#region Apache License
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//
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// Licensed to the Apache Software Foundation (ASF) under one or more
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// contributor license agreements. See the NOTICE file distributed with
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// this work for additional information regarding copyright ownership.
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// The ASF licenses this file to you under the Apache License, Version 2.0
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// (the "License"); you may not use this file except in compliance with
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// the License. You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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#endregion
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using System;
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using System.Collections;
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namespace log4net.Util
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{
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/// <summary>
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/// Implementation of Properties collection for the <see cref="log4net.GlobalContext"/>
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/// </summary>
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/// <remarks>
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/// <para>
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/// This class implements a properties collection that is thread safe and supports both
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/// storing properties and capturing a read only copy of the current propertied.
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/// </para>
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/// <para>
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/// This class is optimized to the scenario where the properties are read frequently
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/// and are modified infrequently.
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/// </para>
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/// </remarks>
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/// <author>Nicko Cadell</author>
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public sealed class GlobalContextProperties : ContextPropertiesBase
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{
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#region Private Instance Fields
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/// <summary>
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/// The read only copy of the properties.
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/// </summary>
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/// <remarks>
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/// <para>
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/// This variable is declared <c>volatile</c> to prevent the compiler and JIT from
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/// reordering reads and writes of this thread performed on different threads.
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/// </para>
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/// </remarks>
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#if NETCF
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private ReadOnlyPropertiesDictionary m_readOnlyProperties = new ReadOnlyPropertiesDictionary();
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#else
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private volatile ReadOnlyPropertiesDictionary m_readOnlyProperties = new ReadOnlyPropertiesDictionary();
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#endif
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/// <summary>
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/// Lock object used to synchronize updates within this instance
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/// </summary>
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private readonly object m_syncRoot = new object();
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#endregion Private Instance Fields
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#region Public Instance Constructors
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/// <summary>
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/// Constructor
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/// </summary>
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/// <remarks>
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/// <para>
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/// Initializes a new instance of the <see cref="GlobalContextProperties" /> class.
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/// </para>
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/// </remarks>
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internal GlobalContextProperties()
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{
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}
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#endregion Public Instance Constructors
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#region Public Instance Properties
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/// <summary>
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/// Gets or sets the value of a property
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/// </summary>
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/// <value>
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/// The value for the property with the specified key
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/// </value>
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/// <remarks>
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/// <para>
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/// Reading the value for a key is faster than setting the value.
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/// When the value is written a new read only copy of
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/// the properties is created.
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/// </para>
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/// </remarks>
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override public object this[string key]
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{
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get
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{
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return m_readOnlyProperties[key];
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}
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set
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{
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lock(m_syncRoot)
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{
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PropertiesDictionary mutableProps = new PropertiesDictionary(m_readOnlyProperties);
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mutableProps[key] = value;
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m_readOnlyProperties = new ReadOnlyPropertiesDictionary(mutableProps);
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}
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}
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}
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#endregion Public Instance Properties
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#region Public Instance Methods
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/// <summary>
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/// Remove a property from the global context
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/// </summary>
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/// <param name="key">the key for the entry to remove</param>
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/// <remarks>
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/// <para>
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/// Removing an entry from the global context properties is relatively expensive compared
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/// with reading a value.
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/// </para>
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/// </remarks>
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public void Remove(string key)
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{
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lock(m_syncRoot)
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{
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if (m_readOnlyProperties.Contains(key))
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{
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PropertiesDictionary mutableProps = new PropertiesDictionary(m_readOnlyProperties);
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mutableProps.Remove(key);
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m_readOnlyProperties = new ReadOnlyPropertiesDictionary(mutableProps);
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}
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}
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}
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/// <summary>
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/// Clear the global context properties
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/// </summary>
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public void Clear()
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{
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lock(m_syncRoot)
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{
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m_readOnlyProperties = new ReadOnlyPropertiesDictionary();
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}
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}
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#endregion Public Instance Methods
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#region Internal Instance Methods
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/// <summary>
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/// Get a readonly immutable copy of the properties
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/// </summary>
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/// <returns>the current global context properties</returns>
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/// <remarks>
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/// <para>
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/// This implementation is fast because the GlobalContextProperties class
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/// stores a readonly copy of the properties.
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/// </para>
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/// </remarks>
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internal ReadOnlyPropertiesDictionary GetReadOnlyProperties()
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{
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return m_readOnlyProperties;
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}
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#endregion Internal Instance Methods
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}
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}
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