ReadOnlyCollectionBase::ICollection::SyncRoot Property

 
System_CAPS_noteNote

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Gets an object that can be used to synchronize access to a ReadOnlyCollectionBase object.

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

private:
property Object^ SyncRoot {
	virtual Object^ get() sealed = ICollection::SyncRoot::get;
}

Property Value

Type: System::Object^

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

Derived classes can provide their own synchronized version of the ReadOnlyCollectionBase class using the SyncRoot property. The synchronizing code must perform operations on the SyncRoot property of the ReadOnlyCollectionBase object, not directly on the ReadOnlyCollectionBase 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 ReadOnlyCollectionBase 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 property during the entire enumeration.

// Get the ICollection interface from the ReadOnlyCollectionBase
// derived class.
ICollection^ myCollection = myReadOnlyCollection;
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);
    }
}

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

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
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