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Asked: 2026-05-25T01:22:23+00:00

I’m trying to figure out what data type to use… Basically I want a

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I’m trying to figure out what data type to use…
Basically I want a FIFO queue that is thread-safe and will automatically throw out old enough items once it gets to a pre-specified limit.

Well, actually, maybe more of a list, because I don’t want the whole concept of pushing onto the queue and popping an item off the queue at which point it’s no longer available.

The use case is basically for a playlist where I would have up to 5 upcoming items, the currently playing item, and then about 20 items that have already played. Hence, why I guess it cannot be a queue, I would be accessing one of the items in the middle as the “current” item. And I would rather not have to manually manage throwing away old items when the list gets to big… obviously I could write this all myself, but I don’t want to reinvent the wheel if this already exists for C#.

Any ideas of what I could use?

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1 Answer

  1. Editorial Team

    In the Framework there is something almost having the functionality you want – the ConcurrentQueue . It is thread-safe queue with most operations being implemented lock-free, so it is very fast.

    The only function is does not have is the “limit” with automatic “throw-away”…

    But that can be easily added – just create you own class containing a private ConcurrentQueue and implement the “throw-away part” in your public enqueue method by Dequeuing/throwing away till your limit is satisfied before Enqueuing the new element.

    EDIT – as per comment:
    One option would be to make the second “Queue” an ObservableCollection – though not inherently thread-safe (beware) this would be easily bind in WPF…

    Another would be to make your class implement the ObservableCollection interface (which consists of IList<T>, ICollection<T>, IEnumerable<T>, IList, ICollection, IEnumerable, INotifyCollectionChanged, INotifyPropertyChanged) accordingly – that sounds alot, but most of these you get easily implemented by relaying to the internal ConcurrentQueue so there is not much real code to write…
    See http://msdn.microsoft.com/en-us/library/ms752347.aspx

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