jellyfin/MediaBrowser.Controller/Providers/BaseMetadataProvider.cs
2013-02-20 20:33:05 -05:00

409 lines
14 KiB
C#

using MediaBrowser.Common.Extensions;
using MediaBrowser.Common.Logging;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Model.Logging;
using System;
using System.Threading;
using System.Threading.Tasks;
namespace MediaBrowser.Controller.Providers
{
/// <summary>
/// Class BaseMetadataProvider
/// </summary>
public abstract class BaseMetadataProvider : IDisposable
{
/// <summary>
/// Gets the logger.
/// </summary>
/// <value>The logger.</value>
protected ILogger Logger { get; private set; }
// Cache these since they will be used a lot
/// <summary>
/// The false task result
/// </summary>
protected static readonly Task<bool> FalseTaskResult = Task.FromResult(false);
/// <summary>
/// The true task result
/// </summary>
protected static readonly Task<bool> TrueTaskResult = Task.FromResult(true);
/// <summary>
/// The _id
/// </summary>
protected Guid _id;
/// <summary>
/// Gets the id.
/// </summary>
/// <value>The id.</value>
public virtual Guid Id
{
get
{
if (_id == Guid.Empty) _id = GetType().FullName.GetMD5();
return _id;
}
}
/// <summary>
/// Supportses the specified item.
/// </summary>
/// <param name="item">The item.</param>
/// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
public abstract bool Supports(BaseItem item);
/// <summary>
/// Gets a value indicating whether [requires internet].
/// </summary>
/// <value><c>true</c> if [requires internet]; otherwise, <c>false</c>.</value>
public virtual bool RequiresInternet
{
get
{
return false;
}
}
/// <summary>
/// Gets the provider version.
/// </summary>
/// <value>The provider version.</value>
protected virtual string ProviderVersion
{
get
{
return null;
}
}
/// <summary>
/// Gets a value indicating whether [refresh on version change].
/// </summary>
/// <value><c>true</c> if [refresh on version change]; otherwise, <c>false</c>.</value>
protected virtual bool RefreshOnVersionChange
{
get
{
return false;
}
}
/// <summary>
/// Determines if this provider is relatively slow and, therefore, should be skipped
/// in certain instances. Default is whether or not it requires internet. Can be overridden
/// for explicit designation.
/// </summary>
/// <value><c>true</c> if this instance is slow; otherwise, <c>false</c>.</value>
public virtual bool IsSlow
{
get { return RequiresInternet; }
}
/// <summary>
/// Initializes a new instance of the <see cref="BaseMetadataProvider" /> class.
/// </summary>
protected BaseMetadataProvider()
{
Initialize();
}
/// <summary>
/// Initializes this instance.
/// </summary>
protected virtual void Initialize()
{
Logger = LogManager.GetLogger(GetType().Name);
}
/// <summary>
/// Sets the persisted last refresh date on the item for this provider.
/// </summary>
/// <param name="item">The item.</param>
/// <param name="value">The value.</param>
/// <param name="providerVersion">The provider version.</param>
/// <param name="status">The status.</param>
/// <exception cref="System.ArgumentNullException">item</exception>
protected virtual void SetLastRefreshed(BaseItem item, DateTime value, string providerVersion, ProviderRefreshStatus status = ProviderRefreshStatus.Success)
{
if (item == null)
{
throw new ArgumentNullException("item");
}
var data = item.ProviderData.GetValueOrDefault(Id, new BaseProviderInfo { ProviderId = Id });
data.LastRefreshed = value;
data.LastRefreshStatus = status;
data.ProviderVersion = providerVersion;
// Save the file system stamp for future comparisons
if (RefreshOnFileSystemStampChange)
{
data.FileSystemStamp = GetCurrentFileSystemStamp(item);
}
item.ProviderData[Id] = data;
}
/// <summary>
/// Sets the last refreshed.
/// </summary>
/// <param name="item">The item.</param>
/// <param name="value">The value.</param>
/// <param name="status">The status.</param>
protected virtual void SetLastRefreshed(BaseItem item, DateTime value, ProviderRefreshStatus status = ProviderRefreshStatus.Success)
{
SetLastRefreshed(item, value, ProviderVersion, status);
}
/// <summary>
/// Returns whether or not this provider should be re-fetched. Default functionality can
/// compare a provided date with a last refresh time. This can be overridden for more complex
/// determinations.
/// </summary>
/// <param name="item">The item.</param>
/// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
/// <exception cref="System.ArgumentNullException"></exception>
public bool NeedsRefresh(BaseItem item)
{
if (item == null)
{
throw new ArgumentNullException();
}
var providerInfo = item.ProviderData.GetValueOrDefault(Id, new BaseProviderInfo());
return NeedsRefreshInternal(item, providerInfo);
}
/// <summary>
/// Needses the refresh internal.
