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