Clean up WaitForSessionFile logic and support increasing timeout with warning

package.json

@@ -761,6 +761,11 @@
           "default": null,
           "description": "An array of strings that enable experimental features in the PowerShell extension."
         },
+        "powershell.developer.waitForSessionFileNumOfTries": {
+          "type":"number",
+          "default": 120,
+          "description": "When the PowerShell extension is starting up, it checks for a session file in order to connect to the language server. It checks this number of times ever 2 seconds."
+        },
         "powershell.pester.useLegacyCodeLens": {
           "type": "boolean",
           "default": true,

src/process.ts

@@ -174,20 +174,36 @@ export class PowerShellProcess {
         return true;
     }
 
-    private waitForSessionFile(): Promise<utils.IEditorServicesSessionDetails> {
-        return new Promise((resolve, reject) => {
-            utils.waitForSessionFile(this.sessionFilePath, (sessionDetails, error) => {
-                utils.deleteSessionFile(this.sessionFilePath);
+    private sleep(ms: number) {
+        return new Promise(resolve => setTimeout(resolve, ms));
+    }
+
+    private async waitForSessionFile(): Promise<utils.IEditorServicesSessionDetails> {
+        const numOfTries = this.sessionSettings.developer.waitForSessionFileNumOfTries;
 
-                if (error) {
-                    this.log.write(`Error occurred retrieving session file:\n${error}`);
-                    return reject(error);
-                }
+        // This is used to warn the user that the extension is taking longer than expected to startup.
+        const warnUserThreshold = numOfTries / 2;
 
+        for (let i = numOfTries; i > 0; i--) {
+            if (utils.checkIfFileExists(this.sessionFilePath)) {
                 this.log.write("Session file found");
-                resolve(sessionDetails);
-            });
-        });
+                const sessionDetails = utils.readSessionFile(this.sessionFilePath);
+                utils.deleteSessionFile(this.sessionFilePath);
+                return sessionDetails;
+            }
+
+            if (warnUserThreshold === i) {
+                vscode.window.showWarningMessage(`Loading the PowerShell extension is taking longer than expected.
+    If you're using anti-virus software, this can affect start up performance.`);
+            }
+
+            // Wait a bit and try again
+            await this.sleep(2000);
+        }
+
+        const err = "Timed out waiting for session file to appear.";
+        this.log.write(err);
+        throw new Error(err);
     }
 
     private onTerminalClose(terminal: vscode.Terminal) {

src/settings.ts

@@ -72,6 +72,7 @@ export interface IDeveloperSettings {
     bundledModulesPath?: string;
     editorServicesLogLevel?: string;
     editorServicesWaitForDebugger?: boolean;
+    waitForSessionFileNumOfTries?: number;
 }
 
 export interface ISettings {
@@ -142,6 +143,7 @@ export function load(): ISettings {
         bundledModulesPath: "../../../PowerShellEditorServices/module",
         editorServicesLogLevel: "Normal",
         editorServicesWaitForDebugger: false,
+        waitForSessionFileNumOfTries: 120,
     };
 
     const defaultCodeFoldingSettings: ICodeFoldingSettings = {

src/utils.ts

@@ -69,25 +69,6 @@ export function writeSessionFile(sessionFilePath: string, sessionDetails: IEdito
     writeStream.close();
 }
 
-export function waitForSessionFile(sessionFilePath: string, callback: IWaitForSessionFileCallback) {
-
-    function innerTryFunc(remainingTries: number, delayMilliseconds: number) {
-        if (remainingTries === 0) {
-            callback(undefined, "Timed out waiting for session file to appear.");
-        } else if (!checkIfFileExists(sessionFilePath)) {
-            // Wait a bit and try again
-            setTimeout(
-                () => { innerTryFunc(remainingTries - 1, delayMilliseconds); },
-                delayMilliseconds);
-        } else {
-            // Session file was found, load and return it
-            callback(readSessionFile(sessionFilePath), undefined);
-        }
-    }
-
-    // Try once every 2 seconds, 60 times - making two full minutes
-    innerTryFunc(60, 2000);
-}
 
 export function readSessionFile(sessionFilePath: string): IEditorServicesSessionDetails {
     const fileContents = fs.readFileSync(sessionFilePath, "utf-8");