RyuKen/ARMeilleure/Common/Counter.cs

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C#
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using System;
namespace ARMeilleure.Common
{
/// <summary>
/// Represents a numeric counter which can be used for instrumentation of compiled code.
/// </summary>
/// <typeparam name="T">Type of the counter</typeparam>
class Counter<T> : IDisposable where T : unmanaged
{
private bool _disposed;
/// <summary>
/// Index in the <see cref="EntryTable{T}"/>
/// </summary>
private readonly int _index;
private readonly EntryTable<T> _countTable;
/// <summary>
/// Initializes a new instance of the <see cref="Counter{T}"/> class from the specified
/// <see cref="EntryTable{T}"/> instance and index.
/// </summary>
/// <param name="countTable"><see cref="EntryTable{T}"/> instance</param>
/// <exception cref="ArgumentNullException"><paramref name="countTable"/> is <see langword="null"/></exception>
/// <exception cref="ArgumentException"><typeparamref name="T"/> is unsupported</exception>
public Counter(EntryTable<T> countTable)
{
if (typeof(T) != typeof(byte) && typeof(T) != typeof(sbyte) &&
typeof(T) != typeof(short) && typeof(T) != typeof(ushort) &&
typeof(T) != typeof(int) && typeof(T) != typeof(uint) &&
typeof(T) != typeof(long) && typeof(T) != typeof(ulong) &&
typeof(T) != typeof(nint) && typeof(T) != typeof(nuint) &&
typeof(T) != typeof(float) && typeof(T) != typeof(double))
{
throw new ArgumentException("Counter does not support the specified type.");
}
_countTable = countTable ?? throw new ArgumentNullException(nameof(countTable));
_index = countTable.Allocate();
}
/// <summary>
/// Gets a reference to the value of the counter.
/// </summary>
/// <exception cref="ObjectDisposedException"><see cref="Counter{T}"/> instance was disposed</exception>
/// <remarks>
/// This can refer to freed memory if the owning <see cref="EntryTable{TEntry}"/> is disposed.
/// </remarks>
public ref T Value
{
get
{
if (_disposed)
{
throw new ObjectDisposedException(null);
}
return ref _countTable.GetValue(_index);
}
}
/// <summary>
/// Releases all resources used by the <see cref="Counter{T}"/> instance.
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Releases all unmanaged and optionally managed resources used by the <see cref="Counter{T}"/> instance.
/// </summary>
/// <param name="disposing"><see langword="true"/> to dispose managed resources also; otherwise just unmanaged resources</param>
protected virtual void Dispose(bool disposing)
{
if (!_disposed)
{
try
{
// The index into the EntryTable is essentially an unmanaged resource since we allocate and free the
// resource ourselves.
_countTable.Free(_index);
}
catch (ObjectDisposedException)
{
// Can happen because _countTable may be disposed before the Counter instance.
}
_disposed = true;
}
}
/// <summary>
/// Frees resources used by the <see cref="Counter{T}"/> instance.
/// </summary>
~Counter()
{
Dispose(false);
}
}
}