Метод BeginOrderedGroup
Открывает упорядоченную группу в пакете изменений. Эта группа сортируется по идентификатору элемента.
Пространство имен: Microsoft.Synchronization
Сборка: Microsoft.Synchronization (в Microsoft.Synchronization.dll)
Синтаксис
'Декларация
Public Sub BeginOrderedGroup ( _
itemId As SyncId _
)
'Применение
Dim instance As ChangeBatchBase
Dim itemId As SyncId
instance.BeginOrderedGroup(itemId)
public void BeginOrderedGroup(
SyncId itemId
)
public:
void BeginOrderedGroup(
SyncId^ itemId
)
member BeginOrderedGroup :
itemId:SyncId -> unit
public function BeginOrderedGroup(
itemId : SyncId
)
Параметры
- itemId
Тип Microsoft.Synchronization. . :: . .SyncId
Закрытая нижняя граница идентификаторов элементов для этой упорядоченной группы. Чтобы задать нижнюю границу, равную 0, используйте Zero.
Исключения
| Исключение | Условие |
|---|---|
| ArgumentNullException | Параметр itemId равен null Nothing nullptr unit пустая ссылка (Nothing в Visual Basic) . |
| ObjectDisposedException | Этот ChangeBatch уже был удален. |
| SyncInvalidOperationException | Пакет изменений содержит группу, которая была начата, но не была завершена. |
| ChangeBatchIsReadOnlyException | Пакет изменений уже был отправлен стороне, применяющей изменения, или сеансу синхронизации. Изменения нельзя добавлять в пакет после того, как он отправлен. |
Замечания
Изменения элементов, добавляемые к пакету изменений после вызова этого метода, добавляются в открытую группу.
Изменения элементов нельзя добавить в пакет, пока не создана группа.
Примеры
В следующем примере реализуется метод GetChangeBatch путем добавления элементов к упорядоченной группе в пакете изменений. Элемент добавляется, только если его версия изменения не содержится в наборе знаний назначения.
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;
}