Tools.Collections.ConcurrentDictionary.RemoveIf 1.0.0

Tools.Collections.ConcurrentDictionary.RemoveIf

Description

Extensions method for System.Collections.Concurrent.ConcurrentDictionary Namespace: Tools.Collections.Concurrent.Extensions Use: ConcurrentDictionary<TKey, IValueWrapper<TValue>> Description of the mechanism of work: https://stackoverflow.com/questions/39679779/how-to-achieve-remove-if-functionality-in-net-concurrentdictionary

Usage example:

using System.Collections.Concurrent;
using Tools.Collections.Concurrent.Extensions;

public class LinkItem<T>
{
    public int LinkCount { private set; get; }
    public T Value { private set; get; }
    public bool HaveValue { private set; get; }


    public static LinkItem<T> CreateZeroLink()
    {
        return new LinkItem<T>()
        {
            LinkCount = 0,
            HaveValue = false
        };
    }
    public static RealItemWrapper<LinkItem<T>> CreateZeroLinkWrapper()
    {
        return new RealItemWrapper<LinkItem<T>>(
            CreateZeroLink()
            );
    }

    public static LinkItem<T> CreateOneLink(T value) 
    {
        return new LinkItem<T>()
        {
            Value = value,
            LinkCount = 1,
            HaveValue = true
        };
    }
    public static RealItemWrapper<LinkItem<T>> CreateOneLinkWrapper(T value)
    {
        return new RealItemWrapper<LinkItem<T>>(
            CreateOneLink(value)
            );
    }


    public LinkItem<T> IncrementCounter(T value) 
    {
        return new LinkItem<T>()
        {
            LinkCount = LinkCount + 1,
            Value = HaveValue
                ? Value
                : value,
            HaveValue = true
        };
    }
    public RealItemWrapper<LinkItem<T>> IncrementCounterWrapper(T value)
    {
        return new RealItemWrapper<LinkItem<T>>(
            IncrementCounter(value)
            );
    }

    public LinkItem<T> DecrementCounter()
    {
        if (
            HaveValue
            && LinkCount > 0
            )
        {
            return new LinkItem<T>()
            {
                Value = Value,
                LinkCount = LinkCount - 1,
                HaveValue = true
            };
        }
        else
        {
            return this;
        }
    }
    public RealItemWrapper<LinkItem<T>> DecrementCounterWrapper()
    {
        return new RealItemWrapper<LinkItem<T>>(
            DecrementCounter()
            );
    }

}


public static IValueWrapper<LinkItem<TValue>> AddLink<TKey, TValue>(
            ConcurrentDictionary<
                TKey, 
                IValueWrapper<LinkItem<TValue>>
                > dictionary,
            TKey key,
            TValue value
            )
{
    return dictionary
        .AddOrUpdate(
            key,
            LinkItem<TValue>.CreateOneLinkWrapper(value),
            (TKey tkey, IValueWrapper<LinkItem<TValue>> item) =>
                item.Value.IncrementCounterWrapper(value)
            );
}

public static bool RemoveLink<TKey, TValue>(
            ConcurrentDictionary<
                TKey, 
                IValueWrapper<LinkItem<TValue>>
                > dictionary,
            TKey key
            )
{
    var result = dictionary
        .AddOrUpdate(
            key,
            LinkItem<TValue>.CreateZeroLinkWrapper(),                    
            (TKey tkey, IValueWrapper<LinkItem<TValue>> item) =>
                item.Value.DecrementCounterWrapper()
            );

    //Remove item if link count = 0

    //if (result.Value.LinkCount != 0)
    //{
    //    return false;
    //}

    return dictionary.RemoveIf(
        key,
        (IValueWrapper<LinkItem<TValue>> item) 
            => item.Value.LinkCount == 0
        );
}



public static void TestMethod()
{
    ConcurrentDictionary<
                string, 
                IValueWrapper<LinkItem<string>>
                >
                dictionary 
                    = new ConcurrentDictionary<
                        string, 
                        IValueWrapper<LinkItem<string>>
                        >();

    //Add first link to key
    AddLink(dictionary, "key", "value");
    //Add second link to key
    AddLink(dictionary, "key", "value");

    //Remove first link to key
    var removeResult1 = RemoveLink(dictionary, "key");
    //Remove second link to key and remove key Item
    var removeResult2 = RemoveLink(dictionary, "key");

    Console.ReadLine();
}