Move the update engine portion of the SymbolSearch service down to the workspace layer.

src/EditorFeatures/CSharpTest/Diagnostics/AddUsing/AddUsingTests_NuGet.cs

@@ -34,8 +34,8 @@ protected override async Task<TestWorkspace> CreateWorkspaceFromFileAsync(string
             {
                 var workspace = await base.CreateWorkspaceFromFileAsync(definition, parseOptions, compilationOptions);
                 workspace.Options = workspace.Options
-                    .WithChangedOption(AddImportOptions.SuggestForTypesInNuGetPackages, LanguageNames.CSharp, true)
-                    .WithChangedOption(AddImportOptions.SuggestForTypesInReferenceAssemblies, LanguageNames.CSharp, true);
+                    .WithChangedOption(SymbolSearchOptions.SuggestForTypesInNuGetPackages, LanguageNames.CSharp, true)
+                    .WithChangedOption(SymbolSearchOptions.SuggestForTypesInReferenceAssemblies, LanguageNames.CSharp, true);
                 return workspace;
             }
 

src/EditorFeatures/VisualBasicTest/Diagnostics/AddImport/AddImportTests_NuGet.vb

@@ -26,8 +26,8 @@ Namespace Microsoft.CodeAnalysis.Editor.VisualBasic.UnitTests.CodeActions.AddImp
             Protected Overrides Async Function CreateWorkspaceFromFileAsync(definition As String, parseOptions As ParseOptions, compilationOptions As CompilationOptions) As Task(Of TestWorkspace)
                 Dim workspace = Await MyBase.CreateWorkspaceFromFileAsync(definition, parseOptions, compilationOptions)
                 workspace.Options = workspace.Options.
-                    WithChangedOption(AddImportOptions.SuggestForTypesInNuGetPackages, LanguageNames.VisualBasic, True).
-                    WithChangedOption(AddImportOptions.SuggestForTypesInReferenceAssemblies, LanguageNames.VisualBasic, True)
+                    WithChangedOption(SymbolSearchOptions.SuggestForTypesInNuGetPackages, LanguageNames.VisualBasic, True).
+                    WithChangedOption(SymbolSearchOptions.SuggestForTypesInReferenceAssemblies, LanguageNames.VisualBasic, True)
                 Return workspace
             End Function
 

src/Features/Core/Portable/CodeFixes/AddImport/AbstractAddImportCodeFixProvider.SymbolReferenceFinder.cs

@@ -266,9 +266,9 @@ private async Task<IList<SymbolReference>> GetMatchingTypesAsync(SearchScope sea
 
                 var options = workspaceServices.Workspace.Options;
                 var searchReferenceAssemblies = options.GetOption(
-                    AddImportOptions.SuggestForTypesInReferenceAssemblies, language);
+                    SymbolSearchOptions.SuggestForTypesInReferenceAssemblies, language);
                 var searchNugetPackages = options.GetOption(
-                    AddImportOptions.SuggestForTypesInNuGetPackages, language);
+                    SymbolSearchOptions.SuggestForTypesInNuGetPackages, language);
 
                 if (symbolSearchService != null &&
                     searchReferenceAssemblies)

src/Features/Core/Portable/Features.csproj

@@ -372,13 +372,10 @@
     <Compile Include="RemoveUnnecessaryImports\AbstractRemoveUnnecessaryImportsService.cs" />
     <Compile Include="ReplaceMethodWithProperty\ReplaceMethodWithPropertyCodeRefactoringProvider.cs" />
     <Compile Include="ReplaceMethodWithProperty\IReplaceMethodWithPropertyService.cs" />
-    <Compile Include="Shared\Options\AddImportOptionsProvider.cs" />
     <Compile Include="Shared\Extensions\ProjectExtensions.cs" />
-    <Compile Include="Shared\Options\AddImportOptions.cs" />
     <Compile Include="Shared\Options\ServiceComponentOnOffOptionsProvider.cs" />
     <Compile Include="Shared\Options\ServiceFeatureOnOffOptions.cs" />
     <Compile Include="Shared\Options\ServiceFeatureOnOffOptionsProvider.cs" />
-    <Compile Include="Shared\Utilities\IOUtilities.cs" />
     <Compile Include="Shared\Utilities\LinkedFilesSymbolEquivalenceComparer.cs" />
     <Compile Include="Shared\Utilities\SupportedPlatformData.cs" />
     <Compile Include="Completion\Providers\SymbolCompletionItem.cs" />

src/Features/Core/Portable/Shared/Options/ServiceComponentOnOffOptions.cs

@@ -10,7 +10,5 @@ namespace Microsoft.CodeAnalysis.Shared.Options
     internal static class ServiceComponentOnOffOptions
     {
         public static readonly Option<bool> DiagnosticProvider = new Option<bool>(nameof(ServiceComponentOnOffOptions), nameof(DiagnosticProvider), defaultValue: true);
-
-        public static readonly Option<bool> SymbolSearch = new Option<bool>(nameof(ServiceComponentOnOffOptions), nameof(SymbolSearch), defaultValue: true);
     }
 }

src/Features/Core/Portable/Shared/Options/ServiceComponentOnOffOptionsProvider.cs

