NameObjectCollectionBase.KeysCollection.ICollection.SyncRoot Property
Definition
Important
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Gets an object that can be used to synchronize access to the NameObjectCollectionBase.KeysCollection.
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.SyncRootProperty Value
An object that can be used to synchronize access to the NameObjectCollectionBase.KeysCollection.
Implements
Examples
The following code example shows how to lock the collection using the SyncRoot during the entire enumeration.
// Create a collection derived from NameObjectCollectionBase
NameObjectCollectionBase^ myBaseCollection = gcnew DerivedCollection();
// Get the ICollection from NameObjectCollectionBase.KeysCollection
ICollection^ myKeysCollection = myBaseCollection->Keys;
bool lockTaken = false;
try
{
Monitor::Enter(myKeysCollection->SyncRoot, lockTaken);
for each (Object^ item in myKeysCollection)
{
// Insert your code here.
}
}
finally
{
if (lockTaken)
{
Monitor::Exit(myKeysCollection->SyncRoot);
}
}
// Create a collection derived from NameObjectCollectionBase
NameObjectCollectionBase myBaseCollection = new DerivedCollection();
// Get the ICollection from NameObjectCollectionBase.KeysCollection
ICollection myKeysCollection = myBaseCollection.Keys;
lock(myKeysCollection.SyncRoot)
{
foreach (object item in myKeysCollection)
{
// Insert your code here.
}
}
' Create a collection derived from NameObjectCollectionBase
Dim myBaseCollection As NameObjectCollectionBase = New DerivedCollection()
' Get the ICollection from NameObjectCollectionBase.KeysCollection
Dim myKeysCollection As ICollection = myBaseCollection.Keys
SyncLock myKeysCollection.SyncRoot
For Each item As Object In myKeysCollection
' Insert your code here.
Next item
End SyncLock
Retrieving the value of this property is an O(1) operation.
Remarks
Derived classes can provide their own synchronized version of the NameObjectCollectionBase.KeysCollection using the SyncRoot property. The synchronizing code must perform operations on the SyncRoot of the NameObjectCollectionBase.KeysCollection, not directly on the NameObjectCollectionBase.KeysCollection. 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.KeysCollection 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.
