SqlParameterCollection.SyncRoot Property
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Gets an object that can be used to synchronize access to the SqlParameterCollection.
public:
virtual property System::Object ^ SyncRoot { System::Object ^ get(); };
public override object SyncRoot { get; }
member this.SyncRoot : obj
Public Overrides ReadOnly Property SyncRoot As Object
Property Value
An object that can be used to synchronize access to the SqlParameterCollection.
Examples
The following code example shows how to lock the collection using the SyncRoot property during the entire enumeration.
ICollection^ myCollection = someCollection;
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);
}
}
ICollection myCollection = someCollection;
lock(myCollection.SyncRoot)
{
foreach (object item in myCollection)
{
// Insert your code here.
}
}
Dim myCollection As ICollection = someCollection
SyncLock myCollection.SyncRoot
For Each item In myCollection
' Insert your code here.
Next item
End SyncLock
Remarks
This member is an explicit interface member implementation. It can be used only when the SqlParameterCollection instance is cast to an ICollection interface.
For collections whose underlying store is not publicly available, the expected implementation is to return the current instance. Note that the pointer to the current instance might not be sufficient for collections that wrap other collections; those should return the underlying collection's SyncRoot
property.
Most collection classes in the System.Collections namespace also implement a Synchronized
method, which provides a synchronized wrapper around the underlying collection. However, derived classes can provide their own synchronized version of the collection using the SyncRoot property. The synchronizing code must perform operations on the SyncRoot property of the collection, not directly on the collection. 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 collection instance.
In the absence of a Synchronized
method on a collection, the expected usage for SyncRoot looks as follows:
ICollection^ myCollection = someCollection;
bool lockTaken = false;
try
{
Monitor::Enter(myCollection->SyncRoot, lockTaken);
// Some operation on the collection, which is now thread safe.
}
finally
{
if (lockTaken)
{
Monitor::Exit(myCollection->SyncRoot);
}
}
ICollection myCollection = someCollection;
lock(myCollection.SyncRoot)
{
// Some operation on the collection, which is now thread safe.
}
Dim myCollection As ICollection = someCollection
SyncLock myCollection.SyncRoot
' Some operation on the collection, which is now thread safe.
End SyncLock
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.