public static void AddChat(string room_name, string speaker, string words)
{
//Trace.TraceInformation("ChatPond.AddChat. room_name={0}.", room_name);
ChatRoll roll = get(room_name);
roll.Add(speaker, words);
}
public static IEnumerable <UserWords> Get(string room_name)
{
// When Get and AddChat are called in different threads at very close time, both will trigger insertNew.
// 2 rolls of the same room are inserted into cache, latter one kicks former one out of cache.
//Trace.TraceInformation("ChatPond.Get. room_name={0}.", room_name);
ChatRoll roll = get(room_name);
return(roll.Get());
}
private static ChatRoll get(string room_name)
{
ChatRoll obj = (ChatRoll)HttpRuntime.Cache.Get(key(room_name));
if (obj == null)
{
obj = insertNew(room_name);
}
return(obj);
}
private static ChatRoll insertNew(string room_name)
{
string key2 = key(room_name);
//Trace.TraceInformation("ChatPond.insertNew. key={0}.", key2);
ChatRoll obj = new ChatRoll(room_name); // if concurrency happens, this will be done more than once.
HttpRuntime.Cache.Insert(key2, obj, null, DateTime.Now.AddSeconds(Config.DEFAULT_CACHE_SECONDS),
Cache.NoSlidingExpiration, CacheItemPriority.Default, removedCallback);
// expires after some time for multi-node synchronization (unreliable).
return(obj);
}
private static void removedCallback(string key, Object value, CacheItemRemovedReason reason)
{
// Reason=Removed happens when an existing key is inserted again.
//Trace.TraceInformation("ChatPond.removedCallback. key={0}, reason={1}.", key, reason);
ChatRoll obj = (ChatRoll)value;
obj.Save();
if (reason == CacheItemRemovedReason.Expired)
{
// insertNew(key); // Not needed to keep it always in memory.
}
}
