Explains how to synchronise two .NET collections by applying differences, with thread safety using locks, ensuring target lists match source lists efficiently.
I recently found the need to Sync two lists. I have one list that is used for display, and I want to dynamically sync that list with a new one by applying a delta.
I thought that this would be difficult, but I was surprised at its ease.
1 1:
1 2: Module SyncExtensions
1 3:
1 4: <System.Runtime.CompilerServices.Extension()> _
1 5: Public Sub Sync(Of TItem)(ByVal targetItems As ICollection(Of TItem), ByVal sourceItems As IEnumerable(Of TItem))
1 6: Dim o As Object = DirectCast(targetItems, ICollection).SyncRoot
1 7: If Monitor.TryEnter(o, TimeSpan.FromSeconds(10)) Then
1 8: ' Find items in source that are not in target
1 9: Dim itemsToAdd As New Collection(Of TItem)
1 10: For Each Item In sourceItems
1 11: If Not targetItems.Contains(Item) Then
1 12: itemsToAdd.Add(Item)
1 13: End If
1 14: Next
1 15: ' Apply all adds
1 16: For Each Item In itemsToAdd
1 17: targetItems.Add(Item)
1 18: Next
1 19: ' Find tags in target that should not be in source
1 20: Dim itemsToRemove As New Collection(Of TItem)
1 21: For Each Item In targetItems
1 22: If Not sourceItems.Contains(Item) Then
1 23: itemsToRemove.Add(Item)
1 24: End If
1 25: Next
1 26: ' Apply all removes
1 27: For Each Item In itemsToRemove
1 28: targetItems.Remove(Item)
1 29: Next
1 30: ' Dispose Timer
1 31: Monitor.Exit(o)
1 32: End If
1 33: End Sub
1 34:
1 35: End Module
You need to remember to lock the object while you sync. This is to allow your threading to take place without incident. The nitty gritty is just a case of comparing the two lists and building a list of changes to make and then removing them :)
Technorati Tags: .NET
No related videos found.
If you've made it this far, it's worth connecting with our principal consultant and coach, Martin Hinshelwood, for a 30-minute 'ask me anything' call.
We partner with businesses across diverse industries, including finance, insurance, healthcare, pharmaceuticals, technology, engineering, transportation, hospitality, entertainment, legal, government, and military sectors.
Philips
Graham & Brown
Epic Games
Hubtel Ghana
Lean SA
SuperControl
Alignment Healthcare
Boeing
Trayport
Emerson Process Management
Healthgrades
NIT A/S
Lockheed Martin
Kongsberg Maritime
ProgramUtvikling
Brandes Investment Partners L.P.
Freadom
Capita Secure Information Solutions Ltd
Washington Department of Enterprise Services
Department of Work and Pensions (UK)
Ghana Police Service
Royal Air Force
Washington Department of Transport
Nottingham County Council
Flowmaster (a Mentor Graphics Company)
Sage
Deliotte
Alignment Healthcare
CR2
New Signature