async Task LeaseRenewer()

in src/DurableTask.AzureStorage/Partitioning/LeaseCollectionBalancer.cs [172:268]
82 lines of code
12 McCabe index (conditional complexity)

        async Task LeaseRenewer()
        {
            this.settings.Logger.PartitionManagerInfo(
                this.accountName,
                this.taskHub,
                this.workerName,
                string.Empty /* partitionId */,
                $"Starting background renewal of {this.leaseType} leases with interval: {this.options.RenewInterval}.");

            while (this.isStarted == 1 || !this.shutdownComplete)
            {
                try
                {
                    var nonRenewedLeases = new ConcurrentBag<T>();
                    var renewTasks = new List<Task>();

                    // Renew leases for all currently owned partitions in parallel
                    foreach (T lease in this.currentlyOwnedShards.Values)
                    {
                        if (this.shouldRenewLeaseDelegate(lease.PartitionId))
                        {
                            renewTasks.Add(this.RenewLeaseAsync(lease).ContinueWith(renewResult =>
                            {
                                if (!renewResult.Result)
                                {
                                    // Keep track of all failed attempts to renew so we can trigger shutdown for these partitions
                                    nonRenewedLeases.Add(lease);
                                }
                            }));
                        } 
                        else 
                        {
                            nonRenewedLeases.Add(lease);
                        }
                    }

                    // Renew leases for all partitions currently in shutdown 
                    var failedToRenewShutdownLeases = new List<T>();
                    foreach (T shutdownLease in this.keepRenewingDuringClose.Values)
                    {
                        if (this.shouldRenewLeaseDelegate(shutdownLease.PartitionId))
                        {
                            renewTasks.Add(this.RenewLeaseAsync(shutdownLease).ContinueWith(renewResult =>
                            {
                                if (!renewResult.Result)
                                {
                                    // Keep track of all failed attempts to renew shutdown leases so we can remove them from further renew attempts
                                    failedToRenewShutdownLeases.Add(shutdownLease);
                                }
                            }));
                        }
                    }

                    // Wait for all renews to complete
                    await Task.WhenAll(renewTasks.ToArray());

                    // Trigger shutdown of all partitions we did not successfully renew leases for
                    await nonRenewedLeases.ParallelForEachAsync(lease => this.RemoveLeaseAsync(lease, false));

                    // Now remove all failed renewals of shutdown leases from further renewals
                    foreach (T failedToRenewShutdownLease in failedToRenewShutdownLeases)
                    {
                        T removedLease = null;
                        this.keepRenewingDuringClose.TryRemove(failedToRenewShutdownLease.PartitionId, out removedLease);
                    }

                    await Task.Delay(this.options.RenewInterval, this.leaseRenewerCancellationTokenSource.Token);
                }
                catch (OperationCanceledException)
                {
                    this.settings.Logger.PartitionManagerInfo(
                        this.accountName,
                        this.taskHub,
                        this.workerName,
                        string.Empty /* partitionId */,
                        $"Background renewal task for {this.leaseType} leases was canceled.");
                }
                catch (Exception ex)
                {
                    this.settings.Logger.PartitionManagerError(
                        this.accountName,
                        this.taskHub,
                        this.workerName,
                        string.Empty,
                        $"Failed during {this.leaseType} lease renewal: {ex}");
                }
            }

            this.currentlyOwnedShards.Clear();
            this.keepRenewingDuringClose.Clear();
            this.settings.Logger.PartitionManagerInfo(
                this.accountName,
                this.taskHub,
                this.workerName,
                string.Empty /* partitionId */,
                $"Background renewer task for {this.leaseType} leases completed.");
        }