public async ValueTask <bool> MoveNextAsync(ITrace trace)
{
this.cancellationToken.ThrowIfCancellationRequested();
if (trace == null)
{
throw new ArgumentNullException(nameof(trace));
}
if (!await this.crossPartitionRangePageAsyncEnumerator.MoveNextAsync(trace))
{
this.Current = default;
return(false);
}
TryCatch <CrossFeedRangePage <QueryPage, QueryState> > currentCrossPartitionPage = this.crossPartitionRangePageAsyncEnumerator.Current;
if (currentCrossPartitionPage.Failed)
{
this.Current = TryCatch <QueryPage> .FromException(currentCrossPartitionPage.Exception);
return(true);
}
CrossFeedRangePage <QueryPage, QueryState> crossPartitionPageResult = currentCrossPartitionPage.Result;
QueryPage backendQueryPage = crossPartitionPageResult.Page;
CrossFeedRangeState <QueryState> crossPartitionState = crossPartitionPageResult.State;
QueryState queryState;
if (crossPartitionState == null)
{
queryState = null;
}
else
{
// left most and any non null continuations
IOrderedEnumerable <FeedRangeState <QueryState> > feedRangeStates = crossPartitionState
.Value
.ToArray()
.OrderBy(tuple => ((FeedRangeEpk)tuple.FeedRange).Range.Min);
List <ParallelContinuationToken> activeParallelContinuationTokens = new List <ParallelContinuationToken>();
{
FeedRangeState <QueryState> firstState = feedRangeStates.First();
ParallelContinuationToken firstParallelContinuationToken = new ParallelContinuationToken(
token: firstState.State != null ? ((CosmosString)firstState.State.Value).Value : null,
range: ((FeedRangeEpk)firstState.FeedRange).Range);
activeParallelContinuationTokens.Add(firstParallelContinuationToken);
}
foreach (FeedRangeState <QueryState> feedRangeState in feedRangeStates.Skip(1))
{
this.cancellationToken.ThrowIfCancellationRequested();
if (feedRangeState.State != null)
{
ParallelContinuationToken parallelContinuationToken = new ParallelContinuationToken(
token: feedRangeState.State != null ? ((CosmosString)feedRangeState.State.Value).Value : null,
range: ((FeedRangeEpk)feedRangeState.FeedRange).Range);
activeParallelContinuationTokens.Add(parallelContinuationToken);
}
}
IEnumerable <CosmosElement> cosmosElementContinuationTokens = activeParallelContinuationTokens
.Select(token => ParallelContinuationToken.ToCosmosElement(token));
CosmosArray cosmosElementParallelContinuationTokens = CosmosArray.Create(cosmosElementContinuationTokens);
queryState = new QueryState(cosmosElementParallelContinuationTokens);
}
QueryPage crossPartitionQueryPage = new QueryPage(
backendQueryPage.Documents,
backendQueryPage.RequestCharge,
backendQueryPage.ActivityId,
backendQueryPage.ResponseLengthInBytes,
backendQueryPage.CosmosQueryExecutionInfo,
backendQueryPage.DisallowContinuationTokenMessage,
queryState);
this.Current = TryCatch <QueryPage> .FromResult(crossPartitionQueryPage);
return(true);
}
// In order to maintain the continuation token for the user we must drain with a few constraints
// 1) We fully drain from the left most partition before moving on to the next partition
// 2) We drain only full pages from the document producer so we aren't left with a partial page
// otherwise we would need to add to the continuation token how many items to skip over on that page.
public async ValueTask <bool> MoveNextAsync()
{
this.cancellationToken.ThrowIfCancellationRequested();
if (!await this.crossPartitionRangePageAsyncEnumerator.MoveNextAsync())
{
this.Current = default;
return(false);
}
TryCatch <CrossPartitionPage <QueryPage, QueryState> > currentCrossPartitionPage = this.crossPartitionRangePageAsyncEnumerator.Current;
if (currentCrossPartitionPage.Failed)
{
this.Current = TryCatch <QueryPage> .FromException(currentCrossPartitionPage.Exception);
return(true);
}
CrossPartitionPage <QueryPage, QueryState> crossPartitionPageResult = currentCrossPartitionPage.Result;
QueryPage backendQueryPage = crossPartitionPageResult.Page;
CrossPartitionState <QueryState> crossPartitionState = crossPartitionPageResult.State;
QueryState queryState;
if (crossPartitionState == null)
{
queryState = null;
}
else
{
// Left most and any non null continuations
List <(PartitionKeyRange, QueryState)> rangesAndStates = crossPartitionState.Value.OrderBy(tuple => tuple.Item1, PartitionKeyRangeComparer.Singleton).ToList();
List <ParallelContinuationToken> activeParallelContinuationTokens = new List <ParallelContinuationToken>();
for (int i = 0; i < rangesAndStates.Count; i++)
{
this.cancellationToken.ThrowIfCancellationRequested();
(PartitionKeyRange range, QueryState state) = rangesAndStates[i];
if ((i == 0) || (state != null))
{
ParallelContinuationToken parallelContinuationToken = new ParallelContinuationToken(
token: state != null ? ((CosmosString)state.Value).Value : null,
range: range.ToRange());
activeParallelContinuationTokens.Add(parallelContinuationToken);
}
}
IEnumerable <CosmosElement> cosmosElementContinuationTokens = activeParallelContinuationTokens
.Select(token => ParallelContinuationToken.ToCosmosElement(token));
CosmosArray cosmosElementParallelContinuationTokens = CosmosArray.Create(cosmosElementContinuationTokens);
queryState = new QueryState(cosmosElementParallelContinuationTokens);
}
QueryPage crossPartitionQueryPage = new QueryPage(
backendQueryPage.Documents,
backendQueryPage.RequestCharge,
backendQueryPage.ActivityId,
backendQueryPage.ResponseLengthInBytes,
backendQueryPage.CosmosQueryExecutionInfo,
backendQueryPage.DisallowContinuationTokenMessage,
queryState);
this.Current = TryCatch <QueryPage> .FromResult(crossPartitionQueryPage);
return(true);
}
