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詳解Asp.net Core 使用Redis存儲(chǔ)Session

更新時(shí)間：2016年12月07日 14:18:17 作者：韓天偉

本篇文章主要介紹了Asp.net Core 使用Redis存儲(chǔ)Session ，小編覺得挺不錯(cuò)的，現(xiàn)在分享給大家，也給大家做個(gè)參考。一起跟隨小編過來看看吧。

前言

Asp.net Core 改變了之前的封閉，現(xiàn)在開源且開放，下面我們來用Redis存儲(chǔ)Session來做一個(gè)簡(jiǎn)單的測(cè)試，或者叫做中間件（middleware）。

對(duì)于Session來說褒貶不一，很多人直接說不要用，也有很多人在用，這個(gè)也沒有絕對(duì)的這義，個(gè)人認(rèn)為只要不影什么且又可以方便實(shí)現(xiàn)的東西是可以用的，現(xiàn)在不對(duì)可不可用做表態(tài)，我們只關(guān)心實(shí)現(xiàn)。

類庫引用

這個(gè)相對(duì)于之前的.net是方便了不少，需要在project.json中的dependencies節(jié)點(diǎn)中添加如下內(nèi)容：

  "StackExchange.Redis": "1.1.604-alpha",
  "Microsoft.AspNetCore.Session": "1.1.0-alpha1-21694"

Redis實(shí)現(xiàn)

這里并非我實(shí)現(xiàn)，而是借用不知道為什么之前還有這個(gè)類庫，而現(xiàn)在NUGET止沒有了，為了不影響日后升級(jí)我的命名空間也用 Microsoft.Extensions.Caching.Redis

可以看到微軟這里有四個(gè)類，其實(shí)我們只需要三個(gè)，第四個(gè)拿過來反而會(huì)出錯(cuò)：

using System;
using System.Threading.Tasks;
using Microsoft.Extensions.Caching.Distributed;
using Microsoft.Extensions.Options;
using StackExchange.Redis;

namespace Microsoft.Extensions.Caching.Redis
{
  public class RedisCache : IDistributedCache, IDisposable
  {
    // KEYS[1] = = key
    // ARGV[1] = absolute-expiration - ticks as long (-1 for none)
    // ARGV[2] = sliding-expiration - ticks as long (-1 for none)
    // ARGV[3] = relative-expiration (long, in seconds, -1 for none) - Min(absolute-expiration - Now, sliding-expiration)
    // ARGV[4] = data - byte[]
    // this order should not change LUA script depends on it
    private const string SetScript = (@"
        redis.call('HMSET', KEYS[1], 'absexp', ARGV[1], 'sldexp', ARGV[2], 'data', ARGV[4])
        if ARGV[3] ~= '-1' then
         redis.call('EXPIRE', KEYS[1], ARGV[3])
        end
        return 1");
    private const string AbsoluteExpirationKey = "absexp";
    private const string SlidingExpirationKey = "sldexp";
    private const string DataKey = "data";
    private const long NotPresent = -1;

    private ConnectionMultiplexer _connection;
    private IDatabase _cache;

    private readonly RedisCacheOptions _options;
    private readonly string _instance;

    public RedisCache(IOptions<RedisCacheOptions> optionsAccessor)
    {
      if (optionsAccessor == null)
      {
        throw new ArgumentNullException(nameof(optionsAccessor));
      }

      _options = optionsAccessor.Value;

      // This allows partitioning a single backend cache for use with multiple apps/services.
      _instance = _options.InstanceName ?? string.Empty;
    }

    public byte[] Get(string key)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      return GetAndRefresh(key, getData: true);
    }

    public async Task<byte[]> GetAsync(string key)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      return await GetAndRefreshAsync(key, getData: true);
    }

    public void Set(string key, byte[] value, DistributedCacheEntryOptions options)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      if (value == null)
      {
        throw new ArgumentNullException(nameof(value));
      }

      if (options == null)
      {
        throw new ArgumentNullException(nameof(options));
      }

