35 lines
1.4 KiB
C#
35 lines
1.4 KiB
C#
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/* ****************************************************************************
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*
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* Copyright (c) Microsoft Corporation. All rights reserved.
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*
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* This software is subject to the Microsoft Public License (Ms-PL).
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* A copy of the license can be found in the license.htm file included
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* in this distribution.
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*
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* You must not remove this notice, or any other, from this software.
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*
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* ***************************************************************************/
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namespace System.Web.Mvc {
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using System;
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using System.Linq;
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using System.Threading;
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internal static class DescriptorUtil {
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public static TDescriptor[] LazilyFetchOrCreateDescriptors<TReflection, TDescriptor>(ref TDescriptor[] cacheLocation, Func<TReflection[]> initializer, Func<TReflection, TDescriptor> converter) {
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// did we already calculate this once?
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TDescriptor[] existingCache = Interlocked.CompareExchange(ref cacheLocation, null, null);
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if (existingCache != null) {
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return existingCache;
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}
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TReflection[] memberInfos = initializer();
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TDescriptor[] descriptors = memberInfos.Select(converter).Where(descriptor => descriptor != null).ToArray();
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TDescriptor[] updatedCache = Interlocked.CompareExchange(ref cacheLocation, descriptors, null);
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return updatedCache ?? descriptors;
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}
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}
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}
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