public Announcement Read(ReadAnnouncement request)
{
using (var connection = Connections.ConnectToInitializedTopic(request.TopicName))
{
var topicSubscriber = connection.FirstOrDefault <Subscriber>(subscriber =>
subscriber.Id == request.SubscriberId);
if (topicSubscriber == null)
{
throw new ArgumentException("Unknown subscriber");
}
var announcement = ReadFromDb(connection, topicSubscriber, request);
return(announcement);
}
}
Announcement ReadFromDb(IDbConnection connection, Subscriber subscriber, ReadAnnouncement request)
{
var topicLock = Locks.TakeTopicLock(request.TopicName);
lock (topicLock)
{
var query = NextAnnouncement.make(connection, subscriber);
var announcement = connection.FirstOrDefault(query);
while (announcement == null)
{
Monitor.Wait(topicLock);
announcement = connection.FirstOrDefault(query);
}
return(announcement);
}
}