一个简单的用C#实现的分布式雪花ID算法

雪花ID是一个依赖时间戳根据算法生成的一个Int64的数字ID，一般用来做主键或者订单号等。以下是一个用C#写的雪花ID的简单实现方法

using System;
using System.Collections.Concurrent;
using System.Diagnostics;public class SnowflakeIdGenerator
{// 配置常量private const int SignBits = 1;// 符号位private const int TimestampBits = 41;// 时间戳位，最大值2^41-1=2,147,483,647ms，69年private const int DataCenterIdBits = 4;// 数据中心ID位，最大值2^4-1=15private const int MachineIdBits = 6;// 机器ID位，最大值2^6-1=63private const int DefaultSequenceBits = 12;// 自增序号位，最大值2^12-1=4095private const int ProcessIdBits = 4;// 进程ID位，最大值2^4-1=15private const int SequenceBitsWithProcess = 8;//如果使用进程ID，则为8位，否则为12位，最大值2^8-1=255// 位移计算常量private const int TimestampShift = 64 - SignBits - TimestampBits;private const int DataCenterShift = TimestampShift - DataCenterIdBits;private const int MachineShift = DataCenterShift - MachineIdBits;private const int ProcessShift = SequenceBitsWithProcess;// 基准时间private static readonly DateTime Epoch = new(2025, 3, 1, 0, 0, 0, DateTimeKind.Utc);private const long MaxTimestamp = (1L << TimestampBits) - 1;// 单例存储private static readonly ConcurrentDictionary<string, SnowflakeIdGenerator> _instances = new();// 各ID最大值private readonly long _maxDataCenterId = (1 << DataCenterIdBits) - 1;private readonly long _maxMachineId = (1 << MachineIdBits) - 1;private readonly long _maxProcessId = (1 << ProcessIdBits) - 1;private readonly long _maxSequence;// 状态控制private readonly object _lock = new object();private long _lastTimestamp = -1L;private int _sequence = 0;// 节点信息public int DataCenterId { get; }// 数据中心IDpublic int MachineId { get; }// 机器IDpublic int ProcessId { get; }// 进程IDpublic bool UseProcessId { get; }// 是否使用进程IDprivate SnowflakeIdGenerator(int dataCenterId, int machineId, int processId){// 参数校验逻辑ValidateId(dataCenterId, (1 << DataCenterIdBits) - 1, nameof(dataCenterId));ValidateId(machineId, (1 << MachineIdBits) - 1, nameof(machineId));UseProcessId = processId != 0;if (UseProcessId){ValidateId(processId, (1 << ProcessIdBits) - 1, nameof(processId));}DataCenterId = dataCenterId;MachineId = machineId;ProcessId = processId;}public static SnowflakeIdGenerator GetInstance(int dataCenterId, int machineId, int processId = 0){var key = $"{dataCenterId}-{machineId}-{processId}";return _instances.GetOrAdd(key, _ => new SnowflakeIdGenerator(dataCenterId, machineId, processId));}/// <summary>/// 产生下一个ID/// </summary>/// <returns></returns>public long NextId(){lock (_lock){var timestamp = GetValidTimestamp();if (timestamp == _lastTimestamp){_sequence++;if (_sequence > MaxSequence){timestamp = WaitNextMillis(timestamp);_sequence = 0;}}else{_sequence = 0;}_lastTimestamp = timestamp;return BuildId(timestamp);}}/// <summary>/// 获取最大序号/// </summary>private int MaxSequence => UseProcessId ?(1 << SequenceBitsWithProcess) - 1 :(1 << DefaultSequenceBits) - 1;/// <summary>/// 拼接生成ID/// </summary>/// <param name="timestamp"></param>/// <returns></returns>private long BuildId(long timestamp){var id = (timestamp << TimestampShift)| ((long)DataCenterId << DataCenterShift)| ((long)MachineId << MachineShift);if (UseProcessId){return id | ((long)ProcessId << ProcessShift) | (uint)_sequence;}return id | (uint)_sequence;}/// <summary>/// 获取有效的时间戳，防止时间回拨或系统时钟溢出/// </summary>/// <returns></returns>/// <exception cref="InvalidOperationException"></exception>private long GetValidTimestamp(){var timestamp = (DateTimeOffset.UtcNow.Ticks - Epoch.Ticks) / TimeSpan.TicksPerMillisecond;if (timestamp < _lastTimestamp){throw new InvalidOperationException($"Clock moved backwards. Refusing to generate ID for {_lastTimestamp - timestamp}ms");}if (timestamp > MaxTimestamp){throw new InvalidOperationException($"System clock overflow. Timestamp exceeds {TimestampBits} bits.");}return timestamp;}// 等待下一毫秒，产生新的时间戳private static long WaitNextMillis(long currentTimestamp){long timestamp;var spinWait = new SpinWait();do{spinWait.SpinOnce();timestamp = (DateTimeOffset.UtcNow.Ticks - Epoch.Ticks) / TimeSpan.TicksPerMillisecond;} while (timestamp <= currentTimestamp);return timestamp;}// 校验ID，必须在0到最大值之间private static void ValidateId(int value, long maxValue, string paramName){if (value < 0 || value > maxValue){throw new ArgumentOutOfRangeException(paramName,$"Value must be between 0 and {maxValue}");}}
}

调用方式

 //获取单例实例var generator = SnowflakeIdGenerator.GetInstance(dataCenterId: 1, machineId: 5);//推荐long id = generator.NextId();//或者，加入进程IDvar generator = SnowflakeIdGenerator.GetInstance(dataCenterId: 1, machineId: 5, processId: 10);long id = generator.NextId();