[analysis_server] Add a missing 'await' that may prevent handling of InconsistentAnalysisException

This test (without the code fix) reproduces an infinite loop in the GetFixes handler. There is error handling for `InconsistentAnalysisException` but it didn't appear to work (at least in some cases) because it's async and there was no `await`.

Change-Id: I835398062ea3da1386c2bc065bbdaf93cf10cdf1
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/396820
Reviewed-by: Konstantin Shcheglov <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: DanTup

pkg/analysis_server/lib/src/analysis_server.dart

@@ -763,7 +763,7 @@ abstract class AnalysisServer {
       return null;
     }
     try {
-      return driver.currentSession.getResolvedContainingLibrary(path);
+      return await driver.currentSession.getResolvedContainingLibrary(path);
     } on InconsistentAnalysisException {
       return null;
     } catch (exception, stackTrace) {

pkg/analysis_server/test/edit/fixes_test.dart

@@ -2,6 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'dart:async';
+
 import 'package:analysis_server/protocol/protocol_generated.dart';
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/plugin/plugin_manager.dart';
@@ -33,6 +35,29 @@ class FixesTest extends PubPackageAnalysisServerTest {
     await setRoots(included: [workspaceRootPath], excluded: []);
   }
 
+  Future<void> test_concurrentModifications() async {
+    var file = server.resourceProvider.getFile(testFile.path);
+    var futures = <Future<void>>[];
+
+    // Send many requests to modify files and get fixes.
+    for (var i = 1; i < 100; i++) {
+      futures.add(_addOverlay(testFile.path, 'var i = $i;'));
+      await pumpEventQueue();
+      futures.add(
+        handleSuccessfulRequest(
+          EditGetFixesParams(
+            file.path,
+            0,
+          ).toRequest('$i', clientUriConverter: server.uriConverter),
+        ),
+      );
+      await pumpEventQueue();
+    }
+
+    // Except all to complete.
+    await Future.wait(futures);
+  }
+
   Future<void> test_fileOutsideRoot() async {
     var outsideFile = '/foo/test.dart';
     newFile(outsideFile, 'bad code to create error');