442 lines
20 KiB
C#
442 lines
20 KiB
C#
/*
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* Copyright (c) Contributors, http://opensimulator.org/
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* See CONTRIBUTORS.TXT for a full list of copyright holders.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of the OpenSimulator Project nor the
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* names of its contributors may be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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using System;
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using System.Collections.Generic;
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namespace OpenSim.Framework
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{
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/// <summary>
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/// Represent generic cache to store key/value pairs (elements) limited by time, size and count of elements.
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/// </summary>
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/// <typeparam name="TKey">
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/// The type of keys in the cache.
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/// </typeparam>
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/// <typeparam name="TValue">
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/// The type of values in the cache.
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/// </typeparam>
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/// <remarks>
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/// <para>
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/// Cache store limitations:
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/// </para>
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/// <list type="table">
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/// <listheader>
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/// <term>Limitation</term>
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/// <description>Description</description>
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/// </listheader>
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/// <item>
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/// <term>Time</term>
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/// <description>
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/// Element that is not accessed through <see cref="TryGetValue"/> or <see cref="Set"/> in last <see cref="ExpirationTime"/> are
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/// removed from the cache automatically. Depending on implementation of the cache some of elements may stay longer in cache.
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/// <see cref="IsTimeLimited"/> returns <see langword="true"/>, if cache is limited by time.
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/// </description>
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/// </item>
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/// <item>
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/// <term>Count</term>
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/// <description>
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/// When adding an new element to cache that already have <see cref="MaxCount"/> of elements, cache will remove less recently
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/// used element(s) from the cache, until element fits to cache.
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/// <see cref="IsCountLimited"/> returns <see langword="true"/>, if cache is limiting element count.
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/// </description>
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/// </item>
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/// <item>
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/// <term>Size</term>
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/// <description>
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/// <description>
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/// When adding an new element to cache that already have <see cref="MaxSize"/> of elements, cache will remove less recently
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/// used element(s) from the cache, until element fits to cache.
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/// <see cref="IsSizeLimited"/> returns <see langword="true"/>, if cache is limiting total size of elements.
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/// Normally size is bytes used by element in the cache. But it can be any other suitable unit of measure.
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/// </description>
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/// </description>
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/// </item>
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/// </list>
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/// </remarks>
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public interface ICnmCache<TKey, TValue> : IEnumerable<KeyValuePair<TKey, TValue>>
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{
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/// <summary>
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/// Gets current count of elements stored to <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <remarks>
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/// <para>
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/// When adding an new element to <see cref="ICnmCache{TKey,TValue}"/> that is limiting element count,
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/// <see cref="ICnmCache{TKey,TValue}"/> will remove less recently used elements until it can fit an new element.
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/// </para>
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/// </remarks>
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/// <seealso cref="MaxCount"/>
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/// <seealso cref="IsCountLimited"/>
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/// <seealso cref="IsSizeLimited"/>
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/// <seealso cref="IsTimeLimited"/>
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int Count { get; }
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/// <summary>
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/// Gets or sets elements expiration time.
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/// </summary>
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/// <value>
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/// Elements expiration time.
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/// </value>
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/// <remarks>
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/// <para>
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/// When element has been stored in <see cref="ICnmCache{TKey,TValue}"/> longer than <see cref="ExpirationTime"/>
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/// and it is not accessed through <see cref="TryGetValue"/> method or element's value is
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/// not replaced by <see cref="Set"/> method, then it is automatically removed from the
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/// <see cref="ICnmCache{TKey,TValue}"/>.
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/// </para>
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/// <para>
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/// It is possible that <see cref="ICnmCache{TKey,TValue}"/> implementation removes element before it's expiration time,
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/// because total size or count of elements stored to cache is larger than <see cref="MaxSize"/> or <see cref="MaxCount"/>.
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/// </para>
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/// <para>
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/// It is also possible that element stays in cache longer than <see cref="ExpirationTime"/>.
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/// </para>
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/// <para>
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/// Calling <see cref="PurgeExpired"/> try to remove all elements that are expired.
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/// </para>
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/// <para>
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/// To disable time limit in cache, set <see cref="ExpirationTime"/> to <see cref="DateTime.MaxValue"/>.
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/// </para>
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/// </remarks>
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/// <seealso cref="IsTimeLimited"/>
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/// <seealso cref="IsCountLimited"/>
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/// <seealso cref="IsSizeLimited"/>
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/// <seealso cref="PurgeExpired"/>
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/// <seealso cref="Count"/>
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/// <seealso cref="MaxCount"/>
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/// <seealso cref="MaxSize"/>
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/// <seealso cref="Size"/>
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TimeSpan ExpirationTime { get; set; }
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/// <summary>
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/// Gets a value indicating whether or not access to the <see cref="ICnmCache{TKey,TValue}"/> is synchronized (thread safe).
