internal QueryStream(MigratingTable outer, TableQuery <TElement> query, TableRequestOptions requestOptions, OperationContext operationContext)
{
this.outer = outer;
origFilterExpr = ChainTableUtils.ParseFilterString(query.FilterString);
mtableQuery = ChainTableUtils.CopyQuery <TElement, MTableEntity>(query);
this.requestOptions = requestOptions;
this.operationContext = operationContext;
}
public override async Task <IList <TElement> > ExecuteQueryAtomicAsync <TElement>(TableQuery <TElement> query, TableRequestOptions requestOptions = null, OperationContext operationContext = null)
{
if (query.SelectColumns != null)
{
throw new NotImplementedException("select");
}
if (query.TakeCount != null)
{
throw new NotImplementedException("top");
}
FilterExpression origFilterExpr = ChainTableUtils.ParseFilterString(query.FilterString);
string partitionKey = ChainTableUtils.GetSingleTargetedPartitionKey(origFilterExpr);
TableQuery <MTableEntity> mtableQuery = ChainTableUtils.CopyQuery <TElement, MTableEntity>(query);
MTableConfiguration config;
using (configService.Subscribe(FixedSubscriber <MTableConfiguration> .Instance, out config))
{
IEnumerable <MTableEntity> results;
if (config.state <= TableClientState.USE_OLD_HIDE_METADATA)
{
results = await oldTable.ExecuteQueryAtomicAsync(mtableQuery, requestOptions, operationContext);
await monitor.AnnotateLastBackendCallAsync(wasLinearizationPoint : true);
}
else if (config.state >= TableClientState.USE_NEW_WITH_TOMBSTONES)
{
results = await newTable.ExecuteQueryAtomicAsync(mtableQuery, requestOptions, operationContext);
await monitor.AnnotateLastBackendCallAsync(wasLinearizationPoint : true);
}
else
{
// Modify the filter to make sure it matches the meta row.
if (origFilterExpr is ComparisonExpression)
{
// filterExpr must be "PartitionKey eq A", which already matches the meta row; nothing to do.
}
else
{
// filterExpr must be "(PartitionKey eq A) and (B)".
// Rewrite to "(PartitionKey eq A) and ((RowKey eq ROW_KEY_PARTITION_META) or (B))".
var boe = (BooleanOperatorExpression)origFilterExpr;
mtableQuery.FilterString =
TableQuery.CombineFilters(boe.Left.ToFilterString(), TableOperators.And,
TableQuery.CombineFilters(
TableQuery.GenerateFilterCondition(TableConstants.RowKey, QueryComparisons.Equal, ROW_KEY_PARTITION_META),
TableOperators.Or, boe.Right.ToFilterString()));
}
IList <MTableEntity> oldRows = await oldTable.ExecuteQueryAtomicAsync(mtableQuery, requestOptions, operationContext);
MTablePartitionState?state =
(from r in oldRows where r.RowKey == ROW_KEY_PARTITION_META select r.partitionState).SingleOrDefault();
IList <MTableEntity> newRows;
if (state == MTablePartitionState.SWITCHED)
{
await monitor.AnnotateLastBackendCallAsync();
// If the filter string includes conditions on user-defined properties,
// a row in the old table can be shadowed by a row in the new table
// that doesn't satisfy those conditions. To make sure we retrieve all
// potential shadowing rows, retrieve the entire partition.
// XXX: At a minimum, we should try to keep conditions on the
// primary key, but how clever do we want to get with query rewriting?
if (!IsBugEnabled(MTableOptionalBug.QueryAtomicFilterShadowing))
{
mtableQuery.FilterString = TableQuery.GenerateFilterCondition(
TableConstants.PartitionKey, QueryComparisons.Equal, partitionKey);
}
newRows = await newTable.ExecuteQueryAtomicAsync(mtableQuery, requestOptions, operationContext);
await monitor.AnnotateLastBackendCallAsync(wasLinearizationPoint : true);
}
else
{
await monitor.AnnotateLastBackendCallAsync(wasLinearizationPoint : true);
newRows = new List <MTableEntity>();
}
// Merge lists. Hopefully this is pretty clear. Walking the lists
// in lockstep might be faster but is a lot more code.
var merged = new SortedDictionary <string, MTableEntity>(StringComparer.Ordinal);
foreach (MTableEntity ent in oldRows)
{
merged[ent.RowKey] = ent;
}
foreach (MTableEntity ent in newRows)
{
merged[ent.RowKey] = ent;
}
results = merged.Values;
}
return((from ent in results where !RowKeyIsInternal(ent.RowKey) &&
origFilterExpr.Evaluate(ent) && !ent.deleted
select ent.Export <TElement>()).ToList());
}
}
