diff --git a/ICSharpCode.Decompiler.Tests/ResolutionSnapshotTests.cs b/ICSharpCode.Decompiler.Tests/ResolutionSnapshotTests.cs
new file mode 100644
index 000000000..73b8d4989
--- /dev/null
+++ b/ICSharpCode.Decompiler.Tests/ResolutionSnapshotTests.cs
@@ -0,0 +1,135 @@
+// Copyright (c) 2026 Siegfried Pammer
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System.IO;
+
+using ICSharpCode.Decompiler.Metadata;
+
+using NUnit.Framework;
+
+namespace ICSharpCode.Decompiler.Tests
+{
+ [TestFixture]
+ public class ResolutionSnapshotTests
+ {
+ static UniversalAssemblyResolver Resolver()
+ {
+ return new UniversalAssemblyResolver(null, throwOnError: false, targetFramework: null);
+ }
+
+ [Test]
+ public void DirectoryIsScannedOnceWhileASnapshotIsOpen()
+ {
+ var resolver = Resolver();
+ int scans = 0;
+
+ using (resolver.BeginSnapshot())
+ {
+ for (int i = 0; i < 3; i++)
+ {
+ Assert.That(resolver.GetOrAddVersionFolder("/shared/pack", _ => { scans++; return "9.0.0"; }),
+ Is.EqualTo("9.0.0"));
+ }
+ }
+
+ Assert.That(scans, Is.EqualTo(1));
+ }
+
+ [Test]
+ public void DirectoryIsScannedEveryTimeWithoutASnapshot()
+ {
+ var resolver = Resolver();
+ int scans = 0;
+
+ for (int i = 0; i < 3; i++)
+ {
+ resolver.GetOrAddVersionFolder("/shared/pack", _ => { scans++; return "9.0.0"; });
+ }
+
+ Assert.That(scans, Is.EqualTo(3));
+ }
+
+ [Test]
+ public void WhatWasScannedIsForgottenWhenTheSnapshotEnds()
+ {
+ // The point of the scope: outside it the file system is read afresh, so an assembly
+ // list reloaded after a runtime was installed or removed sees the new state.
+ var resolver = Resolver();
+ int scans = 0;
+
+ using (resolver.BeginSnapshot())
+ {
+ resolver.GetOrAddVersionFolder("/shared/pack", _ => { scans++; return "9.0.0"; });
+ }
+ using (resolver.BeginSnapshot())
+ {
+ resolver.GetOrAddVersionFolder("/shared/pack", _ => { scans++; return "10.0.0"; });
+ }
+
+ Assert.That(scans, Is.EqualTo(2));
+ }
+
+ [Test]
+ public void ASecondScopeDoesNotStackWithTheFirst()
+ {
+ // Two decompilations can overlap on the resolver a LoadedAssembly owns. Whichever scope
+ // ends first takes the cache with it and the other reads the file system again, which
+ // costs that one its head start and nothing else.
