break loops when loading assets through a mod loader

5 files changed, 87 insertions, 9 deletions

diff --git a/src/StardewModdingAPI/Framework/SContentManager.cs b/src/StardewModdingAPI/Framework/SContentManager.cs
index 9e086870..25775291 100644
--- a/src/StardewModdingAPI/Framework/SContentManager.cs
+++ b/src/StardewModdingAPI/Framework/SContentManager.cs
@@ -9,6 +9,7 @@ using Microsoft.Xna.Framework.Content;
 using StardewModdingAPI.AssemblyRewriters;
 using StardewModdingAPI.Framework.Content;
 using StardewModdingAPI.Framework.Reflection;
+using StardewModdingAPI.Framework.Utilities;
 using StardewModdingAPI.Metadata;
 using StardewValley;
 
@@ -44,6 +45,9 @@ namespace StardewModdingAPI.Framework
         /// <summary>Provides metadata for core game assets.</summary>
         private readonly CoreAssets CoreAssets;
 
+        /// <summary>The assets currently being intercepted by <see cref="IAssetLoader"/> instances. This is used to prevent infinite loops when a loader loads a new asset.</summary>
+        private readonly ContextHash<string> AssetsBeingLoaded = new ContextHash<string>();
+
 
         /*********
         ** Accessors
@@ -139,11 +143,21 @@ namespace StardewModdingAPI.Framework
 
             // load asset
             T data;
+            if (this.AssetsBeingLoaded.Contains(assetName))
             {
-                IAssetInfo info = new AssetInfo(this.GetLocale(), assetName, typeof(T), this.NormaliseAssetName);
-                IAssetData asset = this.ApplyLoader<T>(info) ?? new AssetDataForObject(info, base.Load<T>(assetName), this.NormaliseAssetName);
-                asset = this.ApplyEditors<T>(info, asset);
-                data = (T)asset.Data;
+                this.Monitor.Log($"Broke loop while loading asset '{assetName}'.", LogLevel.Warn);
+                this.Monitor.Log($"Bypassing mod loaders for this asset. Stack trace:\n{Environment.StackTrace}", LogLevel.Trace);
+                data = base.Load<T>(assetName);
+            }
+            else
+            {
+                data = this.AssetsBeingLoaded.Track(assetName, () =>
+                {
+                    IAssetInfo info = new AssetInfo(this.GetLocale(), assetName, typeof(T), this.NormaliseAssetName);
+                    IAssetData asset = this.ApplyLoader<T>(info) ?? new AssetDataForObject(info, base.Load<T>(assetName), this.NormaliseAssetName);
+                    asset = this.ApplyEditors<T>(info, asset);
+                    return (T)asset.Data;
+                });
             }
 
             // update cache & return data
diff --git a/src/StardewModdingAPI/Framework/SGame.cs b/src/StardewModdingAPI/Framework/SGame.cs
index 755f0274..997e0c8c 100644
--- a/src/StardewModdingAPI/Framework/SGame.cs
+++ b/src/StardewModdingAPI/Framework/SGame.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -11,6 +11,7 @@ using Microsoft.Xna.Framework.Graphics;
 using Microsoft.Xna.Framework.Input;
 using StardewModdingAPI.Events;
 using StardewModdingAPI.Framework.Reflection;
+using StardewModdingAPI.Framework.Utilities;
 using StardewModdingAPI.Utilities;
 using StardewValley;
 using StardewValley.BellsAndWhistles;
@@ -322,7 +323,7 @@ namespace StardewModdingAPI.Framework
 #if !SMAPI_1_x
                     if (Game1.dayOfMonth != 0) // wait until new-game intro finishes (world not fully initialised yet)
 #endif
-                        this.AfterLoadTimer--;
+                    this.AfterLoadTimer--;
 
