public async Task Run(IProgress<double> progress, CancellationToken cancellationToken)
        {
            var users = _userManager.Users
                .DistinctBy(ChannelDownloadScheduledTask.GetUserDistinctValue)
                .Select(i => i.Id.ToString("N"))
                .ToList();

            var numComplete = 0;

            foreach (var user in users)
            {
                double percentPerUser = 1;
                percentPerUser /= users.Count;
                var startingPercent = numComplete * percentPerUser * 100;

                var innerProgress = new ActionableProgress<double>();
                innerProgress.RegisterAction(p => progress.Report(startingPercent + (percentPerUser * p)));

                await DownloadContent(user, cancellationToken, innerProgress).ConfigureAwait(false);

                numComplete++;
                double percent = numComplete;
                percent /= users.Count;
                progress.Report(percent * 100);
            }

            progress.Report(100);
        }

        public async Task Execute(CancellationToken cancellationToken, IProgress<double> progress)
        {
            CleanChannelContent(cancellationToken);

            var users = _userManager.Users.Select(i => i.Id.ToString("N")).ToList();

            var numComplete = 0;

            foreach (var user in users)
            {
                double percentPerUser = 1;
                percentPerUser /= users.Count;
                var startingPercent = numComplete * percentPerUser * 100;

                var innerProgress = new ActionableProgress<double>();
                innerProgress.RegisterAction(p => progress.Report(startingPercent + (.8 * p)));

                await DownloadContent(user, cancellationToken, innerProgress).ConfigureAwait(false);

                numComplete++;
                double percent = numComplete;
                percent /= users.Count;
                progress.Report(percent * 100);
            }

            progress.Report(100);
        }

        public async Task Sync(IServerSyncProvider provider,
            ISyncDataProvider dataProvider,
            SyncTarget target,
            IProgress<double> progress,
            CancellationToken cancellationToken)
        {
            var serverId = _appHost.SystemId;
            var serverName = _appHost.FriendlyName;

            await SyncData(provider, dataProvider, serverId, target, cancellationToken).ConfigureAwait(false);
            progress.Report(3);

            var innerProgress = new ActionableProgress<double>();
            innerProgress.RegisterAction(pct =>
            {
                var totalProgress = pct * .97;
                totalProgress += 1;
                progress.Report(totalProgress);
            });
            await GetNewMedia(provider, dataProvider, target, serverId, serverName, innerProgress, cancellationToken);

            // Do the data sync twice so the server knows what was removed from the device
            await SyncData(provider, dataProvider, serverId, target, cancellationToken).ConfigureAwait(false);
            
            progress.Report(100);
        }

        public async Task<FFMpegInfo> GetFFMpegInfo(IProgress<double> progress)
        {
            var versionedDirectoryPath = Path.Combine(GetMediaToolsPath(true), FFMpegDownloadInfo.Version);

            var info = new FFMpegInfo
            {
                ProbePath = Path.Combine(versionedDirectoryPath, FFMpegDownloadInfo.FFProbeFilename),
                Path = Path.Combine(versionedDirectoryPath, FFMpegDownloadInfo.FFMpegFilename),
                Version = FFMpegDownloadInfo.Version
            };

            Directory.CreateDirectory(versionedDirectoryPath);

            var tasks = new List<Task>();

            double ffmpegPercent = 0;
            double fontPercent = 0;
            var syncLock = new object();

            if (!File.Exists(info.ProbePath) || !File.Exists(info.Path))
            {
                var ffmpegProgress = new ActionableProgress<double>();
                ffmpegProgress.RegisterAction(p =>
                {
                    ffmpegPercent = p;

                    lock (syncLock)
                    {
                        progress.Report((ffmpegPercent / 2) + (fontPercent / 2));
                    }
                });

                tasks.Add(DownloadFFMpeg(info, ffmpegProgress));
            }
            else
            {
                ffmpegPercent = 100;
                progress.Report(50);
            }