+ var resolver = Resolver();
+ int scans = 0;
+
+ var outer = resolver.BeginSnapshot();
+ var inner = resolver.BeginSnapshot();
+ inner.Dispose();
+ resolver.GetOrAddVersionFolder("/shared/pack", _ => { scans++; return "9.0.0"; });
+ outer.Dispose();
+
+ Assert.That(scans, Is.EqualTo(1), "the scan happens, it is simply not held any more");
+ }
+
+ [Test]
+ public void ResolverFindsTheSameFileInsideAndOutsideASnapshot()
+ {
+ string directory = Path.Combine(Path.GetTempPath(), "ILSpySnapshotTest_" + Path.GetRandomFileName());
+ Directory.CreateDirectory(directory);
+ try
+ {
+ string file = Path.Combine(directory, "SomeLibrary.dll");
+ File.WriteAllBytes(file, new byte[0]);
+
+ var resolver = new UniversalAssemblyResolver(null, throwOnError: false, targetFramework: null);
+ resolver.AddSearchDirectory(directory);
+ var reference = AssemblyNameReference.Parse("SomeLibrary, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null");
+
+ string outside = resolver.FindAssemblyFile(reference);
+ string inside;
+ using (resolver.BeginSnapshot())
+ {
+ inside = resolver.FindAssemblyFile(reference);
+ }
+
+ Assert.That(outside, Is.EqualTo(file));
+ Assert.That(inside, Is.EqualTo(file));
+ }
+ finally
+ {
+ Directory.Delete(directory, recursive: true);
+ }
+ }
+ }
+}
diff --git a/ICSharpCode.Decompiler.Tests/TypeSystem/DuplicateAssemblyReferenceTests.cs b/ICSharpCode.Decompiler.Tests/TypeSystem/DuplicateAssemblyReferenceTests.cs
index 00df00eeb..d3def0338 100644
--- a/ICSharpCode.Decompiler.Tests/TypeSystem/DuplicateAssemblyReferenceTests.cs
+++ b/ICSharpCode.Decompiler.Tests/TypeSystem/DuplicateAssemblyReferenceTests.cs
@@ -173,6 +173,9 @@ namespace ICSharpCode.Decompiler.Tests.TypeSystem
///
class VersionedResolver : IAssemblyResolver
{
+ ///
+ public IDisposable BeginSnapshot() => null;
+
static readonly string runtimeDirectory = Path.GetDirectoryName(typeof(object).Assembly.Location);
readonly string directory;
diff --git a/ICSharpCode.Decompiler/Metadata/AssemblyReferences.cs b/ICSharpCode.Decompiler/Metadata/AssemblyReferences.cs
index baf120fec..f37fa25f4 100644
--- a/ICSharpCode.Decompiler/Metadata/AssemblyReferences.cs
+++ b/ICSharpCode.Decompiler/Metadata/AssemblyReferences.cs
@@ -64,6 +64,12 @@ namespace ICSharpCode.Decompiler.Metadata
MetadataFile? ResolveModule(MetadataFile mainModule, string moduleName);
Task ResolveAsync(IAssemblyReference reference);
Task ResolveModuleAsync(MetadataFile mainModule, string moduleName);
+
+ ///
+ /// Lets the resolver hold what it reads from the file system until the scope is disposed,
+ /// so that a whole reference closure asks the same directories once. Null to hold nothing.
+ ///
+ IDisposable? BeginSnapshot();
#endif
}
diff --git a/ICSharpCode.Decompiler/Metadata/DotNetCorePathFinder.cs b/ICSharpCode.Decompiler/Metadata/DotNetCorePathFinder.cs
index d24cd5a0f..7f21542b1 100644
--- a/ICSharpCode.Decompiler/Metadata/DotNetCorePathFinder.cs
+++ b/ICSharpCode.Decompiler/Metadata/DotNetCorePathFinder.cs
@@ -78,6 +78,12 @@ namespace ICSharpCode.Decompiler.Metadata
readonly string dotnetBasePath = FindDotNetExeDirectory();
readonly string preferredRuntimePack;
+ ///
+ /// The resolver this path finder belongs to, which holds any open scope. Null when nobody
+ /// owns it, and then every scan below reads the file system.
+ ///
+ internal UniversalAssemblyResolver Owner { get; set; }
+
public DotNetCorePathFinder(TargetFrameworkIdentifier targetFramework, Version targetFrameworkVersion,
string preferredRuntimePack)
{
@@ -108,6 +114,10 @@ namespace ICSharpCode.Decompiler.Metadata
{
packages = LoadPackageInfos(depsJsonFileName, targetFrameworkIdString).ToArray();
+ // Every runtime component of a package resolves to the same folder, so without
+ // this the same directory is probed once per assembly the package contains, for
+ // every reference that is looked up.
