Rename Composers.cs and perform minimal spring cleaning.
This commit is contained in:
Paul Johnson
351
src/Umbraco.Core/Composing/ComposerGraph.cs
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351
src/Umbraco.Core/Composing/ComposerGraph.cs
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Reflection;
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using System.Text;
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using Microsoft.Extensions.Logging;
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using Umbraco.Cms.Core.Collections;
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using Umbraco.Cms.Core.DependencyInjection;
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namespace Umbraco.Cms.Core.Composing
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{
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// note: this class is NOT thread-safe in any way
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/// <summary>
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/// Handles the composers.
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/// </summary>
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public class ComposerGraph
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{
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private readonly IUmbracoBuilder _builder;
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private readonly ILogger<ComposerGraph> _logger;
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private readonly IEnumerable<Type> _composerTypes;
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private readonly IEnumerable<Attribute> _enableDisableAttributes;
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/// <summary>
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/// Initializes a new instance of the <see cref="ComposerGraph" /> class.
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/// </summary>
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/// <param name="builder">The composition.</param>
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/// <param name="composerTypes">The <see cref="IComposer" /> types.</param>
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/// <param name="enableDisableAttributes">The <see cref="EnableComposerAttribute" /> and/or <see cref="DisableComposerAttribute" /> attributes.</param>
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/// <param name="logger">The logger.</param>
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/// <exception cref="ArgumentNullException">composition
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/// or
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/// composerTypes
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/// or
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/// enableDisableAttributes
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/// or
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/// logger</exception>
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public ComposerGraph(IUmbracoBuilder builder, IEnumerable<Type> composerTypes, IEnumerable<Attribute> enableDisableAttributes, ILogger<ComposerGraph> logger)
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{
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_builder = builder ?? throw new ArgumentNullException(nameof(builder));
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_composerTypes = composerTypes ?? throw new ArgumentNullException(nameof(composerTypes));
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_enableDisableAttributes = enableDisableAttributes ?? throw new ArgumentNullException(nameof(enableDisableAttributes));
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_logger = logger ?? throw new ArgumentNullException(nameof(logger));
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}
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private class EnableInfo
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{
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public bool Enabled { get; set; }
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public int Weight { get; set; } = -1;
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}
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/// <summary>
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/// Instantiates and composes the composers.
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/// </summary>
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public void Compose()
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{
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// make sure it is there
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_builder.WithCollectionBuilder<ComponentCollectionBuilder>();
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IEnumerable<Type> orderedComposerTypes = PrepareComposerTypes();
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foreach (IComposer composer in InstantiateComposers(orderedComposerTypes))
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{
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composer.Compose(_builder);
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}
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}
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internal IEnumerable<Type> PrepareComposerTypes()
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{
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var requirements = GetRequirements();
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// only for debugging, this is verbose
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//_logger.Debug<ComposerGraph>(GetComposersReport(requirements));
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var sortedComposerTypes = SortComposers(requirements);
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// bit verbose but should help for troubleshooting
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//var text = "Ordered Composers: " + Environment.NewLine + string.Join(Environment.NewLine, sortedComposerTypes) + Environment.NewLine;
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_logger.LogDebug("Ordered Composers: {SortedComposerTypes}", sortedComposerTypes);
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return sortedComposerTypes;
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}
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internal Dictionary<Type, List<Type>> GetRequirements(bool throwOnMissing = true)
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{
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// create a list, remove those that cannot be enabled due to runtime level
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var composerTypeList = _composerTypes.ToList();
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// enable or disable composers
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EnableDisableComposers(_enableDisableAttributes, composerTypeList);
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void GatherInterfaces<TAttribute>(Type type, Func<TAttribute, Type> getTypeInAttribute, HashSet<Type> iset, List<Type> set2)
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where TAttribute : Attribute
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{
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foreach (var attribute in type.GetCustomAttributes<TAttribute>())
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{
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var typeInAttribute = getTypeInAttribute(attribute);
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if (typeInAttribute != null && // if the attribute references a type ...
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typeInAttribute.IsInterface && // ... which is an interface ...
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typeof(IComposer).IsAssignableFrom(typeInAttribute) && // ... which implements IComposer ...
