NameObjectCollectionBase.ICollection.SyncRoot Property

Definition

Namespace:

System.Collections.Specialized

Assembly:

System.Collections.Specialized.dll

Source:

NameObjectCollectionBase.cs

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

property System::Object ^ System::Collections::ICollection::SyncRoot { System::Object ^ get(); };

object System.Collections.ICollection.SyncRoot { get; }

member this.System.Collections.ICollection.SyncRoot : obj

 ReadOnly Property SyncRoot As Object Implements ICollection.SyncRoot

Property Value

Object

An object that can be used to synchronize access to the NameObjectCollectionBase object.

Implements

SyncRoot

Remarks

Derived classes can provide their own synchronized version of the NameObjectCollectionBase class using the SyncRoot property. The synchronizing code must perform operations on the SyncRoot property of the NameObjectCollectionBase object, not directly on the NameObjectCollectionBase object. This ensures proper operation of collections that are derived from other objects. Specifically, it maintains proper synchronization with other threads that might be simultaneously modifying the NameObjectCollectionBase object.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

The following code example shows how to lock the collection using the SyncRoot during the entire enumeration.

// Create a collection derived from NameObjectCollectionBase
ICollection^ myCollection = gcnew DerivedCollection();
bool lockTaken = false;
try
{
    Monitor::Enter(myCollection->SyncRoot, lockTaken);
    for each (Object^ item in myCollection)
    {
        // Insert your code here.
    }
}
finally
{
    if (lockTaken)
    {
        Monitor::Exit(myCollection->SyncRoot);
    }
}

// Create a collection derived from NameObjectCollectionBase
ICollection myCollection = new DerivedCollection();
lock(myCollection.SyncRoot)
{
    foreach (object item in myCollection)
    {
        // Insert your code here.
    }
}

' Create a collection derived from NameObjectCollectionBase
Dim myCollection As ICollection = New DerivedCollection()
SyncLock myCollection.SyncRoot
    For Each item As Object In myCollection
        ' Insert your code here.
    Next item
End SyncLock

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

See also

• IsSynchronized