+ var knownPackageBasePaths = new HashSet();
foreach (var path in LookupPaths)
{
if (string.IsNullOrWhiteSpace(path))
@@ -120,7 +130,7 @@ namespace ICSharpCode.Decompiler.Metadata
{
var itemPath = Path.GetDirectoryName(item);
var fullPath = Path.Combine(path, p.Name, p.Version, itemPath).ToLowerInvariant();
- if (Directory.Exists(fullPath))
+ if (knownPackageBasePaths.Add(fullPath) && Directory.Exists(fullPath))
packageBasePaths.Add(fullPath);
}
}
@@ -146,13 +156,15 @@ namespace ICSharpCode.Decompiler.Metadata
{
foreach (var basePath in searchPaths.Concat(packageBasePaths))
{
- if (File.Exists(Path.Combine(basePath, name.Name + ".dll")))
+ var file = Path.Combine(basePath, name.Name + ".dll");
+ if (File.Exists(file))
{
- return Path.Combine(basePath, name.Name + ".dll");
+ return file;
}
- else if (File.Exists(Path.Combine(basePath, name.Name + ".exe")))
+ file = Path.Combine(basePath, name.Name + ".exe");
+ if (File.Exists(file))
{
- return Path.Combine(basePath, name.Name + ".exe");
+ return file;
}
}
@@ -223,7 +235,9 @@ namespace ICSharpCode.Decompiler.Metadata
if (preferredRuntimePack != null)
{
- runtimePacks = new[] { preferredRuntimePack }.Concat(runtimePacks);
+ // The preferred pack is usually one of the defaults as well; listing it twice means
+ // scanning its directory twice for every reference that is not in it.
+ runtimePacks = new[] { preferredRuntimePack }.Concat(RuntimePacks.Where(p => p != preferredRuntimePack));
}
foreach (string pack in runtimePacks)
@@ -232,14 +246,18 @@ namespace ICSharpCode.Decompiler.Metadata
string basePath = Path.Combine(dotnetBasePath, "shared", pack);
if (!Directory.Exists(basePath))
continue;
- var closestVersion = GetClosestVersionFolder(basePath, targetFrameworkVersion);
- if (File.Exists(Path.Combine(basePath, closestVersion, name.Name + ".dll")))
+ var closestVersion = Owner != null
+ ? Owner.GetOrAddVersionFolder(basePath, p => GetClosestVersionFolder(p, targetFrameworkVersion))
+ : GetClosestVersionFolder(basePath, targetFrameworkVersion);
+ var file = Path.Combine(basePath, closestVersion, name.Name + ".dll");
+ if (File.Exists(file))
{
- return Path.Combine(basePath, closestVersion, name.Name + ".dll");
+ return file;
}
- else if (File.Exists(Path.Combine(basePath, closestVersion, name.Name + ".exe")))
+ file = Path.Combine(basePath, closestVersion, name.Name + ".exe");
+ if (File.Exists(file))
{
- return Path.Combine(basePath, closestVersion, name.Name + ".exe");
+ return file;
}
}
runtimePack = null;
diff --git a/ICSharpCode.Decompiler/Metadata/UniversalAssemblyResolver.cs b/ICSharpCode.Decompiler/Metadata/UniversalAssemblyResolver.cs
index afee1ed2b..2d91be352 100644
--- a/ICSharpCode.Decompiler/Metadata/UniversalAssemblyResolver.cs
+++ b/ICSharpCode.Decompiler/Metadata/UniversalAssemblyResolver.cs
@@ -19,6 +19,7 @@
#nullable enable
using System;
+using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.IO;
@@ -76,6 +77,7 @@ namespace ICSharpCode.Decompiler.Metadata
}
readonly Lazy dotNetCorePathFinder;
+ ConcurrentDictionary? versionFolders;
readonly bool throwOnError;
readonly PEStreamOptions streamOptions;
readonly MetadataReaderOptions metadataOptions;
@@ -85,6 +87,39 @@ namespace ICSharpCode.Decompiler.Metadata
static readonly List gac_paths = GetGacPaths();
static readonly DecompilerRuntime decompilerRuntime;
+ ///
+ public IDisposable? BeginSnapshot()
+ {
+ versionFolders = new ConcurrentDictionary();
+ return new Snapshot(this);
+ }
+
+ ///
+ /// The version folder to use inside , determined by
+ /// once per open scope, and on every call outside one.
+ ///
+ internal string GetOrAddVersionFolder(string basePath, Func valueFactory)
+ {
+ return versionFolders is { } cache ? cache.GetOrAdd(basePath, valueFactory) : valueFactory(basePath);
+ }
+
+ ///
+ /// Holds what the resolver read from the file system until it is disposed. Two of these on
+ /// one resolver do not stack: the first to end takes the cache with it, and the other reads
+ /// the file system again.
