Metodo ChangeBatchBase.BeginOrderedGroup

Apre un gruppo ordinato nel batch di modifiche. Questo gruppo è ordinato in base all'ID elemento.

Spazio dei nomi: Microsoft.Synchronization
Assembly: Microsoft.Synchronization (in microsoft.synchronization.dll)

Sintassi

'Dichiarazione
Public Sub BeginOrderedGroup ( _
    itemId As SyncId _
)
'Utilizzo
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
)

Parametri

• itemId
  Limite inferiore chiuso di ID elemento per questo gruppo ordinato. Per specificare un limite inferiore pari a 0, utilizzare Zero.

Osservazioni

Le modifiche dell'elemento aggiunte al batch di modifiche dopo la chiamata a questo metodo vengono aggiunte al gruppo aperto.

Non è possibile aggiungere modifiche dell'elemento al batch di modifiche finché non viene aperto un gruppo.

Esempio

Nell'esempio seguente viene implementato GetChangeBatch aggiungendo elementi a un gruppo ordinato in un batch di modifiche. Viene aggiunto un elemento solo quando la versione di modifica non è contenuta nella conoscenza di destinazione.

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;
}

Vedere anche

Riferimento

Classe ChangeBatchBase
Membri ChangeBatchBase
Spazio dei nomi Microsoft.Synchronization