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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
using System;
using System.Collections;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Linq;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis.Internal.Log;
/// <summary>
/// helper class to aggregate some numeric value log in client side
/// </summary>
internal abstract class AbstractLogAggregator<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
where TKey : notnull
where TValue : class // TValue being constrained to a class will ensure that the ConcurrentDictionaries won't be JITted with structs
{
/// <remarks>
/// The key here is an object even though we will often be putting enums into this map; the problem with the use of enums or other value
/// types is they prevent the runtime from sharing the same JITted code for each different generic instantiation. In this case,
/// the cost of boxing is cheaper than the cost of the extra JIT.
/// </remarks>
private readonly ConcurrentDictionary<object, TValue> _map = new(concurrencyLevel: 2, capacity: 2);
private readonly Func<object, TValue> _createCounter;
protected AbstractLogAggregator()
{
_createCounter = _ => CreateCounter();
}
protected abstract TValue CreateCounter();
public bool IsEmpty => _map.IsEmpty;
public void Clear() => _map.Clear();
public IEnumerator<KeyValuePair<TKey, TValue>> GetEnumerator()
=> _map.Select(static kvp => KeyValuePairUtil.Create((TKey)kvp.Key, kvp.Value)).GetEnumerator();
IEnumerator IEnumerable.GetEnumerator()
=> this.GetEnumerator();
[PerformanceSensitive("https://devdiv.visualstudio.com/DevDiv/_workitems/edit/1279909", AllowCaptures = false)]
protected TValue GetCounter(TKey key)
=> _map.GetOrAdd((object)key, _createCounter);
protected bool TryGetCounter(TKey key, [MaybeNullWhen(false)] out TValue counter)
{
if (_map.TryGetValue((object)key, out counter))
{
return true;
}
return false;
}
}
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