@@ -12,8 +12,7 @@ namespace Microsoft.CodeAnalysis.Shared.Options
     internal class ServiceComponentOnOffOptionsProvider : IOptionProvider
     {
         private readonly IEnumerable<IOption> _options = ImmutableArray.Create(
-            ServiceComponentOnOffOptions.DiagnosticProvider,
-            ServiceComponentOnOffOptions.SymbolSearch);
+            ServiceComponentOnOffOptions.DiagnosticProvider);
 
         public IEnumerable<IOption> GetOptions() => _options;
     }

src/Features/Core/Portable/project.json

 {
   "dependencies": {
-    "System.Reflection": "4.1.0"
+    "System.Reflection": "4.1.0",
   },
   "frameworks": {
     "netstandard1.3": {

src/VisualStudio/CSharp/Impl/Options/AdvancedOptionPageControl.xaml.cs

@@ -7,6 +7,7 @@
 using Microsoft.CodeAnalysis.Editor.Shared.Options;
 using Microsoft.CodeAnalysis.ExtractMethod;
 using Microsoft.CodeAnalysis.Shared.Options;
+using Microsoft.CodeAnalysis.SymbolSearch;
 using Microsoft.VisualStudio.LanguageServices.Implementation;
 using Microsoft.VisualStudio.LanguageServices.Implementation.Options;
 
@@ -19,8 +20,8 @@ public AdvancedOptionPageControl(IServiceProvider serviceProvider) : base(servic
             InitializeComponent();
 
             BindToOption(PlaceSystemNamespaceFirst, GenerationOptions.PlaceSystemNamespaceFirst, LanguageNames.CSharp);
-            BindToOption(SuggestForTypesInReferenceAssemblies, AddImportOptions.SuggestForTypesInReferenceAssemblies, LanguageNames.CSharp);
-            BindToOption(SuggestForTypesInNuGetPackages, AddImportOptions.SuggestForTypesInNuGetPackages, LanguageNames.CSharp);
+            BindToOption(SuggestForTypesInReferenceAssemblies, SymbolSearchOptions.SuggestForTypesInReferenceAssemblies, LanguageNames.CSharp);
+            BindToOption(SuggestForTypesInNuGetPackages, SymbolSearchOptions.SuggestForTypesInNuGetPackages, LanguageNames.CSharp);
             BindToOption(Split_string_literals_on_enter, SplitStringLiteralOptions.Enabled, LanguageNames.CSharp);
 
             BindToOption(EnterOutliningMode, FeatureOnOffOptions.Outlining, LanguageNames.CSharp);

src/VisualStudio/CSharp/Impl/Options/AutomationObject.cs

@@ -15,6 +15,7 @@
 using Microsoft.CodeAnalysis.Options;
 using Microsoft.CodeAnalysis.Shared.Options;
 using Microsoft.CodeAnalysis.Simplification;
+using Microsoft.CodeAnalysis.SymbolSearch;
 
 namespace Microsoft.VisualStudio.LanguageServices.CSharp.Options
 {
@@ -359,14 +360,14 @@ public int SortUsings_PlaceSystemFirst
 
         public int AddImport_SuggestForTypesInReferenceAssemblies
         {
-            get { return GetBooleanOption(AddImportOptions.SuggestForTypesInReferenceAssemblies); }
-            set { SetBooleanOption(AddImportOptions.SuggestForTypesInReferenceAssemblies, value); }
+            get { return GetBooleanOption(SymbolSearchOptions.SuggestForTypesInReferenceAssemblies); }
+            set { SetBooleanOption(SymbolSearchOptions.SuggestForTypesInReferenceAssemblies, value); }
         }
 
         public int AddImport_SuggestForTypesInNuGetPackages
         {
-            get { return GetBooleanOption(AddImportOptions.SuggestForTypesInNuGetPackages); }
-            set { SetBooleanOption(AddImportOptions.SuggestForTypesInNuGetPackages, value); }
+            get { return GetBooleanOption(SymbolSearchOptions.SuggestForTypesInNuGetPackages); }
+            set { SetBooleanOption(SymbolSearchOptions.SuggestForTypesInNuGetPackages, value); }
         }
 
         public int Space_AfterBasesColon

src/VisualStudio/Core/Def/Packaging/PackageInstallerServiceFactory.cs

@@ -15,6 +15,7 @@
 using Microsoft.CodeAnalysis.Packaging;
 using Microsoft.CodeAnalysis.Shared.Options;
 using Microsoft.CodeAnalysis.Shared.Utilities;
+using Microsoft.CodeAnalysis.SymbolSearch;
 using Microsoft.CodeAnalysis.Text;
 using Microsoft.VisualStudio.ComponentModelHost;
 using Microsoft.VisualStudio.Editor;
@@ -61,9 +62,9 @@ internal partial class PackageInstallerService : AbstractDelayStartedService, IP
         public PackageInstallerService(
             VisualStudioWorkspaceImpl workspace,
             IVsEditorAdaptersFactoryService editorAdaptersFactoryService)
-            : base(workspace, ServiceComponentOnOffOptions.SymbolSearch,
-                              AddImportOptions.SuggestForTypesInReferenceAssemblies,
-                              AddImportOptions.SuggestForTypesInNuGetPackages)
+            : base(workspace, SymbolSearchOptions.Enabled,
+                              SymbolSearchOptions.SuggestForTypesInReferenceAssemblies,
+                              SymbolSearchOptions.SuggestForTypesInNuGetPackages)
         {
             _workspace = workspace;
             _editorAdaptersFactoryService = editorAdaptersFactoryService;

src/VisualStudio/Core/Def/SymbolSearch/SymbolSearchService.cs

@@ -75,9 +75,9 @@ internal partial class SymbolSearchService : AbstractDelayStartedService, ISymbo
             string localSettingsDirectory,
             Func<Exception, bool> reportAndSwallowException,
             CancellationTokenSource cancellationTokenSource) 
-            : base(workspace, ServiceComponentOnOffOptions.SymbolSearch,
-                              AddImportOptions.SuggestForTypesInReferenceAssemblies,
-                              AddImportOptions.SuggestForTypesInNuGetPackages)
+            : base(workspace, SymbolSearchOptions.Enabled,
+                              SymbolSearchOptions.SuggestForTypesInReferenceAssemblies,
+                              SymbolSearchOptions.SuggestForTypesInNuGetPackages)
         {
             if (remoteControlService == null)
             {

src/VisualStudio/VisualBasic/Impl/Options/AdvancedOptionPageControl.xaml.vb

@@ -5,6 +5,7 @@ Imports Microsoft.CodeAnalysis.Editing
 Imports Microsoft.CodeAnalysis.Editor.Shared.Options
 Imports Microsoft.CodeAnalysis.ExtractMethod
 Imports Microsoft.CodeAnalysis.Shared.Options
+Imports Microsoft.CodeAnalysis.SymbolSearch
 Imports Microsoft.VisualStudio.LanguageServices.Implementation
 
