opensim-development – Rev 1
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/*
* Copyright (c) Contributors, http://opensimulator.org/
* See CONTRIBUTORS.TXT for a full list of copyright holders.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the OpenSimulator Project nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
using System;
using System.Collections.Generic;
namespace OpenSim.Framework
{
/// <summary>
/// Stores two synchronized collections: a mutable dictionary and an
/// immutable array. Slower inserts/removes than a normal dictionary,
/// but provides safe iteration while maintaining fast hash lookups
/// </summary>
/// <typeparam name="TKey">Key type to use for hash lookups</typeparam>
/// <typeparam name="TValue">Value type to store</typeparam>
public sealed class MapAndArray<TKey, TValue>
{
private Dictionary<TKey, TValue> m_dict;
private TValue[] m_array;
private object m_syncRoot = new object();
/// <summary>Number of values currently stored in the collection</summary>
public int Count { get { return m_array.Length; } }
/// <summary>NOTE: This collection is thread safe. You do not need to
/// acquire a lock to add, remove, or enumerate entries. This
/// synchronization object should only be locked for larger
/// transactions</summary>
public object SyncRoot { get { return m_syncRoot; } }
/// <summary>
/// Constructor
/// </summary>
public MapAndArray()
{
m_dict = new Dictionary<TKey, TValue>();
m_array = new TValue[0];
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="capacity">Initial capacity of the dictionary</param>
public MapAndArray(int capacity)
{
m_dict = new Dictionary<TKey, TValue>(capacity);
m_array = new TValue[0];
}
/// <summary>
/// Adds a key/value pair to the collection, or updates an existing key
/// with a new value
/// </summary>
/// <param name="key">Key to add or update</param>
/// <param name="value">Value to add</param>
/// <returns>True if a new key was added, false if an existing key was
/// updated</returns>
public bool AddOrReplace(TKey key, TValue value)
{
lock (m_syncRoot)
{
bool containedKey = m_dict.ContainsKey(key);
m_dict[key] = value;
CreateArray();
return !containedKey;
}
}
/// <summary>
/// Adds a key/value pair to the collection. This will throw an
/// exception if the key is already present in the collection
/// </summary>
/// <param name="key">Key to add or update</param>
/// <param name="value">Value to add</param>
/// <returns>Index of the inserted item</returns>
public int Add(TKey key, TValue value)
{
lock (m_syncRoot)
{
m_dict.Add(key, value);
CreateArray();
return m_array.Length;
}
}
/// <summary>
/// Removes a key/value pair from the collection
/// </summary>
/// <param name="key">Key to remove</param>
/// <returns>True if the key was found and removed, otherwise false</returns>
public bool Remove(TKey key)
{
lock (m_syncRoot)
{
bool removed = m_dict.Remove(key);
CreateArray();
return removed;
}
}
/// <summary>
/// Determines whether the collections contains a specified key
/// </summary>
/// <param name="key">Key to search for</param>
/// <returns>True if the key was found, otherwise false</returns>
public bool ContainsKey(TKey key)
{
lock (m_syncRoot)
return m_dict.ContainsKey(key);
}
/// <summary>
/// Gets the value associated with the specified key
/// </summary>
/// <param name="key">Key of the value to get</param>
/// <param name="value">Will contain the value associated with the
/// given key if the key is found. If the key is not found it will
/// contain the default value for the type of the value parameter</param>
/// <returns>True if the key was found and a value was retrieved,
/// otherwise false</returns>
public bool TryGetValue(TKey key, out TValue value)
{
lock (m_syncRoot)
return m_dict.TryGetValue(key, out value);
}
/// <summary>
/// Clears all key/value pairs from the collection
/// </summary>
public void Clear()
{
lock (m_syncRoot)
{
m_dict = new Dictionary<TKey, TValue>();
m_array = new TValue[0];
}
}
/// <summary>
/// Gets a reference to the immutable array of values stored in this
/// collection. This array is thread safe for iteration
/// </summary>
/// <returns>A thread safe reference ton an array of all of the stored
/// values</returns>
public TValue[] GetArray()
{
return m_array;
}
private void CreateArray()
{
// Rebuild the array from the dictionary. This method must be
// called from inside a lock
TValue[] array = new TValue[m_dict.Count];
int i = 0;
foreach (TValue value in m_dict.Values)
array[i++] = value;
m_array = array;
}
}
}