ChangeBatchBase.AddChange Method
Adds a specified item change to the group that is currently open
Namespace: Microsoft.Synchronization
Assembly: Microsoft.Synchronization (in Microsoft.Synchronization.dll)
Syntax
'Declaration
Public Sub AddChange ( _
change As ItemChange _
)
'Usage
Dim instance As ChangeBatchBase
Dim change As ItemChange
instance.AddChange(change)
public void AddChange(
ItemChange change
)
public:
void AddChange(
ItemChange^ change
)
member AddChange :
change:ItemChange -> unit
public function AddChange(
change : ItemChange
)
Parameters
- change
Type: Microsoft.Synchronization.ItemChange
An item change to add to the group that is currently open.
Exceptions
| Exception | Condition |
|---|---|
| ChangeBatchIsReadOnlyException | The change batch has already been sent to a change applier or synchronization session. Changes cannot be added to the batch after it has been sent. |
| ArgumentNullException | change is a null reference (Nothing in Visual Basic). |
| ObjectDisposedException | This ChangeBatchBase has been disposed. |
| InvalidOperationException |
—or—
|
Remarks
Before item changes can be added to a ChangeBatchBase object, a group must be opened by calling BeginOrderedGroup or the BeginUnorderedGroup method of the ChangeBatch object. Otherwise, this method throws InvalidOperationException.
Examples
The following example implements GetChangeBatch by adding items to an ordered group in a change batch. An item is only added when its change version is not contained in the destination knowledge.
Public Overrides Function GetChangeBatch(ByVal batchSize As UInteger, ByVal destinationKnowledge As SyncKnowledge) As ChangeBatch
' The destination knowledge must be converted to be compatible with the source replica
' before it can be used.
Dim mappedDestKnowledge As SyncKnowledge = _knowledge.MapRemoteKnowledgeToLocal(destinationKnowledge)
' Create a new change batch, initialized by using the current knowledge of the source replica
' and a new ForgottenKnowledge object.
Dim changeBatch As New ChangeBatch(IdFormats, GetKnowledge(), New ForgottenKnowledge())
' Start a group of changes in the change batch. The group is ordered by item ID.
' _getChangeBatchCurrent is 0 the first time GetChangeBatch is called, and is used to track the
' position in the metadata store for subsequent calls to GetChangeBatch.
changeBatch.BeginOrderedGroup(_items.Values(_getChangeBatchCurrent).GlobalId)
' itemsAdded is incremented each time a change is added to the change batch. When itemsAdded
' is greater than the requested batch size, enumeration stops and the change batch is returned.
Dim itemsAdded As Integer = 0
Dim itemMeta As ItemMetadata
' Enumerate items and add a change to the change batch if it is not contained in the
' destination knowledge.
' _items is a SortedList that contains ItemMetadata objects that are ordered by item ID.
While itemsAdded <= batchSize AndAlso _getChangeBatchCurrent < _items.Count
itemMeta = _items.Values(_getChangeBatchCurrent)
Dim kind As ChangeKind = If((itemMeta.IsDeleted), ChangeKind.Deleted, ChangeKind.Update)
Dim change As New ItemChange(IdFormats, ReplicaId, itemMeta.GlobalId, kind, itemMeta.CreationVersion, itemMeta.ChangeVersion)
' If the change is not contained in the destination knowledge, add it to the change batch.
If Not mappedDestKnowledge.Contains(change) Then
changeBatch.AddChange(change)
itemsAdded += 1
End If
_getChangeBatchCurrent += 1
End While
' End the group of changes in the change batch. Pass the current source knowledge.
changeBatch.EndOrderedGroup(_items.Values(_getChangeBatchCurrent - 1).GlobalId, _knowledge)
' When all items in the metadata store have been enumerated, set this batch as the
' last batch.
If _getChangeBatchCurrent = _items.Count Then
changeBatch.SetLastBatch()
End If
Return changeBatch
End Function
public override ChangeBatch GetChangeBatch(uint batchSize, SyncKnowledge destinationKnowledge)
{
// The destination knowledge must be converted to be compatible with the source replica
// before it can be used.
SyncKnowledge mappedDestKnowledge = _knowledge.MapRemoteKnowledgeToLocal(destinationKnowledge);
// Create a new change batch, initialized by using the current knowledge of the source replica
// and a new ForgottenKnowledge object.
ChangeBatch changeBatch = new ChangeBatch(IdFormats, GetKnowledge(), new ForgottenKnowledge());
// Start a group of changes in the change batch. The group is ordered by item ID.
// _getChangeBatchCurrent is 0 the first time GetChangeBatch is called, and is used to track the
// position in the metadata store for subsequent calls to GetChangeBatch.
changeBatch.BeginOrderedGroup(_items.Values[_getChangeBatchCurrent].GlobalId);
// itemsAdded is incremented each time a change is added to the change batch. When itemsAdded
// is greater than the requested batch size, enumeration stops and the change batch is returned.
int itemsAdded = 0;
ItemMetadata itemMeta;
// Enumerate items and add a change to the change batch if it is not contained in the
// destination knowledge.
// _items is a SortedList that contains ItemMetadata objects that are ordered by item ID.
for (; itemsAdded <= batchSize && _getChangeBatchCurrent < _items.Count; _getChangeBatchCurrent++)
{
itemMeta = _items.Values[_getChangeBatchCurrent];
ChangeKind kind = (itemMeta.IsDeleted) ? ChangeKind.Deleted : ChangeKind.Update;
ItemChange change = new ItemChange(IdFormats, ReplicaId, itemMeta.GlobalId, kind, itemMeta.CreationVersion,
itemMeta.ChangeVersion);
// If the change is not contained in the destination knowledge, add it to the change batch.
if (!mappedDestKnowledge.Contains(change))
{
changeBatch.AddChange(change);
itemsAdded++;
}
}
// End the group of changes in the change batch. Pass the current source knowledge.
changeBatch.EndOrderedGroup(_items.Values[_getChangeBatchCurrent - 1].GlobalId, _knowledge);
// When all items in the metadata store have been enumerated, set this batch as the
// last batch.
if (_getChangeBatchCurrent == _items.Count)
{
changeBatch.SetLastBatch();
}
return changeBatch;
}