Article
11/18/2011

ReadOnlyCollection<T>.ICollection.SyncRoot Property

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Gets an object that can be used to synchronize access to the ICollection.

Namespace: System.Collections.ObjectModel
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
Private ReadOnly Property SyncRoot As Object
    Implements ICollection.SyncRoot

Object ICollection.SyncRoot { get; }

Property Value

Type: System.Object
An object that can be used to synchronize access to the ICollection. In the default implementation of ReadOnlyCollection<T>, this property always returns the current instance.

Implements

ICollection.SyncRoot

Remarks

Default implementations of collections in System.Collections.Generic are not synchronized.

Enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.

SyncRoot returns an object that can be used to synchronize access to the ICollection. Synchronization is effective only if all threads lock this object before accessing the collection. The following code shows the use of the SyncRoot property for C#, Visual C++, and Visual Basic.

ICollection ic = ...;
lock (ic.SyncRoot) {
   // Access the collection.
}

Dim ic As ICollection = ...
SyncLock ic.SyncRoot
   ' Access the collection.
End SyncLock

ICollection^ ic = ...;
try {
   Monitor::Enter(ic->SyncRoot);
   // Access the collection.
}
finally {
   Monitor::Exit(ic->SyncRoot);
}

Retrieving the value of this property is an O(1) operation.

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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