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/// </summary>
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/// <value>
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/// <see langword="true"/> if access to the <see cref="ICnmCache{TKey,TValue}"/> is synchronized (thread safe);
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/// otherwise, <see langword="false"/>.
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/// </value>
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/// <remarks>
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/// <para>
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/// To get synchronized (thread safe) access to <see cref="ICnmCache{TKey,TValue}"/> object, use
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/// <see cref="CnmSynchronizedCache{TKey,TValue}.Synchronized"/> in <see cref="CnmSynchronizedCache{TKey,TValue}"/> class
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/// to retrieve synchronized wrapper for <see cref="ICnmCache{TKey,TValue}"/> object.
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/// </para>
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/// </remarks>
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/// <seealso cref="SyncRoot"/>
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/// <seealso cref="CnmSynchronizedCache{TKey,TValue}"/>
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bool IsSynchronized { get; }
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/// <summary>
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/// Gets a value indicating whether <see cref="ICnmCache{TKey,TValue}"/> is limiting count of elements.
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/// </summary>
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/// <value>
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/// <see langword="true"/> if the <see cref="ICnmCache{TKey,TValue}"/> count of elements is limited;
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/// otherwise, <see langword="false"/>.
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/// </value>
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/// <remarks>
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/// <para>
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/// When adding an new element to <see cref="ICnmCache{TKey,TValue}"/> that is limiting element count,
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/// <see cref="ICnmCache{TKey,TValue}"/> will remove less recently used elements until it can fit an new element.
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/// </para>
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/// </remarks>
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/// <seealso cref="Count"/>
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/// <seealso cref="MaxCount"/>
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/// <seealso cref="IsSizeLimited"/>
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/// <seealso cref="IsTimeLimited"/>
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bool IsCountLimited { get; }
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/// <summary>
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/// Gets a value indicating whether <see cref="ICnmCache{TKey,TValue}"/> is limiting size of elements.
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/// </summary>
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/// <value>
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/// <see langword="true"/> if the <see cref="ICnmCache{TKey,TValue}"/> total size of elements is limited;
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/// otherwise, <see langword="false"/>.
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/// </value>
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/// <remarks>
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/// <para>
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/// When adding an new element to <see cref="ICnmCache{TKey,TValue}"/> that is limiting total size of elements,
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/// <see cref="ICnmCache{TKey,TValue}"/> will remove less recently used elements until it can fit an new element.
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/// </para>
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/// </remarks>
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/// <seealso cref="MaxElementSize"/>
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/// <seealso cref="Size"/>
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/// <seealso cref="MaxSize"/>
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/// <seealso cref="IsCountLimited"/>
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/// <seealso cref="IsTimeLimited"/>
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bool IsSizeLimited { get; }
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/// <summary>
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/// Gets a value indicating whether elements stored to <see cref="ICnmCache{TKey,TValue}"/> have limited inactivity time.
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/// </summary>
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/// <value>
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/// <see langword="true"/> if the <see cref="ICnmCache{TKey,TValue}"/> has a fixed total size of elements;
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/// otherwise, <see langword="false"/>.
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/// </value>
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/// <remarks>
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/// If <see cref="ICnmCache{TKey,TValue}"/> have limited inactivity time and element is not accessed through <see cref="Set"/>
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/// or <see cref="TryGetValue"/> methods in <see cref="ExpirationTime"/> , then element is automatically removed from
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/// the cache. Depending on implementation of the <see cref="ICnmCache{TKey,TValue}"/>, some of the elements may
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/// stay longer in cache.
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/// </remarks>
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/// <seealso cref="ExpirationTime"/>
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/// <seealso cref="PurgeExpired"/>
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/// <seealso cref="IsCountLimited"/>
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/// <seealso cref="IsSizeLimited"/>
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bool IsTimeLimited { get; }
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/// <summary>
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/// Gets or sets maximal allowed count of elements that can be stored to <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <value>
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/// <see cref="int.MaxValue"/>, if <see cref="ICnmCache{TKey,TValue}"/> is not limited by count of elements;
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/// otherwise maximal allowed count of elements.
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/// </value>
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/// <remarks>
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/// <para>
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/// When adding an new element to <see cref="ICnmCache{TKey,TValue}"/> that is limiting element count,
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/// <see cref="ICnmCache{TKey,TValue}"/> will remove less recently used elements until it can fit an new element.
