Merge pull request #15036 from CyrusNajmabadi/metadataIdMemory

Shave off hundreds of MB of allocations during FindReferences.

Fixes #14946

src/Compilers/Core/Portable/MetadataReference/PortableExecutableReference.cs

@@ -170,6 +170,19 @@ public Metadata GetMetadata()
             return GetMetadataNoCopy().Copy();
         }
 
+        /// <summary>
+        /// Returns the <see cref="MetadataId"/> for this reference's <see cref="Metadata"/>.
+        /// This will be equivalent to calling <see cref="GetMetadata()"/>.<see cref="Metadata.Id"/>,
+        /// but can be done more efficiently.
+        /// </summary>
+        /// <exception cref="BadImageFormatException">If the PE image format is invalid.</exception>
+        /// <exception cref="IOException">The metadata image content can't be read.</exception>
+        /// <exception cref="FileNotFoundException">The metadata image is stored in a file that can't be found.</exception>
+        public MetadataId GetMetadataId()
+        {
+            return GetMetadataNoCopy().Id;
+        }
+
         internal static Diagnostic ExceptionToDiagnostic(Exception e, CommonMessageProvider messageProvider, Location location, string display, MetadataImageKind kind)
         {
             if (e is BadImageFormatException)

src/Compilers/Core/Portable/PublicAPI.Unshipped.txt

@@ -175,6 +175,7 @@ Microsoft.CodeAnalysis.OperationKind.VariableDeclarationStatement = 3 -> Microso
 Microsoft.CodeAnalysis.OperationKind.WithStatement = 82 -> Microsoft.CodeAnalysis.OperationKind
 Microsoft.CodeAnalysis.OperationKind.YieldBreakStatement = 12 -> Microsoft.CodeAnalysis.OperationKind
 Microsoft.CodeAnalysis.OperationKind.YieldReturnStatement = 16 -> Microsoft.CodeAnalysis.OperationKind
+Microsoft.CodeAnalysis.PortableExecutableReference.GetMetadataId() -> Microsoft.CodeAnalysis.MetadataId
 Microsoft.CodeAnalysis.SemanticModel.GetOperation(Microsoft.CodeAnalysis.SyntaxNode node, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken)) -> Microsoft.CodeAnalysis.IOperation
 Microsoft.CodeAnalysis.Semantics.ArgumentKind
 Microsoft.CodeAnalysis.Semantics.ArgumentKind.DefaultValue = 4 -> Microsoft.CodeAnalysis.Semantics.ArgumentKind

src/Workspaces/Core/Portable/FindSymbols/SymbolTree/SymbolTreeInfo_Metadata.cs

@@ -54,6 +54,18 @@ private static int IndexOfCharacter(BlobReader blobReader, char ch)
             }
         }
 
+        private static MetadataId GetMetadataIdNoThrow(PortableExecutableReference reference)
+        {
+            try
+            {
+                return reference.GetMetadataId();
+            }
+            catch (Exception e) when (e is BadImageFormatException || e is IOException)
+            {
+                return null;
+            }
+        }
+
         private static Metadata GetMetadataNoThrow(PortableExecutableReference reference)
         {
             try
@@ -77,8 +89,8 @@ private static Metadata GetMetadataNoThrow(PortableExecutableReference reference
             bool loadOnly,
             CancellationToken cancellationToken)
         {
-            var metadata = GetMetadataNoThrow(reference);
-            if (metadata == null)
+            var metadataId = GetMetadataIdNoThrow(reference);
+            if (metadataId == null)
             {
                 return SpecializedTasks.Default<SymbolTreeInfo>();
             }
@@ -87,12 +99,17 @@ private static Metadata GetMetadataNoThrow(PortableExecutableReference reference
             // allocations around acquiring the task for it.  Note: once ValueTask is available
             // (and enabled in the language), we'd likely want to use it here. (Presuming 
             // the lock is not being held most of the time).
-            Task<SymbolTreeInfo> infoTask;
-            if (s_metadataIdToInfo.TryGetValue(metadata.Id, out infoTask))
+            if (s_metadataIdToInfo.TryGetValue(metadataId, out var infoTask))
             {
                 return infoTask;
             }
 
+            var metadata = GetMetadataNoThrow(reference);
+            if (metadata == null)
+            {
+                return SpecializedTasks.Default<SymbolTreeInfo>();
+            }
+
             return TryGetInfoForMetadataReferenceSlowAsync(
                 solution, reference, loadOnly, metadata, cancellationToken);
         }
@@ -107,9 +124,7 @@ private static Metadata GetMetadataNoThrow(PortableExecutableReference reference
             using (await gate.DisposableWaitAsync(cancellationToken).ConfigureAwait(false))
             {
                 cancellationToken.ThrowIfCancellationRequested();
-
-                Task<SymbolTreeInfo> infoTask;
-                if (s_metadataIdToInfo.TryGetValue(metadata.Id, out infoTask))
+                if (s_metadataIdToInfo.TryGetValue(metadata.Id, out var infoTask))
                 {
                     return await infoTask.ConfigureAwait(false);
                 }
@@ -693,11 +708,9 @@ public MetadataDefinition(MetadataDefinitionKind kind, string name)
             public static MetadataDefinition Create(
                 MetadataReader reader, TypeDefinition definition)
             {
-                string typeName = GetMetadataNameWithoutBackticks(reader, definition.Name);
+                var typeName = GetMetadataNameWithoutBackticks(reader, definition.Name);
 
-                return new MetadataDefinition(
-                    MetadataDefinitionKind.Type,
-                    typeName)
+                return new MetadataDefinition(MetadataDefinitionKind.Type,typeName)
                 {
                     Type = definition
                 };