What thread-safe collection is appropriate for this scenario?


I have a singleton class handling Subscribe and Unsubscribe requests from different clients running in different threads. The singleton contains a collection of Subscribers. Before adding or removing, the class needs to validate that the element hasn't already been added or deleted.

Normally I would implement this using a List or a HashSet calling Contains before each operation, but if I want to use one of the new classes in the System.Collections.Concurrent namespace, the only option I see is to use a ConcurrentDictionary with a dummy value.

Is this my best option or is there something I'm overlooking? By the way, performance is not really a factor to consider.


I think you should stick with <a href="http://msdn.microsoft.com/en-us/library/dd287191.aspx" rel="nofollow">ConcurrentDictionary</a> ...


Why dont you use ConcurrentDictionary backed with Blocking Queue. BlockingQueue seems to fit your producer/consumer scheme, and ConcurrentDictionary for your lookups.


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