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  • 常用负载均衡算法及实现

    1.轮询负载均衡算法

     1 /// <summary>
 2     /// 轮询负载均衡算法
 3     /// </summary>
 4     public static class RoundRobin
 5     {
 6         private static object obj = new object();
 7 
 8         static Dictionary<string, int> dic = new Dictionary<string, int>
 9         {
10             { "192.168.1.12", 1},
11             {"192.168.1.13", 1 },
12             { "192.168.1.14", 3},
13             { "192.168.1.15", 1},
14             {"192.168.1.16", 1},
15             {"192.168.1.17", 1 },
16             { "192.168.1.18", 1},
17             { "192.168.1.19", 1}
18         };
19 
20         static int pos = 0;
21         public static string roundRobin()
22         {
23             var keyList = dic.Keys.ToList();
24 
25 
26             string server = null;
27 
28             lock (obj)
29             {
30                 if (pos >= keyList.Count)
31                 {
32                     pos = 0;
33                 }
34                 server = keyList[pos];
35                 pos++;
36             }
37             return server;
38         }
39     }
40 
41 优点：
42    请求分配平均
43 缺点：
44    不能根据机器配置的好坏进行分配
    轮询负载均衡算法

    2.加权轮询负载均衡算法

     1  /// <summary>
 2     /// 加权轮询算法
 3     /// </summary>
 4     public static class WeightRoundRobin
 5     {
 6         private static object obj = new object();
 7         private static int pos = 0;
 8 
 9         static Dictionary<string, int> dic = new Dictionary<string, int>
10         {
11             { "192.168.1.12", 1},
12             {"192.168.1.13", 1 },
13             { "192.168.1.14", 3},
14             { "192.168.1.15", 1},
15             {"192.168.1.16", 1},
16             {"192.168.1.17", 1 },
17             { "192.168.1.18", 1},
18             { "192.168.1.19", 1}
19         };
20 
21         public static string roundRobin()
22         {
23             //獲取ip列表list
24             List<string> it = dic.Keys.ToList();
25 
26             List<String> serverList = new List<string>();
27 
28             foreach (var item in it)
29             {
30                 int weight = 0;
31                 dic.TryGetValue(item, out weight);
32 
33                 for (int i = 0; i < weight; i++)
34                 {
35                     serverList.Add(item);
36                 }
37             }
38 
39             string server = null;
40 
41             lock (obj)
42             {
43                 if (pos >= serverList.Count)
44                 {
45                     pos = 0;
46                 }
47                 server = serverList[pos];
48                 pos++;
49             }
50             return server;
51         }
52 
53     }
    加权轮询算法

    3.加权随机负载均衡算法

     1  /// <summary>
 2     /// 加权随机负载均衡算法
 3     /// </summary>
 4     public static class WeightRandom
 5     {
 6 
 7         static Dictionary<string, int> dic = new Dictionary<string, int>
 8         {
 9             { "192.168.1.12", 1},
10             {"192.168.1.13", 1 },
11             { "192.168.1.14", 3},
12             { "192.168.1.15", 1},
13             {"192.168.1.16", 1},
14             {"192.168.1.17", 1 },
15             { "192.168.1.18", 1},
16             { "192.168.1.19", 1}
17         };
18 
19         public static string weightRandom()
20         {
21             //獲取ip列表list
22             List<string> it = dic.Keys.ToList();
23 
24             List<String> serverList = new List<string>();
25 
26             foreach (var item in it)
27             {
28                 int weight = 0;
29                 dic.TryGetValue(item, out weight);
30 
31                 for (int i = 0; i < weight; i++)
32                 {
33                     serverList.Add(item);
34                 }
35             }
36             Random random = new Random();
37             int randomPos = random.Next(serverList.Count);
38             string server = serverList[randomPos];
39             return server;
40         }
41     }
    加权随机负载均衡算法

    4.IP Hash负载均衡算法

     1    /// <summary>
 2     /// IP Hash负载均衡算法
 3     /// </summary>
 4     public static class IpHash
 5     {
 6         static Dictionary<string, int> dic = new Dictionary<string, int>
 7         {
 8             { "192.168.1.12", 1},
 9             {"192.168.1.13", 1 },
10             { "192.168.1.14", 3},
11             { "192.168.1.15", 1},
12             {"192.168.1.16", 1},
13             {"192.168.1.17", 1 },
14             { "192.168.1.18", 1},
15             { "192.168.1.19", 1}
16         };
17 
18         public static string ipHash(string remoteIp)
19         {
20             List<string> keys = dic.Keys.ToList();
21 
22             int hashCode = Math.Abs(remoteIp.GetHashCode());
23             int serverListSize = keys.Count;
24             int serverPos = hashCode % serverListSize;
25 
26             return keys[serverPos];
27         }
28 
29     }
    IP Hash负载均衡算法

