from django.conf import settings from zephyr.models import Message, UserProfile, UserMessage, \ Recipient, Stream, get_stream from zephyr.decorator import JsonableError from zephyr.lib.cache_helpers import cache_get_message from zephyr.lib.queue import queue_json_publish import os import sys import logging import requests import simplejson import subprocess import collections from django.db import connection class Callbacks(object): # A user received a message. The key is user_profile.id. TYPE_USER_RECEIVE = 0 # A stream received a message. The key is a tuple # (realm_id, lowercased stream name). # See comment attached to the global stream_messages for why. # Callers of this callback need to be careful to provide # a lowercased stream name. TYPE_STREAM_RECEIVE = 1 # A user's pointer was updated. The key is user_profile.id. TYPE_POINTER_UPDATE = 2 TYPE_MAX = 3 def __init__(self): self.table = {} def add(self, key, cb_type, callback): if not self.table.has_key(key): self.create_key(key) self.table[key][cb_type].append(callback) def call(self, key, cb_type, **kwargs): if not self.table.has_key(key): self.create_key(key) for cb in self.table[key][cb_type]: cb(**kwargs) self.table[key][cb_type] = [] def create_key(self, key): self.table[key] = [[] for i in range(0, Callbacks.TYPE_MAX)] callbacks_table = Callbacks() def add_user_receive_callback(user_profile, cb): callbacks_table.add(user_profile.id, Callbacks.TYPE_USER_RECEIVE, cb) def add_stream_receive_callback(realm_id, stream_name, cb): callbacks_table.add((realm_id, stream_name.lower()), Callbacks.TYPE_STREAM_RECEIVE, cb) def add_pointer_update_callback(user_profile, cb): callbacks_table.add(user_profile.id, Callbacks.TYPE_POINTER_UPDATE, cb) # in-process caching mechanism for tracking usermessages # # user table: Map user_profile_id => [deque of message ids he received] # # We don't use all the features of a deque -- the important ones are: # * O(1) insert of new highest message id # * O(k) read of highest k message ids # * Automatic maximum size support. # # stream table: Map (realm_id, lowercased stream name) => [deque of message ids it received] # # Why don't we index by the stream_id? Because the client will make a # request that specifies a particular realm and stream name, and since # we're running within tornado, we don't want to have to do a database # lookup to find the matching entry in this table. mtables = { 'user': {}, 'stream': {}, } USERMESSAGE_CACHE_COUNT = 25000 STREAMMESSAGE_CACHE_COUNT = 5000 cache_minimum_id = sys.maxint def initialize_user_messages(): global cache_minimum_id try: cache_minimum_id = Message.objects.all().order_by("-id")[0].id - USERMESSAGE_CACHE_COUNT except Message.DoesNotExist: cache_minimum_id = 1 # These next few lines implement the following Django ORM # algorithm using raw SQL: ## for um in UserMessage.objects.filter(message_id__gte=cache_minimum_id).order_by("message"): ## add_user_message(um.user_profile_id, um.message_id) # We do this because marshalling the Django objects is very # inefficient; total time consumed with the raw SQL is about # 600ms, vs. 3000ms-5000ms if we go through the ORM. cursor = connection.cursor() cursor.execute("SELECT user_profile_id, message_id from zephyr_usermessage " + "where message_id >= %s order by message_id", [cache_minimum_id]) for row in cursor.fetchall(): (user_profile_id, message_id) = row add_user_message(user_profile_id, message_id) streams = {} for stream in Stream.objects.select_related().all(): streams[stream.id] = stream for m in (Message.objects.only("id", "recipient").select_related("recipient") .filter(id__gte=cache_minimum_id + (USERMESSAGE_CACHE_COUNT - STREAMMESSAGE_CACHE_COUNT), recipient__type=Recipient.STREAM).order_by("id")): stream = streams[m.recipient.type_id] add_stream_message(stream.realm.id, stream.name, m.id) if not settings.DEPLOYED: # Filling the memcached cache is a little slow, so do it in a child process. # For DEPLOYED cases, we run this from restart_server. subprocess.Popen(["python", os.path.join(os.path.dirname(__file__), "..", "manage.py"), "fill_memcached_caches"]) def add_user_message(user_profile_id, message_id): add_table_message("user", user_profile_id, message_id) def add_stream_message(realm_id, stream_name, message_id): add_table_message("stream", (realm_id, stream_name.lower()), message_id) def add_table_message(table, key, message_id): if cache_minimum_id == sys.maxint: initialize_user_messages() mtables[table].setdefault(key, collections.deque(maxlen=400)) mtables[table][key].appendleft(message_id) def fetch_user_messages(user_profile_id, last): return fetch_table_messages("user", user_profile_id, last) def fetch_stream_messages(realm_id, stream_name, last): return fetch_table_messages("stream", (realm_id, stream_name.lower()), last) def fetch_table_messages(table, key, last): if cache_minimum_id == sys.maxint: initialize_user_messages() # We need to initialize the