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/*
* Copyright (c) 2023 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Plugins.Essentials
* File: TimestampedCounter.cs
*
* TimestampedCounter.cs is part of VNLib.Plugins.Essentials which is part of the larger
* VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Essentials is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* VNLib.Plugins.Essentials is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
using System;
namespace VNLib.Plugins.Essentials
{
/// <summary>
/// Stucture that allows for convient storage of a counter value
/// and a second precision timestamp into a 64-bit unsigned integer
/// </summary>
public readonly record struct TimestampedCounter(uint Count, uint UnixMs)
{
/// <summary>
/// The time the count was last modifed
/// </summary>
public readonly DateTimeOffset LastModified => DateTimeOffset.FromUnixTimeSeconds(UnixMs);
/// <summary>
/// Compacts and converts the counter value and timestamp into
/// a 64bit unsigned integer
/// </summary>
/// <returns>The uint64 compacted value</returns>
public readonly ulong ToUInt64()
{
//Upper 32 bits time, lower 32 bits count
ulong value = UnixMs;
//Lshift to upper32
value <<= 32;
//Set count as lower32
value |= Count;
return value;
}
/// <summary>
/// The previously compacted <see cref="TimestampedCounter"/>
/// value to cast back to a counter
/// </summary>
/// <param name="value">The uint64 encoded <see cref="TimestampedCounter"/></param>
/// <returns>
/// The decoded <see cref="TimestampedCounter"/> from its
/// compatcted representation
/// </returns>
public static TimestampedCounter FromUInt64(ulong value)
{
//Upper 32 bits time, lower 32 bits count
uint time = (uint)(value >> 32);
uint count = (uint)(value & uint.MaxValue);
return new TimestampedCounter(count, time);
}
/// <summary>
/// Creates a new <see cref="TimestampedCounter"/> from the given counter
/// value and the <see cref="DateTimeOffset"/> unix ms value
/// </summary>
/// <param name="count"></param>
/// <param name="time">The internal time to store in the counter</param>
/// <returns>An initialized <see cref="TimestampedCounter"/></returns>
/// <exception cref="StackOverflowException"></exception>
public static TimestampedCounter FromValues(uint count, DateTimeOffset time)
{
//The time in seconds truncated to a uint32
uint sec = Convert.ToUInt32(time.ToUnixTimeSeconds());
return new TimestampedCounter(count, sec);
}
/// <summary>
/// The previously compacted <see cref="TimestampedCounter"/>
/// value to cast back to a counter
/// </summary>
/// <param name="value"></param>
public static explicit operator TimestampedCounter(ulong value) => FromUInt64(value);
/// <summary>
/// Compacts and converts the counter value and timestamp into
/// a 64bit unsigned integer
/// </summary>
/// <param name="count">The counter to convert</param>
public static explicit operator ulong(TimestampedCounter count) => count.ToUInt64();
}
}
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