chore(cli-repl): log telemetry flushing errors and duration MONGOSH-1038 (#1145)

Author: addaleax

packages/cli-repl/src/cli-repl.spec.ts

@@ -817,6 +817,17 @@ describe('CliRepl', () => {
           expect(apiEvents[0].properties.count).to.equal(1);
         });
 
+        it('includes a statement about flushed telemetry in the log', async() => {
+          await cliRepl.start(await testServer.connectionString(), {});
+          const { logFilePath } = cliRepl.logWriter;
+          input.write('db.hello()\n');
+          input.write('exit\n');
+          await waitBus(cliRepl.bus, 'mongosh:closed');
+          const flushEntry = (await readReplLogfile(logFilePath)).find(entry => entry.id === 1_000_000_045);
+          expect(flushEntry.attr.flushError).to.equal(null);
+          expect(flushEntry.attr.flushDuration).to.be.a('number');
+        });
+
         context('with a 5.0+ server', () => {
           skipIfServerVersion(testServer, '<= 4.4');
 

packages/cli-repl/src/cli-repl.ts

@@ -500,13 +500,25 @@ class CliRepl {
     }
     this.closing = true;
     const analytics = this.analytics;
+    let flushError: string | null = null;
+    let flushDuration: number | null = null;
     if (analytics) {
+      const flushStart = Date.now();
       try {
         await promisify(analytics.flush.bind(analytics))();
-      } catch { /* ignore */ }
+      } catch (err: any) {
+        flushError = err.message;
+      } finally {
+        flushDuration = Date.now() - flushStart;
+      }
     }
     this.mongocryptdManager.close();
-    await this.logWriter?.flush?.();
+    // eslint-disable-next-line chai-friendly/no-unused-expressions
+    this.logWriter?.info('MONGOSH', mongoLogId(1_000_000_045), 'analytics', 'Flushed outstanding data', {
+      flushError,
+      flushDuration
+    });
+    await this.logWriter?.flush();
     this.bus.emit('mongosh:closed');
   }
 

packages/logging/src/setup-logger-and-telemetry.ts

@@ -488,4 +488,6 @@ export function setupLoggerAndTelemetry(
       error: ev.error.message
     });
   });
+
+  // NB: mongoLogId(1_000_000_045) is used in cli-repl itself
 }