 Namespace Microsoft.VisualStudio.LanguageServices.VisualBasic.Options
@@ -15,8 +16,8 @@ Namespace Microsoft.VisualStudio.LanguageServices.VisualBasic.Options
             InitializeComponent()
 
             BindToOption(PlaceSystemNamespaceFirst, GenerationOptions.PlaceSystemNamespaceFirst, LanguageNames.VisualBasic)
-            BindToOption(SuggestForTypesInReferenceAssemblies, AddImportOptions.SuggestForTypesInReferenceAssemblies, LanguageNames.VisualBasic)
-            BindToOption(SuggestForTypesInNuGetPackages, AddImportOptions.SuggestForTypesInNuGetPackages, LanguageNames.VisualBasic)
+            BindToOption(SuggestForTypesInReferenceAssemblies, SymbolSearchOptions.SuggestForTypesInReferenceAssemblies, LanguageNames.VisualBasic)
+            BindToOption(SuggestForTypesInNuGetPackages, SymbolSearchOptions.SuggestForTypesInNuGetPackages, LanguageNames.VisualBasic)
 
             BindToOption(EnableEndConstruct, FeatureOnOffOptions.EndConstruct, LanguageNames.VisualBasic)
             BindToOption(EnableOutlining, FeatureOnOffOptions.Outlining, LanguageNames.VisualBasic)

src/VisualStudio/VisualBasic/Impl/Options/AutomationObject.vb

@@ -10,6 +10,7 @@ Imports Microsoft.CodeAnalysis.ExtractMethod
 Imports Microsoft.CodeAnalysis.Options
 Imports Microsoft.CodeAnalysis.Shared.Options
 Imports Microsoft.CodeAnalysis.Simplification
+Imports Microsoft.CodeAnalysis.SymbolSearch
 
 Namespace Microsoft.VisualStudio.LanguageServices.VisualBasic.Options
     <ComVisible(True)>
@@ -207,19 +208,19 @@ Namespace Microsoft.VisualStudio.LanguageServices.VisualBasic.Options
 
         Public Property Option_SuggestImportsForTypesInReferenceAssemblies As Boolean
             Get
-                Return GetBooleanOption(AddImportOptions.SuggestForTypesInReferenceAssemblies)
+                Return GetBooleanOption(SymbolSearchOptions.SuggestForTypesInReferenceAssemblies)
             End Get
             Set(value As Boolean)
-                SetBooleanOption(AddImportOptions.SuggestForTypesInReferenceAssemblies, value)
+                SetBooleanOption(SymbolSearchOptions.SuggestForTypesInReferenceAssemblies, value)
             End Set
         End Property
 
         Public Property Option_SuggestImportsForTypesInNuGetPackages As Boolean
             Get
-                Return GetBooleanOption(AddImportOptions.SuggestForTypesInNuGetPackages)
+                Return GetBooleanOption(SymbolSearchOptions.SuggestForTypesInNuGetPackages)
             End Get
             Set(value As Boolean)
-                SetBooleanOption(AddImportOptions.SuggestForTypesInNuGetPackages, value)
+                SetBooleanOption(SymbolSearchOptions.SuggestForTypesInNuGetPackages, value)
             End Set
         End Property
 