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/// </para>
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/// </remarks>
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int MaxCount { get; set; }
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/// <summary>
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/// <para>Gets maximal allowed element size.</para>
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/// </summary>
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/// <value>
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/// Maximal allowed element size.
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/// </value>
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/// <remarks>
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/// <para>
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/// If element's size is larger than <see cref="MaxElementSize"/>, then element is
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/// not added to the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </para>
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/// </remarks>
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/// <seealso cref="Set"/>
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/// <seealso cref="IsSizeLimited"/>
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/// <seealso cref="Size"/>
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/// <seealso cref="MaxSize"/>
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long MaxElementSize { get; }
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/// <summary>
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/// Gets or sets maximal allowed total size for elements stored to <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <value>
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/// Maximal allowed total size for elements stored to <see cref="ICnmCache{TKey,TValue}"/>.
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/// </value>
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/// <remarks>
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/// <para>
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/// Normally size is total bytes used by elements in the cache. But it can be any other suitable unit of measure.
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/// </para>
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/// <para>
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/// When adding an new element to <see cref="ICnmCache{TKey,TValue}"/> that is limiting total size of elements,
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/// <see cref="ICnmCache{TKey,TValue}"/> will remove less recently used elements until it can fit an new element.
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/// </para>
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/// </remarks>
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/// <exception cref="ArgumentOutOfRangeException">value is less than 0.</exception>
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/// <seealso cref="MaxElementSize"/>
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/// <seealso cref="IsSizeLimited"/>
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/// <seealso cref="Size"/>
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long MaxSize { get; set; }
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/// <summary>
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/// Gets total size of elements stored to <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <value>
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/// Total size of elements stored to <see cref="ICnmCache{TKey,TValue}"/>.
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/// </value>
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/// <remarks>
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/// <para>
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/// Normally bytes, but can be any suitable unit of measure.
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/// </para>
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/// <para>
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/// Element's size is given when element is added or replaced by <see cref="Set"/> method.
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/// </para>
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/// <para>
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/// When adding an new element to <see cref="ICnmCache{TKey,TValue}"/> that is limiting total size of elements,
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/// <see cref="ICnmCache{TKey,TValue}"/> will remove less recently used elements until it can fit an new element.
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/// </para>
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/// </remarks>
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/// <seealso cref="MaxElementSize"/>
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/// <seealso cref="IsSizeLimited"/>
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/// <seealso cref="MaxSize"/>
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/// <seealso cref="IsCountLimited"/>
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/// <seealso cref="ExpirationTime"/>
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long Size { get; }
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/// <summary>
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/// Gets an object that can be used to synchronize access to the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <value>
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/// An object that can be used to synchronize access to the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </value>
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/// <remarks>
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/// <para>
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/// To get synchronized (thread safe) access to <see cref="ICnmCache{TKey,TValue}"/>, use <see cref="CnmSynchronizedCache{TKey,TValue}"/>
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/// method <see cref="CnmSynchronizedCache{TKey,TValue}.Synchronized"/> to retrieve synchronized wrapper interface to
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/// <see cref="ICnmCache{TKey,TValue}"/>.
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/// </para>
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/// </remarks>
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/// <seealso cref="IsSynchronized"/>
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/// <seealso cref="CnmSynchronizedCache{TKey,TValue}"/>
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object SyncRoot { get; }
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/// <summary>
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/// Removes all elements from the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <seealso cref="Set"/>
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/// <seealso cref="Remove"/>
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/// <seealso cref="RemoveRange"/>
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/// <seealso cref="TryGetValue"/>
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/// <seealso cref="PurgeExpired"/>
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void Clear();
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/// <summary>
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/// Purge expired elements from the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <remarks>
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/// <para>
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/// Element becomes expired when last access time to it has been longer time than <see cref="ExpirationTime"/>.
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/// </para>
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/// <para>
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/// Depending on <see cref="ICnmCache{TKey,TValue}"/> implementation, some of expired elements
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/// may stay longer than <see cref="ExpirationTime"/> in the cache.
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/// </para>
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/// </remarks>
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/// <seealso cref="IsTimeLimited"/>
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/// <seealso cref="ExpirationTime"/>
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/// <seealso cref="Set"/>
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/// <seealso cref="Remove"/>
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/// <seealso cref="RemoveRange"/>
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/// <seealso cref="TryGetValue"/>
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/// <seealso cref="Clear"/>
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void PurgeExpired();
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/// <summary>
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/// Removes element associated with <paramref name="key"/> from the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <param name="key">
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/// The key that is associated with element to remove from the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </param>
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/// <exception cref="ArgumentNullException">
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/// <paramref name="key"/> is <see langword="null"/>.
