ConcurrentDictionary Lazy AddOrUpdate

Question

I found this Extension for C# to convert GetOrAdd to Lazy and I want to do the same for AddOrUpdate.

Can someone help me convert this to AddOrUpdate?

 public static class ConcurrentDictionaryExtensions
{
    public static TValue LazyGetOrAdd<TKey, TValue>(
        this ConcurrentDictionary<TKey, Lazy<TValue>> dictionary,
        TKey key,
        Func<TKey, TValue> valueFactory)
    {
        if (dictionary == null) throw new ArgumentNullException("dictionary");
        var result = dictionary.GetOrAdd(key, new Lazy<TValue>(() => valueFactory(key)));
        return result.Value;
    }


}

score 1 · Accepted Answer · answered May 25 '15 at 14:39

1

It is this:

public static TValue AddOrUpdate<TKey, TValue>(this ConcurrentDictionary<TKey, Lazy<TValue>> dictionary, TKey key, Func<TKey, TValue> addValueFactory, Func<TKey, TValue, TValue> updateValueFactory)
{
    if (dictionary == null) throw new ArgumentNullException("dictionary");
    var result = dictionary.AddOrUpdate(key, new Lazy<TValue>(() => addValueFactory(key)), (key2, old) => new Lazy<TValue>(() => updateValueFactory(key2, old.Value)));
    return result.Value;
}

Note the format of the second parameter: a delegate that returns a new Lazy<> object... so from a certain standpoint, it is double-lazy :-)

answered May 25 '15 at 14:39

xanatos

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Any chance you can show me a sample how to use it? before the lazy I used it like this ConcurrentDictionary.AddOrUpdate(CustomerID, 1, (k, v) => v + 1); – Andre DeMattia May 25 '15 at 15:04
I think this might be it. dictionary.LazyAddOrUpdate(1, (ka) => 1, (k, v) => v + 1); – Andre DeMattia May 25 '15 at 15:11
@AndreDeMattia what does ka represent ? within the argument of your comment. – eaglei22 Jun 06 '17 at 16:15
@eaglei when the key is not found, the delegate is called and ka is the key. Berger would be to call it k. – xanatos Jun 06 '17 at 16:18

ConcurrentDictionary Lazy AddOrUpdate

1 Answers1