Wait for InstrumentationService.shutdown() before exit(0).

Otherwise we don't get the last portion of instrumentation data in the
file at all.

R=brianwilkerson@google.com
BUG=

Review URL: https://codereview.chromium.org/1413403007 .

pkg/analysis_server/lib/src/server/driver.dart

@@ -428,11 +428,11 @@ class Driver implements ServerStarter {
     }
 
     _captureExceptions(service, () {
-      stdioServer.serveStdio().then((_) {
+      stdioServer.serveStdio().then((_) async {
         if (serve_http) {
           httpServer.close();
         }
-        service.shutdown();
+        await service.shutdown();
         exit(0);
       });
     },

pkg/analyzer/lib/instrumentation/file_instrumentation.dart

@@ -4,6 +4,7 @@
 
 library file_instrumentation;
 
+import 'dart:async';
 import 'dart:io';
 
 import 'package:analyzer/instrumentation/instrumentation.dart';
@@ -30,8 +31,8 @@ class FileInstrumentationServer implements InstrumentationServer {
   }
 
   @override
-  void shutdown() {
-    _sink.close();
+  Future shutdown() async {
+    await _sink.close();
     _sink = null;
   }
 }

pkg/analyzer/lib/instrumentation/instrumentation.dart

@@ -4,6 +4,7 @@
 
 library instrumentation;
 
+import 'dart:async';
 import 'dart:convert';
 
 import 'package:analyzer/task/model.dart';
@@ -43,7 +44,7 @@ abstract class InstrumentationServer {
    * server. This method should be invoked exactly one time and no other methods
    * should be invoked on this instance after this method has been invoked.
    */
-  void shutdown();
+  Future shutdown();
 }
 
 /**
@@ -83,7 +84,7 @@ class InstrumentationService {
   int _subprocessCounter = 0;
 
   /**
-   * Initialize a newly created instrumentation service to comunicate with the
+   * Initialize a newly created instrumentation service to communicate with the
    * given [instrumentationServer].
    */
   InstrumentationService(this._instrumentationServer);
@@ -216,7 +217,7 @@ class InstrumentationService {
 
   /**
    * Log the result of executing a subprocess.  [subprocessId] should be the
-   * unique IDreturned by [logSubprocessStart].
+   * unique ID returned by [logSubprocessStart].
    */
   void logSubprocessResult(
       int subprocessId, int exitCode, String stdout, String stderr) {
@@ -290,9 +291,9 @@ class InstrumentationService {
    * server. This method should be invoked exactly one time and no other methods
    * should be invoked on this instance after this method has been invoked.
    */
-  void shutdown() {
+  Future shutdown() async {
     if (_instrumentationServer != null) {
-      _instrumentationServer.shutdown();
+      await _instrumentationServer.shutdown();
       _instrumentationServer = null;
     }
   }
@@ -373,9 +374,9 @@ class MulticastInstrumentationServer implements InstrumentationServer {
   }
 
   @override
-  void shutdown() {
+  Future shutdown() async {
     for (InstrumentationServer server in _servers) {
-      server.shutdown();
+      await server.shutdown();
     }
   }
 }

pkg/analyzer/test/instrumentation/instrumentation_test.dart

@@ -4,6 +4,8 @@
 
 library test.instrumentation;
 
+import 'dart:async';
+
 import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:unittest/unittest.dart';
 
@@ -174,7 +176,7 @@ class TestInstrumentationServer implements InstrumentationServer {
   }
 
   @override
-  void shutdown() {
+  Future shutdown() async {
     // Ignored
   }
 }