50 lines
1.7 KiB
C#
50 lines
1.7 KiB
C#
using System;
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namespace NadekoBot.Core.Common.Caching
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{
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/// <summary>
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/// A caching object which loads its value with a factory method when it expires.
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/// </summary>
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/// <typeparam name="T">Type of the value which is cached.</typeparam>
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public class FactoryCache<T> : IFactoryCache
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{
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public DateTime LastUpdate { get; set; } = DateTime.MinValue;
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private readonly object _locker = new object();
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private TimeSpan _expireAfter;
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private readonly Func<T> _factory;
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private T Value;
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/// <summary>
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/// Creates a new factory cache object.
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/// </summary>
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/// <param name="factory">Method which loads the value when it expires or if it's not loaded the first time.</param>
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/// <param name="expireAfter">Time after which the value will be reloaded.</param>
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/// <param name="loadImmediately">Should the value be loaded right away. If set to false, value will load when it's first retrieved.</param>
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public FactoryCache(Func<T> factory, TimeSpan expireAfter,
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bool loadImmediately = false)
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{
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_expireAfter = expireAfter;
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_factory = factory;
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if (loadImmediately)
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{
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Value = _factory();
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LastUpdate = DateTime.UtcNow;
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}
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}
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public T GetValue()
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{
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lock (_locker)
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{
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if (DateTime.UtcNow - LastUpdate > _expireAfter)
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{
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LastUpdate = DateTime.UtcNow;
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return Value = _factory();
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}
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return Value;
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}
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}
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}
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}
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