            var fontProgress = new ActionableProgress<double>();
            fontProgress.RegisterAction(p =>
            {
                fontPercent = p;

                lock (syncLock)
                {
                    progress.Report((ffmpegPercent / 2) + (fontPercent / 2));
                }
            });

            tasks.Add(DownloadFonts(versionedDirectoryPath, fontProgress));

            await Task.WhenAll(tasks).ConfigureAwait(false);

            return info;
        }

        /// <summary>
        /// Runs the specified progress.
        /// </summary>
        /// <param name="progress">The progress.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        public async Task Run(IProgress<double> progress, CancellationToken cancellationToken)
        {
            var allItems = _libraryManager.RootFolder.GetRecursiveChildren();

            var allSongs = allItems.OfType<Audio>().ToList();

            var innerProgress = new ActionableProgress<double>();

            innerProgress.RegisterAction(pct => progress.Report(pct * .8));

            var allArtists = await GetAllArtists(allSongs, cancellationToken, innerProgress).ConfigureAwait(false);

            progress.Report(80);

            var numComplete = 0;

            var userLibraries = _userManager.Users
                .Select(i => new Tuple<Guid, List<IHasArtist>>(i.Id, i.RootFolder.GetRecursiveChildren(i).OfType<IHasArtist>().ToList()))
                .ToList();

            var numArtists = allArtists.Count;

            foreach (var artist in allArtists)
            {
                cancellationToken.ThrowIfCancellationRequested();

                // Only do this for artists accessed by name. Folder-based artists use ArtistInfoFromSongsProvider
                if (artist.IsAccessedByName && !artist.LockedFields.Contains(MetadataFields.Genres))
                {
                    // Avoid implicitly captured closure
                    var artist1 = artist;

                    artist.Genres = allSongs.Where(i => i.HasArtist(artist1.Name))
                        .SelectMany(i => i.Genres)
                        .Distinct(StringComparer.OrdinalIgnoreCase)
                        .ToList();
                }

                // Populate counts of items
                //SetItemCounts(artist, null, allItems.OfType<IHasArtist>());

                foreach (var lib in userLibraries)
                {
                    SetItemCounts(artist, lib.Item1, lib.Item2);
                }

                numComplete++;
                double percent = numComplete;
                percent /= numArtists;
                percent *= 20;

                progress.Report(80 + percent);
            }

            progress.Report(100);
        }

        /// <summary>
        /// Runs the specified progress.
        /// </summary>
        /// <param name="progress">The progress.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        public async Task Run(IProgress<double> progress, CancellationToken cancellationToken)
        {
            var allItems = _libraryManager.RootFolder.RecursiveChildren.ToList();

            var allArtists = await GetAllArtists(allItems).ConfigureAwait(false);

            progress.Report(10);

            var allMusicArtists = allItems.OfType<MusicArtist>().ToList();
            var allSongs = allItems.OfType<Audio>().ToList();

            var numComplete = 0;

            foreach (var artist in allArtists)
            {
                var musicArtist = FindMusicArtist(artist, allMusicArtists);

                if (musicArtist != null)
                {
                    artist.Images = new Dictionary<ImageType, string>(musicArtist.Images);

                    artist.BackdropImagePaths = musicArtist.BackdropImagePaths.ToList();
                    artist.ScreenshotImagePaths = musicArtist.ScreenshotImagePaths.ToList();
                    artist.SetProviderId(MetadataProviders.Musicbrainz, musicArtist.GetProviderId(MetadataProviders.Musicbrainz));
                    artist.Genres = musicArtist.Genres.ToList();
                }
                else
                {
                    // Avoid implicitly captured closure
                    var artist1 = artist;

                    artist.Genres = allSongs.Where(i => i.HasArtist(artist1.Name))
                        .SelectMany(i => i.Genres)
                        .Distinct(StringComparer.OrdinalIgnoreCase)
                        .ToList();
                }

