using System;
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using System.Runtime.Caching;
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using System.Threading;
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namespace IStation
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{
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internal sealed partial class SharedMemoryCache
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{
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/// <summary>
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/// Set a cache item by key, function and optional eviction
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/// </summary>
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/// <param name="key">A unique identifier for the cache entry to insert</param>
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/// <param name="valueFunction">A function to execute to get the data for the cache entry</param>
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/// <param name="policy">(Optional) An object that contains eviction details for the cache entry</param>
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public void Set(string key, Func<object> valueFunction, CacheItemPolicy policy = null)
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{
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if (key == null || valueFunction == null) { return; }
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Exception ex_func = null;
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this._cacheKeysBeingHandled.TryAdd(key, new CacheKeyBeingHandled());
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lock (this._cacheKeysBeingHandled[key].SetOperation.CounterLock)
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{
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this._cacheKeysBeingHandled[key].SetOperation.Counter++;
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}
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lock (this._cacheKeysBeingHandled[key].SetOperation.Lock)
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{
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if (this._cacheKeysBeingHandled[key].SetOperation.Thread != null)
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{
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try
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{
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this._cacheKeysBeingHandled[key].SetOperation.Thread.Abort();
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}
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finally
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{
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this._cacheKeysBeingHandled[key].SetOperation.Thread = null;
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}
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}
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}
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lock (_cacheKeysBeingHandled[key].SetOperation.CounterLock)
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{
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if (this._cacheKeysBeingHandled[key].SetOperation.Counter > 1)
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{
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this._cacheKeysBeingHandled[key].SetOperation.Counter--;
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}
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}
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if (this._cacheKeysBeingHandled[key].SetOperation.Counter > 1)
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{
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return; // it's not the most recent thread, so ignore it
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}
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lock (_cacheKeysBeingHandled[key].SetOperation.Lock)
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{
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if (this._cacheKeysBeingHandled[key].SetOperation.Thread == null)
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{
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this._cacheKeysBeingHandled[key].SetOperation.Thread = new Thread(() =>
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{
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try
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{
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object value = valueFunction();
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((IMemoryCacheDirect)this).Set(key, value, policy);
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}
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catch (ThreadAbortException)
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{
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}
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catch (Exception ex)
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{
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ex_func = ex;
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}
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finally
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{
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}
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});
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this._cacheKeysBeingHandled[key].SetOperation.Thread.Start();
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this._cacheKeysBeingHandled[key].SetOperation.Thread.Join();
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}
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}
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if (ex_func != null)
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throw ex_func;
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}
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/// <summary>
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/// Set a cache item by key, value and optional eviction
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/// </summary>
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/// <param name="key">A unique identifier for the cache entry to insert</param>
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/// <param name="value">The data for the cache entry</param>
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/// <param name="policy">(Optional) An object that contains eviction details for the cache item</param>
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public void Set(string key, object value, CacheItemPolicy policy = null)
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{
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if (key == null) { return; }
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if (value != null)
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{
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((IMemoryCacheDirect)this).Set(key, value, policy);
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// if there's currently a function opterating on this key
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if (this._cacheKeysBeingHandled.TryGetValue(key, out CacheKeyBeingHandled cacheKeyBeingHandled))
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{
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cacheKeyBeingHandled.SetOperation.Thread?.Abort();
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// if it wants the same type, then cancel it and give it this value
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if (cacheKeyBeingHandled.GetSetOperation.Type == value.GetType())
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{
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cacheKeyBeingHandled.GetSetOperation.Value = value;
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cacheKeyBeingHandled.GetSetOperation.Thread.Abort();
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}
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}
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}
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else
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{
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if (this._isWiping) { return; }
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this.Remove(key);
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}
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}
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/// <summary>
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/// The core method that directly sets a value in the wrapped memory cache
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/// </summary>
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/// <param name="key">key of cache item to set</param>
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/// <param name="value">The data for the cache entry</param>
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/// <param name="policy">(Optional) An object that contains eviction details for the cache entry</param>
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void IMemoryCacheDirect.Set(string key, object value, CacheItemPolicy policy)
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{
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var set = new Action(() =>
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{
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this._isSetting = true;
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policy = policy ?? this.DefaultPolicy;
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try
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{
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if (policy != null)
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{
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this._memoryCache.Set(key, value, policy);
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}
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else
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{
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this._memoryCache[key] = value;
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}
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}
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finally
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{
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this._isSetting = false;
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}
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});
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if (!this._isWiping)
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{
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set();
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}
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else // hold the set until wiping is complete
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{
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lock (this._setLock)
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{
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SpinWait.SpinUntil(() => !this._isWiping); // one thread watching until wipe complete
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set();
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}
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}
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}
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}
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}
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