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| 1 | +using System; |
| 2 | + |
| 3 | +namespace Admin.Core.Common.Helpers |
| 4 | +{ |
| 5 | + public class Snowflake |
| 6 | + { |
| 7 | + //基准时间 |
| 8 | + private static long StartStmp = 1288834974657L; |
| 9 | + //private const long START_STMP = 1480166465631L; |
| 10 | + /*每一部分占用的位数*/ |
| 11 | + //机器标识位数 |
| 12 | + const int MachineIdBits = 5; |
| 13 | + //数据标志位数 |
| 14 | + const int DatacenterIdBits = 5; |
| 15 | + //序列号识位数 |
| 16 | + const int SequenceBits = 12; |
| 17 | + |
| 18 | + /* 每一部分的最大值*/ |
| 19 | + //机器ID最大值 |
| 20 | + const long MaxMachineNum = -1L ^ (-1L << MachineIdBits); |
| 21 | + //数据标志ID最大值 |
| 22 | + const long MaxDatacenterNum = -1L ^ (-1L << DatacenterIdBits); |
| 23 | + //序列号ID最大值 |
| 24 | + private const long MaxSequenceNum = -1L ^ (-1L << SequenceBits); |
| 25 | + |
| 26 | + /*每一部分向左的位移*/ |
| 27 | + //机器ID偏左移12位 |
| 28 | + private const int MachineShift = SequenceBits; |
| 29 | + //数据ID偏左移17位 |
| 30 | + private const int DatacenterIdShift = SequenceBits + MachineIdBits; |
| 31 | + //时间毫秒左移22位 |
| 32 | + public const int TimestampLeftShift = SequenceBits + MachineIdBits + DatacenterIdBits; |
| 33 | + |
| 34 | + |
| 35 | + private long _sequence = 0L;//序列号 |
| 36 | + private long _lastTimestamp = -1L;//上一次时间戳 |
| 37 | + public long MachineId { get; protected set; }//机器标识 |
| 38 | + public long DatacenterId { get; protected set; }//数据中心 |
| 39 | + //public long Sequence = 0L;//序列号 |
| 40 | + //{ |
| 41 | + // get { return _sequence; } |
| 42 | + // internal set { _sequence = value; } |
| 43 | + //} |
| 44 | + |
| 45 | + private readonly DateTime Jan1st1970 = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc); |
| 46 | + private readonly object _lock = new Object(); |
| 47 | + public Snowflake(long machineId, long datacenterId) |
| 48 | + { |
| 49 | + // 如果超出范围就抛出异常 |
| 50 | + if (machineId > MaxMachineNum || machineId < 0) |
| 51 | + { |
| 52 | + throw new ArgumentException(string.Format("machineId 必须大于0，MaxMachineNum： {0}", MaxMachineNum)); |
| 53 | + } |
| 54 | + |
| 55 | + if (datacenterId > MaxDatacenterNum || datacenterId < 0) |
| 56 | + { |
| 57 | + throw new ArgumentException(string.Format("datacenterId必须大于0，且不能大于MaxDatacenterNum： {0}", MaxDatacenterNum)); |
| 58 | + } |
| 59 | + |
| 60 | + //先检验再赋值 |
| 61 | + MachineId = machineId; |
| 62 | + DatacenterId = datacenterId; |
| 63 | + //_sequence = sequence; |
| 64 | + } |
| 65 | + |
| 66 | + //public static Init(long machineId, long datacenterId) |
| 67 | + //{ |
| 68 | + |
| 69 | + //} |
| 70 | + public long NextId() |
| 71 | + { |
| 72 | + lock (_lock) |
| 73 | + { |
| 74 | + var timestamp = TimeGen(); |
| 75 | + if (timestamp < _lastTimestamp) |
| 76 | + { |
| 77 | + throw new Exception(string.Format("时间戳必须大于上一次生成ID的时间戳. 拒绝为{0}毫秒生成id", _lastTimestamp - timestamp)); |
| 78 | + } |
| 79 | + |
| 80 | + //如果上次生成时间和当前时间相同,在同一毫秒内 |
| 81 | + if (_lastTimestamp == timestamp) |
| 82 | + { |
| 83 | + //sequence自增，和sequenceMask相与一下，去掉高位 |
| 84 | + _sequence = (_sequence + 1) & MaxSequenceNum; |
| 85 | + //判断是否溢出,也就是每毫秒内超过1024，当为1024时，与sequenceMask相与，sequence就等于0 |
| 86 | + if (_sequence == 0L) |
| 87 | + { |
| 88 | + //等待到下一毫秒 |
| 89 | + timestamp = TilNextMillis(_lastTimestamp); |
| 90 | + } |
| 91 | + } |
| 92 | + else |
| 93 | + { |
| 94 | + //如果和上次生成时间不同,重置sequence，就是下一毫秒开始，sequence计数重新从0开始累加, |
| 95 | + //为了保证尾数随机性更大一些,最后一位可以设置一个随机数 |
| 96 | + _sequence = 0L;//new Random().Next(10); |
| 97 | + } |
| 98 | + |
| 99 | + _lastTimestamp = timestamp; |
| 100 | + return ((timestamp - StartStmp) << TimestampLeftShift) | (DatacenterId << DatacenterIdShift) | (MachineId << MachineShift) | _sequence; |
| 101 | + } |
| 102 | + } |
| 103 | + |
| 104 | + // 防止产生的时间比之前的时间还要小（由于NTP回拨等问题）,保持增量的趋势. |
| 105 | + protected virtual long TilNextMillis(long lastTimestamp) |
| 106 | + { |
| 107 | + var timestamp = TimeGen(); |
| 108 | + while (timestamp <= lastTimestamp) |
| 109 | + { |
| 110 | + timestamp = TimeGen(); |
| 111 | + } |
| 112 | + return timestamp; |
| 113 | + } |
| 114 | + |
| 115 | + // 获取当前的时间戳 |
| 116 | + protected virtual long TimeGen() |
| 117 | + { |
| 118 | + //return TimeExtensions.CurrentTimeMillis(); |
| 119 | + return (long)(DateTime.UtcNow - Jan1st1970).TotalMilliseconds; |
| 120 | + } |
| 121 | + } |
| 122 | + |
| 123 | + public class IdWorkerHelper |
| 124 | + { |
| 125 | + private static Snowflake _idWorker= null; |
| 126 | + private IdWorkerHelper() |
| 127 | + { |
| 128 | + |
| 129 | + } |
| 130 | + |
| 131 | + static IdWorkerHelper() |
| 132 | + { |
| 133 | + _idWorker = new Snowflake(1, 1); |
| 134 | + } |
| 135 | + |
| 136 | + public static long GenId64() |
| 137 | + { |
| 138 | + return _idWorker.NextId(); |
| 139 | + |
| 140 | + } |
| 141 | + } |
| 142 | + |
| 143 | +} |
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