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/// </exception>
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/// <seealso cref="Set"/>
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/// <seealso cref="RemoveRange"/>
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/// <seealso cref="TryGetValue"/>
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/// <seealso cref="Clear"/>
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/// <seealso cref="PurgeExpired"/>
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void Remove(TKey key);
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/// <summary>
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/// Removes elements that are associated with one of <paramref name="keys"/> from the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <param name="keys">
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/// The keys that are associated with elements to remove from the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </param>
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/// <exception cref="ArgumentNullException">
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/// <paramref name="keys"/> is <see langword="null"/>.
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/// </exception>
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/// <seealso cref="Set"/>
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/// <seealso cref="Remove"/>
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/// <seealso cref="TryGetValue"/>
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/// <seealso cref="Clear"/>
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/// <seealso cref="PurgeExpired"/>
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void RemoveRange(IEnumerable<TKey> keys);
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/// <summary>
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/// Add or replace an element with the provided <paramref name="key"/>, <paramref name="value"/> and <paramref name="size"/> to
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/// <see cref="ICnmCache{TKey,TValue}"/>.
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/// </summary>
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/// <param name="key">
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/// The object used as the key of the element. Can't be <see langword="null"/> reference.
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/// </param>
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/// <param name="value">
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/// The object used as the value of the element to add or replace. <see langword="null"/> is allowed.
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/// </param>
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/// <param name="size">
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/// The element's size. Normally bytes, but can be any suitable unit of measure.
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/// </param>
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/// <returns>
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/// <see langword="true"/> if element has been added successfully to the <see cref="ICnmCache{TKey,TValue}"/>;
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/// otherwise <see langword="false"/>.
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/// </returns>
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/// <exception cref="ArgumentNullException">
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/// <paramref name="key"/>is <see langword="null"/>.
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/// </exception>
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/// <exception cref="ArgumentOutOfRangeException">
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/// The element's <paramref name="size"/> is less than 0.
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/// </exception>
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/// <remarks>
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/// <para>
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/// If element's <paramref name="size"/> is larger than <see cref="MaxElementSize"/>, then element is
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/// not added to the <see cref="ICnmCache{TKey,TValue}"/>, however - possible older element is
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/// removed from the <see cref="ICnmCache{TKey,TValue}"/>.
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/// </para>
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/// <para>
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/// When adding an new element to <see cref="ICnmCache{TKey,TValue}"/> that is limiting total size of elements,
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/// <see cref="ICnmCache{TKey,TValue}"/>will remove less recently used elements until it can fit an new element.
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/// </para>
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/// <para>
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/// When adding an new element to <see cref="ICnmCache{TKey,TValue}"/> that is limiting element count,
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/// <see cref="ICnmCache{TKey,TValue}"/>will remove less recently used elements until it can fit an new element.
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/// </para>
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/// </remarks>
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/// <seealso cref="IsSizeLimited"/>
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/// <seealso cref="IsCountLimited"/>
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/// <seealso cref="Remove"/>
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/// <seealso cref="RemoveRange"/>
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/// <seealso cref="TryGetValue"/>
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/// <seealso cref="Clear"/>
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/// <seealso cref="PurgeExpired"/>
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bool Set(TKey key, TValue value, long size);
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/// <summary>
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/// Gets the <paramref name="value"/> associated with the specified <paramref name="key"/>.
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/// </summary>
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/// <returns>
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/// <see langword="true"/>if the <see cref="ICnmCache{TKey,TValue}"/> contains an element with
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/// the specified key; otherwise, <see langword="false"/>.
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/// </returns>
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/// <param name="key">
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/// The key whose <paramref name="value"/> to get.
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/// </param>
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/// <param name="value">
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/// When this method returns, the value associated with the specified <paramref name="key"/>,
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/// if the <paramref name="key"/> is found; otherwise, the
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/// default value for the type of the <paramref name="value"/> parameter. This parameter is passed uninitialized.
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/// </param>
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/// <exception cref="ArgumentNullException">
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/// <paramref name="key"/>is <see langword="null"/>.
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/// </exception>
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/// <seealso cref="Set"/>
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/// <seealso cref="Remove"/>
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/// <seealso cref="RemoveRange"/>
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|
/// <seealso cref="Clear"/>
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|
/// <seealso cref="PurgeExpired"/>
|
|
bool TryGetValue(TKey key, out TValue value);
|
|
}
|
|
}
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