+ ///
+ sealed class Snapshot : IDisposable
+ {
+ readonly UniversalAssemblyResolver resolver;
+
+ public Snapshot(UniversalAssemblyResolver resolver)
+ {
+ this.resolver = resolver;
+ }
+
+ public void Dispose() => resolver.versionFolders = null;
+ }
+
public void AddSearchDirectory(string? directory)
{
directories.Add(directory);
@@ -358,6 +393,7 @@ namespace ICSharpCode.Decompiler.Metadata
dotNetCorePathFinder = new DotNetCorePathFinder(targetFrameworkIdentifier, targetFrameworkVersion, runtimePack);
else
dotNetCorePathFinder = new DotNetCorePathFinder(mainAssemblyFileName, targetFramework, runtimePack, targetFrameworkIdentifier, targetFrameworkVersion);
+ dotNetCorePathFinder.Owner = this;
foreach (var directory in directories)
{
dotNetCorePathFinder.AddSearchDirectory(directory);
@@ -555,9 +591,12 @@ namespace ICSharpCode.Decompiler.Metadata
return IsZeroOrAllOnes(reference.Version) || reference.IsRetargetable;
}
+ static readonly string[] assemblyExtensions = { ".dll", ".exe" };
+ static readonly string[] windowsMetadataExtensions = { ".winmd", ".dll" };
+
string? SearchDirectory(IAssemblyReference name, string directory)
{
- var extensions = name.IsWindowsRuntime ? new[] { ".winmd", ".dll" } : new[] { ".dll", ".exe" };
+ var extensions = name.IsWindowsRuntime ? windowsMetadataExtensions : assemblyExtensions;
foreach (var extension in extensions)
{
string file = Path.Combine(directory, name.Name + extension);
@@ -772,17 +811,17 @@ namespace ICSharpCode.Decompiler.Metadata
return null;
}
+ static readonly string[] gacFolders = { "GAC_MSIL", "GAC_32", "GAC_64", "GAC" };
+ static readonly string[] gacFolderPrefixes = { string.Empty, "v4.0_" };
+
static string? GetAssemblyInNetGac(IAssemblyReference reference)
{
- var gacs = new[] { "GAC_MSIL", "GAC_32", "GAC_64", "GAC" };
- var prefixes = new[] { string.Empty, "v4.0_" };
-
for (int i = 0; i < gac_paths.Count; i++)
{
- for (int j = 0; j < gacs.Length; j++)
+ for (int j = 0; j < gacFolders.Length; j++)
{
- var gac = Path.Combine(gac_paths[i], gacs[j]);
- var file = GetAssemblyFile(reference, prefixes[i], gac);
+ var gac = Path.Combine(gac_paths[i], gacFolders[j]);
+ var file = GetAssemblyFile(reference, gacFolderPrefixes[i], gac);
if (File.Exists(file))
return file;
}
@@ -792,10 +831,10 @@ namespace ICSharpCode.Decompiler.Metadata
// the whole GAC rather than a fallback within one folder.
for (int i = 0; i < gac_paths.Count; i++)
{
- for (int j = 0; j < gacs.Length; j++)
+ for (int j = 0; j < gacFolders.Length; j++)
{
- var gac = Path.Combine(gac_paths[i], gacs[j]);
- var file = FindUnifiedAssemblyInGacFolder(reference, prefixes[i], gac);
+ var gac = Path.Combine(gac_paths[i], gacFolders[j]);
+ var file = FindUnifiedAssemblyInGacFolder(reference, gacFolderPrefixes[i], gac);
if (file != null)
return file;
}
@@ -865,10 +904,9 @@ namespace ICSharpCode.Decompiler.Metadata
///
public static IEnumerable EnumerateGac()
{
- var gacs = new[] { "GAC_MSIL", "GAC_32", "GAC_64", "GAC" };
foreach (var path in GetGacPaths())
{
- foreach (var gac in gacs)
+ foreach (var gac in gacFolders)
{
string rootPath = Path.Combine(path, gac);
if (!Directory.Exists(rootPath))
diff --git a/ICSharpCode.Decompiler/TypeSystem/DecompilerTypeSystem.cs b/ICSharpCode.Decompiler/TypeSystem/DecompilerTypeSystem.cs
index 87812d19d..1d0f0d7e5 100644
--- a/ICSharpCode.Decompiler/TypeSystem/DecompilerTypeSystem.cs
+++ b/ICSharpCode.Decompiler/TypeSystem/DecompilerTypeSystem.cs
@@ -287,7 +287,13 @@ namespace ICSharpCode.Decompiler.TypeSystem
int referencedAssembliesResolved = 0;
try
{
- referencedAssembliesResolved = await InitializeCoreAsync(mainModule, assemblyResolver).ConfigureAwait(false);
+ // The whole reference closure is resolved here, and every reference in it asks the
+ // same framework directories the same questions. A resolver that can hold what it
+ // read answers them once for this build and forgets it again afterwards.
