84 lines
2.7 KiB
C#
84 lines
2.7 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Threading.Tasks;
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using Data.Abstractions;
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using Microsoft.EntityFrameworkCore;
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using Microsoft.Extensions.Logging;
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namespace Data.Helpers
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{
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public class DataValueCache<T, V> : IDataValueCache<T, V> where T : class
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{
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private readonly ILogger _logger;
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private readonly IDatabaseContextFactory _contextFactory;
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private readonly Dictionary<string, CacheState> _cacheStates = new Dictionary<string, CacheState>();
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private const int DefaultExpireMinutes = 15;
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private class CacheState
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{
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public string Key { get; set; }
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public DateTime LastRetrieval { get; set; }
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public TimeSpan ExpirationTime { get; set; }
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public Func<DbSet<T>, Task<V>> Getter { get; set; }
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public V Value { get; set; }
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public bool IsExpired => (DateTime.Now - LastRetrieval.Add(ExpirationTime)).TotalSeconds > 0;
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}
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public DataValueCache(ILogger<DataValueCache<T, V>> logger, IDatabaseContextFactory contextFactory)
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{
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_logger = logger;
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_contextFactory = contextFactory;
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}
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public void SetCacheItem(Func<DbSet<T>, Task<V>> getter, string key, TimeSpan? expirationTime = null)
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{
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if (_cacheStates.ContainsKey(key))
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{
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_logger.LogDebug("Cache key {key} is already added", key);
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return;
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}
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var state = new CacheState()
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{
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Key = key,
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Getter = getter,
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ExpirationTime = expirationTime ?? TimeSpan.FromMinutes(DefaultExpireMinutes)
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};
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_cacheStates.Add(key, state);
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}
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public async Task<V> GetCacheItem(string keyName)
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{
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if (!_cacheStates.ContainsKey(keyName))
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{
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throw new ArgumentException("No cache found for key {key}", keyName);
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}
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var state = _cacheStates[keyName];
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if (state.IsExpired)
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{
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await RunCacheUpdate(state);
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}
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return state.Value;
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}
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private async Task RunCacheUpdate(CacheState state)
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{
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try
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{
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await using var context = _contextFactory.CreateContext(false);
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var set = context.Set<T>();
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var value = await state.Getter(set);
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state.Value = value;
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state.LastRetrieval = DateTime.Now;
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}
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catch (Exception ex)
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{
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_logger.LogError(ex, "Could not get cached value for {key}", state.Key);
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}
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}
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}
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}
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