    5.Twitter全局唯一ID生成算法

      1  测试：private static void TestIdWorker()
  2         {
  3             HashSet<long> set = new HashSet<long>();
  4             IdWorker idWorker1 = new IdWorker(0, 0);
  5             IdWorker idWorker2 = new IdWorker(1, 0);
  6             //762884413578018816
  7             //762884520121729024
  8             Stopwatch sw = new Stopwatch();
  9             sw.Start();
 10             for (int i = 0; i < 1; i++)
 11             {
 12                 long id = idWorker1.nextId();
 13                 set.Add(id);
 14                 //if (!set.Add(id))
 15                 //{
 16                 //Console.WriteLine("duplicate:" + id);
 17                 //}
 18             }
 19             sw.Stop();
 20             foreach (var item in set)
 21             {
 22                 Console.WriteLine("结果:" + item);
 23             }
 24             Console.WriteLine("时间:" + sw.ElapsedTicks);
 25             return;
 26 }
 27 
 28 
 29 算法：
 30 
 31  /// <summary>
 32     /// From: https://github.com/twitter/snowflake
 33     /// An object that generates IDs.
 34     /// This is broken into a separate class in case
 35     /// we ever want to support multiple worker threads
 36     /// per process
 37     /// </summary>
 38     public class IdWorker
 39     {
 40         private long workerId;
 41         private long datacenterId;
 42         private long sequence = 0L;
 43 
 44         private static long twepoch = 1288834974657L;
 45 
 46         private static long workerIdBits = 5L;
 47         private static long datacenterIdBits = 5L;
 48         private static long maxWorkerId = -1L ^ (-1L << (int)workerIdBits);
 49         private static long maxDatacenterId = -1L ^ (-1L << (int)datacenterIdBits);
 50         private static long sequenceBits = 12L;
 51 
 52         private long workerIdShift = sequenceBits;
 53         private long datacenterIdShift = sequenceBits + workerIdBits;
 54         private long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits;
 55         private long sequenceMask = -1L ^ (-1L << (int)sequenceBits);
 56 
 57         private long lastTimestamp = -1L;
 58         private static object syncRoot = new object();
 59 
 60         public IdWorker(long workerId, long datacenterId)
 61         {
 62 
 63             // sanity check for workerId
 64             if (workerId > maxWorkerId || workerId < 0)
 65             {
 66                 throw new ArgumentException(string.Format("worker Id can't be greater than %d or less than 0", maxWorkerId));
 67             }
 68             if (datacenterId > maxDatacenterId || datacenterId < 0)
 69             {
 70                 throw new ArgumentException(string.Format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
 71             }
 72             this.workerId = workerId;
 73             this.datacenterId = datacenterId;
 74         }
 75 
 76         public long nextId()
 77         {
 78             lock (syncRoot)
 79             {
 80                 long timestamp = timeGen();
 81 
 82                 if (timestamp < lastTimestamp)
 83                 {
 84                     throw new ApplicationException(string.Format("Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
 85                 }
 86 
 87                 if (lastTimestamp == timestamp)
 88                 {
 89                     sequence = (sequence + 1) & sequenceMask;
 90                     if (sequence == 0)
 91                     {
 92                         timestamp = tilNextMillis(lastTimestamp);
 93                     }
 94                 }
 95                 else
 96                 {
 97                     sequence = 0L;
 98                 }
 99 
100                 lastTimestamp = timestamp;
101 
102                 return ((timestamp - twepoch) << (int)timestampLeftShift) | (datacenterId << (int)datacenterIdShift) | (workerId << (int)workerIdShift) | sequence;
103             }
104         }
105 
106         protected long tilNextMillis(long lastTimestamp)
107         {
108             long timestamp = timeGen();
109             while (timestamp <= lastTimestamp)
110             {
111                 timestamp = timeGen();
112             }
113             return timestamp;
114         }
115 
116         protected long timeGen()
117         {
118             return (long)(DateTime.UtcNow - new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)).TotalMilliseconds;
119         }
120     }
    Twitter全局唯一ID生成算法
     
     
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  • 原文地址：https://www.cnblogs.com/taomylife/p/6392977.html
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