Redis学习指南

Posted 2022-06-04 xsddxz

Redis学习指南

一、数据结构

• string(字符串)

• list(列表)

• set(集合)

• hash(散列)

• zset(有序集合)

二、命令列表

2.1 Redis Strings

> set mykey somevalue
OK
> get mykey
"somevalue"

> set counter 100
OK
> incr counter
(integer) 101
> incr counter
(integer) 102
> incrby counter 50
(integer) 152

> mset a 10 b 20 c 30
OK
> mget a b c
1) "10"
2) "20"
3) "30"

> set mykey hello
OK
> exists mykey
(integer) 1
> del mykey
(integer) 1
> exists mykey
(integer) 0

> set mykey x
OK
> type mykey
string
> del mykey
(integer) 1
> type mykey
none

> set key some-value
OK
> expire key 5
(integer) 1
> get key (immediately)
"some-value"
> get key (after some time)
(nil)

> set key 100 ex 10
OK
> ttl key
(integer) 9

2.2 Redis Lists

> rpush mylist A
(integer) 1
> rpush mylist B
(integer) 2
> lpush mylist first
(integer) 3
> lrange mylist 0 -1
1) "first"
2) "A"
3) "B"

> rpush mylist 1 2 3 4 5 "foo bar"
(integer) 9
> lrange mylist 0 -1
1) "first"
2) "A"
3) "B"
4) "1"
5) "2"
6) "3"
7) "4"
8) "5"
9) "foo bar"

> rpush mylist a b c
(integer) 3
> rpop mylist
"c"
> rpop mylist
"b"
> rpop mylist
"a"

> rpush mylist 1 2 3 4 5
(integer) 5
> ltrim mylist 0 2
OK
> lrange mylist 0 -1
1) "1"
2) "2"
3) "3"

> brpop tasks 5
1) "tasks"
2) "do_something"

2.3 Redis Hashes

> hmset user:1000 username antirez birthyear 1977 verified 1
OK
> hget user:1000 username
"antirez"
> hget user:1000 birthyear
"1977"
> hgetall user:1000
1) "username"
2) "antirez"
3) "birthyear"
4) "1977"
5) "verified"
6) "1"

> hmget user:1000 username birthyear no-such-field
1) "antirez"
2) "1977"
3) (nil)

> hincrby user:1000 birthyear 10
(integer) 1987
> hincrby user:1000 birthyear 10
(integer) 1997

2.4 Redis Sets

> sadd myset 1 2 3
(integer) 3
> smembers myset
1. 3
2. 1
3. 2

2.5 Redis Sorted Sets

> zadd hackers 1940 "Alan Kay"
(integer) 1
> zadd hackers 1957 "Sophie Wilson"
(integer) 1
> zadd hackers 1953 "Richard Stallman"
(integer) 1
> zadd hackers 1949 "Anita Borg"
(integer) 1
> zadd hackers 1965 "Yukihiro Matsumoto"
(integer) 1
> zadd hackers 1914 "Hedy Lamarr"
(integer) 1
> zadd hackers 1916 "Claude Shannon"
(integer) 1
> zadd hackers 1969 "Linus Torvalds"
(integer) 1
> zadd hackers 1912 "Alan Turing"
(integer) 1
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> zrange hackers 0 -1
1) "Alan Turing"
2) "Hedy Lamarr"
3) "Claude Shannon"
4) "Alan Kay"
5) "Anita Borg"
6) "Richard Stallman"
7) "Sophie Wilson"
8) "Yukihiro Matsumoto"
9) "Linus Torvalds"

 

三、应用示例

3.1 分布式锁

需要安装nuget包：StackExchange.Redis。

using StackExchange.Redis;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
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namespace Redlock.CSharp

    public class Lock
    
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        public Lock(RedisKey resource, RedisValue val, TimeSpan validity)
        
            this.resource = resource;
            this.val = val ;
            this.validity_time = validity;
        
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        private RedisKey resource;
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        private RedisValue val;
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        private TimeSpan validity_time;
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        public RedisKey Resource  get  return resource;  
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        public RedisValue Value  get  return val;  
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        public TimeSpan Validity  get  return validity_time;  
    

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using StackExchange.Redis;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
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namespace Redlock.CSharp

    public class Redlock
    
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        public Redlock(params ConnectionMultiplexer[] list)
         
            foreach(var item in list)
                this.redisMasterDictionary.Add(item.GetEndPoints().First().ToString(),item);
        