src/Workspaces/Core/Desktop/SymbolSearch/DefaultSymbolSearchUpdateEngine.DatabaseFactoryService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.IO;
+using Microsoft.CodeAnalysis.Elfie.Model;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    internal partial class DefaultSymbolSearchUpdateEngine
+    {
+        private class DatabaseFactoryService : IDatabaseFactoryService
+        {
+            public AddReferenceDatabase CreateDatabaseFromBytes(byte[] bytes)
+            {
+                using (var memoryStream = new MemoryStream(bytes))
+                using (var streamReader = new StreamReader(memoryStream))
+                {
+                    var database = new AddReferenceDatabase();
+                    database.ReadText(streamReader);
+                    return database;
+                }
+            }
+        }
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/DefaultSymbolSearchUpdateEngine.DelayService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    internal partial class DefaultSymbolSearchUpdateEngine
+    {
+        private class DelayService : IDelayService
+        {
+            public TimeSpan CachePollDelay { get; } = TimeSpan.FromMinutes(1);
+            public TimeSpan FileWriteDelay { get; } = TimeSpan.FromSeconds(10);
+            public TimeSpan ExpectedFailureDelay { get; } = TimeSpan.FromMinutes(1);
+            public TimeSpan CatastrophicFailureDelay { get; } = TimeSpan.FromDays(1);
+            public TimeSpan UpdateSucceededDelay { get; } = TimeSpan.FromDays(1);
+        }
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/DefaultSymbolSearchUpdateEngine.IOService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.IO;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    internal partial class DefaultSymbolSearchUpdateEngine
+    {
+        private class IOService : IIOService
+        {
+            public void Create(DirectoryInfo directory) => directory.Create();
+
+            public void Delete(FileInfo file) => file.Delete();
+
+            public bool Exists(FileSystemInfo info) => info.Exists;
+
+            public byte[] ReadAllBytes(string path) => File.ReadAllBytes(path);
+
+            public void Replace(string sourceFileName, string destinationFileName, string destinationBackupFileName, bool ignoreMetadataErrors) =>
+                File.Replace(sourceFileName, destinationFileName, destinationBackupFileName, ignoreMetadataErrors);
+
+            public void Move(string sourceFileName, string destinationFileName) =>
+                File.Move(sourceFileName, destinationFileName);
+
+            public void WriteAndFlushAllBytes(string path, byte[] bytes)
+            {
+                using (var fileStream = new FileStream(path, FileMode.Create))
+                {
+                    fileStream.Write(bytes, 0, bytes.Length);
+                    fileStream.Flush(flushToDisk: true);
+                }
+            }
+        }
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/DefaultSymbolSearchUpdateEngine.PatchService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    internal partial class DefaultSymbolSearchUpdateEngine
+    {
+        private class PatchService : IPatchService
+        {
+            public byte[] ApplyPatch(byte[] databaseBytes, byte[] patchBytes)
+            {
+                return Patching.Delta.ApplyPatch(databaseBytes, patchBytes);
+            }
+        }
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/DefaultSymbolSearchUpdateEngine.RemoteControlService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using Microsoft.VisualStudio.RemoteControl;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    internal partial class DefaultSymbolSearchUpdateEngine
+    {
+        private class RemoteControlService : IRemoteControlService
+        {
+            public IRemoteControlClient CreateClient(string hostId, string serverPath, int pollingMinutes)
+            {
+                const string BaseUrl = "https://az700632.vo.msecnd.net/pub";
+
+                return new RemoteControlClient(hostId, BaseUrl, serverPath, pollingMinutes);
+            }
+        }
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/DefaultSymbolSearchUpdateEngine.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.Elfie.Model;
+using Microsoft.CodeAnalysis.Elfie.Model.Structures;
+using Microsoft.CodeAnalysis.Elfie.Model.Tree;
+using Microsoft.CodeAnalysis.ErrorReporting;
+using Microsoft.CodeAnalysis.Host;
+using Microsoft.CodeAnalysis.Packaging;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    /// <summary>
+    /// A service which enables searching for packages matching certain criteria.
+    /// It works against an <see cref="Microsoft.CodeAnalysis.Elfie"/> database to find results.
+    /// 
+    /// This implementation also spawns a task which will attempt to keep that database up to
+    /// date by downloading patches on a daily basis.
+    /// </summary>
+    internal partial class DefaultSymbolSearchUpdateEngine : ISymbolSearchUpdateEngine
+    {
+        private ConcurrentDictionary<string, IAddReferenceDatabaseWrapper> _sourceToDatabase = 
+            new ConcurrentDictionary<string, IAddReferenceDatabaseWrapper>();
+
+        public DefaultSymbolSearchUpdateEngine(HostWorkspaceServices workspaceServices)
+            : this(workspaceServices.GetService<IPackageInstallerService>(),
+                   workspaceServices.GetService<ISymbolSearchLogService>(),
+                   new RemoteControlService(),
+                   new DelayService(),
+                   new IOService(),
+                   new PatchService(),
+                   new DatabaseFactoryService(),
+                   // Report all exceptions we encounter, but don't crash on them.
+                   FatalError.ReportWithoutCrash,
+                   new CancellationTokenSource())
+        {
+        }
+
+        /// <summary>
+        /// For testing purposes only.
+        /// </summary>
+        internal DefaultSymbolSearchUpdateEngine(
+            IPackageInstallerService installerService,
+            ISymbolSearchLogService logService,
+            IRemoteControlService remoteControlService,
+            IDelayService delayService,
+            IIOService ioService,
+            IPatchService patchService,
+            IDatabaseFactoryService databaseFactoryService,
+            Func<Exception, bool> reportAndSwallowException,
+            CancellationTokenSource cancellationTokenSource)
+        {
+            _installerService = installerService;
+            _delayService = delayService;
+            _ioService = ioService;
+            _logService = logService;
+            _remoteControlService = remoteControlService;
+            _patchService = patchService;
+            _databaseFactoryService = databaseFactoryService;
+            _reportAndSwallowException = reportAndSwallowException;
+
+            _cancellationTokenSource = cancellationTokenSource;
+            _cancellationToken = _cancellationTokenSource.Token;
+        }
+
+        //protected override void EnableService()
+        //{
+        //    // When our service is enabled hook up to package source changes.
+        //    // We need to know when the list of sources have changed so we can
+        //    // kick off the work to process them.
+        //    _installerService.PackageSourcesChanged += OnPackageSourcesChanged;
+        //}
+
+        //private void OnPackageSourcesChanged(object sender, EventArgs e)
+        //{
+        //    StartWorking();
+        //}
+
+        //protected override void StartWorking()
+        //{
+        //    // Kick off a database update.  Wait a few seconds before starting so we don't
+        //    // interfere too much with solution loading.
+        //    var sources = _installerService.PackageSources;
+
+        //    // Always pull down the nuget.org index.  It contains the MS reference assembly index
+        //    // inside of it.
+        //    var allSources = sources.Concat(new PackageSource(NugetOrgSource, source: null));
