over. Note that this is the *same* letter list, so it will have
+    # the exact order.
+    while True:
+        random.shuffle(letters)
+        random.shuffle(colours)
+        parts.append(letters)
+        yield parts
+
+# construct an iterator that will endlessly generate names:
+# 1) for each parts list p in name_parts() we take the cartesian product
+# 2) the product iterators are generated by the for...in generator
+# 3) we chain these iterators so that when the first is exhausted, we can
+#    continue with the second, etc.
+# 4) we map the function '-'.join over the list of parts from the chain
+names =  map('-'.join, chain.from_iterable((product(*p) for p in name_parts())))
+
+
+class SessionCookie(httpd.Filter):
+    """
+    The actual HTTP filter that will apply the cookie handling logic to each
+    request. This filter defers to the SessionManager with respect to the
+    cookie name to use and the activation of sessions.
+    """
+    def bind(self, manager):
+        """Post constructor configuration of filter."""
+        self.manager = manager
+
+    def handle(self):
+        """
+        Determine if a cookie needs to be set and let the session manager
+        handle activation.
+        """
+        cookies = self.request.cookies
+        morsel = cookies.get(self.manager.cookie)
+
+        if not morsel:
+            # Determine new cookie
+            value = self.manager.generate_name()
+
+            # Set new cookie
+            cookies[self.manager.cookie] = value
+            cookies[self.manager.cookie]['path'] = '/'
+
+            # Send the new cookie as header
+            self.request.send_header('Set-Cookie', cookies[self.manager.cookie].OutputString())
+        else:
+            value = morsel.value
+
+        self.manager.activate(value)
+
+
+class Session:
+    """
+    The Session bookkeeping data.
+    """
+    def __init__(self, context, seen):
+        self.context = context
+        self.seen = seen
+
+    def activate(self):
+        """Activate the session. Updates last seen time."""
+        self.seen = time.time()
+        context_activate(self.context)
+
+
+class SessionManager:
+    """
+    The SessionManager class. This class is callable so it can be used in place
+    of a constructor in the configuration.
+    """
+    def __init__(self, cookie_name):
+        self.sessions = {}
+        self.cookie = cookie_name
+
+    def __call__(self, *args, **kwargs):
+        handler = SessionCookie(*args, **kwargs)
+        handler.bind(self)
+        return handler
+
+    def generate_name(self):
+        result = next(names)
+        while result in self.sessions:
+            result = next(names)
+        return result
+
+    def _new_session(self, name):
+        result = Session(Context(name=name, init_data={'name': name}), time.time())
+        result.context.start()
+        return result
+
+    def activate(self, name):
+        if name not in self.sessions:
+            self.sessions[name] = self._new_session(name)
+        self.sessions[name].activate()
+