ChangeBatchBase.EndOrderedGroup Method

Closes a previously opened ordered group in the change batch.

Namespace: Microsoft.Synchronization
Assembly: Microsoft.Synchronization (in microsoft.synchronization.dll)

Syntax

'Declaration
Public Sub EndOrderedGroup ( _
    itemId As SyncId, _
    madeWithKnowledge As SyncKnowledge _
)
'Usage
Dim instance As ChangeBatchBase
Dim itemId As SyncId
Dim madeWithKnowledge As SyncKnowledge

instance.EndOrderedGroup(itemId, madeWithKnowledge)

public void EndOrderedGroup (
    SyncId itemId,
    SyncKnowledge madeWithKnowledge
)

public:
void EndOrderedGroup (
    SyncId^ itemId, 
    SyncKnowledge^ madeWithKnowledge
)

public void EndOrderedGroup (
    SyncId itemId, 
    SyncKnowledge madeWithKnowledge
)

public function EndOrderedGroup (
    itemId : SyncId, 
    madeWithKnowledge : SyncKnowledge
)

Parameters

• itemId
  The closed upper bound of item IDs for this ordered group. To specify an upper bound of infinity, use Infinity.

• madeWithKnowledge
  The knowledge of the replica that made this group.

Remarks

After a group is closed, item changes can no longer be added to the change batch until a new group is opened.

Example

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;
}

See Also

Reference

ChangeBatchBase Class
ChangeBatchBase Members
Microsoft.Synchronization Namespace