                numComplete++;
                double percent = numComplete;
                percent /= allArtists.Length;
                percent *= 5;

                progress.Report(10 + percent);
            }

            var innerProgress = new ActionableProgress<double>();

            innerProgress.RegisterAction(pct => progress.Report(15 + pct * .85));

            await _libraryManager.ValidateArtists(cancellationToken, innerProgress).ConfigureAwait(false);
        }

        private async Task DownloadContent(string user, CancellationToken cancellationToken, IProgress<double> progress)
        {
            var channels = await _channelManager.GetChannelsInternal(new ChannelQuery
            {
                UserId = user

            }, cancellationToken);

            var numComplete = 0;
            var numItems = channels.Items.Length;

            foreach (var channel in channels.Items)
            {
                var channelId = channel.Id.ToString("N");

                var features = _channelManager.GetChannelFeatures(channelId);

                const int currentRefreshLevel = 1;
                var maxRefreshLevel = features.AutoRefreshLevels ?? 0;

                if (maxRefreshLevel > 0)
                {
                    var innerProgress = new ActionableProgress<double>();

                    var startingNumberComplete = numComplete;
                    innerProgress.RegisterAction(p =>
                    {
                        double innerPercent = startingNumberComplete;
                        innerPercent += (p / 100);
                        innerPercent /= numItems;
                        progress.Report(innerPercent * 100);
                    });

                    try
                    {
                        await GetAllItems(user, channelId, null, currentRefreshLevel, maxRefreshLevel, innerProgress, cancellationToken).ConfigureAwait(false);
                    }
                    catch (Exception ex)
                    {
                        _logger.ErrorException("Error getting channel content", ex);
                    }
                }

                numComplete++;
                double percent = numComplete;
                percent /= numItems;
                progress.Report(percent * 100);
            }

            progress.Report(100);
        }

        public async Task Execute(CancellationToken cancellationToken, IProgress<double> progress)
        {
            var innerProgress = new ActionableProgress<double>();
            innerProgress.RegisterAction(p => progress.Report(.95 * p));

            await UpdateToLatestSchema(cancellationToken, innerProgress).ConfigureAwait(false);

            innerProgress = new ActionableProgress<double>();
            innerProgress.RegisterAction(p => progress.Report(95 + (.05 * p)));

            //await CleanDeadItems(cancellationToken, innerProgress).ConfigureAwait(false);

            progress.Report(100);
        }

        /// <summary>
        /// Validates the people.
        /// </summary>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <param name="progress">The progress.</param>
        /// <returns>Task.</returns>
        public async Task ValidatePeople(CancellationToken cancellationToken, IProgress<double> progress)
        {
            var innerProgress = new ActionableProgress<double>();

            innerProgress.RegisterAction(pct => progress.Report(pct * .15));

            // Run prescan tasks
            await RunPrescanTasks(innerProgress, cancellationToken).ConfigureAwait(false);

            progress.Report(15);
            
            var people = _libraryManager.RootFolder.GetRecursiveChildren()
                .SelectMany(c => c.People)
                .DistinctBy(p => p.Name, StringComparer.OrdinalIgnoreCase)
                .ToList();

            var numComplete = 0;

            foreach (var person in people)
            {
                cancellationToken.ThrowIfCancellationRequested();

                try
                {
                    var item = _libraryManager.GetPerson(person.Name);

                    await item.RefreshMetadata(cancellationToken).ConfigureAwait(false);
                }
                catch (Exception ex)
                {
                    _logger.ErrorException("Error validating IBN entry {0}", ex, person.Name);
                }

                // Update progress
                numComplete++;
                double percent = numComplete;
                percent /= people.Count;

                progress.Report(15 + 85 * percent);
            }

            progress.Report(100);

            _logger.Info("People validation complete");

            // Bad practice, i know. But we keep a lot in memory, unfortunately.
            GC.Collect(2, GCCollectionMode.Forced, true);
            GC.Collect(2, GCCollectionMode.Forced, true);
        }

