Método ChangeBatchBase.BeginOrderedGroup

Abre um grupo ordenado no lote de alterações. Esse grupo é ordenado por ID de item.

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

Sintaxe

'Declaração
Public Sub BeginOrderedGroup ( _
    itemId As SyncId _
)
'Uso
Dim instance As ChangeBatchBase
Dim itemId As SyncId

instance.BeginOrderedGroup(itemId)

public void BeginOrderedGroup (
    SyncId itemId
)

public:
void BeginOrderedGroup (
    SyncId^ itemId
)

public void BeginOrderedGroup (
    SyncId itemId
)

public function BeginOrderedGroup (
    itemId : SyncId
)

Parâmetros

• itemId
  O limite inferior fechado das IDs de item desse grupo ordenado. Para especificar um limite inferior igual a 0, use Zero.

Comentários

As alterações de item adicionadas ao lote de alterações depois de este método ser chamado são adicionadas ao grupo aberto.

As alterações de item não podem ser adicionadas ao lote de alterações até que um grupo seja aberto.

Exemplo

O exemplo a seguir implementa GetChangeBatch adicionando itens a um grupo ordenado em um lote de alterações. Um item só é adicionado quando sua versão de alteração não está contida no conhecimento de destino.

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;
}

Consulte também

Referência

Classe ChangeBatchBase
Membros ChangeBatchBase
Namespace Microsoft.Synchronization