+        //    foreach (var source in allSources)
+        //    {
+        //        Task.Run(() => UpdateSourceInBackgroundAsync(source.Name));
+        //    }
+        //}
+
+        //protected override void StopWorking()
+        //{
+        //    _installerService.PackageSourcesChanged -= OnPackageSourcesChanged;
+        //    _cancellationTokenSource.Cancel();
+        //}
+
+        public IEnumerable<PackageWithTypeResult> FindPackagesWithType(
+            string source, string name, int arity, CancellationToken cancellationToken)
+        {
+            IAddReferenceDatabaseWrapper databaseWrapper;
+            if (!_sourceToDatabase.TryGetValue(source, out databaseWrapper))
+            {
+                // Don't have a database to search.  
+                yield break;
+            }
+
+            var database = databaseWrapper.Database;
+            if (name == "var")
+            {
+                // never find anything named 'var'.
+                yield break;
+            }
+
+            var query = new MemberQuery(name, isFullSuffix: true, isFullNamespace: false);
+            var symbols = new PartialArray<Symbol>(100);
+
+            if (query.TryFindMembers(database, ref symbols))
+            {
+                var types = FilterToViableTypes(symbols);
+
+                var typesFromPackagesUsedInOtherProjects = new List<Symbol>();
+                var typesFromPackagesNotUsedInOtherProjects = new List<Symbol>();
+
+                foreach (var type in types)
+                {
+                    // Ignore any reference assembly results.
+                    if (type.PackageName.ToString() != MicrosoftAssemblyReferencesName)
+                    {
+                        var packageName = type.PackageName.ToString();
+                        if (_installerService.GetInstalledVersions(packageName).Any())
+                        {
+                            typesFromPackagesUsedInOtherProjects.Add(type);
+                        }
+                        else
+                        {
+                            typesFromPackagesNotUsedInOtherProjects.Add(type);
+                        }
+                    }
+                }
+
+                var result = new List<Symbol>();
+
+                // We always returm types from packages that we've use elsewhere in the project.
+                int? bestRank = null;
+                foreach (var type in typesFromPackagesUsedInOtherProjects)
+                {
+                    yield return CreateResult(database, type);
+                }
+
+                // For all other hits include as long as the popularity is high enough.  
+                // Popularity ranks are in powers of two.  So if two packages differ by 
+                // one rank, then one is at least twice as popular as the next.  Two 
+                // ranks would be four times as popular.  Three ranks = 8 times,  etc. 
+                // etc.  We keep packages that within 1 rank of the best package we find.
+                foreach (var type in typesFromPackagesNotUsedInOtherProjects)
+                {
+                    var rank = GetRank(type);
+                    bestRank = bestRank == null ? rank : Math.Max(bestRank.Value, rank);
+
+                    if (Math.Abs(bestRank.Value - rank) > 1)
+                    {
+                        yield break;
+                    }
+
+                    yield return CreateResult(database, type);
+                }
+            }
+        }
+
+        public IEnumerable<ReferenceAssemblyWithTypeResult> FindReferenceAssembliesWithType(
+            string name, int arity, CancellationToken cancellationToken)
+        {
+            // Our reference assembly data is stored in the nuget.org DB.
+            IAddReferenceDatabaseWrapper databaseWrapper;
+            if (!_sourceToDatabase.TryGetValue(NugetOrgSource, out databaseWrapper))
+            {
+                // Don't have a database to search.  
+                yield break;
+            }
+
+            var database = databaseWrapper.Database;
+            if (name == "var")
+            {
+                // never find anything named 'var'.
+                yield break;
+            }
+
+            var query = new MemberQuery(name, isFullSuffix: true, isFullNamespace: false);
+            var symbols = new PartialArray<Symbol>(100);
+
+            if (query.TryFindMembers(database, ref symbols))
+            {
+                var types = FilterToViableTypes(symbols);
+
+                foreach (var type in types)
+                {
+                    // Only look at reference assembly results.
+                    if (type.PackageName.ToString() == MicrosoftAssemblyReferencesName)
+                    {
+                        var nameParts = new List<string>();
+                        GetFullName(nameParts, type.FullName.Parent);
+                        yield return new ReferenceAssemblyWithTypeResult(
+                            type.AssemblyName.ToString(), type.Name.ToString(), containingNamespaceNames: nameParts);
+                    }
+                }
+            }
+        }
+
+        private List<Symbol> FilterToViableTypes(PartialArray<Symbol> symbols)
+        {
+            // Don't return nested types.  Currently their value does not seem worth
+            // it given all the extra stuff we'd have to plumb through.  Namely 
+            // going down the "using static" code path and whatnot.
+            return new List<Symbol>(
+                from symbol in symbols
+                where this.IsType(symbol) && !this.IsType(symbol.Parent())
+                select symbol);
+        }
+
+        private PackageWithTypeResult CreateResult(AddReferenceDatabase database, Symbol type)
+        {
+            var nameParts = new List<string>();
+            GetFullName(nameParts, type.FullName.Parent);
+
+            var packageName = type.PackageName.ToString();
+
+            var version = database.GetPackageVersion(type.Index).ToString();
+
+            return new PackageWithTypeResult(
+                packageName: packageName, 
+                typeName: type.Name.ToString(), 
+                version: version,
+                containingNamespaceNames: nameParts);
+        }
+
+        private int GetRank(Symbol symbol)
+        {
+            Symbol rankingSymbol;
+            int rank;
+            if (!TryGetRankingSymbol(symbol, out rankingSymbol) ||
+                !int.TryParse(rankingSymbol.Name.ToString(), out rank))
+            {
+                return 0;
+            }
+
+            return rank;
+        }
+
+        private bool TryGetRankingSymbol(Symbol symbol, out Symbol rankingSymbol)
+        {
+            for (var current = symbol; current.IsValid; current = current.Parent())
+            {
+                if (current.Type == SymbolType.Package || current.Type == SymbolType.Version)
+                {
+                    return TryGetRankingSymbolForPackage(current, out rankingSymbol);
+                }
+            }
+
+            rankingSymbol = default(Symbol);
+            return false;
+        }
+
+        private bool TryGetRankingSymbolForPackage(Symbol package, out Symbol rankingSymbol)
+        {
+            for (var child = package.FirstChild(); child.IsValid; child = child.NextSibling())
+            {
+                if (child.Type == SymbolType.PopularityRank)
+                {
+                    rankingSymbol = child;
+                    return true;
+                }
+            }
+
+            rankingSymbol = default(Symbol);
+            return false;
+        }
+
+        private bool IsType(Symbol symbol)
+        {
+            return symbol.Type.IsType();
+        }
+
+        private void GetFullName(List<string> nameParts, Path8 path)
+        {
+            if (!path.IsEmpty)
+            {
+                GetFullName(nameParts, path.Parent);
+                nameParts.Add(path.Name.ToString());
+            }
+        }
+    }
+}
\ No newline at end of file

