void MoveNext()
{
do
{
if (!enumerator.MoveNext())
{
enumerator = null;
return;
}
} while (!filterExpr.Evaluate(enumerator.Current.Value));
}
public override Task <IList <TElement> > ExecuteQueryAtomicAsync <TElement>(
TableQuery <TElement> query, TableRequestOptions requestOptions = null, OperationContext operationContext = null)
{
FilterExpression filterExpr = ChainTableUtils.ParseFilterString(query.FilterString);
ChainTableUtils.GetSingleTargetedPartitionKey(filterExpr); // validation, ignore result
if (query.SelectColumns != null)
{
throw new NotImplementedException("select");
}
if (query.TakeCount != null)
{
throw new NotImplementedException("top");
}
return(Task.FromResult(
(IList <TElement>)(from kvp in table where filterExpr.Evaluate(kvp.Value)
select ChainTableUtils.CopyEntity <TElement>(kvp.Value)).ToList()));
}
// XXX: This could loop a long time. Do we want to make it cancelable?
public async Task <TElement> ReadRowAsync()
{
using (await LockAsyncBuggable())
{
CheckDisposed();
for (;;)
{
// Figure out which side has the next primary key to return (or
// both) and pull the row(s) with that key from one or both sides.
int?cmp = DetermineNextSide();
if (cmp == null)
{
return(default(TElement));
}
MTableEntity nextInOld = null, nextInNew = null;
if (cmp <= 0)
{
nextInOld = oldTableNext;
oldTableNext = await oldTableStream.ReadRowAsync();
}
if (cmp >= 0)
{
nextInNew = newTableNext;
newTableNext = await newTableStream.ReadRowAsync();
}
MTableEntity ent = (nextInNew != null) ? nextInNew : nextInOld;
// Compare to end of ExecuteQueryAtomicAsync.
if (!RowKeyIsInternal(ent.RowKey) &&
origFilterExpr.Evaluate(ent) && !ent.deleted)
{
return(ent.Export <TElement>());
}
// Otherwise keep going.
}
}
}
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());
}
}
internal List <DynamicTableEntity> GetValidStreamReadRows(int startRevision, FilterExpression filterExpr, PrimaryKey continuationKey)
{
IEnumerable <IEnumerable <DynamicTableEntity> > filteredDumps =
from dump in dumps.Skip(startRevision)
select dump.Values.Where(row =>
(row.GetPrimaryKey().CompareTo(continuationKey) >= 0) && filterExpr.Evaluate(row));
PrimaryKey nextMandatoryKey = (from dump in filteredDumps select dump.Select(row => row.GetPrimaryKey())).IntersectAll().FirstOrDefault();
List <DynamicTableEntity> possible = filteredDumps.SelectMany(dump => dump.Where(row =>
(nextMandatoryKey == null || row.GetPrimaryKey().CompareTo(nextMandatoryKey) <= 0)))
.Distinct((IEqualityComparer <DynamicTableEntity>)BetterComparer.Instance).ToList();
if (nextMandatoryKey == null)
{
possible.Add(null); // i.e., "end of stream" is a valid read
}
return(possible);
}