        /// <summary>
        /// Runs the specified progress.
        /// </summary>
        /// <param name="progress">The progress.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        public async Task Run(IProgress<double> progress, CancellationToken cancellationToken)
        {
            var allItems = _libraryManager.RootFolder.GetRecursiveChildren();

            var allSongs = allItems.OfType<Audio>().ToList();

            var innerProgress = new ActionableProgress<double>();

            innerProgress.RegisterAction(pct => progress.Report(pct * .8));

            var allArtists = await GetAllArtists(allSongs, cancellationToken, innerProgress).ConfigureAwait(false);

            progress.Report(80);

            var numComplete = 0;

            var numArtists = allArtists.Count;

            foreach (var artist in allArtists)
            {
                cancellationToken.ThrowIfCancellationRequested();

                // Only do this for artists accessed by name. Folder-based artists get it from the normal refresh
                if (artist.IsAccessedByName && !artist.LockedFields.Contains(MetadataFields.Genres))
                {
                    // Avoid implicitly captured closure
                    var artist1 = artist;

                    artist.Genres = allSongs.Where(i => i.HasArtist(artist1.Name))
                        .SelectMany(i => i.Genres)
                        .Distinct(StringComparer.OrdinalIgnoreCase)
                        .ToList();
                }

                numComplete++;
                double percent = numComplete;
                percent /= numArtists;
                percent *= 20;

                progress.Report(80 + percent);
            }

            progress.Report(100);
        }

        /// <summary>
        /// Runs the specified progress.
        /// </summary>
        /// <param name="progress">The progress.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        public async Task Run(IProgress<double> progress, CancellationToken cancellationToken)
        {
            if (!_config.Configuration.EnableInternetProviders && !_config.Configuration.EnableTmdbUpdates)
            {
                progress.Report(100);
                return;
            }

            var innerProgress = new ActionableProgress<double>();
            innerProgress.RegisterAction(pct => progress.Report(pct * .8));
            await Run(innerProgress, false, cancellationToken).ConfigureAwait(false);

            progress.Report(80);

            //innerProgress = new ActionableProgress<double>();
            //innerProgress.RegisterAction(pct => progress.Report(80 + pct * .2));
            //await Run(innerProgress, true, cancellationToken).ConfigureAwait(false);

            progress.Report(100);
        }

        public async Task Sync(IEnumerable<IServerSyncProvider> providers, IProgress<double> progress, CancellationToken cancellationToken)
        {
            var targets = providers
                .SelectMany(i => i.GetAllSyncTargets().Select(t => new Tuple<IServerSyncProvider, SyncTarget>(i, t)))
                .ToList();

            var numComplete = 0;
            double startingPercent = 0;
            double percentPerItem = 1;
            if (targets.Count > 0)
            {
                percentPerItem /= targets.Count;
            }

            foreach (var target in targets)
            {
                cancellationToken.ThrowIfCancellationRequested();

                var currentPercent = startingPercent;
                var innerProgress = new ActionableProgress<double>();
                innerProgress.RegisterAction(pct =>
                {
                    var totalProgress = pct * percentPerItem;
                    totalProgress += currentPercent;
                    progress.Report(totalProgress);
                });

                var dataProvider = _syncManager.GetDataProvider(target.Item1, target.Item2);

                await new MediaSync(_logger, _syncManager, _appHost, _fileSystem, _config)
                    .Sync(target.Item1, dataProvider, target.Item2, innerProgress, cancellationToken)
                    .ConfigureAwait(false);

                numComplete++;
                startingPercent = numComplete;
                startingPercent /= targets.Count;
                startingPercent *= 100;
                progress.Report(startingPercent);
            }
        }