src/Workspaces/Core/Desktop/SymbolSearch/IAddReferenceDatabaseWrapper.cs

+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Elfie.Model;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    // Wrapper types to ensure we delay load the elfie database.
+    internal interface IAddReferenceDatabaseWrapper
+    {
+        AddReferenceDatabase Database { get; }
+    }
+
+    internal class AddReferenceDatabaseWrapper : IAddReferenceDatabaseWrapper
+    {
+        public AddReferenceDatabase Database { get; }
+
+        public AddReferenceDatabaseWrapper(AddReferenceDatabase database)
+        {
+            Database = database;
+        }
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/IDatabaseFactoryService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using Microsoft.CodeAnalysis.Elfie.Model;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    internal interface IDatabaseFactoryService
+    {
+        AddReferenceDatabase CreateDatabaseFromBytes(byte[] bytes);
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/IDelayService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    /// <summary>
+    /// Used so we can mock out how the search service delays work for testing purposes.
+    /// </summary>
+    internal interface IDelayService
+    {
+        /// <summary>
+        /// The time to wait after a successful update (default = 1 day).
+        /// </summary>
+        TimeSpan UpdateSucceededDelay { get; }
+
+        /// <summary>
+        /// The time to wait after a simple expected sort of failure (i.e. IO exceptions, 
+        /// network exceptions, etc).  Things we can recover from and would expect would 
+        /// be transient.
+        /// </summary>
+        TimeSpan ExpectedFailureDelay { get; }
+
+        /// <summary>
+        /// The time to wait after a catastrophic failed update (default = 1 day).  For
+        /// example, if we download the full DB xml from the server and we cannot parse
+        /// it.  Retrying soon after will not help.  We'll just have to wait until proper
+        /// data is on the server for us to query.
+        /// </summary>
+        TimeSpan CatastrophicFailureDelay { get; }
+
+        /// <summary>
+        /// The time to wait after writing to disk fails (default = 10 seconds).
+        /// </summary>
+        TimeSpan FileWriteDelay { get; }
+
+        /// <summary>
+        /// How long to wait between each poll of the cache (default = 1 minute).
+        /// </summary>
+        TimeSpan CachePollDelay { get; }
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/IIOService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.IO;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    /// <summary>
+    /// Used so we can mock out how the search service does IO for testing purposes.
+    /// </summary>
+    internal interface IIOService
+    {
+        void Create(DirectoryInfo directory);
+        void Delete(FileInfo file);
+        bool Exists(FileSystemInfo info);
+        byte[] ReadAllBytes(string path);
+        void Replace(string sourceFileName, string destinationFileName, string destinationBackupFileName, bool ignoreMetadataErrors);
+        void Move(string sourceFileName, string destinationFileName);
+        void WriteAndFlushAllBytes(string path, byte[] bytes);
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/ILogService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Composition;
+using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.Host;
+using Microsoft.CodeAnalysis.Host.Mef;
+using Roslyn.Utilities;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    /// <summary>
+    /// Used so we can mock out logging in unit tests.
+    /// </summary>
+    internal interface ISymbolSearchLogService : IWorkspaceService
+    {
+        Task LogExceptionAsync(Exception e, string text);
+        Task LogInfoAsync(string text);
+    }
+
+    [ExportWorkspaceService(typeof(ISymbolSearchLogService)), Shared]
+    internal class DefaultSymbolSearchLogService : ISymbolSearchLogService
+    {
+        public Task LogExceptionAsync(Exception e, string text) => SpecializedTasks.EmptyTask;
+
+        public Task LogInfoAsync(string text) => SpecializedTasks.EmptyTask;
+    }
+}
\ No newline at end of file

src/Workspaces/Core/Desktop/SymbolSearch/IPatchService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    /// <summary>
+    /// Used so we can mock out patching in unit tests.
+    /// </summary>
+    internal interface IPatchService
+    {
+        byte[] ApplyPatch(byte[] databaseBytes, byte[] patchBytes);
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/IRemoteControlService.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using Microsoft.VisualStudio.RemoteControl;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    /// <summary>
+    /// Used so we can mock out the remote control service in unit tests.
+    /// </summary>
+    internal interface IRemoteControlService
+    {
+        IRemoteControlClient CreateClient(string hostId, string serverPath, int pollingMinutes);
+    }
+}

src/Workspaces/Core/Desktop/SymbolSearch/ISymbolSearchUpdateEngine.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System.Composition;
+using Microsoft.CodeAnalysis.Host;
+using Microsoft.CodeAnalysis.Host.Mef;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
+{
+    internal interface ISymbolSearchUpdateEngine : IWorkspaceService
+    {
+    }
+
+    [ExportWorkspaceServiceFactory(typeof(ISymbolSearchUpdateEngine)), Shared]
+    internal class DefaultSymbolSearchUpdateEngineFactory : IWorkspaceServiceFactory
+    {
+        public IWorkspaceService CreateService(HostWorkspaceServices workspaceServices)
+        {
+            return new DefaultSymbolSearchUpdateEngine(workspaceServices);
+        }
+    }
+}
\ No newline at end of file

