File: FindSymbols\SymbolTree\SymbolTreeInfo_Source.cs
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Project: ..\..\..\src\Workspaces\Core\Portable\Microsoft.CodeAnalysis.Workspaces.csproj (Microsoft.CodeAnalysis.Workspaces)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System;
using System.Diagnostics;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.Collections;
using Microsoft.CodeAnalysis.PooledObjects;
using Microsoft.CodeAnalysis.Serialization;
using Microsoft.CodeAnalysis.Storage;
using Roslyn.Utilities;
 
namespace Microsoft.CodeAnalysis.FindSymbols
{
    internal partial class SymbolTreeInfo
    {
        private static readonly SimplePool<MultiDictionary<string, INamespaceOrTypeSymbol>> s_symbolMapPool = new(() => new());
 
        private static MultiDictionary<string, INamespaceOrTypeSymbol> AllocateSymbolMap()
            => s_symbolMapPool.Allocate();
 
        private static void FreeSymbolMap(MultiDictionary<string, INamespaceOrTypeSymbol> symbolMap)
        {
            symbolMap.Clear();
            s_symbolMapPool.Free(symbolMap);
        }
 
        private static string GetSourceKeySuffix(Project project)
            => "_Source_" + project.FilePath;
 
        public static Task<SymbolTreeInfo> GetInfoForSourceAssemblyAsync(
            Project project, Checksum checksum, CancellationToken cancellationToken)
        {
            var solution = project.Solution;
 
            return LoadOrCreateAsync(
                solution.Services,
                SolutionKey.ToSolutionKey(solution),
                checksum,
                createAsync: checksum => CreateSourceSymbolTreeInfoAsync(project, checksum, cancellationToken),
                keySuffix: GetSourceKeySuffix(project),
                cancellationToken);
        }
 
        /// <summary>
        /// Loads any info we have for this project from our persistence store.  Will succeed regardless of the
        /// checksum of the <paramref name="project"/>.  Should only be used by clients that are ok with potentially
        /// stale data.
        /// </summary>
        public static async Task<SymbolTreeInfo?> LoadAnyInfoForSourceAssemblyAsync(
            Project project, CancellationToken cancellationToken)
        {
            return await LoadAsync(
                project.Solution.Services,
                SolutionKey.ToSolutionKey(project.Solution),
                checksum: await GetSourceSymbolsChecksumAsync(project, cancellationToken).ConfigureAwait(false),
                checksumMustMatch: false,
                GetSourceKeySuffix(project),
                cancellationToken).ConfigureAwait(false);
        }
 
        /// <summary>
        /// Cache of project to the checksum for it so that we don't have to expensively recompute
        /// this each time we get a project.
        /// </summary>
        private static readonly ConditionalWeakTable<ProjectState, AsyncLazy<Checksum>> s_projectToSourceChecksum = new();
 
        public static Task<Checksum> GetSourceSymbolsChecksumAsync(Project project, CancellationToken cancellationToken)
        {
            var lazy = s_projectToSourceChecksum.GetValue(
                project.State, static p => new AsyncLazy<Checksum>(c => ComputeSourceSymbolsChecksumAsync(p, c), cacheResult: true));
 
            return lazy.GetValueAsync(cancellationToken);
        }
 
        private static async Task<Checksum> ComputeSourceSymbolsChecksumAsync(ProjectState projectState, CancellationToken cancellationToken)
        {
            // The SymbolTree for source is built from the source-symbols from the project's compilation's
            // assembly.  Specifically, we only get the name, kind and parent/child relationship of all the
            // child symbols.  So we want to be able to reuse the index as long as none of these have 
            // changed.  The only thing that can make those source-symbols change in that manner are if
            // the text of any document changes, or if options for the project change.  So we build our
            // checksum out of that data.
            var serializer = projectState.LanguageServices.SolutionServices.GetService<ISerializerService>();
            var projectStateChecksums = await projectState.GetStateChecksumsAsync(cancellationToken).ConfigureAwait(false);
 
            // Order the documents by FilePath.  Default ordering in the RemoteWorkspace is
            // to be ordered by Guid (which is not consistent across VS sessions).
            var textChecksumsTasks = projectState.DocumentStates.States.Values.OrderBy(state => state.FilePath, StringComparer.Ordinal).Select(async state =>
            {
                var documentStateChecksum = await state.GetStateChecksumsAsync(cancellationToken).ConfigureAwait(false);
                return documentStateChecksum.Text;
            });
 
            var compilationOptionsChecksum = projectStateChecksums.CompilationOptions;
            var parseOptionsChecksum = projectStateChecksums.ParseOptions;
            var textChecksums = await Task.WhenAll(textChecksumsTasks).ConfigureAwait(false);
 
            using var _ = ArrayBuilder<Checksum>.GetInstance(out var allChecksums);
 
            allChecksums.AddRange(textChecksums);
            allChecksums.Add(compilationOptionsChecksum);
            allChecksums.Add(parseOptionsChecksum);
 
