详解Asp.net Core 使用Redis存储Session

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

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;    }  }}

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

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

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"));      }