src/Workspaces/Core/Desktop/SymbolSearch/Patching/Delta.cs

+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.ComponentModel;
+using System.Linq;
+using System.Runtime.InteropServices;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch.Patching
+{
+    /// <summary>
+    /// Wrapper around the msdelta api so we can consume patches produced by the Elfie service.
+    /// Pinvokes and code provided by Dan Thompson
+    /// </summary>
+    internal static unsafe class Delta
+    {
+        [StructLayout(LayoutKind.Sequential)]
+        private struct DeltaInput
+        {
+            public byte* pBuf;
+            public IntPtr cbBuf; // SIZE_T, so different size on x86/x64
+            [MarshalAs(UnmanagedType.Bool)]
+            public bool editable;
+
+            public DeltaInput(byte* pBuf_, int cbBuf_, bool editable_) : this()
+            {
+                pBuf = pBuf_;
+                cbBuf = new IntPtr(cbBuf_);
+                editable = editable_;
+            }
+
+            public static DeltaInput Empty = new DeltaInput();
+        }
+
+        [StructLayout(LayoutKind.Sequential)]
+        private struct DeltaOutput
+        {
+            public IntPtr pBuf;
+            public IntPtr cbBuf; // SIZE_T, so different size on x86/x64
+        }
+
+        [Flags]
+        private enum DeltaApplyFlag : long
+        {
+            None = 0,
+            AllowPa19 = 0x00000001
+        }
+
+        [return: MarshalAs(UnmanagedType.Bool)]
+        [DllImport("msdelta.dll", SetLastError = true)]
+        private static extern bool ApplyDeltaB(
+                DeltaApplyFlag applyFlags,
+                DeltaInput source,
+                DeltaInput delta,
+                out DeltaOutput target);
+
+        [return: MarshalAs(UnmanagedType.Bool)]
+        [DllImport("msdelta.dll", SetLastError = true)]
+        private static extern bool DeltaFree(IntPtr memory);
+
+        public static unsafe byte[] ApplyPatch(byte[] sourceBytes, byte[] patchBytes)
+        {
+            fixed (byte* pSourceBuf = sourceBytes)
+            fixed (byte* pPatchBuf = patchBytes)
+            {
+                DeltaInput ds = new DeltaInput(pSourceBuf, sourceBytes.Length, true);
+                DeltaInput dp = new DeltaInput(pPatchBuf, patchBytes.Length, true);
+                DeltaOutput output;
+
+                if (!ApplyDeltaB(DeltaApplyFlag.None,
+                                  ds,
+                                  dp,
+                                  out output))
+                {
+                    throw new Win32Exception();
+                }
+
+                byte[] targetBytes = new byte[output.cbBuf.ToInt32()];
+                Marshal.Copy(output.pBuf, targetBytes, 0, targetBytes.Length);
+                DeltaFree(output.pBuf);
+                return targetBytes;
+            }
+        }
+    }
+}
\ No newline at end of file

src/Workspaces/Core/Desktop/Workspaces.Desktop.csproj

@@ -51,13 +51,29 @@
     <Compile Include="..\..\..\Compilers\Shared\GlobalAssemblyCacheHelpers\GlobalAssemblyCacheLocation.cs">
       <Link>InternalUtilities\GlobalAssemblyCache.cs</Link>
     </Compile>
+    <Compile Include="SymbolSearch\DefaultSymbolSearchUpdateEngine.DatabaseFactoryService.cs" />
+    <Compile Include="SymbolSearch\DefaultSymbolSearchUpdateEngine.DelayService.cs" />
+    <Compile Include="SymbolSearch\DefaultSymbolSearchUpdateEngine.IOService.cs" />
+    <Compile Include="SymbolSearch\DefaultSymbolSearchUpdateEngine.PatchService.cs" />
+    <Compile Include="SymbolSearch\DefaultSymbolSearchUpdateEngine.RemoteControlService.cs" />
+    <Compile Include="SymbolSearch\DefaultSymbolSearchUpdateEngine.cs" />
     <Compile Include="Execution\DesktopReferenceSerializationServiceFactory.cs" />
     <Compile Include="Execution\SerializationAnalyzerAssemblyLoader.cs" />
+    <Compile Include="SymbolSearch\ISymbolSearchUpdateEngine.cs" />
     <Compile Include="Options\ExportOptionAttribute.cs" />
     <Compile Include="InternalUtilities\FilePathUtilities.cs" />
     <Compile Include="Log\EtwLogger.cs" />
     <Compile Include="Log\RoslynEventSource.cs" />
     <Compile Include="Options\Providers\ExportedOptionKeyOptionProvider.cs" />
+    <Compile Include="SymbolSearch\IAddReferenceDatabaseWrapper.cs" />
+    <Compile Include="SymbolSearch\IDatabaseFactoryService.cs" />
+    <Compile Include="SymbolSearch\IDelayService.cs" />
+    <Compile Include="SymbolSearch\IIOService.cs" />
+    <Compile Include="SymbolSearch\ILogService.cs" />
+    <Compile Include="SymbolSearch\IPatchService.cs" />
+    <Compile Include="SymbolSearch\IRemoteControlService.cs" />
+    <Compile Include="SymbolSearch\Patching\Delta.cs" />
+    <Compile Include="SymbolSearch\DefaultSymbolSearchUpdateEngine.Update.cs" />
     <Compile Include="Utilities\Documentation\FileBasedXmlDocumentationProvider.cs" />
     <Compile Include="Utilities\ReferencePathUtilities_Desktop.cs" />
     <Compile Include="WorkspaceDesktopResources.Designer.cs">