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!iset.Contains(typeInAttribute)) // ... which is not already in the list
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{
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// add it to the new list
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iset.Add(typeInAttribute);
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set2.Add(typeInAttribute);
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// add all its interfaces implementing IComposer
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foreach (var i in typeInAttribute.GetInterfaces().Where(x => typeof(IComposer).IsAssignableFrom(x)))
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{
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iset.Add(i);
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set2.Add(i);
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}
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}
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}
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}
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// gather interfaces too
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var interfaces = new HashSet<Type>(composerTypeList.SelectMany(x => x.GetInterfaces().Where(y => typeof(IComposer).IsAssignableFrom(y))));
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composerTypeList.AddRange(interfaces);
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var list1 = composerTypeList;
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while (list1.Count > 0)
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{
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var list2 = new List<Type>();
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foreach (var t in list1)
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{
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GatherInterfaces<ComposeAfterAttribute>(t, a => a.RequiredType, interfaces, list2);
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GatherInterfaces<ComposeBeforeAttribute>(t, a => a.RequiringType, interfaces, list2);
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}
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composerTypeList.AddRange(list2);
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list1 = list2;
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}
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// sort the composers according to their dependencies
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var requirements = new Dictionary<Type, List<Type>>();
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foreach (var type in composerTypeList)
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requirements[type] = null;
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foreach (var type in composerTypeList)
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{
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GatherRequirementsFromAfterAttribute(type, composerTypeList, requirements, throwOnMissing);
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GatherRequirementsFromBeforeAttribute(type, composerTypeList, requirements);
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}
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return requirements;
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}
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internal IEnumerable<Type> SortComposers(Dictionary<Type, List<Type>> requirements)
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{
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// sort composers
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var graph = new TopoGraph<Type, KeyValuePair<Type, List<Type>>>(kvp => kvp.Key, kvp => kvp.Value);
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graph.AddItems(requirements);
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List<Type> sortedComposerTypes;
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try
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{
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sortedComposerTypes = graph.GetSortedItems().Select(x => x.Key).Where(x => !x.IsInterface).ToList();
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}
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catch (Exception e)
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{
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// in case of an error, force-dump everything to log
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_logger.LogInformation("Composer Report:\r\n{ComposerReport}", GetComposersReport(requirements));
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_logger.LogError(e, "Failed to sort composers.");
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throw;
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}
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return sortedComposerTypes;
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}
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internal static string GetComposersReport(Dictionary<Type, List<Type>> requirements)
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{
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var text = new StringBuilder();
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text.AppendLine("Composers & Dependencies:");
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text.AppendLine(" < compose before");
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text.AppendLine(" > compose after");
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text.AppendLine(" : implements");
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text.AppendLine(" = depends");
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text.AppendLine();
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bool HasReq(IEnumerable<Type> types, Type type)
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=> types.Any(x => type.IsAssignableFrom(x) && !x.IsInterface);
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foreach (var kvp in requirements)
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{
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var type = kvp.Key;
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text.AppendLine(type.FullName);
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foreach (var attribute in type.GetCustomAttributes<ComposeAfterAttribute>())
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{
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var weak = !(attribute.RequiredType.IsInterface ? attribute.Weak == false : attribute.Weak != true);
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text.AppendLine(" > " + attribute.RequiredType +
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(weak ? " (weak" : " (strong") + (HasReq(requirements.Keys, attribute.RequiredType) ? ", found" : ", missing") + ")");
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}
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foreach (var attribute in type.GetCustomAttributes<ComposeBeforeAttribute>())
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text.AppendLine(" < " + attribute.RequiringType);
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foreach (var i in type.GetInterfaces())
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text.AppendLine(" : " + i.FullName);
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if (kvp.Value != null)
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foreach (var t in kvp.Value)
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text.AppendLine(" = " + t);
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text.AppendLine();
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}
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text.AppendLine("/");
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text.AppendLine();
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return text.ToString();
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}
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private static void EnableDisableComposers(IEnumerable<Attribute> enableDisableAttributes, ICollection<Type> types)
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{
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var enabled = new Dictionary<Type, EnableInfo>();
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// process the enable/disable attributes
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// these two attributes are *not* inherited and apply to *classes* only (not interfaces).
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// remote declarations (when a composer enables/disables *another* composer)
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// have priority over local declarations (when a composer disables itself) so that
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// ppl can enable composers that, by default, are disabled.
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// what happens in case of conflicting remote declarations is unspecified. more
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// precisely, the last declaration to be processed wins, but the order of the
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// declarations depends on the type finder and is unspecified.