                     if (this.AfterLoadTimer == 0)
                     {
diff --git a/src/StardewModdingAPI/Framework/Utilities/ContextHash.cs b/src/StardewModdingAPI/Framework/Utilities/ContextHash.cs
new file mode 100644
index 00000000..0d8487bb
--- /dev/null
+++ b/src/StardewModdingAPI/Framework/Utilities/ContextHash.cs
@@ -0,0 +1,62 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace StardewModdingAPI.Framework.Utilities
+{
+    /// <summary>A <see cref="HashSet{T}"/> wrapper meant for tracking recursive contexts.</summary>
+    /// <typeparam name="T">The key type.</typeparam>
+    internal class ContextHash<T> : HashSet<T>
+    {
+        /*********
+        ** Public methods
+        *********/
+        /// <summary>Construct an instance.</summary>
+        public ContextHash() { }
+
+        /// <summary>Construct an instance.</summary>
+        /// <param name="comparer">The <see cref="IEqualityComparer{T}"/> implementation to use when comparing values in the set, or <c>null</c> to use the default comparer for the set type.</param>
+        public ContextHash(IEqualityComparer<T> comparer)
+            : base(comparer) { }
+
+        /// <summary>Add a key while an action is in progress, and remove it when it completes.</summary>
+        /// <param name="key">The key to add.</param>
+        /// <param name="action">The action to perform.</param>
+        /// <exception cref="InvalidOperationException">The specified key is already added.</exception>
+        public void Track(T key, Action action)
+        {
+            if(this.Contains(key))
+                throw new InvalidOperationException($"Can't track context for key {key} because it's already added.");
+
+            this.Add(key);
+            try
+            {
+                action();
+            }
+            finally
+            {
+                this.Remove(key);
+            }
+        }
+
+        /// <summary>Add a key while an action is in progress, and remove it when it completes.</summary>
+        /// <typeparam name="TResult">The value type returned by the method.</typeparam>
+        /// <param name="key">The key to add.</param>
+        /// <param name="action">The action to perform.</param>
+        public TResult Track<TResult>(T key, Func<TResult> action)
+        {
+            if (this.Contains(key))
+                throw new InvalidOperationException($"Can't track context for key {key} because it's already added.");
+
+            this.Add(key);
+            try
+            {
+                return action();
+            }
+            finally
+            {
+                this.Remove(key);
+            }
+        }
+    }
+}
diff --git a/src/StardewModdingAPI/Framework/Countdown.cs b/src/StardewModdingAPI/Framework/Utilities/Countdown.cs
index 25ca2546..921a35ce 100644
--- a/src/StardewModdingAPI/Framework/Countdown.cs
+++ b/src/StardewModdingAPI/Framework/Utilities/Countdown.cs
@@ -1,4 +1,4 @@
-namespace StardewModdingAPI.Framework
+namespace StardewModdingAPI.Framework.Utilities
 {
     /// <summary>Counts down from a baseline value.</summary>
     internal class Countdown
diff --git a/src/StardewModdingAPI/StardewModdingAPI.csproj b/src/StardewModdingAPI/StardewModdingAPI.csproj
index d7e10ca5..73112983 100644
--- a/src/StardewModdingAPI/StardewModdingAPI.csproj
+++ b/src/StardewModdingAPI/StardewModdingAPI.csproj
@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
   <PropertyGroup>
@@ -91,6 +91,7 @@
       <Link>Properties\GlobalAssemblyInfo.cs</Link>
     </Compile>
     <Compile Include="Command.cs" />
+    <Compile Include="Framework\Utilities\ContextHash.cs" />
     <Compile Include="Metadata\CoreAssets.cs" />
     <Compile Include="ContentSource.cs" />
     <Compile Include="Events\ContentEvents.cs" />
@@ -126,7 +127,7 @@
     <Compile Include="Events\EventArgsStringChanged.cs" />
     <Compile Include="Events\GameEvents.cs" />
     <Compile Include="Events\GraphicsEvents.cs" />
-    <Compile Include="Framework\Countdown.cs" />
+    <Compile Include="Framework\Utilities\Countdown.cs" />
     <Compile Include="Framework\GameVersion.cs" />
     <Compile Include="Framework\IModMetadata.cs" />
     <Compile Include="Framework\Models\DisabledMod.cs" />