public override async Task GetHistoryEventsAsync()

in src/DurableTask.AzureStorage/Tracking/AzureTableTrackingStore.cs [152:232]
56 lines of code
10 McCabe index (conditional complexity)

        public override async Task<OrchestrationHistory> GetHistoryEventsAsync(string instanceId, string expectedExecutionId, CancellationToken cancellationToken = default)
        {
            TableQueryResults<TableEntity> results = await this
                .GetHistoryEntitiesResponseInfoAsync(instanceId, expectedExecutionId, null, cancellationToken)
                .GetResultsAsync(cancellationToken: cancellationToken);

            // The sentinel row should always be the last row
            TableEntity sentinel = results.Entities.LastOrDefault(e => e.RowKey == SentinelRowKey);

            IList<HistoryEvent> historyEvents;
            string executionId;
            TrackingStoreContext trackingStoreContext = new TrackingStoreContext();

            // If expectedExecutionId is provided but it does not match the sentinel executionId,
            // it may belong to a previous generation. In that case, treat it as an unknown executionId
            // and skip loading history.
            if (results.Entities.Count > 0 && (expectedExecutionId == null ||
                                               expectedExecutionId == sentinel?.GetString("ExecutionId")))
            {
                // The most recent generation will always be in the first history event.
                executionId = sentinel?.GetString("ExecutionId") ?? results.Entities[0].GetString("ExecutionId");

                // Convert the table entities into history events.
                var events = new List<HistoryEvent>(results.Entities.Count);

                foreach (TableEntity entity in results.Entities)
                {
                    if (entity.GetString("ExecutionId") != executionId)
                    {
                        // The remaining entities are from a previous generation and can be discarded.
                        break;
                    }

                    // The sentinel row does not contain any history events, so ignore and continue
                    if (entity == sentinel)
                    {
                        continue;
                    }

                    // Some entity properties may be stored in blob storage.
                    await this.DecompressLargeEntityProperties(entity, trackingStoreContext.Blobs, cancellationToken);

                    events.Add((HistoryEvent)TableEntityConverter.Deserialize(entity, GetTypeForTableEntity(entity)));
                }

                historyEvents = events;
            }
            else
            {
                historyEvents = Array.Empty<HistoryEvent>();
                executionId = expectedExecutionId;
            }

            // Read the checkpoint completion time from the sentinel row.
            // A sentinel won't exist only if no instance of this ID has ever existed or the instance history
            // was purged. The IsCheckpointCompleteProperty was newly added _after_ v1.6.4.
            DateTime checkpointCompletionTime = DateTime.MinValue;
            ETag? eTagValue = sentinel?.ETag;
            if (sentinel != null &&
                sentinel.TryGetValue(CheckpointCompletedTimestampProperty, out object timestampObj) &&
                timestampObj is DateTimeOffset timestampProperty)
            {
                checkpointCompletionTime = timestampProperty.DateTime;
            }

            int currentEpisodeNumber = Utils.GetEpisodeNumber(historyEvents);

            this.settings.Logger.FetchedInstanceHistory(
                this.storageAccountName,
                this.taskHubName,
                instanceId,
                executionId,
                historyEvents.Count,
                currentEpisodeNumber,
                results.RequestCount,
                results.ElapsedMilliseconds,
                eTagValue?.ToString(),
                checkpointCompletionTime);

            return new OrchestrationHistory(historyEvents, checkpointCompletionTime, eTagValue, trackingStoreContext);
        }