added extra check to prevent multiple installation of the same typing, added version field to telemetry event

src/compiler/core.ts

@@ -3,6 +3,9 @@
 
 /* @internal */
 namespace ts {
+
+    export const version = "2.0.9";
+
     /**
      * Ternary values are defined such that
      * x & y is False if either x or y is False.

src/compiler/program.ts

@@ -5,8 +5,6 @@
 namespace ts {
     /** The version of the TypeScript compiler release */
 
-    export const version = "2.0.9";
-
     const emptyArray: any[] = [];
 
     export function findConfigFile(searchPath: string, fileExists: (fileName: string) => boolean, configName = "tsconfig.json"): string {

src/server/protocol.ts

@@ -1968,6 +1968,11 @@ namespace ts.server.protocol {
          * true if install request succeeded, otherwise - false
          */
         installSuccess: boolean;
+
+        /**
+         * version of typings installer
+         */
+        typingsInstallerVersion: string;
     }
 
     export interface NavBarResponse extends Response {

src/server/server.ts

@@ -266,7 +266,8 @@ namespace ts.server {
                         telemetryEventName: "typingsInstalled",
                         payload: {
                             installedPackages: response.packagesToInstall.join(","),
-                            installSuccess: response.installSuccess
+                            installSuccess: response.installSuccess,
+                            typingsInstallerVersion: response.typingsInstallerVersion
                         }
                     };
                     const eventName: protocol.TelemetryEventName = "telemetry";

src/server/types.d.ts

@@ -63,6 +63,7 @@ declare namespace ts.server {
         readonly packagesToInstall: ReadonlyArray<string>;
         readonly kind: EventInstall;
         readonly installSuccess: boolean;
+        readonly typingsInstallerVersion: string;
     }
 
     export interface InstallTypingHost extends JsTyping.TypingResolutionHost {

src/server/typingsInstaller/typingsInstaller.ts

@@ -230,7 +230,7 @@ namespace ts.server.typingsInstaller {
             }
             const result: string[] = [];
             for (const typing of typingsToInstall) {
-                if (this.missingTypingsSet[typing]) {
+                if (this.missingTypingsSet[typing] || this.packageNameToTypingLocation[typing]) {
                     continue;
                 }
                 const validationResult = validatePackageName(typing);
@@ -308,7 +308,8 @@ namespace ts.server.typingsInstaller {
                     this.sendResponse(<TypingsInstallEvent>{
                         kind: EventInstall,
                         packagesToInstall: scopedTypings,
-                        installSuccess: ok
+                        installSuccess: ok,
+                        typingsInstallerVersion: ts.version // qualified explicitly to prevent occasional shadowing
                     });
                 }