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Refactor app event resolver weights

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This commit is contained in:
Stephan
2016-11-28 09:38:50 +01:00
parent bb9bc73daa
commit 13f7f96101
3 changed files with 59 additions and 88 deletions
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82
src/Umbraco.Core/ObjectResolution/ApplicationEventsResolver.cs
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@@ -11,7 +11,13 @@ namespace Umbraco.Core.ObjectResolution
/// A resolver to return all IApplicationEvents objects
/// </summary>
/// <remarks>
/// This is disposable because after the app has started it should be disposed to release any memory being occupied by instances.
/// <para>This is disposable because after the app has started it should be disposed to release any memory being occupied by instances.</para>
/// <para>Ordering handlers: handlers are ordered by (ascending) weight. By default, handlers from the Umbraco.* or Concorde.*
/// assemblies have a -100 weight whereas any other handler has a weight of +100. A custom weight can be assigned to a handler
/// by marking the class with the WeightAttribute. For example, the CacheRefresherEventHandler is marked with [Weight(int.MinValue)]
/// because its events need to run before anything else. Positive weights are considered "user-space" while negative weights are
/// "core". Finally, users can register a filter to process the list (after it has been ordered) and re-order it, or remove handlers.</para>
/// <para>BEWARE! handlers order is an important thing, and removing handlers or reordering handlers can have unexpected consequences.</para>
/// </remarks>
public sealed class ApplicationEventsResolver : ManyObjectsResolverBase<ApplicationEventsResolver, IApplicationEventHandler>, IDisposable
{
@@ -25,9 +31,9 @@ namespace Umbraco.Core.ObjectResolution
/// <param name="serviceProvider"></param>
internal ApplicationEventsResolver(IServiceProvider serviceProvider, ILogger logger, IEnumerable<Type> applicationEventHandlers)
: base(serviceProvider, logger, applicationEventHandlers)
{
{
//create the legacy resolver and only include the legacy types
_legacyResolver = new LegacyStartupHandlerResolver(
_legacyResolver = new LegacyStartupHandlerResolver(
serviceProvider, logger,
applicationEventHandlers.Where(x => TypeHelper.IsTypeAssignableFrom<IApplicationEventHandler>(x) == false));
}
@@ -52,26 +58,29 @@ namespace Umbraco.Core.ObjectResolution
{
if (_orderedAndFiltered == null)
{
_resolved = true;
_orderedAndFiltered = GetSortedValues().ToList();
OnCollectionResolved(_orderedAndFiltered);
_orderedAndFiltered = GetSortedValues().ToList();
if (FilterCollection != null)
FilterCollection(_orderedAndFiltered);
}
return _orderedAndFiltered;
}
}
/// <summary>
/// A delegate that can be set in the pre-boot phase in order to filter or re-order the event handler collection
/// </summary>
/// <remarks>
/// This can be set on startup in the pre-boot process in either a custom boot manager or global.asax (UmbracoApplication)
/// </remarks>
public Action<IList<IApplicationEventHandler>> FilterCollection
/// <summary>
/// Gets or sets a delegate to filter the event handler list (EXPERT!).
/// </summary>
/// <remarks>
/// <para>This can be set on startup in the pre-boot process in either a custom boot manager or global.asax (UmbracoApplication).</para>
/// <para>Allows custom logic to execute in order to filter and/or re-order the event handlers prior to executing.</para>
/// <para>To be used by custom boot sequences where the boot loader needs to remove some handlers, or raise their priority.</para>
/// <para>Filtering the event handler collection can have ugly consequences. Use with care.</para>
/// </remarks>
public Action<IList<IApplicationEventHandler>> FilterCollection
{
get { return _filterCollection; }
set
{
if (_resolved)
if (_orderedAndFiltered != null)
throw new InvalidOperationException("Cannot set the FilterCollection delegate once the ApplicationEventHandlers are resolved");
if (_filterCollection != null)
throw new InvalidOperationException("Cannot set the FilterCollection delegate once it's already been specified");
@@ -80,40 +89,16 @@ namespace Umbraco.Core.ObjectResolution
}
}
/// <summary>
/// Allow any filters to be applied to the event handler list
/// </summary>
/// <param name="handlers"></param>
/// <remarks>
/// This allows custom logic to execute in order to filter or re-order the event handlers prior to executing,
/// however this also ensures that any core handlers are executed first to ensure the stabiliy of Umbraco.
/// </remarks>
private void OnCollectionResolved(List<IApplicationEventHandler> handlers)
{
if (FilterCollection != null)
{
FilterCollection(handlers);
}
protected override int GetObjectWeight(object o)
{
var type = o.GetType();
var attr = type.GetCustomAttribute<WeightAttribute>(true);
if (attr != null) return attr.Weight;
var name = type.Assembly.FullName;
//find all of the core handlers and their weight, remove them from the main list
var coreItems = new List<Tuple<IApplicationEventHandler, int>>();
foreach (var handler in handlers.ToArray())
{
//Yuck, but not sure what else we can do
if (
handler.GetType().Assembly.FullName.StartsWith("Umbraco.", StringComparison.OrdinalIgnoreCase)
|| handler.GetType().Assembly.FullName.StartsWith("Concorde."))
{
coreItems.Add(new Tuple<IApplicationEventHandler, int>(handler, GetObjectWeight(handler)));
handlers.Remove(handler);
}
}
//re-add the core handlers to the beginning of the list ordered by their weight
foreach (var coreHandler in coreItems.OrderBy(x => x.Item2))
{
handlers.Insert(0, coreHandler.Item1);
}
// we should really attribute all our Core handlers, so this is temp
var core = name.InvariantStartsWith("Umbraco.") || name.InvariantStartsWith("Concorde.");
return core ? -DefaultPluginWeight : DefaultPluginWeight;
}
/// <summary>
@@ -157,7 +142,6 @@ namespace Umbraco.Core.ObjectResolution
private bool _disposed;
private readonly ReaderWriterLockSlim _disposalLocker = new ReaderWriterLockSlim();
private Action<IList<IApplicationEventHandler>> _filterCollection;
private bool _resolved = false;
/// <summary>
/// Gets a value indicating whether this instance is disposed.
@@ -215,7 +199,7 @@ namespace Umbraco.Core.ObjectResolution
_legacyResolver.Dispose();
ResetCollections();
_orderedAndFiltered.Clear();
_orderedAndFiltered = null;
_orderedAndFiltered = null;
}
}
}