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void UpdateEnableInfo(Type composerType, int weight2, Dictionary<Type, EnableInfo> enabled2, bool value)
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{
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if (enabled.TryGetValue(composerType, out var enableInfo) == false) enableInfo = enabled2[composerType] = new EnableInfo();
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if (enableInfo.Weight > weight2) return;
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enableInfo.Enabled = value;
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enableInfo.Weight = weight2;
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}
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foreach (var attr in enableDisableAttributes.OfType<EnableComposerAttribute>())
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{
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var type = attr.EnabledType;
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UpdateEnableInfo(type, 2, enabled, true);
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}
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foreach (var attr in enableDisableAttributes.OfType<DisableComposerAttribute>())
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{
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var type = attr.DisabledType;
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UpdateEnableInfo(type, 2, enabled, false);
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}
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foreach (var composerType in types)
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{
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foreach (var attr in composerType.GetCustomAttributes<EnableAttribute>())
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{
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var type = attr.EnabledType ?? composerType;
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var weight = type == composerType ? 1 : 3;
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UpdateEnableInfo(type, weight, enabled, true);
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}
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foreach (var attr in composerType.GetCustomAttributes<DisableAttribute>())
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{
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var type = attr.DisabledType ?? composerType;
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var weight = type == composerType ? 1 : 3;
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UpdateEnableInfo(type, weight, enabled, false);
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}
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}
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// remove composers that end up being disabled
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foreach (var kvp in enabled.Where(x => x.Value.Enabled == false))
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types.Remove(kvp.Key);
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}
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private static void GatherRequirementsFromAfterAttribute(Type type, ICollection<Type> types, IDictionary<Type, List<Type>> requirements, bool throwOnMissing = true)
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{
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// get 'require' attributes
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// these attributes are *not* inherited because we want to "custom-inherit" for interfaces only
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var afterAttributes = type
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.GetInterfaces().SelectMany(x => x.GetCustomAttributes<ComposeAfterAttribute>()) // those marking interfaces
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.Concat(type.GetCustomAttributes<ComposeAfterAttribute>()); // those marking the composer
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// what happens in case of conflicting attributes (different strong/weak for same type) is not specified.
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foreach (var attr in afterAttributes)
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{
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if (attr.RequiredType == type) continue; // ignore self-requirements (+ exclude in implems, below)
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// requiring an interface = require any enabled composer implementing that interface
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// unless strong, and then require at least one enabled composer implementing that interface
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if (attr.RequiredType.IsInterface)
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{
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var implems = types.Where(x => x != type && attr.RequiredType.IsAssignableFrom(x) && !x.IsInterface).ToList();
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if (implems.Count > 0)
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{
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if (requirements[type] == null) requirements[type] = new List<Type>();
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requirements[type].AddRange(implems);
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}
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else if (attr.Weak == false && throwOnMissing) // if explicitly set to !weak, is strong, else is weak
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throw new Exception($"Broken composer dependency: {type.FullName} -> {attr.RequiredType.FullName}.");
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}
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// requiring a class = require that the composer is enabled
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// unless weak, and then requires it if it is enabled
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else
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{
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if (types.Contains(attr.RequiredType))
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{
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if (requirements[type] == null) requirements[type] = new List<Type>();
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requirements[type].Add(attr.RequiredType);
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}
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else if (attr.Weak != true && throwOnMissing) // if not explicitly set to weak, is strong
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throw new Exception($"Broken composer dependency: {type.FullName} -> {attr.RequiredType.FullName}.");
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}
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}
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}
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private static void GatherRequirementsFromBeforeAttribute(Type type, ICollection<Type> types, IDictionary<Type, List<Type>> requirements)
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{
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// get 'required' attributes
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// these attributes are *not* inherited because we want to "custom-inherit" for interfaces only
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var beforeAttributes = type
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.GetInterfaces().SelectMany(x => x.GetCustomAttributes<ComposeBeforeAttribute>()) // those marking interfaces
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.Concat(type.GetCustomAttributes<ComposeBeforeAttribute>()); // those marking the composer
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foreach (var attr in beforeAttributes)
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{
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if (attr.RequiringType == type) continue; // ignore self-requirements (+ exclude in implems, below)
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// required by an interface = by any enabled composer implementing this that interface
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if (attr.RequiringType.IsInterface)
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{
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var implems = types.Where(x => x != type && attr.RequiringType.IsAssignableFrom(x) && !x.IsInterface).ToList();
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foreach (var implem in implems)
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{
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if (requirements[implem] == null) requirements[implem] = new List<Type>();
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requirements[implem].Add(type);
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}
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}
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// required by a class
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else
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{
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if (types.Contains(attr.RequiringType))
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{
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if (requirements[attr.RequiringType] == null) requirements[attr.RequiringType] = new List<Type>();
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requirements[attr.RequiringType].Add(type);
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}
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}
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}
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}
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private static IEnumerable<IComposer> InstantiateComposers(IEnumerable<Type> types)
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{
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foreach (Type type in types)
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{
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ConstructorInfo ctor = type.GetConstructor(Array.Empty<Type>());
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if (ctor == null)
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{
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throw new InvalidOperationException($"Composer {type.FullName} does not have a parameter-less constructor.");
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}
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yield return (IComposer) ctor.Invoke(Array.Empty<object>());
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}
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}
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}
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}
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