MasstransferExporter/MasstransferCommon/Utils/SnowflakeId.cs

103 lines
2.9 KiB
C#

namespace MasstransferCommon.Utils;
using System;
public class SnowflakeId
{
private static readonly DateTime Epoch = new DateTime(2020, 1, 1, 0, 0, 0, DateTimeKind.Utc);
private const int WorkerIdBits = 5;
private const int DatacenterIdBits = 5;
private const int SequenceBits = 12;
private const long MaxWorkerId = -1L ^ (-1L << WorkerIdBits);
private const long MaxDatacenterId = -1L ^ (-1L << DatacenterIdBits);
private const long WorkerIdShift = SequenceBits;
private const long DatacenterIdShift = SequenceBits + WorkerIdBits;
private const long TimestampLeftShift = SequenceBits + WorkerIdBits + DatacenterIdBits;
private const long SequenceMask = -1L ^ (-1L << SequenceBits);
private readonly object _lock = new object();
private long _lastTimestamp = -1L;
private long _sequence = 0L;
private static readonly SnowflakeId Instance = new SnowflakeId(0, 0);
public long WorkerId { get; }
public long DatacenterId { get; }
public SnowflakeId(long workerId, long datacenterId)
{
if (workerId > MaxWorkerId || workerId < 0)
{
throw new ArgumentException($"workerId must be between 0 and {MaxWorkerId}");
}
if (datacenterId > MaxDatacenterId || datacenterId < 0)
{
throw new ArgumentException($"datacenterId must be between 0 and {MaxDatacenterId}");
}
WorkerId = workerId;
DatacenterId = datacenterId;
}
public static string GetNextId()
{
return Instance.NextId().ToString();
}
private long NextId()
{
lock (_lock)
{
var timestamp = TimeGen();
if (timestamp < _lastTimestamp)
{
throw new InvalidOperationException("Clock moved backwards. Refusing to generate id");
}
if (_lastTimestamp == timestamp)
{
_sequence = (_sequence + 1) & SequenceMask;
if (_sequence == 0)
{
timestamp = TilNextMillis(_lastTimestamp);
}
}
else
{
_sequence = 0L;
}
_lastTimestamp = timestamp;
return ((timestamp - EpochTicks()) << (int)TimestampLeftShift) |
(DatacenterId << (int)DatacenterIdShift) |
(WorkerId << (int)WorkerIdShift) |
_sequence;
}
}
private long TilNextMillis(long lastTimestamp)
{
var timestamp = TimeGen();
while (timestamp <= lastTimestamp)
{
timestamp = TimeGen();
}
return timestamp;
}
private long TimeGen()
{
return (long)(DateTime.UtcNow - Epoch).TotalMilliseconds;
}
private static long EpochTicks()
{
return (long)(Epoch - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;
}
}