/// </summary>
/// <param name="item">The item.</param>
/// <param name="providerInfo">The provider info.</param>
/// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
/// <exception cref="System.ArgumentNullException"></exception>
protected virtual bool NeedsRefreshInternal(BaseItem item, BaseProviderInfo providerInfo)
{
if (item == null)
{
throw new ArgumentNullException("item");
}
if (providerInfo == null)
{
throw new ArgumentNullException("providerInfo");
}
if (CompareDate(item) > providerInfo.LastRefreshed)
{
return true;
}
if (RefreshOnFileSystemStampChange && HasFileSystemStampChanged(item, providerInfo))
{
return true;
}
if (RefreshOnVersionChange && !string.Equals(ProviderVersion, providerInfo.ProviderVersion))
{
return true;
}
return false;
}
/// <summary>
/// Determines if the item's file system stamp has changed from the last time the provider refreshed
/// </summary>
/// <param name="item">The item.</param>
/// <param name="providerInfo">The provider info.</param>
/// <returns><c>true</c> if [has file system stamp changed] [the specified item]; otherwise, <c>false</c>.</returns>
protected bool HasFileSystemStampChanged(BaseItem item, BaseProviderInfo providerInfo)
{
return GetCurrentFileSystemStamp(item) != providerInfo.FileSystemStamp;
}
/// <summary>
/// Override this to return the date that should be compared to the last refresh date
/// to determine if this provider should be re-fetched.
/// </summary>
/// <param name="item">The item.</param>
/// <returns>DateTime.</returns>
protected virtual DateTime CompareDate(BaseItem item)
{
return DateTime.MinValue.AddMinutes(1); // want this to be greater than mindate so new items will refresh
}
/// <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>
/// <exception cref="System.ArgumentNullException"></exception>
public async Task<bool> FetchAsync(BaseItem item, bool force, CancellationToken cancellationToken)
{
if (item == null)
{
throw new ArgumentNullException();
}
cancellationToken.ThrowIfCancellationRequested();
Logger.Info("Running for {0}", item.Path ?? item.Name ?? "--Unknown--");
// This provides the ability to cancel just this one provider
var innerCancellationTokenSource = new CancellationTokenSource();
Kernel.Instance.ProviderManager.OnProviderRefreshBeginning(this, item, innerCancellationTokenSource);
try
{
var task = FetchAsyncInternal(item, force, CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, innerCancellationTokenSource.Token).Token);
await task.ConfigureAwait(false);
if (task.IsFaulted)
{
// Log the AggregateException
if (task.Exception != null)
{
Logger.ErrorException("AggregateException:", task.Exception);
}
return false;
}
return task.Result;
}
catch (OperationCanceledException ex)
{
Logger.Info("{0} cancelled for {1}", GetType().Name, item.Name);
// If the outer cancellation token is the one that caused the cancellation, throw it
if (cancellationToken.IsCancellationRequested && ex.CancellationToken == cancellationToken)
{
throw;
}
return false;
}
catch (Exception ex)
{
Logger.ErrorException("failed refreshing {0}", ex, item.Name);
SetLastRefreshed(item, DateTime.UtcNow, ProviderRefreshStatus.Failure);
return true;
}
finally
{
innerCancellationTokenSource.Dispose();
Kernel.Instance.ProviderManager.OnProviderRefreshCompleted(this, item);
}
}
/// <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>
protected abstract Task<bool> FetchAsyncInternal(BaseItem item, bool force, CancellationToken cancellationToken);
/// <summary>
/// Gets the priority.
/// </summary>
/// <value>The priority.</value>
public abstract MetadataProviderPriority Priority { get; }
/// <summary>
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
/// </summary>
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
/// <summary>
/// Releases unmanaged and - optionally - managed resources.
/// </summary>
/// <param name="dispose"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
protected virtual void Dispose(bool dispose)
{
}
/// <summary>
/// Returns true or false indicating if the provider should refresh when the contents of it's directory changes
/// </summary>
/// <value><c>true</c> if [refresh on file system stamp change]; otherwise, <c>false</c>.</value>
protected virtual bool RefreshOnFileSystemStampChange
{
get
{
return false;
}
}
/// <summary>
/// Determines if the parent's file system stamp should be used for comparison
/// </summary>
/// <param name="item">The item.</param>
/// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
protected virtual bool UseParentFileSystemStamp(BaseItem item)
{
// True when the current item is just a file
return !item.ResolveArgs.IsDirectory;
}
/// <summary>
/// Gets the item's current file system stamp
/// </summary>
/// <param name="item">The item.</param>
/// <returns>Guid.</returns>
private Guid GetCurrentFileSystemStamp(BaseItem item)
{
if (UseParentFileSystemStamp(item) && item.Parent != null)
{
return item.Parent.FileSystemStamp;
}
return item.FileSystemStamp;
}
}
/// <summary>
/// Determines when a provider should execute, relative to others
/// </summary>
public enum MetadataProviderPriority
{
// Run this provider at the beginning
/// <summary>
/// The first
/// </summary>
First = 1,
// Run this provider after all first priority providers
/// <summary>
/// The second
/// </summary>
Second = 2,
// Run this provider after all second priority providers
/// <summary>
/// The third
/// </summary>
Third = 3,
// Run this provider last
/// <summary>
/// The last
/// </summary>
Last = 4
}
}