      Connect();

      var creationTime = DateTimeOffset.UtcNow;

      var absoluteExpiration = GetAbsoluteExpiration(creationTime, options);

      var result = _cache.ScriptEvaluate(SetScript, new RedisKey[] { _instance + key },
        new RedisValue[]
        {
            absoluteExpiration?.Ticks ?? NotPresent,
            options.SlidingExpiration?.Ticks ?? NotPresent,
            GetExpirationInSeconds(creationTime, absoluteExpiration, options) ?? NotPresent,
            value
        });
    }

    public async Task SetAsync(string key, byte[] value, DistributedCacheEntryOptions options)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      if (value == null)
      {
        throw new ArgumentNullException(nameof(value));
      }

      if (options == null)
      {
        throw new ArgumentNullException(nameof(options));
      }

      await ConnectAsync();

      var creationTime = DateTimeOffset.UtcNow;

      var absoluteExpiration = GetAbsoluteExpiration(creationTime, options);

      await _cache.ScriptEvaluateAsync(SetScript, new RedisKey[] { _instance + key },
        new RedisValue[]
        {
            absoluteExpiration?.Ticks ?? NotPresent,
            options.SlidingExpiration?.Ticks ?? NotPresent,
            GetExpirationInSeconds(creationTime, absoluteExpiration, options) ?? NotPresent,
            value
        });
    }

    public void Refresh(string key)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      GetAndRefresh(key, getData: false);
    }

    public async Task RefreshAsync(string key)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      await GetAndRefreshAsync(key, getData: false);
    }

    private void Connect()
    {
      if (_connection == null)
      {
        _connection = ConnectionMultiplexer.Connect(_options.Configuration);
        _cache = _connection.GetDatabase();
      }
    }

    private async Task ConnectAsync()
    {
      if (_connection == null)
      {
        _connection = await ConnectionMultiplexer.ConnectAsync(_options.Configuration);
        _cache = _connection.GetDatabase();
      }
    }

    private byte[] GetAndRefresh(string key, bool getData)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      Connect();

      // This also resets the LRU status as desired.
      // TODO: Can this be done in one operation on the server side? Probably, the trick would just be the DateTimeOffset math.
      RedisValue[] results;
      if (getData)
      {
        results = _cache.HashMemberGet(_instance + key, AbsoluteExpirationKey, SlidingExpirationKey, DataKey);
      }
      else
      {
        results = _cache.HashMemberGet(_instance + key, AbsoluteExpirationKey, SlidingExpirationKey);
      }

      // TODO: Error handling
      if (results.Length >= 2)
      {
        // Note we always get back two results, even if they are all null.
        // These operations will no-op in the null scenario.
        DateTimeOffset? absExpr;
        TimeSpan? sldExpr;
        MapMetadata(results, out absExpr, out sldExpr);
        Refresh(key, absExpr, sldExpr);
      }

      if (results.Length >= 3 && results[2].HasValue)
      {
        return results[2];
      }

      return null;
    }

    private async Task<byte[]> GetAndRefreshAsync(string key, bool getData)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      await ConnectAsync();

      // This also resets the LRU status as desired.
      // TODO: Can this be done in one operation on the server side? Probably, the trick would just be the DateTimeOffset math.
      RedisValue[] results;
      if (getData)
      {
        results = await _cache.HashMemberGetAsync(_instance + key, AbsoluteExpirationKey, SlidingExpirationKey, DataKey);
      }
      else
      {
        results = await _cache.HashMemberGetAsync(_instance + key, AbsoluteExpirationKey, SlidingExpirationKey);
      }

      // TODO: Error handling
      if (results.Length >= 2)
      {
        // Note we always get back two results, even if they are all null.
        // These operations will no-op in the null scenario.
        DateTimeOffset? absExpr;
        TimeSpan? sldExpr;
        MapMetadata(results, out absExpr, out sldExpr);
        await RefreshAsync(key, absExpr, sldExpr);
      }

      if (results.Length >= 3 && results[2].HasValue)
      {
        return results[2];
      }

      return null;
    }

    public void Remove(string key)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      Connect();

