// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Diagnostics.Metrics;
 
#nullable enable
 
namespace Microsoft.AspNetCore;
 
internal sealed class PinnedBlockMemoryPoolMetrics
{
    public const string MeterName = "Microsoft.AspNetCore.MemoryPool";
 
    private readonly Meter _meter;
    private readonly UpDownCounter<long> _currentMemory;
    private readonly Counter<long> _totalAllocatedMemory;
    private readonly Counter<long> _evictedMemory;
    private readonly Counter<long> _totalRented;
 
    public PinnedBlockMemoryPoolMetrics(IMeterFactory meterFactory)
    {
        _meter = meterFactory.Create(MeterName);
 
        _currentMemory = _meter.CreateUpDownCounter<long>(
            "aspnetcore.memorypool.current_memory",
            unit: "{bytes}",
            description: "Number of bytes that are currently pooled by the pool.");
 
        _totalAllocatedMemory = _meter.CreateCounter<long>(
           "aspnetcore.memorypool.total_allocated",
            unit: "{bytes}",
            description: "Total number of allocations made by the pool.");
 
        _evictedMemory = _meter.CreateCounter<long>(
           "aspnetcore.memorypool.evicted_memory",
            unit: "{bytes}",
            description: "Total number of bytes that have been evicted.");
 
        _totalRented = _meter.CreateCounter<long>(
            "aspnetcore.memorypool.total_rented",
            unit: "{bytes}",
            description: "Total number of rented bytes from the pool.");
    }
 
    public void UpdateCurrentMemory(int bytes)
    {
        _currentMemory.Add(bytes);
    }
 
    public void IncrementTotalMemory(int bytes)
    {
        _totalAllocatedMemory.Add(bytes);
    }
 
    public void EvictBlock(int bytes)
    {
        _evictedMemory.Add(bytes);
    }
 
    public void Rent(int bytes)
    {
        _totalRented.Add(bytes);
    }
}