public CrossPartitionRangePageAsyncEnumerator(
IFeedRangeProvider feedRangeProvider,
CreatePartitionRangePageAsyncEnumerator <TPage, TState> createPartitionRangeEnumerator,
IComparer <PartitionRangePageAsyncEnumerator <TPage, TState> > comparer,
int?maxConcurrency,
CancellationToken cancellationToken,
CrossPartitionState <TState> state = default)
{
if (comparer == null)
{
throw new ArgumentNullException(nameof(comparer));
}
this.feedRangeProvider = feedRangeProvider ?? throw new ArgumentNullException(nameof(feedRangeProvider));
this.createPartitionRangeEnumerator = createPartitionRangeEnumerator ?? throw new ArgumentNullException(nameof(createPartitionRangeEnumerator));
this.cancellationToken = cancellationToken;
this.lazyEnumerators = new AsyncLazy <PriorityQueue <PartitionRangePageAsyncEnumerator <TPage, TState> > >(async(CancellationToken token) =>
{
IReadOnlyList <(PartitionKeyRange, TState)> rangeAndStates;
if (state != default)
{
rangeAndStates = state.Value;
}
else
{
// Fan out to all partitions with default state
IEnumerable <PartitionKeyRange> ranges = await feedRangeProvider.GetFeedRangesAsync(token);
List <(PartitionKeyRange, TState)> rangesAndStatesBuilder = new List <(PartitionKeyRange, TState)>();
foreach (PartitionKeyRange range in ranges)
{
rangesAndStatesBuilder.Add((range, default));
}
rangeAndStates = rangesAndStatesBuilder;
}
List <BufferedPartitionRangePageAsyncEnumerator <TPage, TState> > bufferedEnumerators = rangeAndStates
.Select(rangeAndState =>
{
PartitionRangePageAsyncEnumerator <TPage, TState> enumerator = createPartitionRangeEnumerator(rangeAndState.Item1, rangeAndState.Item2);
BufferedPartitionRangePageAsyncEnumerator <TPage, TState> bufferedEnumerator = new BufferedPartitionRangePageAsyncEnumerator <TPage, TState>(enumerator, cancellationToken);
return(bufferedEnumerator);
})
.ToList();
if (maxConcurrency.HasValue)
{
await ParallelPrefetch.PrefetchInParallelAsync(bufferedEnumerators, maxConcurrency.Value, token);
}
PriorityQueue <PartitionRangePageAsyncEnumerator <TPage, TState> > enumerators = new PriorityQueue <PartitionRangePageAsyncEnumerator <TPage, TState> >(
bufferedEnumerators,
comparer);
return(enumerators);
});
}
public CrossPartitionRangePageAsyncEnumerator(
IFeedRangeProvider feedRangeProvider,
CreatePartitionRangePageAsyncEnumerator <TPage, TState> createPartitionRangeEnumerator,
IComparer <PartitionRangePageAsyncEnumerator <TPage, TState> > comparer,
int?maxConcurrency,
CancellationToken cancellationToken,
CrossFeedRangeState <TState> state = default)
{
this.feedRangeProvider = feedRangeProvider ?? throw new ArgumentNullException(nameof(feedRangeProvider));
this.createPartitionRangeEnumerator = createPartitionRangeEnumerator ?? throw new ArgumentNullException(nameof(createPartitionRangeEnumerator));
this.cancellationToken = cancellationToken;
this.lazyEnumerators = new AsyncLazy <IQueue <PartitionRangePageAsyncEnumerator <TPage, TState> > >(async(ITrace trace, CancellationToken token) =>
{
ReadOnlyMemory <FeedRangeState <TState> > rangeAndStates;
if (state != default)
{
rangeAndStates = state.Value;
}
else
{
// Fan out to all partitions with default state
List <FeedRangeEpk> ranges = await feedRangeProvider.GetFeedRangesAsync(trace, token);
List <FeedRangeState <TState> > rangesAndStatesBuilder = new List <FeedRangeState <TState> >(ranges.Count);
foreach (FeedRangeInternal range in ranges)
{
rangesAndStatesBuilder.Add(new FeedRangeState <TState>(range, default));
}
rangeAndStates = rangesAndStatesBuilder.ToArray();
}
List <BufferedPartitionRangePageAsyncEnumerator <TPage, TState> > bufferedEnumerators = new List <BufferedPartitionRangePageAsyncEnumerator <TPage, TState> >(rangeAndStates.Length);
for (int i = 0; i < rangeAndStates.Length; i++)
{
FeedRangeState <TState> feedRangeState = rangeAndStates.Span[i];
PartitionRangePageAsyncEnumerator <TPage, TState> enumerator = createPartitionRangeEnumerator(feedRangeState);
BufferedPartitionRangePageAsyncEnumerator <TPage, TState> bufferedEnumerator = new BufferedPartitionRangePageAsyncEnumerator <TPage, TState>(enumerator, cancellationToken);
bufferedEnumerators.Add(bufferedEnumerator);
}
if (maxConcurrency.HasValue)
{
await ParallelPrefetch.PrefetchInParallelAsync(bufferedEnumerators, maxConcurrency.Value, trace, token);
}
IQueue <PartitionRangePageAsyncEnumerator <TPage, TState> > queue;
if (comparer == null)
{
queue = new QueueWrapper <PartitionRangePageAsyncEnumerator <TPage, TState> >(
new Queue <PartitionRangePageAsyncEnumerator <TPage, TState> >(bufferedEnumerators));
}
else
{
queue = new PriorityQueueWrapper <PartitionRangePageAsyncEnumerator <TPage, TState> >(
new PriorityQueue <PartitionRangePageAsyncEnumerator <TPage, TState> >(
bufferedEnumerators,
comparer));
}
return(queue);
});
}