+ using (assemblyResolver.BeginSnapshot())
+ {
+ referencedAssembliesResolved = await InitializeCoreAsync(mainModule, assemblyResolver).ConfigureAwait(false);
+ }
}
finally
{
diff --git a/ICSharpCode.ILSpyX/LoadedAssembly.cs b/ICSharpCode.ILSpyX/LoadedAssembly.cs
index d9f30d9d7..5380157eb 100644
--- a/ICSharpCode.ILSpyX/LoadedAssembly.cs
+++ b/ICSharpCode.ILSpyX/LoadedAssembly.cs
@@ -615,6 +615,12 @@ namespace ICSharpCode.ILSpyX
///
public ReferenceLoadInfo LoadInfo => referenceLoadInfo;
+ ///
+ public IDisposable? BeginSnapshot()
+ {
+ return parent.GetUniversalResolver(applyWinRTProjections).BeginSnapshot();
+ }
+
public MetadataFile? Resolve(IAssemblyReference reference)
{
return ResolveAsync(reference).GetAwaiter().GetResult();
diff --git a/ICSharpCode.ILSpyX/LoadedPackage.cs b/ICSharpCode.ILSpyX/LoadedPackage.cs
index 35cc5368f..4571e77b3 100644
--- a/ICSharpCode.ILSpyX/LoadedPackage.cs
+++ b/ICSharpCode.ILSpyX/LoadedPackage.cs
@@ -299,6 +299,9 @@ namespace ICSharpCode.ILSpyX
public sealed class PackageFolder : IAssemblyResolver
{
+ ///
+ public IDisposable? BeginSnapshot() => null;
+
///
/// Gets the short name of the folder.
///
diff --git a/ILSpy.BamlDecompiler.Tests/MissingReferencesTests.cs b/ILSpy.BamlDecompiler.Tests/MissingReferencesTests.cs
index 196f4dbb7..8732ff953 100644
--- a/ILSpy.BamlDecompiler.Tests/MissingReferencesTests.cs
+++ b/ILSpy.BamlDecompiler.Tests/MissingReferencesTests.cs
@@ -50,6 +50,9 @@ namespace ILSpy.BamlDecompiler.Tests
///
sealed class WpfHidingResolver : IAssemblyResolver
{
+ ///
+ public IDisposable BeginSnapshot() => null;
+
static readonly HashSet hidden = new(StringComparer.OrdinalIgnoreCase) {
"WindowsBase", "PresentationCore", "PresentationFramework", "PresentationUI", "System.Xaml"
};
diff --git a/TestTools/nugetfuzz.cs b/TestTools/nugetfuzz.cs
index e49df6efb..68e92f4ad 100644
--- a/TestTools/nugetfuzz.cs
+++ b/TestTools/nugetfuzz.cs
@@ -855,6 +855,8 @@ class LoggingResolver(IAssemblyResolver inner, List dirs, Func Resolutions = new();
readonly Dictionary loaded = new();
+ public IDisposable? BeginSnapshot() => inner.BeginSnapshot();
+
public MetadataFile? Resolve(IAssemblyReference reference)
{
var file = ResolveFromDirs(reference) ?? inner.Resolve(reference);