APP
Redis
redis是一種非關(guān)系型數(shù)據(jù)庫(關(guān)系型數(shù)據(jù)庫即SQL server,MySQL等),但多用于緩存技術(shù).因?yàn)樗且环N內(nèi)存告訴緩存數(shù)據(jù)庫,存儲(chǔ)數(shù)據(jù)的方式為Key-value,即鍵值對(duì).而且redis還支持多種數(shù)據(jù)類型,如:string、list、set、zset(sorted set)、hash。
redis特點(diǎn):
①redis以內(nèi)存作為存儲(chǔ)的介質(zhì),讀寫速率極高,遠(yuǎn)超過數(shù)據(jù)庫,
②redis跟memcache不同,redis存儲(chǔ)的數(shù)據(jù)是持久化的,不會(huì)因?yàn)閿嚯娭貑⒃斐傻臄?shù)據(jù)丟失.(reids的存儲(chǔ)分為內(nèi)存存儲(chǔ),磁盤存儲(chǔ)和log文件三部分,重啟后,redis從磁盤重新將數(shù)據(jù)加載到內(nèi)存中,再通過配置文件對(duì)其進(jìn)行配置,持久化的原因)
③redis可以配置集群,就像一些大公司的服務(wù)器一樣,它可以建立多個(gè)redis用來緩存,而且redis不在客戶端,也不再服務(wù)端,是一個(gè)獨(dú)立的部分
redis兩種文件格式:
①全量數(shù)據(jù):是把內(nèi)存中的數(shù)據(jù)寫入磁盤,便于下次讀取文件進(jìn)行夾雜
②增量請(qǐng)求:是將內(nèi)存中的數(shù)據(jù)序列化為操作請(qǐng)求,用于讀取文件進(jìn)行replay得到數(shù)據(jù),序列化的操作包括SET,RPUSH,SADD,ZADD
1. 要進(jìn)行Master-slave配置，出現(xiàn)服務(wù)故障時(shí)可以支持切換。
2. 在master側(cè)禁用數(shù)據(jù)持久化，只需在slave上配置數(shù)據(jù)持久化。
3. 物理內(nèi)存+虛擬內(nèi)存不足，這個(gè)時(shí)候dump一直死著，時(shí)間久了機(jī)器掛掉。這個(gè)情況就是災(zāi)難！
4. 當(dāng)Redis物理內(nèi)存使用超過內(nèi)存總?cè)萘康?/5時(shí)就會(huì)開始比較危險(xiǎn)了，就開始做swap,內(nèi)存碎片大
5. 當(dāng)達(dá)到最大內(nèi)存時(shí)，會(huì)清空帶有過期時(shí)間的key，即使key未到過期時(shí)間.
6. redis與DB同步寫的問題，先寫DB，后寫redis，因?yàn)閷憙?nèi)存基本上沒有問題
Redis的安裝:
包地址:https://files.cnblogs.com/files/lbjlbj/Redis3.7z
運(yùn)行->cmd->CD C: edis(C: edis CD 進(jìn)入到盤符(記得有空格),上面那個(gè)解壓后把它改名為redis,放到了C盤,也可以放其他盤)
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set auth 密碼名,是用來設(shè)置密碼.(如果忘記了密碼:redis文件夾下redis.windows-service.conf記事本打開CTRL+F requirepass 即可)
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redis在C#中的實(shí)際用法:
******在使用redis緩存時(shí),須先啟動(dòng)服務(wù)器,CD C: edis redis-server.exe?redis.windows.conf
dll文件:https://files.cnblogs.com/files/lbjlbj/dll.7z
可能會(huì)存在ConfigurationManager會(huì)報(bào)錯(cuò),還需自行搜索添加引用,
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奉上一個(gè)封裝好的Helper類
using StackExchange.Redis;
using System;
using System.Collections.Generic;
using System.Configuration;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Newtonsoft.Json;
namespace ConsoleApp1
{
/// <summary>
/// Redis 操作類
/// </summary>
public class RedisHelper
{
/// <summary>
/// 連接字符串
/// </summary>
private static readonly string ConnectionString = ConfigurationManager.ConnectionStrings["RedisConnectionString"].ConnectionString;
/// <summary>
/// 鎖
/// </summary>
private readonly object _lock = new object();
/// <summary>
/// 連接對(duì)象
/// </summary>
private volatile IConnectionMultiplexer _connection;
/// <summary>
/// 數(shù)據(jù)庫
/// </summary>
private IDatabase _db;
public RedisHelper()
{
_connection = ConnectionMultiplexer.Connect(ConnectionString);
_db = GetDatabase();
}
/// <summary>
/// 獲取連接
/// </summary>
/// <returns></returns>
protected IConnectionMultiplexer GetConnection()
{
if (_connection != null && _connection.IsConnected)
{
return _connection;
}
lock (_lock)
{
if (_connection != null && _connection.IsConnected)
{
return _connection;
}
if (_connection != null)
{
_connection.Dispose();
}
_connection = ConnectionMultiplexer.Connect(ConnectionString);
}
return _connection;
}
/// <summary>
/// 獲取數(shù)據(jù)庫
/// </summary>
/// <param name="db"></param>
/// <returns></returns>
public IDatabase GetDatabase(int? db = null)
{
return GetConnection().GetDatabase(db ?? -1);
}
/// <summary>
/// 設(shè)置
/// </summary>
/// <param name="key">鍵</param>
/// <param name="data">值</param>
/// <param name="cacheTime">時(shí)間</param>
public virtual void Set(string key, object data, int cacheTime)
{
if (data == null)
{
return;
}
var entryBytes = Serialize(data);
var expiresIn = TimeSpan.FromMinutes(cacheTime);
_db.StringSet(key, entryBytes, expiresIn);
}
/// <summary>
/// 根據(jù)鍵獲取值
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="key"></param>
/// <returns></returns>
public virtual T Get<T>(string key)
{
var rValue = _db.StringGet(key);
if (!rValue.HasValue)
{
return default(T);
}
var result = Deserialize<T>(rValue);
return result;
}
/// <summary>
/// 反序列化
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="serializedObject"></param>
/// <returns></returns>
protected virtual T Deserialize<T>(byte[] serializedObject)
{
if (serializedObject == null)
{
return default(T);
}
var json = Encoding.UTF8.GetString(serializedObject);
return JsonConvert.DeserializeObject<T>(json);
}
/// <summary>
/// 判斷是否已經(jīng)設(shè)置
/// </summary>
/// <param name="key"></param>
/// <returns></returns>
public virtual bool IsSet(string key)
{
return _db.KeyExists(key);
}
/// <summary>
/// 序列化
/// </summary>
/// <param name="data"></param>
/// <returns>byte[]</returns>
private byte[] Serialize(object data)
{
var json = JsonConvert.SerializeObject(data);
return Encoding.UTF8.GetBytes(json);
}
}
}
AppConfig中配置:
<connectionStrings>
<add name="RedisConnectionString" connectionString="localhost"/>
</connectionStrings>
最后功能實(shí)現(xiàn):
class Program
{
static void Main(string[] args)
{
var s = "a";
//RedisCacheHelper.Add("abc",s,DateTime.Now.AddDays(1));
//Console.WriteLine("ok");
//Console.WriteLine(RedisCacheHelper.Get<string>("abc"));
new RedisHelper().Set("abc", s, 10);
Console.WriteLine("ok");
Console.ReadKey();
}
}
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本文摘自 ：https://www.cnblogs.com/