deque here for any new users or # streams that were created since Tornado was started mtables[table].setdefault(key, collections.deque(maxlen=400)) # We need to do this check after initialize_user_messages has been called. if len(mtables[table][key]) == 0: # Since the request contains a value of "last", we can assume # that the relevant user or stream has actually received a # message, which means that mtabes[table][key] will not remain # empty after the below completes. # # Thus, we will run this code at most once per key (user or # stream that is being lurked on). Further, we only do this # query for those keys that have not received a message since # cache_minimum_id. So we can afford to do a database query # from Tornado in this case. if table == "user": logging.info("tornado: Doing database query for user %d" % (key,),) for um in reversed(UserMessage.objects.filter(user_profile_id=key).order_by('-message')[:400]): add_user_message(um.user_profile_id, um.message_id) elif table == "stream": logging.info("tornado: Doing database query for stream %s" % (key,)) (realm_id, stream_name) = key stream = get_stream(stream_name, realm_id) # If a buggy client submits a "last" value with a nonexistent stream, # do nothing (and proceed to longpoll) rather than crashing. if stream is not None: recipient = Recipient.objects.get(type=Recipient.STREAM, type_id=stream.id) for m in Message.objects.only("id", "recipient").filter(recipient=recipient).order_by("id")[:400]: add_stream_message(realm_id, stream_name, m.id) if len(mtables[table][key]) == 0: # Check the our assumption above that there are messages here. # If false, this may just mean a misbehaving client submitted # "last" even though it has no messages (in which case we # should proceed with longpolling by falling through). But it # could also be a server bug, so we log a warning. logging.warning("Unexpected empty message queue for key %s!" % (key,)) elif last < mtables[table][key][-1]: # The user's client has a way-too-old value for 'last' # (presumably 400 messages old), we should return an error # The error handler for get_updates in zephyr.js parses this # message. If you change this message, you must update that # error handler. raise JsonableError("last value of %d too old! Minimum valid is %d!" % (last, mtables[table][key][-1])) message_list = [] for message_id in mtables[table][key]: if message_id <= last: return reversed(message_list) message_list.append(message_id) return [] # The user receives this message def user_receive_message(user_profile_id, message): add_user_message(user_profile_id, message.id) callbacks_table.call(user_profile_id, Callbacks.TYPE_USER_RECEIVE, messages=[message], update_types=["new_messages"]) # The stream receives this message def stream_receive_message(realm_id, stream_name, message): add_stream_message(realm_id, stream_name, message.id) callbacks_table.call((realm_id, stream_name.lower()), Callbacks.TYPE_STREAM_RECEIVE, messages=[message], update_types=["new_messages"]) # Simple caching implementation module for user pointers # # TODO: Write something generic in cache.py to support this # functionality? The current primitives there don't support storing # to the cache. user_pointers = {} def get_user_pointer(user_profile_id): if user_pointers == {}: # Once, on startup, fill in the user_pointers table with # everyone's current pointers for u in UserProfile.objects.all(): user_pointers[u.id] = u.pointer if user_profile_id not in user_pointers: # This is a new user created since Tornado was started, so # they will have an initial pointer of -1. return -1 return user_pointers[user_profile_id] def set_user_pointer(user_profile_id, pointer): user_pointers[user_profile_id] = pointer def update_pointer(user_profile_id, new_pointer): set_user_pointer(user_profile_id, new_pointer) callbacks_table.call(user_profile_id, Callbacks.TYPE_POINTER_UPDATE, new_pointer=new_pointer, update_types=["pointer_update"]) def process_new_message(data): message = cache_get_message(data['message']) for user_profile_id in data['users']: user_receive_message(user_profile_id, message) if 'stream_name' in data: stream_receive_message(data['realm_id'], data['stream_name'], message) def process_notification(data): if data['type'] == 'new_message': process_new_message(data) elif data['type'] == 'pointer_update': update_pointer(data['user'], data['new_pointer']) else: raise JsonableError('bad notification type ' + data['type']) # Runs in the Django process to send a notification to Tornado. # # We use JSON rather than bare form parameters, so that we can represent # different types and for compatibility with non-HTTP transports. def send_notification_http(data): requests.post(settings.TORNADO_SERVER + '/notify_tornado', data=dict( data = simplejson.dumps(data), secret = settings.SHARED_SECRET)) def send_notification(data): return queue_json_publish("notify_tornado", data, send_notification_http)