            // Include serialization format version in our checksum.  That way if the 
            // version ever changes, all persisted data won't match the current checksum
            // we expect, and we'll recompute things.
            allChecksums.Add(SerializationFormatChecksum);
 
            return Checksum.Create(allChecksums);
        }
 
        internal static async ValueTask<SymbolTreeInfo> CreateSourceSymbolTreeInfoAsync(
            Project project, Checksum checksum, CancellationToken cancellationToken)
        {
            var compilation = await project.GetCompilationAsync(cancellationToken).ConfigureAwait(false);
            var assembly = compilation?.Assembly;
            if (assembly == null)
                return CreateEmpty(checksum);
 
            var symbolMap = AllocateSymbolMap();
            try
            {
                // generate nodes for the global namespace and all descendants
                using var _ = ArrayBuilder<BuilderNode>.GetInstance(out var unsortedBuilderNodes);
 
                var globalNamespaceName = assembly.GlobalNamespace.Name;
                symbolMap.Add(globalNamespaceName, assembly.GlobalNamespace);
                GenerateSourceNodes(globalNamespaceName, RootNodeParentIndex, symbolMap[globalNamespaceName], unsortedBuilderNodes);
 
                return CreateSymbolTreeInfo(
                    checksum,
                    unsortedBuilderNodes.ToImmutable(),
                    inheritanceMap: new OrderPreservingMultiDictionary<string, string>(),
                    receiverTypeNameToExtensionMethodMap: null);
            }
            finally
            {
                FreeSymbolMap(symbolMap);
            }
        }
 
        private static void GenerateSourceNodes(
            string name,
            int parentIndex,
            MultiDictionary<string, INamespaceOrTypeSymbol>.ValueSet symbolsWithSameName,
            ArrayBuilder<BuilderNode> list)
        {
            // Add the node for this name, and record which parent it points at.  And keep track of the index of the
            // node we just added.
            var node = new BuilderNode(name, parentIndex);
            var nodeIndex = list.Count;
            list.Add(node);
 
            var symbolMap = AllocateSymbolMap();
            using var _ = PooledHashSet<string>.GetInstance(out var seenNames);
            try
            {
                // Walk the symbols with this name, and add all their child namespaces and types, grouping them together
                // based on their name.  There may be multiple (for example, Action<T1>, Action<T1, T2>, etc.)
                foreach (var symbol in symbolsWithSameName)
                    AddChildNamespacesAndTypes(symbol, symbolMap);
 
                // Now, go through all those groups and make the single mapping from their name to the builder-node we
                // just created above, and recurse into their children as well.
                foreach (var (childName, childSymbols) in symbolMap)
                {
                    seenNames.Add(childName);
                    GenerateSourceNodes(childName, nodeIndex, childSymbols, list);
                }
 
                // The above loops only create nodes for namespaces and types.  we also want nodes for members as well.
                // However, we do not want to force the symbols for those members to be created just to get the names.
                //
                // So walk through the symbols again, and for the named-types grab all the member-names contained
                // therein.  If we didn't already see that child name when recursing above, then make a builder-node for
                // it that points to the builder-node we just created above.
 
                foreach (var symbol in symbolsWithSameName)
                {
                    if (symbol is INamedTypeSymbol namedType)
                    {
                        foreach (var childMemberName in namedType.MemberNames)
                        {
                            if (seenNames.Add(childMemberName))
                                list.Add(new BuilderNode(childMemberName, nodeIndex));
                        }
                    }
                }
            }
            finally
            {
                FreeSymbolMap(symbolMap);
            }
        }
 
        private static void AddChildNamespacesAndTypes(INamespaceOrTypeSymbol symbol, MultiDictionary<string, INamespaceOrTypeSymbol> symbolMap)
        {
            if (symbol is INamespaceSymbol namespaceSymbol)
            {
                foreach (var childNamespaceOrType in namespaceSymbol.GetMembers())
                    symbolMap.Add(childNamespaceOrType.Name, childNamespaceOrType);
            }
            else if (symbol is INamedTypeSymbol namedTypeSymbol)
            {
                // for named-types, we only need to recurse into child types.  Call GetTypeMembers instead of GetMembers
                // so we do not cause all child symbols to be created.
                foreach (var childType in namedTypeSymbol.GetTypeMembers())
                    symbolMap.Add(childType.Name, childType);
            }
        }
    }
}