public static TryCatch <ParallelContinuationToken> TryCreateFromCosmosElement(CosmosElement cosmosElement)
{
if (!(cosmosElement is CosmosObject cosmosObject))
{
return(TryCatch <ParallelContinuationToken> .FromException(
new MalformedContinuationTokenException($"{nameof(ParallelContinuationToken)} is not an object: {cosmosElement}")));
}
if (!cosmosObject.TryGetValue(PropertyNames.Token, out CosmosElement rawToken))
{
return(TryCatch <ParallelContinuationToken> .FromException(
new MalformedContinuationTokenException($"{nameof(ParallelContinuationToken)} is missing field: '{PropertyNames.Token}': {cosmosElement}")));
}
string token;
if (rawToken is CosmosString rawTokenString)
{
token = rawTokenString.Value;
}
else
{
token = null;
}
if (!cosmosObject.TryGetValue(PropertyNames.Range, out CosmosObject rawRange))
{
return(TryCatch <ParallelContinuationToken> .FromException(
new MalformedContinuationTokenException($"{nameof(ParallelContinuationToken)} is missing field: '{PropertyNames.Range}': {cosmosElement}")));
}
if (!rawRange.TryGetValue(PropertyNames.Min, out CosmosString rawMin))
{
return(TryCatch <ParallelContinuationToken> .FromException(
new MalformedContinuationTokenException($"{nameof(ParallelContinuationToken)} is missing field: '{PropertyNames.Min}': {cosmosElement}")));
}
string min = rawMin.Value;
if (!rawRange.TryGetValue(PropertyNames.Max, out CosmosString rawMax))
{
return(TryCatch <ParallelContinuationToken> .FromException(
new MalformedContinuationTokenException($"{nameof(ParallelContinuationToken)} is missing field: '{PropertyNames.Max}': {cosmosElement}")));
}
string max = rawMax.Value;
Range <string> range = new Documents.Routing.Range <string>(min, max, isMinInclusive: true, isMaxInclusive: false);
ParallelContinuationToken parallelContinuationToken = new ParallelContinuationToken(token, range);
return(TryCatch <ParallelContinuationToken> .FromResult(parallelContinuationToken));
}
public static CosmosElement ToCosmosElement(ParallelContinuationToken parallelContinuationToken)
{
CosmosElement token = parallelContinuationToken.Token == null ? (CosmosElement)CosmosNull.Create() : (CosmosElement)CosmosString.Create(parallelContinuationToken.Token);
return(CosmosObject.Create(
new Dictionary <string, CosmosElement>()
{
{ ParallelContinuationToken.PropertyNames.Token, token },
{
ParallelContinuationToken.PropertyNames.Range,
CosmosObject.Create(
new Dictionary <string, CosmosElement>()
{
{ PropertyNames.Min, CosmosString.Create(parallelContinuationToken.Range.Min) },
{ PropertyNames.Max, CosmosString.Create(parallelContinuationToken.Range.Max) }
})
},
}));
}
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);
}
private static TryCatch <CrossFeedRangeState <QueryState> > MonadicExtractState(
CosmosElement continuationToken,
IReadOnlyList <FeedRangeEpk> ranges)
{
if (continuationToken == null)
{
// Full fan out to the ranges with null continuations
CrossFeedRangeState <QueryState> fullFanOutState = new CrossFeedRangeState <QueryState>(ranges.Select(range => new FeedRangeState <QueryState>(range, (QueryState)null)).ToArray());
return(TryCatch <CrossFeedRangeState <QueryState> > .FromResult(fullFanOutState));
}
if (!(continuationToken is CosmosArray parallelContinuationTokenListRaw))
{
return(TryCatch <CrossFeedRangeState <QueryState> > .FromException(
new MalformedContinuationTokenException(
$"Invalid format for continuation token {continuationToken} for {nameof(ParallelCrossPartitionQueryPipelineStage)}")));
}
if (parallelContinuationTokenListRaw.Count == 0)
{
return(TryCatch <CrossFeedRangeState <QueryState> > .FromException(
new MalformedContinuationTokenException(
$"Invalid format for continuation token {continuationToken} for {nameof(ParallelCrossPartitionQueryPipelineStage)}")));
}
List <ParallelContinuationToken> parallelContinuationTokens = new List <ParallelContinuationToken>();
foreach (CosmosElement parallelContinuationTokenRaw in parallelContinuationTokenListRaw)
{
TryCatch <ParallelContinuationToken> tryCreateParallelContinuationToken = ParallelContinuationToken.TryCreateFromCosmosElement(parallelContinuationTokenRaw);
if (tryCreateParallelContinuationToken.Failed)
{
return(TryCatch <CrossFeedRangeState <QueryState> > .FromException(
tryCreateParallelContinuationToken.Exception));
}
parallelContinuationTokens.Add(tryCreateParallelContinuationToken.Result);
}
TryCatch <PartitionMapping <ParallelContinuationToken> > partitionMappingMonad = PartitionMapper.MonadicGetPartitionMapping(
ranges,
parallelContinuationTokens);
if (partitionMappingMonad.Failed)
{
return(TryCatch <CrossFeedRangeState <QueryState> > .FromException(
partitionMappingMonad.Exception));
}
PartitionMapping <ParallelContinuationToken> partitionMapping = partitionMappingMonad.Result;
List <FeedRangeState <QueryState> > feedRangeStates = new List <FeedRangeState <QueryState> >();
List <IReadOnlyDictionary <FeedRangeEpk, ParallelContinuationToken> > rangesToInitialize = new List <IReadOnlyDictionary <FeedRangeEpk, ParallelContinuationToken> >()
{
// Skip all the partitions left of the target range, since they have already been drained fully.
partitionMapping.TargetMapping,
partitionMapping.MappingRightOfTarget,
};
foreach (IReadOnlyDictionary <FeedRangeEpk, ParallelContinuationToken> rangeToInitalize in rangesToInitialize)
{
foreach (KeyValuePair <FeedRangeEpk, ParallelContinuationToken> kvp in rangeToInitalize)
{
FeedRangeState <QueryState> feedRangeState = new FeedRangeState <QueryState>(kvp.Key, kvp.Value?.Token != null ? new QueryState(CosmosString.Create(kvp.Value.Token)) : null);
feedRangeStates.Add(feedRangeState);
}
}
CrossFeedRangeState <QueryState> crossPartitionState = new CrossFeedRangeState <QueryState>(feedRangeStates.ToArray());
return(TryCatch <CrossFeedRangeState <QueryState> > .FromResult(crossPartitionState));
}
// 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);
}