src/Workspaces/Core/Desktop/project.json

 {
     "dependencies": {
         "ManagedEsent": "1.9.4",
-        "Roslyn.Microsoft.Build": "0.0.2"
+        "Roslyn.Microsoft.Build": "0.0.2",
+		"Microsoft.CodeAnalysis.Elfie": {
+			"version": "0.10.6-rc2",
+			"suppressParent": "all"
+		},
+		"Microsoft.VisualStudio.RemoteControl": {
+			"version": "14.0.249-master2E2DC10C",
+			"suppressParent": "all"
+		},
     },
     "frameworks": {
         "net46": { }

src/Features/Core/Portable/Shared/Options/AddImportOptions.cs → src/Workspaces/Core/Portable/SymbolSearch/SymbolSearchOptions.cs

-using Microsoft.CodeAnalysis.Options;
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
-namespace Microsoft.CodeAnalysis.Shared.Options
+using Microsoft.CodeAnalysis.Options;
+
+namespace Microsoft.CodeAnalysis.SymbolSearch
 {
-    internal class AddImportOptions
+    internal static class SymbolSearchOptions
     {
+        public static readonly Option<bool> Enabled = new Option<bool>(nameof(SymbolSearchOptions), nameof(Enabled), defaultValue: true);
+
         public static PerLanguageOption<bool> SuggestForTypesInReferenceAssemblies =
-            new PerLanguageOption<bool>(nameof(AddImportOptions), nameof(SuggestForTypesInReferenceAssemblies), defaultValue: false,
+            new PerLanguageOption<bool>(nameof(SymbolSearchOptions), nameof(SuggestForTypesInReferenceAssemblies), defaultValue: false,
                 storageLocations: new RoamingProfileStorageLocation("TextEditor.%LANGUAGE%.Specific.SuggestForTypesInReferenceAssemblies"));
 
         public static PerLanguageOption<bool> SuggestForTypesInNuGetPackages =
-            new PerLanguageOption<bool>(nameof(AddImportOptions), nameof(SuggestForTypesInNuGetPackages), defaultValue: false,
+            new PerLanguageOption<bool>(nameof(SymbolSearchOptions), nameof(SuggestForTypesInNuGetPackages), defaultValue: false,
                 storageLocations: new RoamingProfileStorageLocation("TextEditor.%LANGUAGE%.Specific.SuggestForTypesInNuGetPackages"));
     }
 }

src/Features/Core/Portable/Shared/Options/AddImportOptionsProvider.cs → src/Workspaces/Core/Portable/SymbolSearch/SymbolSearchOptionsProvider.cs

-using Microsoft.CodeAnalysis.Options;
+// Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
+
+using Microsoft.CodeAnalysis.Options;
 using Microsoft.CodeAnalysis.Options.Providers;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Composition;
 
-namespace Microsoft.CodeAnalysis.Shared.Options
+namespace Microsoft.CodeAnalysis.SymbolSearch
 {
     [ExportOptionProvider, Shared]
-    internal class AddImportOptionsProvider : IOptionProvider
+    internal class SymbolSearchOptionsProvider : IOptionProvider
     {
         private readonly IEnumerable<IOption> _options = ImmutableArray.Create<IOption>(
-            AddImportOptions.SuggestForTypesInReferenceAssemblies,
-            AddImportOptions.SuggestForTypesInNuGetPackages);
+            SymbolSearchOptions.Enabled,
+            SymbolSearchOptions.SuggestForTypesInReferenceAssemblies,
+            SymbolSearchOptions.SuggestForTypesInNuGetPackages);
 
         public IEnumerable<IOption> GetOptions() => _options;
     }

src/Workspaces/Core/Portable/Workspaces.csproj

@@ -394,6 +394,7 @@
     <Compile Include="Options\IWorkspaceOptionService.cs" />
     <Compile Include="Shared\RuntimeOptions.cs" />
     <Compile Include="Shared\RuntimeOptionsProvider.cs" />
+    <Compile Include="Shared\Utilities\IOUtilities.cs" />
     <Compile Include="Shared\Utilities\IStreamingProgressTracker.cs" />
     <Compile Include="Shared\Utilities\StreamingProgressTracker.cs" />
     <Compile Include="Options\OptionStorageLocation.cs" />
@@ -493,12 +494,14 @@
     <Compile Include="SymbolKey\SymbolKey.ArrayTypeSymbolKey.cs" />
     <Compile Include="SymbolKey\SymbolKey.SymbolKeyWriter.cs" />
     <Compile Include="SymbolKey\SymbolKey.cs" />
+    <Compile Include="SymbolSearch\SymbolSearchOptionsProvider.cs" />
     <Compile Include="SymbolSearch\ISymbolSearchService.cs" />
     <Compile Include="FindSymbols\SymbolTree\ISymbolTreeInfoCacheService.cs" />
     <Compile Include="FindSymbols\FindReferences\MetadataUnifyingEquivalenceComparer.cs" />
     <Compile Include="Shared\Utilities\IProgressTracker.cs" />
     <Compile Include="SolutionCrawler\NullSolutionCrawlerRegisterationService.cs" />
     <Compile Include="SolutionCrawler\WellKnownSolutionCrawlerAnalyzers.cs" />
+    <Compile Include="SymbolSearch\SymbolSearchOptions.cs" />
     <Compile Include="Utilities\ArraySlice.cs" />
     <Compile Include="Utilities\BKTree.cs" />
     <Compile Include="FindSymbols\SyntaxTree\AbstractSyntaxTreeInfo.cs" />