2 cents on the concurrent collections

Published on , by Vincent Jacquet In Programming Tags #async

IProducerConsumerCollection<T>

IProducerConsumerCollection<T> is the starting point. It is an interface derived from ICollection and IEnumerator<T>. Basically, these two interfaces are read only, so the new interface add TryAdd and TryTake methods. The others methods are a generic CopyTo and a ToArray.

I am not very found of the Add/Take semantics, as it is generally Add/Remove. I guess Push/Pull would have been better suited for a Producer/Consumer interface.

I also believe CopyTo to be dangerous. How do I know which size to allocate for the array when it could very well change before I call CopyTo ?

And last, but not least, how do I know that the producer is done producing?

ConcurrentBag<T>, ConcurrentStack<T>, ConcurrentQueue<T>

These are the 3 collections implementing the IProducerConsumerCollection interface:

  • ConcurrentBag, when no specific ordering is required to take from the collection;
  • ConcurrentStack, when you want to take the last produced item first;
  • ConcurrentQueue, when you want to consume in the order it was produced.

These collections implement an IsEmpty property, suggesting that the Count property is not in constant time.

BlockingCollection<T>

The BlockingCollection is a wrapper for the Producer/Consumer interface. It provides Add/Take helpers and a GetConsumingEnumerator() function to consume in a for each loop.

It also add TryAddToAny and TryTakeFromAny static functions. This I do not get. Why not using composition instead of static functions.

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