117 lines
4.6 KiB
C#
117 lines
4.6 KiB
C#
using SiteManagementSystem_SoftwareEngineering_.Interface;
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using StackExchange.Redis;
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using System.Configuration;
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namespace SiteManagementSystem_SoftwareEngineering_.Service
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{
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public class RedisService<TCategoryName>(ILogger<RedisService<TCategoryName>> logger, RedisUtils redisHelper) : ICacheService<TCategoryName>
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{
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private readonly ILogger<RedisService<TCategoryName>> _logger = logger;
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private readonly RedisUtils _redisHelper = redisHelper;
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private readonly LinkedList<string> _values = [];
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private readonly string _categoryName = typeof(TCategoryName).Name;
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public int Capacity { get; set; } = int.MaxValue;
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private Action<string>? _expiredCallbackFunc = null;
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public Action<string>? ExpiredCallbackFunc
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{
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set
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{
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_expiredCallbackFunc = value;
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_redisHelper.SetExpiredCallbackFunction(_categoryName, KeyDrop);
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}
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}
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public async Task<bool> SetAsync(string key, string value, TimeSpan? expiry = null)
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{
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// 现在默认容量是最大值，除非调用方设置容量，否则不会调用 RemoveLatestKeyAsync()
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while (_values.Count >= Capacity)
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await RemoveLatestKeyAsync();
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_values.AddLast(key);
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return await _redisHelper.SetAsync(_categoryName, key, value, expiry);
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}
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public async Task<string?> GetAsync(string key) =>
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await _redisHelper.GetAsync(_categoryName, key);
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public async Task<bool> RemoveAsync(string key) =>
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await _redisHelper.RemoveAsync(_categoryName, key);
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/// <summary>
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/// 删除现有的最早加入的数据
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/// </summary>
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/// <returns></returns>
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public async Task<bool> RemoveLatestKeyAsync()
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{
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if (_values.Count == 0)
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return false;
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var key = _values.First();
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_logger.LogWarning($"{key} dropped due to limited capacity.");
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KeyDrop(key);
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return await RemoveAsync(key);
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}
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private void KeyDrop(string key)
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{
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_values.Remove(key);
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_expiredCallbackFunc?.Invoke(key);
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}
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}
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// Redis: CONFIG set notify-keyspace-events Ex
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// Key style: typeName+ ' ' + key
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// IDistributedCache 确实封装了一些有用的方法 但是其最大的问题是无法在键过期后主动发出事件
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// 内部的RedisCache类没有保留IConnectionMultiplexer 而是获取了 dataBase 后就舍弃了
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// 因此 继承再反射不是一个很好的选项，不如重新封装
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public class RedisUtils
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{
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private readonly ConnectionMultiplexer _redis;
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private readonly ILogger<RedisUtils> _logger;
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private readonly Dictionary<string, Action<string>?> _expiredCallbackFunctions = [];
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private readonly IDatabase _database;
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private readonly int _numberOfDB;
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public RedisUtils(string connectionString,int redisDB, ILogger<RedisUtils> logger)
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{
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_numberOfDB = redisDB;
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_logger = logger;
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_redis = ConnectionMultiplexer.Connect(connectionString);
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_redis
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.GetSubscriber()
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.Subscribe(
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RedisChannel.Pattern($"__keyevent@{_numberOfDB}__:expired"),
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(_, message) =>
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{
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DataExpiredHandler(message);
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}
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);
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_database = _redis.GetDatabase(_numberOfDB);
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// TODO: create a func to check if Redis setting is correct
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}
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// typeName+ ' ' + key
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// key is Hash, value is type.When key expired, you can't get value!
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public async Task<bool> SetAsync(
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string typeName,
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string key,
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string value,
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TimeSpan? expiry = null
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) => await _database.StringSetAsync(typeName + " " + key, value, expiry);
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public async Task<string?> GetAsync(string typeName, string key) =>
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await _database.StringGetAsync(typeName + " " + key);
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public async Task<bool> RemoveAsync(string typeName, string key) =>
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await _database.KeyDeleteAsync(typeName + " " + key);
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public void SetExpiredCallbackFunction(string typeName, Action<string>? func) =>
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_expiredCallbackFunctions[typeName] = func;
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private void DataExpiredHandler(RedisValue val)
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{
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var temp = val.ToString().Split(' ');
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if (_expiredCallbackFunctions.TryGetValue(temp[0], out var func))
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func?.Invoke(temp[1]);
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}
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}
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}
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