public Task <BoolResult> RegisterCheckpointAsync(OperationContext context, CheckpointState checkpointState)
{
TriggerGarbageCollection(context);
var msg = checkpointState.ToString();
return(context.PerformOperationWithTimeoutAsync(
Tracer,
context =>
{
var blobName = GenerateBlobName();
checkpointState.Consumers.TryAdd(_primaryMachineLocation);
if (_configuration.WriteLegacyFormat)
{
return _storage.WriteAsync(context, blobName, JsonSerializer.Serialize(checkpointState, _jsonSerializerOptions));
}
else
{
return _storage.WriteAsync(context, blobName, checkpointState);
}
},
traceOperationStarted: false,
extraStartMessage: msg,
extraEndMessage: _ => msg,
timeout: _configuration.RegisterCheckpointTimeout));
}
internal Task <BoolResult> GarbageCollectAsync(OperationContext context, int retentionLimit)
{
Contract.Requires(retentionLimit >= 0);
return(context.PerformOperationWithTimeoutAsync(
Tracer,
async context =>
{
var blobs = ListBlobsRecentFirstAsync(context)
.Skip(retentionLimit);
await foreach (var blob in blobs)
{
try
{
var deleteSucceeded = await _storage.DeleteIfExistsAsync(context, blob);
Tracer.Info(context, $"Delete attempt Name=[{blob.Name}] Succeeded=[{deleteSucceeded}]");
}
catch (Exception e)
{
Tracer.Error(context, e, $"Delete attempt Name=[{blob.Name}]");
}
}
return BoolResult.Success;
},
timeout: _configuration.GarbageCollectionTimeout));
}
public Task <Result <CheckpointState> > GetCheckpointStateAsync(OperationContext context)
{
// NOTE: this function is naturally retried by the heartbeat mechanisms in LLS
return(context.PerformOperationWithTimeoutAsync(
Tracer,
async context =>
{
var blobs = ListBlobsRecentFirstAsync(context);
await foreach (var blob in blobs)
{
try
{
var checkpointState = await _storage.ReadAsync <CheckpointState>(context, blob).ThrowIfFailureAsync();
checkpointState.FileName = blob;
foreach (var consumer in checkpointState.Consumers)
{
_pushLocations.Add(consumer, _configuration.PushCheckpointCandidateExpiry);
}
return Result.Success(checkpointState);
}
catch (TaskCanceledException) when(context.Token.IsCancellationRequested)
{
// We hit timeout or a proper cancellation.
// Breaking from the loop instead of tracing error for each iteration.
break;
}
catch (Exception e)
{
Tracer.Error(context, e, $"Failed to obtain {nameof(CheckpointState)} from blob `{blob.Name}`. Skipping.");
continue;
}
}
// Add slack for start cursor to account for clock skew
return CheckpointState.CreateUnavailable(_clock.UtcNow - _configuration.NewEpochEventStartCursorDelay);
},
extraEndMessage: result =>
{
if (!result.Succeeded)
{
return string.Empty;
}
var checkpointState = result.Value;
return $"CheckpointId=[{checkpointState.CheckpointId}] SequencePoint=[{checkpointState.StartSequencePoint}]";
},
timeout: _configuration.CheckpointStateTimeout));
}