Implement long polling using Tornado.

(imported from commit 4385304b27d7fe55a57a23133cd214fe8fc33482)

zephyr/models.py

@@ -16,10 +16,31 @@ def get_display_recipient(recipient):
         user = User.objects.get(pk=recipient.user_or_class)
         return user.username
 
+callback_table = {}
+
 class UserProfile(models.Model):
     user = models.OneToOneField(User)
     pointer = models.IntegerField()
 
+    # The user receives this message
+    def receive(self, message):
+        global callback_table
+
+        # Should also store in permanent database the receipt
+        for cb in callback_table.get(self.user.id, []):
+            cb([message])
+
+        callback_table[self.user.id] = []
+
+    def add_callback(self, cb, last_received):
+        global callback_table
+
+        # This filter should also restrict to the current user's subs
+        new_zephyrs = Zephyr.objects.filter(id__gt=last_received)
+        if new_zephyrs:
+            return cb(new_zephyrs)
+        callback_table.setdefault(self.user.id, []).append(cb)
+
     def __repr__(self):
         return "<UserProfile: %s>" % (self.user.username,)
 
@@ -55,9 +76,36 @@ class Zephyr(models.Model):
         display_recipient = get_display_recipient(self.recipient)
         return "<Zephyr: %s / %s / %r>" % (display_recipient, self.instance, self.sender)
 
+def send_zephyr(**kwargs):
+    zephyr = kwargs["instance"]
+    if zephyr.recipient.type == "personal":
+        recipients = UserProfile.objects.filter(user=zephyr.recipient.user_or_class)
+        assert(len(recipients) == 1)
+    elif zephyr.recipient.type == "class":
+        recipients = [UserProfile.objects.get(user=s.userprofile_id) for
+                      s in Subscription.objects.filter(recipient_id=zephyr.recipient)]
+    else:
+        raise
+    for recipient in recipients:
+        recipient.receive(zephyr)
+
+post_save.connect(send_zephyr, sender=Zephyr)
+
 class Subscription(models.Model):
     userprofile_id = models.ForeignKey(UserProfile)
     recipient_id = models.ForeignKey(Recipient)
 
     def __repr__(self):
         return "<Subscription: %r -> %r>" % (self.userprofile_id, self.recipient_id)
+
+def filter_by_subscriptions(zephyrs, user):
+    userprofile = UserProfile.objects.get(user=user)
+    subscribed_zephyrs = []
+    subscriptions = [sub.recipient_id for sub in Subscription.objects.filter(userprofile_id=userprofile)]
+    for zephyr in zephyrs:
+        # If you are subscribed to the personal or class, or if you sent the personal, you can see the zephyr.
+        if (zephyr.recipient in subscriptions) or \
+                (zephyr.recipient.type == "personal" and zephyr.sender == userprofile):
+            subscribed_zephyrs.append(zephyr)
+
+    return subscribed_zephyrs