62 lines
1.9 KiB
C#
62 lines
1.9 KiB
C#
// Copyright (c) .NET Foundation. All rights reserved.
|
|
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
|
|
|
|
using System;
|
|
using System.Collections.Generic;
|
|
using System.Linq;
|
|
|
|
namespace Microsoft.AspNetCore.Blazor.Rendering
|
|
{
|
|
internal class WeakValueDictionary<TKey, TValue> where TValue : class
|
|
{
|
|
private IDictionary<TKey, WeakReference<TValue>> _store
|
|
= new Dictionary<TKey, WeakReference<TValue>>();
|
|
private int _cullThreshold = 10;
|
|
|
|
public bool TryGetValue(TKey key, out TValue value)
|
|
{
|
|
if (_store.TryGetValue(key, out var existingWeakRef))
|
|
{
|
|
if (existingWeakRef.TryGetTarget(out value))
|
|
{
|
|
return true;
|
|
}
|
|
|
|
// Since we know it's not there, we might as well drop the entry now
|
|
_store.Remove(key);
|
|
}
|
|
|
|
value = default(TValue);
|
|
return false;
|
|
}
|
|
|
|
public void Add(TKey key, TValue value)
|
|
{
|
|
if (_store.TryGetValue(key, out _))
|
|
{
|
|
throw new ArgumentException($"The given key was already present in the {nameof(WeakValueDictionary<TKey, TValue>)}. Key: {key}");
|
|
}
|
|
|
|
_store[key] = new WeakReference<TValue>(value);
|
|
CullIfApplicable();
|
|
}
|
|
|
|
private void CullIfApplicable()
|
|
{
|
|
if (_store.Count > _cullThreshold)
|
|
{
|
|
var itemsToRemove = _store.Where(x => !x.Value.TryGetTarget(out _)).ToList();
|
|
foreach (var itemToRemove in itemsToRemove)
|
|
{
|
|
_store.Remove(itemToRemove.Key);
|
|
}
|
|
|
|
if (_store.Count > (_cullThreshold / 2))
|
|
{
|
|
_cullThreshold *= 2;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|