protected override async Task <SelectedSnapshot> LoadAsync(string persistenceId,
SnapshotSelectionCriteria criteria)
{
var requestOptions = GenerateOptions();
BlobResultSegment results = null;
using (var cts = new CancellationTokenSource(_settings.RequestTimeout))
{
results = await Container.ListBlobsSegmentedAsync(SeqNoHelper.ToSnapshotSearchQuery(persistenceId),
true,
BlobListingDetails.Metadata, null, null, requestOptions, new OperationContext(), cts.Token);
}
// if we made it down here, the initial request succeeded.
async Task <SelectedSnapshot> FilterAndFetch(BlobResultSegment segment)
{
// apply filter criteria
var filtered = segment.Results
.Where(x => x is CloudBlockBlob)
.Cast <CloudBlockBlob>()
.Where(x => FilterBlobSeqNo(criteria, x))
.Where(x => FilterBlobTimestamp(criteria, x))
.OrderByDescending(x => FetchBlobSeqNo(x)) // ordering matters - get highest seqNo item
.ThenByDescending(x =>
FetchBlobTimestamp(
x)) // if there are multiple snapshots taken at same SeqNo, need latest timestamp
.FirstOrDefault();
// couldn't find what we were looking for. Onto the next part of the query
// or return null to sender possibly.
if (filtered == null)
{
return(null);
}
using (var cts = new CancellationTokenSource(_settings.RequestTimeout))
using (var memoryStream = new MemoryStream())
{
await filtered.DownloadToStreamAsync(memoryStream, AccessCondition.GenerateIfExistsCondition(),
GenerateOptions(), new OperationContext(), cts.Token);
var snapshot = _serialization.SnapshotFromBytes(memoryStream.ToArray());
return(new SelectedSnapshot(new SnapshotMetadata(persistenceId, FetchBlobSeqNo(filtered)),
snapshot.Data));
}
}
// TODO: see if there's ever a scenario where the most recent snapshots aren't in the beginning of the pagination list.
var result = await FilterAndFetch(results);
return(result);
}
protected override async Task <SelectedSnapshot> LoadAsync(string persistenceId,
SnapshotSelectionCriteria criteria)
{
using var cts = new CancellationTokenSource(_settings.RequestTimeout);
{
var results = Container.GetBlobsAsync(
prefix: SeqNoHelper.ToSnapshotSearchQuery(persistenceId),
traits: BlobTraits.Metadata,
cancellationToken: cts.Token);
var pageEnumerator = results.AsPages().GetAsyncEnumerator(cts.Token);
if (!await pageEnumerator.MoveNextAsync())
{
return(null);
}
// TODO: see if there's ever a scenario where the most recent snapshots aren't in the first page of the pagination list.
// apply filter criteria
var filtered = pageEnumerator.Current.Values
.Where(x => FilterBlobSeqNo(criteria, x))
.Where(x => FilterBlobTimestamp(criteria, x))
.OrderByDescending(FetchBlobSeqNo) // ordering matters - get highest seqNo item
.ThenByDescending(FetchBlobTimestamp) // if there are multiple snapshots taken at same SeqNo, need latest timestamp
.FirstOrDefault();
// couldn't find what we were looking for. Onto the next part of the query
// or return null to sender possibly.
if (filtered == null)
{
return(null);
}
using var memoryStream = new MemoryStream();
var blobClient = Container.GetBlockBlobClient(filtered.Name);
var downloadInfo = await blobClient.DownloadAsync(cts.Token);
await downloadInfo.Value.Content.CopyToAsync(memoryStream);
var snapshot = _serialization.SnapshotFromBytes(memoryStream.ToArray());
var result =
new SelectedSnapshot(
new SnapshotMetadata(
persistenceId,
FetchBlobSeqNo(filtered),
new DateTime(FetchBlobTimestamp(filtered))),
snapshot.Data);
return(result);
}
}
protected override async Task DeleteAsync(string persistenceId, SnapshotSelectionCriteria criteria)
{
using var cts = new CancellationTokenSource(_settings.RequestTimeout);
var items = Container.GetBlobsAsync(
prefix: SeqNoHelper.ToSnapshotSearchQuery(persistenceId),
traits: BlobTraits.Metadata,
cancellationToken: cts.Token);
var filtered = items
.Where(x => FilterBlobSeqNo(criteria, x))
.Where(x => FilterBlobTimestamp(criteria, x));
var deleteTasks = new List <Task>();
await foreach (var blob in filtered.WithCancellation(cts.Token))
{
var blobClient = Container.GetBlobClient(blob.Name);
deleteTasks.Add(blobClient.DeleteIfExistsAsync(cancellationToken: cts.Token));
}
await Task.WhenAll(deleteTasks);
}
protected override async Task DeleteAsync(string persistenceId, SnapshotSelectionCriteria criteria)
{
var requestOptions = GenerateOptions();
BlobResultSegment results = null;
using (var cts = new CancellationTokenSource(_settings.RequestTimeout))
{
/*
* Query only the metadata - don't need to stream the entire blob back to us
* in order to delete it from storage in the next request.
*/
results = await Container.ListBlobsSegmentedAsync(SeqNoHelper.ToSnapshotSearchQuery(persistenceId),
true,
BlobListingDetails.Metadata, null, null, requestOptions, new OperationContext(), cts.Token);
}
// if we made it down here, the initial request succeeded.
async Task FilterAndDelete(BlobResultSegment segment)
{
// apply filter criteria
var filtered = segment.Results.Where(x => x is CloudBlockBlob)
.Cast <CloudBlockBlob>()
.Where(x => FilterBlobSeqNo(criteria, x))
.Where(x => FilterBlobTimestamp(criteria, x));
var deleteTasks = new List <Task>();
using (var cts = new CancellationTokenSource(_settings.RequestTimeout))
{
foreach (var blob in filtered)
{
deleteTasks.Add(blob.DeleteIfExistsAsync(DeleteSnapshotsOption.None,
AccessCondition.GenerateIfExistsCondition(),
GenerateOptions(), new OperationContext(), cts.Token));
}
await Task.WhenAll(deleteTasks);
}
}
var continuationToken = results.ContinuationToken;
var deleteTask = FilterAndDelete(results);
while (continuationToken != null)
{
// get the next round of results in parallel with the deletion of the previous
var nextResults = await Container.ListBlobsSegmentedAsync(continuationToken);
// finish our previous delete tasks
await deleteTask;
// start next round of deletes
deleteTask = FilterAndDelete(nextResults);
// move the loop forward if there are more results to be processed still
continuationToken = nextResults.ContinuationToken;
}
// wait for the final delete operation to complete
await deleteTask;
}
