Mercurial > public > sg101
view gpp/core/whos_online.py @ 466:c78c6e007e61
Upgrading to markitup version 1.1.11. This fixes #226.
author | Brian Neal <bgneal@gmail.com> |
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date | Sun, 24 Jul 2011 02:35:17 +0000 |
parents | 3fe60148f75c |
children | 6f5fff924877 |
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""" This module keeps track of who is online. We maintain records for both authenticated users ("users") and non-authenticated visitors ("visitors"). """ import logging from django.conf import settings import redis # Users and visitors each have 2 sets that we store in a Redis database: # a current set and an old set. Whenever a user or visitor is seen, the # current set is updated. At some interval, the current set is renamed # to the old set, thus destroying it. At any given time, the union of the # current and old sets is the "who's online" set. # Redis connection and database settings HOST = getattr(settings, 'WHOS_ONLINE_REDIS_HOST', 'localhost') PORT = getattr(settings, 'WHOS_ONLINE_REDIS_PORT', 6379) DB = getattr(settings, 'WHOS_ONLINE_REDIS_DB', 0) # Redis key names: USER_CURRENT_KEY = "wo_user_current" USER_OLD_KEY = "wo_user_old" USER_KEYS = [USER_CURRENT_KEY, USER_OLD_KEY] VISITOR_CURRENT_KEY = "wo_visitor_current" VISITOR_OLD_KEY = "wo_visitor_old" VISITOR_KEYS = [VISITOR_CURRENT_KEY, VISITOR_OLD_KEY] # Logging: we don't want a Redis malfunction to bring down the site. So we # catch all Redis exceptions, log them, and press on. logger = logging.getLogger(__name__) def _get_connection(): """ Create and return a Redis connection. Returns None on failure. """ try: conn = redis.Redis(host=HOST, port=PORT, db=DB) return conn except redis.RedisError, e: logger.error(e) return None def report_user(username): """ Call this function when a user has been seen. The username will be added to the current set. """ conn = _get_connection() if conn: try: conn.sadd(USER_CURRENT_KEY, username) except redis.RedisError, e: logger.error(e) def report_visitor(ip): """ Call this function when a visitor has been seen. The IP address will be added the current set. """ conn = _get_connection() if conn: try: conn.sadd(VISITOR_CURRENT_KEY, ip) except redis.RedisError, e: logger.error(e) def get_users_online(): """ Returns a set of user names which is the union of the current and old sets. """ conn = _get_connection() if conn: try: # Note that keys that do not exist are considered empty sets return conn.sunion(USER_KEYS) except redis.RedisError, e: logger.error(e) return set() def get_visitors_online(): """ Returns a set of visitor IP addresses which is the union of the current and old sets. """ conn = _get_connection() if conn: try: # Note that keys that do not exist are considered empty sets return conn.sunion(VISITOR_KEYS) except redis.RedisError, e: logger.error(e) return set() def _tick_set(conn, current, old): """ This function renames the set named "current" to "old". """ # An exception may be raised if the current key doesn't exist; if that # happens we have to delete the old set because no one is online. try: conn.rename(current, old) except redis.ResponseError: try: del conn[old] except redis.RedisError, e: logger.error(e) except redis.RedisError, e: logger.error(e) def tick(): """ Call this function to "age out" the old sets by renaming the current sets to the old. """ conn = _get_connection() if conn: _tick_set(conn, USER_CURRENT_KEY, USER_OLD_KEY) _tick_set(conn, VISITOR_CURRENT_KEY, VISITOR_OLD_KEY)