C# 6 Multi-point collections instead of masses

[zymir]

There is a mass int[][a] that requires multiple access to all data transactions. To this end, the ConcurrentDictionary multi-point collections should be used. I'll make it hard to choose between ConcurrentDictionary<int,int[]> and ConcurrentDictionary<int,ConcurrentDictionary<int,int[]>>(close the number of the mass element). What's the difference? Does it make sense to record another Concurrent-Clution as shown in the second case and why? Will conflicts occur in any of these options?

[nishika]

Substitution of mass ConcurrentDictionary For security reasons, it's quite a strange idea, because most operations ConcurrentDictionary It doesn't make sense.

In fact, the only operations over the mass are the element receipt and updating. But in order to get a little bit safe, there's no need to accumulate, because reading. int always atomarno. To update the body of the mass, any Interlocked- surgery. Okay, method. TryUpdate of ConcurrentDictionary directly corresponding to the so-called operation https://msdn.microsoft.com/ru-ru/library/801kt583(v=vs.110).aspx :

Interlocked.CompareExchange(ref a[5], 10, 20);

But perhaps you didn't need a mass of reference: you needed to add elements or remove them. In that case, you did the right thing to do to replace the mass with something else, because the re-establishment of the atomary force is not an operation. What kind of collection do you have to use, depends solely on what you have to do with it.

I can only advise you to try to use different options and see if each of them can only use treasury operations.

I also propose another possible substitute for such a set:

• ConcurrentDictionary<int,int[]>
• ConcurrentDictionary<int,ConcurrentDictionary<int, int>>
• ConcurrentDictionary<Tuple<int, int>, int>

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But I have to warn you, the combination of a few sensitive operations is far from always safe in general. If you feel like you're messing with this, maybe you shouldn't try to use lock-free algorithms, but rather a "traditional" approach with locks.

Simple use of design lock Make any operation safe (if, of course, you'll use the challenge. lock with the same object for any reference to the mass.