Weak Collection : List « Collections Data Structure « C# / C Sharp

1. C# / C Sharp
2. Collections Data Structure
3. List

Weak Collection

       
using System;
using System.Collections.Generic;
using System.Text;

namespace Mihailik.Collections
{
  public class WeakCollection<T>
  {
    const int InventoryThreshold = 256;
    readonly object sync = new object();
    List<WeakReference> innerList = new List<WeakReference>();
    int lastInventoryCount;

    public void Add(T item)
    {
      lock( sync )
      {
        if( innerList.Count > lastInventoryCount + InventoryThreshold )
          PerformInventory();

        innerList.Add(new WeakReference(item));
      }
    }

    public T[] GetItems()
    {
      lock( sync )
      {
        List<T> result = new List<T>(innerList.Count);
        foreach( WeakReference wref in innerList )
        {
          object wrefTarget = wref.Target;
          if( wrefTarget != null )
          {
            result.Add((T)wrefTarget);
          }
        }

        if( innerList.Count - result.Count > InventoryThreshold )
          PerformInventory();

        return result.ToArray();
      }
    }

    void PerformInventory()
    {
      List<WeakReference> newList = new List<WeakReference>();
      foreach( WeakReference wref in innerList )
      {
        if( wref.IsAlive )
          newList.Add(wref);
      }
      innerList = newList;
      lastInventoryCount = innerList.Count;
    }
  }
}

   
    
    
    
    
    
    
  

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