jellyfin/MediaBrowser.Providers/FolderProviderFromXml.cs

using MediaBrowser.Common.IO;
using MediaBrowser.Controller.Configuration;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.IO;
using MediaBrowser.Controller.Providers;
using MediaBrowser.Model.Entities;
using MediaBrowser.Model.Logging;
using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

namespace MediaBrowser.Providers
{
    /// <summary>
    /// Provides metadata for Folders and all subclasses by parsing folder.xml
    /// </summary>
    public class FolderProviderFromXml : BaseMetadataProvider
    {
        public static FolderProviderFromXml Current;
        private readonly IFileSystem _fileSystem;

        public FolderProviderFromXml(ILogManager logManager, IServerConfigurationManager configurationManager, IFileSystem fileSystem)
            : base(logManager, configurationManager)
        {
            _fileSystem = fileSystem;
            Current = this;
        }

        /// <summary>
        /// Supportses the specified item.
        /// </summary>
        /// <param name="item">The item.</param>
        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
        public override bool Supports(BaseItem item)
        {
            return item.IsFolder && item.LocationType == LocationType.FileSystem;
        }

        /// <summary>
        /// Gets the priority.
        /// </summary>
        /// <value>The priority.</value>
        public override MetadataProviderPriority Priority
        {
            get { return MetadataProviderPriority.First; }
        }

        private const string XmlFileName = "folder.xml";
        protected override bool NeedsRefreshBasedOnCompareDate(BaseItem item, BaseProviderInfo providerInfo)
        {
            var xml = item.ResolveArgs.GetMetaFileByPath(Path.Combine(item.MetaLocation, XmlFileName));

            if (xml == null)
            {
                return false;
            }

            return _fileSystem.GetLastWriteTimeUtc(xml) > providerInfo.LastRefreshed;
        }

        /// <summary>
        /// Fetches metadata and returns true or false indicating if any work that requires persistence was done
        /// </summary>
        /// <param name="item">The item.</param>
        /// <param name="force">if set to <c>true</c> [force].</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>Task{System.Boolean}.</returns>
        public override Task<bool> FetchAsync(BaseItem item, bool force, CancellationToken cancellationToken)
        {
            return Fetch(item, cancellationToken);
        }

        /// <summary>
        /// Fetches the specified item.
        /// </summary>
        /// <param name="item">The item.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
        private async Task<bool> Fetch(BaseItem item, CancellationToken cancellationToken)
        {
            cancellationToken.ThrowIfCancellationRequested();

            var metadataFile = item.ResolveArgs.GetMetaFileByPath(Path.Combine(item.MetaLocation, XmlFileName));

            if (metadataFile != null)
            {
                var path = metadataFile.FullName;

                await XmlParsingResourcePool.WaitAsync(cancellationToken).ConfigureAwait(false);

                try
                {
                    new BaseItemXmlParser<Folder>(Logger).Fetch((Folder)item, path, cancellationToken);
                }
                finally
                {
                    XmlParsingResourcePool.Release();
                }

                SetLastRefreshed(item, DateTime.UtcNow);
                return true;
            }

            return false;
        }
    }
}