/* Copyright 2002-2004 by Aidant Systems, Inc., and by Jason Smith. */
using System;
using System.Collections;
using System.Collections.Generic;
namespace Iesi.Collections.Generic{
/// <summary>
/// <p>Implements a thread-safe <c>Set</c> wrapper. The implementation is extremely conservative,
/// serializing critical sections to prevent possible deadlocks, and locking on everything.
/// The one exception is for enumeration, which is inherently not thread-safe. For this, you
/// have to <c>lock</c> the <c>SyncRoot</c> object for the duration of the enumeration.</p>
/// </summary>
[Serializable]
public sealed class SynchronizedSet<T> : Set<T>
{
private ISet<T> mBasisSet;
private object mSyncRoot;
/// <summary>
/// Constructs a thread-safe <c>Set</c> wrapper.
/// </summary>
/// <param name="basisSet">The <c>Set</c> object that this object will wrap.</param>
public SynchronizedSet(ISet<T> basisSet)
{
mBasisSet = basisSet;
mSyncRoot = ((ICollection) basisSet).SyncRoot;
if (mSyncRoot == null)
throw new NullReferenceException("The Set you specified returned a null SyncRoot.");
}
/// <summary>
/// Adds the specified element to this set if it is not already present.
/// </summary>
/// <param name="o">The object to add to the set.</param>
/// <returns><see langword="true" /> is the object was added, <see langword="false" /> if it was already present.</returns>
public override sealed bool Add(T o)
{
lock (mSyncRoot)
{
return mBasisSet.Add(o);
}
}
/// <summary>
/// Adds all the elements in the specified collection to the set if they are not already present.
/// </summary>
/// <param name="c">A collection of objects to add to the set.</param>
/// <returns><see langword="true" /> is the set changed as a result of this operation, <see langword="false" /> if not.</returns>
public override sealed bool AddAll(ICollection<T> c)
{
Set<T> temp;
lock (((ICollection) c).SyncRoot)
{
temp = new HashedSet<T>(c);
}
lock (mSyncRoot)
{
return mBasisSet.AddAll(temp);
}
}
/// <summary>
/// Removes all objects from the set.
/// </summary>
public override sealed void Clear()
{
lock (mSyncRoot)
{
mBasisSet.Clear();
}
}
/// <summary>
/// Returns <see langword="true" /> if this set contains the specified element.
/// </summary>
/// <param name="o">The element to look for.</param>
/// <returns><see langword="true" /> if this set contains the specified element, <see langword="false" /> otherwise.</returns>
public override sealed bool Contains(T o)
{
lock (mSyncRoot)
{
return mBasisSet.Contains(o);
}
}
/// <summary>
/// Returns <see langword="true" /> if the set contains all the elements in the specified collection.
/// </summary>
/// <param name="c">A collection of objects.</param>
/// <returns><see langword="true" /> if the set contains all the elements in the specified collection, <see langword="false" /> otherwise.</returns>
public override sealed bool ContainsAll(ICollection<T> c)
{
Set<T> temp;
lock (((ICollection) c).SyncRoot)
{
temp = new HashedSet<T>(c);
}
lock (mSyncRoot)
{
return mBasisSet.ContainsAll(temp);
}
}
/// <summary>
/// Returns <see langword="true" /> if this set contains no elements.
/// </summary>
public override sealed bool IsEmpty
{
get
{
lock (mSyncRoot)
{
return mBasisSet.IsEmpty;
}
}
}
/// <summary>
/// Removes the specified element from the set.
/// </summary>
/// <param name="o">The element to be removed.</param>
/// <returns><see langword="true" /> if the set contained the specified element, <see langword="false" /> otherwise.</returns>
public override sealed bool Remove(T o)
{
lock (mSyncRoot)
{
return mBasisSet.Remove(o);
}
}
/// <summary>
/// Remove all the specified elements from this set, if they exist in this set.
/// </summary>
/// <param name="c">A collection of elements to remove.</param>
/// <returns><see langword="true" /> if the set was modified as a result of this operation.</returns>
public override sealed bool RemoveAll(ICollection<T> c)
{
Set<T> temp;
lock (((ICollection) c).SyncRoot)
{
temp = new HashedSet<T>(c);
}
lock (mSyncRoot)
{
return mBasisSet.RemoveAll(temp);
}
}
/// <summary>
/// Retains only the elements in this set that are contained in the specified collection.
/// </summary>
/// <param name="c">Collection that defines the set of elements to be retained.</param>
/// <returns><see langword="true" /> if this set changed as a result of this operation.</returns>
public override sealed bool RetainAll(ICollection<T> c)
{
Set<T> temp;
lock (((ICollection) c).SyncRoot)
{
temp = new HashedSet<T>(c);
}
lock (mSyncRoot)
{
return mBasisSet.RetainAll(temp);
}
}
/// <summary>
/// Copies the elements in the <c>Set</c> to an array. The type of array needs
/// to be compatible with the objects in the <c>Set</c>, obviously.
/// </summary>
/// <param name="array">An array that will be the target of the copy operation.</param>
/// <param name="index">The zero-based index where copying will start.</param>
public override sealed void CopyTo(T[] array, int index)
{
lock (mSyncRoot)
{
mBasisSet.CopyTo(array, index);
}
}
/// <summary>
/// The number of elements contained in this collection.
/// </summary>
public override sealed int Count
{
get
{
lock (mSyncRoot)
{
return mBasisSet.Count;
}
}
}
/// <summary>
/// Returns <see langword="true" />, indicating that this object is thread-safe. The exception to this
/// is enumeration, which is inherently not thread-safe. Use the <c>SyncRoot</c> object to
/// lock this object for the entire duration of the enumeration.
/// </summary>
public override sealed bool IsSynchronized
{
get { return true; }
}
/// <summary>
/// Returns an object that can be used to synchronize the <c>Set</c> between threads.
/// </summary>
public override sealed object SyncRoot
{
get { return mSyncRoot; }
}
/// <summary>
/// Enumeration is, by definition, not thread-safe. Use a <c>lock</c> on the <c>SyncRoot</c>
/// to synchronize the entire enumeration process.
/// </summary>
/// <returns></returns>
public override sealed IEnumerator<T> GetEnumerator()
{
return mBasisSet.GetEnumerator();
}
/// <summary>
/// Returns a clone of the <c>Set</c> instance.
/// </summary>
/// <returns>A clone of this object.</returns>
public override object Clone()
{
return new SynchronizedSet((ISet) mBasisSet.Clone());
}
/// <summary>
/// Indicates whether given instace is read-only or not
/// </summary>
public override bool IsReadOnly
{
get
{
lock (mSyncRoot)
{
return mBasisSet.IsReadOnly;
}
}
}
/// <summary>
/// Performs CopyTo when called trhough non-generic ISet (ICollection) interface
/// </summary>
/// <param name="array"></param>
/// <param name="index"></param>
protected override void NonGenericCopyTo(Array array, int index)
{
lock (mSyncRoot)
{
((ICollection) this.mBasisSet).CopyTo(array, index);
}
}
}
}
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