        /// <summary>
        /// Runs the specified progress.
        /// </summary>
        /// <param name="progress">The progress.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        public async Task Run(IProgress<double> progress, CancellationToken cancellationToken)
        {
            var allItems = _libraryManager.RootFolder.RecursiveChildren.ToList();

            var allArtists = await GetAllArtists(allItems).ConfigureAwait(false);

            progress.Report(10);

            var allMusicArtists = allItems.OfType<MusicArtist>().ToList();

            var numComplete = 0;

            foreach (var artist in allArtists)
            {
                var musicArtist = FindMusicArtist(artist, allMusicArtists);

                if (musicArtist != null)
                {
                    artist.Images = new Dictionary<ImageType, string>(musicArtist.Images);

                    artist.BackdropImagePaths = musicArtist.BackdropImagePaths.ToList();
                    artist.ScreenshotImagePaths = musicArtist.ScreenshotImagePaths.ToList();
                    artist.SetProviderId(MetadataProviders.Musicbrainz, musicArtist.GetProviderId(MetadataProviders.Musicbrainz));
                }

                numComplete++;
                double percent = numComplete;
                percent /= allArtists.Length;
                percent *= 5;

                progress.Report(10 + percent);
            }

            var innerProgress = new ActionableProgress<double>();

            innerProgress.RegisterAction(pct => progress.Report(15 + pct * .85));

            await _libraryManager.ValidateArtists(cancellationToken, innerProgress).ConfigureAwait(false);
        }

        private async Task RefreshMetadataRecursive(MetadataRefreshOptions refreshOptions, bool recursive, IProgress<double> progress, CancellationToken cancellationToken)
        {
            var children = ActualChildren.ToList();

            var percentages = new Dictionary<Guid, double>(children.Count);
            var numComplete = 0;
            var count = children.Count;

            foreach (var child in children)
            {
                cancellationToken.ThrowIfCancellationRequested();

                if (child.IsFolder)
                {
                    var innerProgress = new ActionableProgress<double>();

                    // Avoid implicitly captured closure
                    var currentChild = child;
                    innerProgress.RegisterAction(p =>
                    {
                        lock (percentages)
                        {
                            percentages[currentChild.Id] = p / 100;

                            var innerPercent = percentages.Values.Sum();
                            innerPercent /= count;
                            innerPercent *= 100;
                            progress.Report(innerPercent);
                        }
                    });

                    await RefreshChildMetadata(child, refreshOptions, recursive, innerProgress, cancellationToken)
                      .ConfigureAwait(false);
                }
                else
                {
                    await RefreshChildMetadata(child, refreshOptions, false, new Progress<double>(), cancellationToken)
                      .ConfigureAwait(false);
                }

                numComplete++;
                double percent = numComplete;
                percent /= count;
                percent *= 100;

                progress.Report(percent);
            }

            progress.Report(100);
        }

        private async Task DownloadContent(string user,
            CancellationToken cancellationToken,
            IProgress<double> progress)
        {
            var innerProgress = new ActionableProgress<double>();
            innerProgress.RegisterAction(p => progress.Report(0 + (.8 * p)));
            await DownloadAllChannelContent(user, cancellationToken, innerProgress).ConfigureAwait(false);
            progress.Report(80);

            innerProgress = new ActionableProgress<double>();
            innerProgress.RegisterAction(p => progress.Report(80 + (.2 * p)));
            await DownloadLatestChannelContent(user, cancellationToken, progress).ConfigureAwait(false);
            progress.Report(100);
        }

        private async Task DownloadAllChannelContent(string userId,
            CancellationToken cancellationToken,
            IProgress<double> progress)
        {
            var result = await _manager.GetAllMediaInternal(new AllChannelMediaQuery
            {
                UserId = userId