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        const int DefaultRetryCount = 3;
        readonly TimeSpan DefaultRetryDelay = new TimeSpan(0, 0, 0, 0, 200);
        const double ClockDriveFactor = 0.01;
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        protected int Quorum  get  return (redisMasterDictionary.Count / 2) + 1;  
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        /// <summary>
        /// String containing the Lua unlock script.
        /// </summary>
        const String UnlockScript = @"
            if redis.call(""get"",KEYS[1]) == ARGV[1] then
                return redis.call(""del"",KEYS[1])
            else
                return 0
            end";
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        protected static byte[] CreateUniqueLockId()
        
            return Guid.NewGuid().ToByteArray();
        
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        protected Dictionary<String,ConnectionMultiplexer> redisMasterDictionary = new Dictionary<string,ConnectionMultiplexer>();
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        //TODO: Refactor passing a ConnectionMultiplexer
        protected bool LockInstance(string redisServer, string resource, byte[] val, TimeSpan ttl)
        
            
            bool succeeded;
            try
            
                var redis = this.redisMasterDictionary[redisServer];
                succeeded = redis.GetDatabase().StringSet(resource, val, ttl, When.NotExists);
            
            catch (Exception)
            
                succeeded = false;
            
            return succeeded;
        
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        //TODO: Refactor passing a ConnectionMultiplexer
        protected void UnlockInstance(string redisServer, string resource, byte[] val)
        
            RedisKey[] key =  resource ;
            RedisValue[] values =  val ;
            var redis = redisMasterDictionary[redisServer];
            redis.GetDatabase().ScriptEvaluate(
                UnlockScript, 
                key,
                values
                );
        
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        public bool Lock(RedisKey resource, TimeSpan ttl, out Lock lockObject)
        
            var val = CreateUniqueLockId();
            Lock innerLock = null;
            bool successfull = retry(DefaultRetryCount, DefaultRetryDelay, () =>
            
                try
                
                    int n = 0;
                    var startTime = DateTime.Now;
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                    // Use keys
                    for_each_redis_registered(
                        redis =>
                        
                            if (LockInstance(redis, resource, val, ttl)) n += 1;
                        
                    );
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                    /*
                     * Add 2 milliseconds to the drift to account for Redis expires
                     * precision, which is 1 millisecond, plus 1 millisecond min drift 
                     * for small TTLs.        
                     */
                    var drift = Convert.ToInt32((ttl.TotalMilliseconds * ClockDriveFactor) + 2);
                    var validity_time = ttl - (DateTime.Now - startTime) - new TimeSpan(0, 0, 0, 0, drift);
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                    if (n >= Quorum && validity_time.TotalMilliseconds > 0)
                    
                        innerLock = new Lock(resource, val, validity_time);
                        return true;
                    
                    else
                    
                        for_each_redis_registered(
                            redis =>
                            
                                UnlockInstance(redis, resource, val);
                            
                        );
                        return false;
                    
                
                catch (Exception)
                 return false; 
            );
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            lockObject = innerLock;
            return successfull;
        
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        protected void for_each_redis_registered(Action<ConnectionMultiplexer> action)
        
            foreach (var item in redisMasterDictionary)
            
                action(item.Value);
            
        
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        protected void for_each_redis_registered(Action<String> action)
        
            foreach (var item in redisMasterDictionary)
            
                action(item.Key);
            
        
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        protected bool retry(int retryCount, TimeSpan retryDelay, Func<bool> action)
        
            int maxRetryDelay = (int)retryDelay.TotalMilliseconds;
            Random rnd = new Random();
            int currentRetry = 0;
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            while (currentRetry++ < retryCount)
            
                if (action()) return true;
                Thread.Sleep(rnd.Next(maxRetryDelay));
            
            return false;
        
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        public void Unlock(Lock lockObject)
        
            for_each_redis_registered(redis =>
                
                    UnlockInstance(redis, lockObject.Resource, lockObject.Value);
                );
        
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        public override string ToString()
        
            StringBuilder sb = new StringBuilder();
            sb.AppendLine(this.GetType().FullName);
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            sb.AppendLine("Registered Connections:");
            foreach(var item in redisMasterDictionary)
            
                sb.AppendLine(item.Value.GetEndPoints().First().ToString());
            
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            return sb.ToString();
        
    

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