chore: exit by flushing the log stream before termination

Author: ergunsh

src/logger.ts

@@ -31,26 +31,14 @@ export function saveLogsToFile(fileName: string): fs.WriteStream {
   return logFile;
 }
 
-export function saveLogsToFileSync(fileName: string): void {
-  debug.enable(namespacesToEnable.join(','));
-
-  let fd: number | undefined;
-  try {
-    fd = fs.openSync(fileName, 'a+');
-  } catch (error) {
-    console.error(`Error when opening log file: ${error.message}`);
-    process.exit(1);
-  }
-
-  debug.log = function (...chunks: any[]) {
-    if (fd !== undefined) {
-      try {
-        fs.writeSync(fd, `${chunks.join(' ')}\n`);
-      } catch (error) {
-        console.error(`Error when writing to log file: ${error.message}`);
-      }
-    }
-  };
+export function flushLogs(logFile: fs.WriteStream, timeoutMs = 2000): Promise<void> {
+  return new Promise((resolve, reject) => {
+    const timeout = setTimeout(reject, timeoutMs);
+    logFile.end(() => {
+      clearTimeout(timeout);
+      resolve();
+    });
+  });
 }
 
 export const logger = debug(mcpDebugNamespace);

src/telemetry/watchdog/main.ts

@@ -8,7 +8,8 @@ import process from 'node:process';
 import readline from 'node:readline';
 import {parseArgs} from 'node:util';
 
-import {logger, saveLogsToFileSync} from '../../logger.js';
+import {logger, flushLogs, saveLogsToFile} from '../../logger.js';
+import type {WriteStream} from 'node:fs';
 import type {OsType} from '../types.js';
 import {WatchdogMessageType} from '../types.js';
 
@@ -29,16 +30,28 @@ function main() {
   const appVersion = values['app-version'];
   const osType = parseInt(values['os-type'] ?? '', 10);
   const logFile = values['log-file'];
+  let logStream: WriteStream | undefined;
   if (logFile) {
-    saveLogsToFileSync(logFile);
+    logStream = saveLogsToFile(logFile);
   }
 
+  const exit = (code: number) => {
+    if (!logStream) {
+      process.exit(code);
+    }
+
+    flushLogs(logStream).finally(() => {
+      process.exit(code);
+    });
+  };
+
   if (isNaN(parentPid) || !appVersion || isNaN(osType)) {
     logger(
       'Invalid arguments provided for watchdog process: ',
       JSON.stringify({parentPid, appVersion, osType}),
     );
-    process.exit(1);
+    exit(1);
+    return;
   }
 
   logger(
@@ -69,11 +82,11 @@ function main() {
       .sendShutdownEvent()
       .then(() => {
         logger('Shutdown event sent. Exiting.');
-        process.exit(0);
+        exit(0);
       })
       .catch(err => {
         logger('Failed to send shutdown event', err);
-        process.exit(1);
+        exit(1);
       });
   }