            }, cancellationToken).ConfigureAwait(false);

            progress.Report(5);

            var innerProgress = new ActionableProgress<double>();
            innerProgress.RegisterAction(p => progress.Report(5 + (.95 * p)));

            var path = _manager.ChannelDownloadPath;

            await DownloadChannelContent(result, path, cancellationToken, innerProgress).ConfigureAwait(false);
        }

        private async Task RefreshChannelsInternal(IProgress<double> progress, CancellationToken cancellationToken)
        {
            var numComplete = 0;
            double progressPerService = _services.Count == 0
                ? 0
                : 1 / _services.Count;

            var newChannelIdList = new List<Guid>();
            var newProgramIdList = new List<Guid>();

            foreach (var service in _services)
            {
                cancellationToken.ThrowIfCancellationRequested();

                _logger.Debug("Refreshing guide from {0}", service.Name);

                try
                {
                    var innerProgress = new ActionableProgress<double>();
                    innerProgress.RegisterAction(p => progress.Report(p * progressPerService));

                    var idList = await RefreshChannelsInternal(service, innerProgress, cancellationToken).ConfigureAwait(false);

                    newChannelIdList.AddRange(idList.Item1);
                    newProgramIdList.AddRange(idList.Item2);
                }
                catch (OperationCanceledException)
                {
                    throw;
                }
                catch (Exception ex)
                {
                    _logger.ErrorException("Error refreshing channels for service", ex);
                }

                numComplete++;
                double percent = numComplete;
                percent /= _services.Count;

                progress.Report(100 * percent);
            }

            await CleanDatabaseInternal(newChannelIdList, new[] { typeof(LiveTvChannel).Name }, progress, cancellationToken).ConfigureAwait(false);
            await CleanDatabaseInternal(newProgramIdList, new[] { typeof(LiveTvProgram).Name }, progress, cancellationToken).ConfigureAwait(false);

            var coreService = _services.OfType<EmbyTV.EmbyTV>().FirstOrDefault();

            if (coreService != null)
            {
                await coreService.RefreshSeriesTimers(cancellationToken, new Progress<double>()).ConfigureAwait(false);
            }

            // Load these now which will prefetch metadata
            var dtoOptions = new DtoOptions();
            dtoOptions.Fields.Remove(ItemFields.SyncInfo);
            await GetRecordings(new RecordingQuery(), dtoOptions, cancellationToken).ConfigureAwait(false);

            progress.Report(100);
        }

        private async Task GetNewMedia(IServerSyncProvider provider,
            ISyncDataProvider dataProvider,
            SyncTarget target,
            string serverId,
            string serverName,
            IProgress<double> progress,
            CancellationToken cancellationToken)
        {
            var jobItems = await _syncManager.GetReadySyncItems(target.Id).ConfigureAwait(false);

            var numComplete = 0;
            double startingPercent = 0;
            double percentPerItem = 1;
            if (jobItems.Count > 0)
            {
                percentPerItem /= jobItems.Count;
            }

            foreach (var jobItem in jobItems)
            {
                cancellationToken.ThrowIfCancellationRequested();

                var currentPercent = startingPercent;
                var innerProgress = new ActionableProgress<double>();
                innerProgress.RegisterAction(pct =>
                {
                    var totalProgress = pct * percentPerItem;
                    totalProgress += currentPercent;
                    progress.Report(totalProgress);
                });

                try
                {
                    await GetItem(provider, dataProvider, target, serverId, serverName, jobItem, innerProgress, cancellationToken).ConfigureAwait(false);
                }
                catch (Exception ex)
                {
                    _logger.ErrorException("Error syncing item", ex);
                }

                numComplete++;
                startingPercent = numComplete;
                startingPercent /= jobItems.Count;
                startingPercent *= 100;
                progress.Report(startingPercent);
            }
        }

