public Task <TElement> ReadRowAsync()
{
if (continuationKey == null)
{
return(Task.FromResult(default(TElement)));
}
List <DynamicTableEntity> possibleRows = outer.GetValidStreamReadRows(startRevision, filterExpr, continuationKey);
int choiceIndex = PSharpNondeterminism.Choice(possibleRows.Count);
DynamicTableEntity choice = possibleRows[choiceIndex];
Console.WriteLine("NondeterministicQueryStream: possibleRows {0}, choiceIndex {1}",
BetterComparer.ToString(possibleRows), choiceIndex);
continuationKey = (choice == null) ? null : ChainTableUtils.NextValidPrimaryKeyAfter(choice.GetPrimaryKey());
return(Task.FromResult((choice == null) ? default(TElement) : ChainTableUtils.CopyEntity <TElement>(choice)));
}
internal async Task RunQueryStreamedAsync(TableQuery <DynamicTableEntity> query)
{
int startRevision = await peekProxy.GetReferenceTableRevisionAsync();
FilterExpression filterExpr = ChainTableUtils.ParseFilterString(query.FilterString);
Console.WriteLine("{0} starting streaming query: {1}", machineId, query);
using (IQueryStream <DynamicTableEntity> stream = await migratingTable.ExecuteQueryStreamedAsync(query))
{
PrimaryKey lastKey = ChainTableUtils.FirstValidPrimaryKey;
for (;;)
{
PrimaryKey returnedContinuationKey = await stream.GetContinuationPrimaryKeyAsync();
PSharpRuntime.Assert(returnedContinuationKey == null || returnedContinuationKey.CompareTo(lastKey) >= 0,
"{0}: query stream continuation key is {1}, expected >= {2}",
machineId, returnedContinuationKey, lastKey);
DynamicTableEntity row = await stream.ReadRowAsync(); // may be null, meaning end of stream
// Must be after ReadRowAsync, otherwise additional rows could become valid
// due to a mutation between GetValidStreamReadRows and ReadRowAsync and
// we would falsely report a bug if ReadRowAsync returns one of those rows.
List <DynamicTableEntity> validRows = await peekProxy.GetValidStreamReadRows(startRevision, filterExpr, lastKey);
// Three cheers for automatic use of covariance in overload resolution!
PSharpRuntime.Assert(validRows.Contains(row, BetterComparer.Instance),
"{0} query stream returned {1}, which is not one of the valid rows: {2}",
machineId, BetterComparer.ToString(row), BetterComparer.ToString(validRows));
Console.WriteLine("{0} query stream returned row {1}, which is valid", machineId, BetterComparer.ToString(row));
if (row == null)
{
// Any returnedContinuationKey (including null) is less or equal to a row of null.
break;
}
else
{
PSharpRuntime.Assert(returnedContinuationKey != null && returnedContinuationKey.CompareTo(row.GetPrimaryKey()) <= 0,
"{0}: query stream continuation key is {1}, expected <= {2}",
machineId, returnedContinuationKey, row.GetPrimaryKey());
lastKey = ChainTableUtils.NextValidPrimaryKeyAfter(row.GetPrimaryKey());
}
}
}
Console.WriteLine("{0} finished streaming query", machineId);
}
async Task DoQueryStreamed()
{
int startRevision = await peekProxy.GetReferenceTableRevisionAsync();
// XXX: Test the filtering?
var query = new TableQuery <DynamicTableEntity>();
using (IQueryStream <DynamicTableEntity> stream = await migratingTable.ExecuteQueryStreamedAsync(query))
{
PrimaryKey continuationKey = await stream.GetContinuationPrimaryKeyAsync();
await peekProxy.ValidateQueryStreamGapAsync(startRevision, null, continuationKey);
do
{
DynamicTableEntity row = await stream.ReadRowAsync();
PrimaryKey newContinuationKey = await stream.GetContinuationPrimaryKeyAsync();
if (row == null)
{
PSharpRuntime.Assert(newContinuationKey == null);
await peekProxy.ValidateQueryStreamGapAsync(startRevision, continuationKey, null);
}
else
{
await peekProxy.ValidateQueryStreamGapAsync(startRevision, continuationKey, row.GetPrimaryKey());
await peekProxy.ValidateQueryStreamRowAsync(startRevision, row);
await peekProxy.ValidateQueryStreamGapAsync(startRevision,
ChainTableUtils.NextValidPrimaryKeyAfter(row.GetPrimaryKey()), newContinuationKey);
}
continuationKey = newContinuationKey;
} while (continuationKey != null);
}
}
