MQTTnet/Source/MQTTnet/MqttPacketIdentifierProvider.cs

// 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.

namespace MQTTnet;

public sealed class MqttPacketIdentifierProvider
{
    readonly object _syncRoot = new();

    ushort _value;

    public ushort GetNextPacketIdentifier()
    {
        lock (_syncRoot)
        {
            _value++;

            if (_value == 0)
            {
                // As per official MQTT documentation the package identifier should never be 0.
                _value = 1;
            }

            return _value;
        }
    }

    public void Reset()
    {
        lock (_syncRoot)
        {
            _value = 0;
        }
    }
}