        /// <summary>
        /// Refreshes the children.
        /// </summary>
        /// <param name="children">The children.</param>
        /// <param name="directoryService">The directory service.</param>
        /// <param name="progress">The progress.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task.</returns>
        private async Task ValidateSubFolders(IList<Folder> children, IDirectoryService directoryService, IProgress<double> progress, CancellationToken cancellationToken)
        {
            var list = children;
            var childCount = list.Count;

            var percentages = new Dictionary<Guid, double>(list.Count);

            foreach (var item in list)
            {
                cancellationToken.ThrowIfCancellationRequested();

                var child = item;

                var innerProgress = new ActionableProgress<double>();

                innerProgress.RegisterAction(p =>
                {
                    lock (percentages)
                    {
                        percentages[child.Id] = p / 100;

                        var percent = percentages.Values.Sum();
                        percent /= childCount;

                        progress.Report((10 * percent) + 10);
                    }
                });

                await child.ValidateChildrenWithCancellationSupport(innerProgress, cancellationToken, true, false, null, directoryService)
                        .ConfigureAwait(false);
            }
        }

        /// <summary>
        /// Refreshes the children.
        /// </summary>
        /// <param name="children">The children.</param>
        /// <param name="progress">The progress.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <param name="recursive">if set to <c>true</c> [recursive].</param>
        /// <param name="forceRefreshMetadata">if set to <c>true</c> [force refresh metadata].</param>
        /// <returns>Task.</returns>
        private async Task RefreshChildren(IList<Tuple<BaseItem, bool>> children, IProgress<double> progress, CancellationToken cancellationToken, bool? recursive, bool forceRefreshMetadata = false)
        {
            var list = children;

            var percentages = new Dictionary<Guid, double>(list.Count);

            var tasks = new List<Task>();

            foreach (var tuple in list)
            {
                if (tasks.Count > 7)
                {
                    await Task.WhenAll(tasks).ConfigureAwait(false);
                }

                Tuple<BaseItem, bool> currentTuple = tuple;

                tasks.Add(Task.Run(async () =>
                {
                    cancellationToken.ThrowIfCancellationRequested();

                    var child = currentTuple.Item1;
                    try
                    {
                        //refresh it
                        await child.RefreshMetadata(cancellationToken, forceSave: currentTuple.Item2, forceRefresh: forceRefreshMetadata, resetResolveArgs: false).ConfigureAwait(false);
                    }
                    catch (IOException ex)
                    {
                        Logger.ErrorException("Error refreshing {0}", ex, child.Path ?? child.Name);
                    }

                    // Refresh children if a folder and the item changed or recursive is set to true
                    var refreshChildren = child.IsFolder && (currentTuple.Item2 || (recursive.HasValue && recursive.Value));

                    if (refreshChildren)
                    {
                        // Don't refresh children if explicitly set to false
                        if (recursive.HasValue && recursive.Value == false)
                        {
                            refreshChildren = false;
                        }
                    }

                    if (refreshChildren)
                    {
                        cancellationToken.ThrowIfCancellationRequested();

                        var innerProgress = new ActionableProgress<double>();

                        innerProgress.RegisterAction(p =>
                        {
                            lock (percentages)
                            {
                                percentages[child.Id] = p / 100;

                                var percent = percentages.Values.Sum();
                                percent /= list.Count;

                                progress.Report((90 * percent) + 10);
                            }
                        });

                        await ((Folder)child).ValidateChildren(innerProgress, cancellationToken, recursive, forceRefreshMetadata).ConfigureAwait(false);

                        try
                        {
                            // Some folder providers are unable to refresh until children have been refreshed.
                            await child.RefreshMetadata(cancellationToken, resetResolveArgs: false).ConfigureAwait(false);
                        }
                        catch (IOException ex)
                        {
                            Logger.ErrorException("Error refreshing {0}", ex, child.Path ?? child.Name);
                        }
                    }
                    else
                    {
                        lock (percentages)
                        {
                            percentages[child.Id] = 1;

                            var percent = percentages.Values.Sum();
                            percent /= list.Count;

                            progress.Report((90 * percent) + 10);
                        }
                    }
                }));
            }

            cancellationToken.ThrowIfCancellationRequested();
//.........这里部分代码省略.........