      _cache.KeyDelete(_instance + key);
      // TODO: Error handling
    }

    public async Task RemoveAsync(string key)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      await ConnectAsync();

      await _cache.KeyDeleteAsync(_instance + key);
      // TODO: Error handling
    }

    private void MapMetadata(RedisValue[] results, out DateTimeOffset? absoluteExpiration, out TimeSpan? slidingExpiration)
    {
      absoluteExpiration = null;
      slidingExpiration = null;
      var absoluteExpirationTicks = (long?)results[0];
      if (absoluteExpirationTicks.HasValue && absoluteExpirationTicks.Value != NotPresent)
      {
        absoluteExpiration = new DateTimeOffset(absoluteExpirationTicks.Value, TimeSpan.Zero);
      }
      var slidingExpirationTicks = (long?)results[1];
      if (slidingExpirationTicks.HasValue && slidingExpirationTicks.Value != NotPresent)
      {
        slidingExpiration = new TimeSpan(slidingExpirationTicks.Value);
      }
    }

    private void Refresh(string key, DateTimeOffset? absExpr, TimeSpan? sldExpr)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      // Note Refresh has no effect if there is just an absolute expiration (or neither).
      TimeSpan? expr = null;
      if (sldExpr.HasValue)
      {
        if (absExpr.HasValue)
        {
          var relExpr = absExpr.Value - DateTimeOffset.Now;
          expr = relExpr <= sldExpr.Value ? relExpr : sldExpr;
        }
        else
        {
          expr = sldExpr;
        }
        _cache.KeyExpire(_instance + key, expr);
        // TODO: Error handling
      }
    }

    private async Task RefreshAsync(string key, DateTimeOffset? absExpr, TimeSpan? sldExpr)
    {
      if (key == null)
      {
        throw new ArgumentNullException(nameof(key));
      }

      // Note Refresh has no effect if there is just an absolute expiration (or neither).
      TimeSpan? expr = null;
      if (sldExpr.HasValue)
      {
        if (absExpr.HasValue)
        {
          var relExpr = absExpr.Value - DateTimeOffset.Now;
          expr = relExpr <= sldExpr.Value ? relExpr : sldExpr;
        }
        else
        {
          expr = sldExpr;
        }
        await _cache.KeyExpireAsync(_instance + key, expr);
        // TODO: Error handling
      }
    }

    private static long? GetExpirationInSeconds(DateTimeOffset creationTime, DateTimeOffset? absoluteExpiration, DistributedCacheEntryOptions options)
    {
      if (absoluteExpiration.HasValue && options.SlidingExpiration.HasValue)
      {
        return (long)Math.Min(
          (absoluteExpiration.Value - creationTime).TotalSeconds,
          options.SlidingExpiration.Value.TotalSeconds);
      }
      else if (absoluteExpiration.HasValue)
      {
        return (long)(absoluteExpiration.Value - creationTime).TotalSeconds;
      }
      else if (options.SlidingExpiration.HasValue)
      {
        return (long)options.SlidingExpiration.Value.TotalSeconds;
      }
      return null;
    }

    private static DateTimeOffset? GetAbsoluteExpiration(DateTimeOffset creationTime, DistributedCacheEntryOptions options)
    {
      if (options.AbsoluteExpiration.HasValue && options.AbsoluteExpiration <= creationTime)
      {
        throw new ArgumentOutOfRangeException(
          nameof(DistributedCacheEntryOptions.AbsoluteExpiration),
          options.AbsoluteExpiration.Value,
          "The absolute expiration value must be in the future.");
      }
      var absoluteExpiration = options.AbsoluteExpiration;
      if (options.AbsoluteExpirationRelativeToNow.HasValue)
      {
        absoluteExpiration = creationTime + options.AbsoluteExpirationRelativeToNow;
      }

      return absoluteExpiration;
    }

    public void Dispose()
    {
      if (_connection != null)
      {
        _connection.Close();
      }
    }
  }
}

using Microsoft.Extensions.Options;

namespace Microsoft.Extensions.Caching.Redis
{
  /// <summary>
  /// Configuration options for <see cref="RedisCache"/>.
  /// </summary>
  public class RedisCacheOptions : IOptions<RedisCacheOptions>
  {
    /// <summary>
    /// The configuration used to connect to Redis.
    /// </summary>
    public string Configuration { get; set; }

