120 lines
3.5 KiB
C#
120 lines
3.5 KiB
C#
using System.Security.Cryptography;
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namespace Fleet.Core;
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public enum NodeLogLevel
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{
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Info,
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Warn,
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Error,
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}
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/// <summary>节点日志：字段名统一为 logfmt（<c>ts level msg agent probe session task result err</c>）。逐包事件不记录，只累加计数。</summary>
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public interface INodeLog
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{
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void Write(NodeLogLevel level, string message, params (string Key, object? Value)[] fields);
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}
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public sealed class NullNodeLog : INodeLog
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{
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public static NullNodeLog Instance { get; } = new();
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public void Write(NodeLogLevel level, string message, params (string Key, object? Value)[] fields)
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{
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}
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}
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public static class NodeLogExtensions
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{
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public static void Info(this INodeLog log, string message, params (string Key, object? Value)[] fields) => log.Write(NodeLogLevel.Info, message, fields);
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public static void Warn(this INodeLog log, string message, params (string Key, object? Value)[] fields) => log.Write(NodeLogLevel.Warn, message, fields);
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public static void Error(this INodeLog log, string message, params (string Key, object? Value)[] fields) => log.Write(NodeLogLevel.Error, message, fields);
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}
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/// <summary>指数退避（带随机抖动）：1 s → 20 s（对端恢复之后最多等 20 秒；节点数量不大，重连风暴不是问题）。连接成功之后调用 <see cref="Reset"/>。</summary>
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public sealed class Backoff
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{
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private readonly TimeSpan _initial;
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private readonly TimeSpan _max;
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private int _attempt;
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public Backoff(TimeSpan? initial = null, TimeSpan? max = null)
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{
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_initial = initial ?? TimeSpan.FromSeconds(1);
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_max = max ?? TimeSpan.FromSeconds(20);
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}
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public TimeSpan Next()
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{
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double baseMs = Math.Min(_max.TotalMilliseconds, _initial.TotalMilliseconds * Math.Pow(2, Math.Min(_attempt, 20)));
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_attempt++;
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// 抖动：0.5 ~ 1.0 倍，避免所有节点同时重连
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double jitter = 0.5 + (RandomNumberGenerator.GetInt32(0, 1000) / 2000.0);
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return TimeSpan.FromMilliseconds(baseMs * jitter);
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}
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public void Reset() => _attempt = 0;
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}
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/// <summary>
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/// 序号重放窗口（滑动 1024 位）：同一个序号只接受一次；比窗口还旧的序号视为重放。
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/// 用于数据面的 UDP 包，每个 (session, stream) 一个。
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/// </summary>
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public sealed class ReplayWindow
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{
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private const int Size = 1024;
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private readonly ulong[] _bits = new ulong[Size / 64];
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private long _highest = -1;
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public bool TryAccept(uint seq)
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{
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if (_highest < 0)
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{
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_highest = seq;
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Set(seq);
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return true;
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}
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if (seq > _highest)
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{
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long shift = seq - _highest;
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if (shift >= Size)
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{
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Array.Clear(_bits);
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}
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else
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{
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for (long s = _highest + 1; s <= seq; s++)
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{
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Clear((uint)s);
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}
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}
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_highest = seq;
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Set(seq);
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return true;
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}
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if (_highest - seq >= Size)
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{
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return false; // 太旧
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}
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if (IsSet(seq))
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{
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return false; // 重复
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}
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Set(seq);
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return true;
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}
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private void Set(uint seq) => _bits[(int)(seq % Size) / 64] |= 1UL << (int)(seq % 64);
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private void Clear(uint seq) => _bits[(int)(seq % Size) / 64] &= ~(1UL << (int)(seq % 64));
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private bool IsSet(uint seq) => (_bits[(int)(seq % Size) / 64] & (1UL << (int)(seq % 64))) != 0;
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}
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