76 lines
2.5 KiB
C#
76 lines
2.5 KiB
C#
#region License
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// Copyright (c) 2007 James Newton-King
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//
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// Permission is hereby granted, free of charge, to any person
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// obtaining a copy of this software and associated documentation
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// files (the "Software"), to deal in the Software without
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// restriction, including without limitation the rights to use,
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// copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the
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// Software is furnished to do so, subject to the following
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// conditions:
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//
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// The above copyright notice and this permission notice shall be
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// included in all copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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// OTHER DEALINGS IN THE SOFTWARE.
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#endregion
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#if !HAVE_CONCURRENT_DICTIONARY
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using System;
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using System.Collections.Generic;
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using System.Threading;
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namespace Newtonsoft.Json.Serialization
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{
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internal sealed class ConcurrentDictionary<TKey, TValue>
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{
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private readonly object _lock = new object();
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private Dictionary<TKey, TValue> _dictionary = new Dictionary<TKey, TValue>();
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public TValue GetOrAdd(TKey key, Func<TKey, TValue> valueFactory)
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{
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TValue value;
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if (!_dictionary.TryGetValue(key, out value))
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{
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return AddValue(key, valueFactory);
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}
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return value;
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}
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private TValue AddValue(TKey key, Func<TKey, TValue> valueFactory)
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{
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TValue value = valueFactory(key);
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lock (_lock)
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{
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// double check locking
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TValue checkValue;
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if (_dictionary.TryGetValue(key, out checkValue))
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{
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return checkValue;
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}
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Dictionary<TKey, TValue> newDictionary = new Dictionary<TKey, TValue>(_dictionary);
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newDictionary[key] = value;
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#if HAVE_MEMORY_BARRIER
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Thread.MemoryBarrier();
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#endif
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_dictionary = newDictionary;
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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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#endif |