    /// <summary>
    /// The Redis instance name.
    /// </summary>
    public string InstanceName { get; set; }

    RedisCacheOptions IOptions<RedisCacheOptions>.Value
    {
      get { return this; }
    }
  }
}

using System.Threading.Tasks;
using StackExchange.Redis;

namespace Microsoft.Extensions.Caching.Redis
{
  internal static class RedisExtensions
  {
    private const string HmGetScript = (@"return redis.call('HMGET', KEYS[1], unpack(ARGV))");

    internal static RedisValue[] HashMemberGet(this IDatabase cache, string key, params string[] members)
    {
      var result = cache.ScriptEvaluate(
        HmGetScript,
        new RedisKey[] { key },
        GetRedisMembers(members));

      // TODO: Error checking?
      return (RedisValue[])result;
    }

    internal static async Task<RedisValue[]> HashMemberGetAsync(
      this IDatabase cache,
      string key,
      params string[] members)
    {
      var result = await cache.ScriptEvaluateAsync(
        HmGetScript,
        new RedisKey[] { key },
        GetRedisMembers(members));

      // TODO: Error checking?
      return (RedisValue[])result;
    }

    private static RedisValue[] GetRedisMembers(params string[] members)
    {
      var redisMembers = new RedisValue[members.Length];
      for (int i = 0; i < members.Length; i++)
      {
        redisMembers[i] = (RedisValue)members[i];
      }

      return redisMembers;
    }
  }
}

配置啟用Session

我們?cè)赟tartup中ConfigureServices增加

services.AddSingleton<IDistributedCache>(
        serviceProvider =>
          new RedisCache(new RedisCacheOptions
          {
            Configuration = "192.168.178.141:6379",
            InstanceName = "Sample:"
          }));
      services.AddSession();

在Startup中Configure增加

app.UseSession(new SessionOptions() { IdleTimeout = TimeSpan.FromMinutes(30) });

到此我們的配置完畢，可以測(cè)試一下是否寫到了Redis中

驗(yàn)證結(jié)果

在Mvc項(xiàng)目中，我們來實(shí)現(xiàn)如下代碼

if (string.IsNullOrEmpty(HttpContext.Session.GetString("D")))
      {
        var d = DateTime.Now.ToString();
        HttpContext.Session.SetString("D", d);
        HttpContext.Response.ContentType = "text/plain";
        await HttpContext.Response.WriteAsync("Hello First timer///" + d);
      }
      else
      {
        HttpContext.Response.ContentType = "text/plain";
        await HttpContext.Response.WriteAsync("Hello old timer///" + HttpContext.Session.GetString("D"));
      }

運(yùn)行我們發(fā)現(xiàn)第一次出現(xiàn)了Hello First timer字樣，刷新后出現(xiàn)了Hello old timer字樣，證明Session成功，再查看一下Redis看一下，有值了，這樣一個(gè)分布式的Session就成功實(shí)現(xiàn)了。

對(duì)于上面的實(shí)例我把源碼放在了：demo下載

Tianwei.Microsoft.Extensions.Caching.Redis ,只是ID加了Tianwei 空間名還是Microsoft.Extensions.Caching.Redis

從上面的實(shí)例我們發(fā)現(xiàn)微軟這次是真的開放了，這也意味著如果我們使用某些類不順手或不合適時(shí)可以自已寫自已擴(kuò)展

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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