Add telemetry for open JS files (#23833)

* Add telemetry for open JS files

* Send event every time

* Keep stats even for closed files

* Remove tsCheckCountForOpenFilesTelemetry

* Use 'info.path'

* Update API

src/server/editorServices.ts

@@ -6,6 +6,7 @@ namespace ts.server {
     export const ConfigFileDiagEvent = "configFileDiag";
     export const ProjectLanguageServiceStateEvent = "projectLanguageServiceState";
     export const ProjectInfoTelemetryEvent = "projectInfo";
+    export const OpenFileInfoTelemetryEvent = "openFileInfo";
     // tslint:enable variable-name
 
     export interface ProjectsUpdatedInBackgroundEvent {
@@ -55,6 +56,20 @@ namespace ts.server {
         readonly version: string;
     }
 
+    /**
+     * Info that we may send about a file that was just opened.
+     * Info about a file will only be sent once per session, even if the file changes in ways that might affect the info.
+     * Currently this is only sent for '.js' files.
+     */
+    export interface OpenFileInfoTelemetryEvent {
+        readonly eventName: typeof OpenFileInfoTelemetryEvent;
+        readonly data: OpenFileInfoTelemetryEventData;
+    }
+
+    export interface OpenFileInfoTelemetryEventData {
+        readonly info: OpenFileInfo;
+    }
+
     export interface ProjectInfoTypeAcquisitionData {
         readonly enable: boolean;
         // Actual values of include/exclude entries are scrubbed.
@@ -70,7 +85,11 @@ namespace ts.server {
         readonly dts: number;
     }
 
-    export type ProjectServiceEvent = ProjectsUpdatedInBackgroundEvent | ConfigFileDiagEvent | ProjectLanguageServiceStateEvent | ProjectInfoTelemetryEvent;
+    export interface OpenFileInfo {
+        readonly checkJs: boolean;
+    }
+
+    export type ProjectServiceEvent = ProjectsUpdatedInBackgroundEvent | ConfigFileDiagEvent | ProjectLanguageServiceStateEvent | ProjectInfoTelemetryEvent | OpenFileInfoTelemetryEvent;
 
     export type ProjectServiceEventHandler = (event: ProjectServiceEvent) => void;
 
@@ -325,6 +344,9 @@ namespace ts.server {
          * Container of all known scripts
          */
         private readonly filenameToScriptInfo = createMap<ScriptInfo>();
+        // Set of all '.js' files ever opened.
+        private readonly allJsFilesForOpenFileTelemetry = createMap<true>();
+
         /**
          * Map to the real path of the infos
          */
@@ -2095,9 +2117,19 @@ namespace ts.server {
 
             this.printProjects();
 
+            this.telemetryOnOpenFile(info);
             return { configFileName, configFileErrors };
         }
 
+        private telemetryOnOpenFile(scriptInfo: ScriptInfo): void {
+            if (!this.eventHandler || !scriptInfo.isJavaScript() || !addToSeen(this.allJsFilesForOpenFileTelemetry, scriptInfo.path)) {
+                return;
+            }
+
+            const info: OpenFileInfo = { checkJs: !!scriptInfo.getDefaultProject().getSourceFile(scriptInfo.path).checkJsDirective };
+            this.eventHandler({ eventName: OpenFileInfoTelemetryEvent, data: { info } });
+        }
+
         /**
          * Close file whose contents is managed by the client
          * @param filename is absolute pathname

src/server/project.ts

@@ -6,9 +6,12 @@ namespace ts.server {
         External
     }
 
+    /* @internal */
+    export type Mutable<T> = { -readonly [K in keyof T]: T[K]; };
+
     /* @internal */
     export function countEachFileTypes(infos: ScriptInfo[]): FileStats {
-        const result = { js: 0, jsx: 0, ts: 0, tsx: 0, dts: 0 };
+        const result: Mutable<FileStats> = { js: 0, jsx: 0, ts: 0, tsx: 0, dts: 0 };
         for (const info of infos) {
             switch (info.scriptKind) {
                 case ScriptKind.JS:

src/server/typingsCache.ts

@@ -11,7 +11,7 @@ namespace ts.server {
         enqueueInstallTypingsRequest(p: Project, typeAcquisition: TypeAcquisition, unresolvedImports: SortedReadonlyArray<string>): void;
         attach(projectService: ProjectService): void;
         onProjectClosed(p: Project): void;
-        readonly globalTypingsCacheLocation: string;
+        readonly globalTypingsCacheLocation: string | undefined;
     }
 
     export const nullTypingsInstaller: ITypingsInstaller = {