public async Task CleanupDeletedInstancesAsync()

in src/Microsoft.Health.Dicom.Core/Features/Delete/DeleteService.cs [83:147]
58 lines of code
6 McCabe index (conditional complexity)

        public async Task<(bool success, int retrievedInstanceCount)> CleanupDeletedInstancesAsync(CancellationToken cancellationToken)
        {
            bool success = true;
            int retrievedInstanceCount = 0;

            using (ITransactionScope transactionScope = _transactionHandler.BeginTransaction())
            {
                try
                {
                    var deletedInstanceIdentifiers = (await _indexDataStore
                        .RetrieveDeletedInstancesAsync(
                            _deletedInstanceCleanupConfiguration.BatchSize,
                            _deletedInstanceCleanupConfiguration.MaxRetries,
                            cancellationToken))
                        .ToList();

                    retrievedInstanceCount = deletedInstanceIdentifiers.Count;

                    foreach (VersionedInstanceIdentifier deletedInstanceIdentifier in deletedInstanceIdentifiers)
                    {
                        try
                        {
                            Task[] tasks = new[]
                            {
                                _fileStore.DeleteFileIfExistsAsync(deletedInstanceIdentifier, cancellationToken),
                                _metadataStore.DeleteInstanceMetadataIfExistsAsync(deletedInstanceIdentifier, cancellationToken),
                            };

                            await Task.WhenAll(tasks);

                            await _indexDataStore.DeleteDeletedInstanceAsync(deletedInstanceIdentifier, cancellationToken);
                        }
                        catch (Exception cleanupException)
                        {
                            try
                            {
                                int newRetryCount = await _indexDataStore.IncrementDeletedInstanceRetryAsync(deletedInstanceIdentifier, GenerateCleanupAfter(_deletedInstanceCleanupConfiguration.RetryBackOff), cancellationToken);
                                if (newRetryCount > _deletedInstanceCleanupConfiguration.MaxRetries)
                                {
                                    _logger.LogCritical(cleanupException, "Failed to cleanup instance {DeletedInstanceIdentifier}. Retry count is now {NewRetryCount} and retry will not be re-attempted.", deletedInstanceIdentifier, newRetryCount);
                                }
                                else
                                {
                                    _logger.LogError(cleanupException, "Failed to cleanup instance {DeletedInstanceIdentifier}. Retry count is now {NewRetryCount}.", deletedInstanceIdentifier, newRetryCount);
                                }
                            }
                            catch (Exception incrementException)
                            {
                                _logger.LogCritical(incrementException, "Failed to increment cleanup retry for instance {DeletedInstanceIdentifier}.", deletedInstanceIdentifier);
                                success = false;
                            }
                        }
                    }

                    transactionScope.Complete();
                }
                catch (Exception retrieveException)
                {
                    _logger.LogCritical(retrieveException, "Failed to retrieve instances to cleanup.");
                    success = false;
                }
            }

            return (success, retrievedInstanceCount);
        }