private ScaleStatus GetScaleStatusCore()

in Microsoft.Azure.WebJobs.Extensions.AzureCosmosDb.Mongo/Trigger/CosmosDBMongoScaleMonitor.cs [71:120]
40 lines of code
7 McCabe index (conditional complexity)

        private ScaleStatus GetScaleStatusCore(int workerCount, CosmosDBMongoTriggerMetrics[] metrics)
        {
            ScaleStatus status = new ScaleStatus
            {
                Vote = ScaleVote.None
            };

            // Unable to determine the correct vote with no metrics.
            if (metrics == null || metrics.Length == 0)
            {
                return status;
            }

            // At least _minSampleCount samples are required to make a scale decision for the rest of the checks.
            if (metrics.Length < _minSampleCount)
            {
                return status;
            }

            // Samples are in chronological order. Check for a continuous increase in message count.
            // If detected, this results in an automatic scale out for the site container.
            if (metrics[metrics.Length-1].PendingEventsCount > 0)
            {
                bool PendingWorkCountHitMaxForN =
                IsTrueForLastN(
                    metrics,
                    _minSampleCount,
                    (prev, next) => prev.PendingEventsCount <= next.PendingEventsCount && next.PendingEventsCount >= _maxWorkPerInstance);
                if (PendingWorkCountHitMaxForN)
                {
                    status.Vote = ScaleVote.ScaleOut;
                    return status;
                }
            }

            bool PendingWorkCountDecreasing =
                IsTrueForLastN(
                    metrics,
                    _minSampleCount,
                    (prev, next) => prev.PendingEventsCount >= next.PendingEventsCount);
            if (PendingWorkCountDecreasing)
            {
                status.Vote = ScaleVote.ScaleIn;
                return status;
            }

            _logger.LogDebug($"CosmosDB Mongo trigger function '{_functionId}-{_databaseName}-{_collectionName}' is steady.");

            return status;
        }