Improve language server performance

CHANGELOG.md

@@ -21,6 +21,7 @@
 - `apollo-language-server`
   - Fix on-hover bugs introduced by replacing visitWithTypeInfo [#1196](https://github.com/apollographql/apollo-tooling/pull/1196)
   - Add `gql` extension to the default `includes` configuration [#1176](https://github.com/apollographql/apollo-tooling/pull/1176)
+  - Simple perf improvements (debouncer + cache) [#1206](https://github.com/apollographql/apollo-tooling/pull/1206)
 - `apollo-tools`
   - <First `apollo-tools` related entry goes here>
 - `vscode-apollo`

package.json

@@ -65,6 +65,7 @@
     "@types/jest": "24.0.11",
     "@types/listr": "0.13.0",
     "@types/lodash": "4.14.123",
+    "@types/lodash.debounce": "^4.0.6",
     "@types/lodash.sortby": "4.7.6",
     "@types/minimatch": "3.0.3",
     "@types/nock": "9.3.1",

packages/apollo-language-server/package.json

@@ -36,6 +36,7 @@
     "graphql": "^14.0.2",
     "graphql-tag": "^2.10.1",
     "lodash": "^4.17.11",
+    "lodash.debounce": "^4.0.8",
     "minimatch": "^3.0.4",
     "minimist": "^1.2.0",
     "moment": "^2.22.2",

packages/apollo-language-server/src/languageProvider.ts

@@ -19,7 +19,6 @@ import {
   getTokenAtPosition,
   getTypeInfo
 } from "@apollographql/graphql-language-service-interface/dist/getAutocompleteSuggestions";
-
 import { GraphQLWorkspace } from "./workspace";
 import { DocumentUri } from "./project/base";
 

packages/apollo-language-server/src/server.ts

@@ -12,6 +12,7 @@ import { QuickPickItem } from "vscode";
 import { GraphQLWorkspace } from "./workspace";
 import { GraphQLLanguageProvider } from "./languageProvider";
 import { LanguageServerLoadingHandler } from "./loadingHandler";
+import { debounceHandler } from "./utilities";
 
 const connection = createConnection(ProposedFeatures.all);
 
@@ -117,12 +118,14 @@ const documents: TextDocuments = new TextDocuments();
 // for open, change and close text document events
 documents.listen(connection);
 
-documents.onDidChangeContent(params => {
-  const project = workspace.projectForFile(params.document.uri);
-  if (!project) return;
+documents.onDidChangeContent(
+  debounceHandler(params => {
+    const project = workspace.projectForFile(params.document.uri);
+    if (!project) return;
 
-  project.documentDidChange(params.document);
-});
+    project.documentDidChange(params.document);
+  })
+);
 
 connection.onDidChangeWatchedFiles(params => {
   for (const { uri, type } of params.changes) {
@@ -181,16 +184,20 @@ connection.onWorkspaceSymbol((params, token) =>
   languageProvider.provideWorkspaceSymbol(params.query, token)
 );
 
-connection.onCompletion((params, token) =>
-  languageProvider.provideCompletionItems(
-    params.textDocument.uri,
-    params.position,
-    token
+connection.onCompletion(
+  debounceHandler((params, token) =>
+    languageProvider.provideCompletionItems(
+      params.textDocument.uri,
+      params.position,
+      token
+    )
   )
 );
 
-connection.onCodeLens((params, token) =>
-  languageProvider.provideCodeLenses(params.textDocument.uri, token)
+connection.onCodeLens(
+  debounceHandler((params, token) =>
+    languageProvider.provideCodeLenses(params.textDocument.uri, token)
+  )
 );
 
 connection.onNotification("apollographql/reloadService", () =>

packages/apollo-language-server/src/utilities/debouncer.ts

@@ -0,0 +1,5 @@
+import debounce from "lodash.debounce";
+
+export function debounceHandler(handler: (...args: any[]) => any) {
+  return debounce(handler, 400, { trailing: true });
+}

packages/apollo-language-server/src/utilities/index.ts

@@ -0,0 +1 @@
+export * from "./debouncer";

packages/apollo-language-server/src/workspace.ts

@@ -28,6 +28,7 @@ export class GraphQLWorkspace {
   private _onDecorations?: NotificationHandler<any>;
   private _onSchemaTags?: NotificationHandler<[ServiceID, SchemaTag[]]>;
   private _onConfigFilesFound?: NotificationHandler<ApolloConfig[]>;
+  private _projectForFileCache: Map<string, GraphQLProject> = new Map();
 
   private projectsByFolderUri: Map<string, GraphQLProject[]> = new Map();
 
@@ -225,9 +226,15 @@ export class GraphQLWorkspace {
   }
 
   projectForFile(uri: DocumentUri): GraphQLProject | undefined {
+    const cachedResult = this._projectForFileCache.get(uri);
+    if (cachedResult) {
+      return cachedResult;
+    }
+
     for (const projects of this.projectsByFolderUri.values()) {
       const project = projects.find(project => project.includesFile(uri));
       if (project) {
+        this._projectForFileCache.set(uri, project);
         return project;
       }
     }