[analysis_server] don't create futures for stalled plugins.

Also looks like "cannot stop a plugin that's already running" occurred
from this case, which was also an easy fix.

Change-Id: I113170e65ced26d1113cdb4e0cf206c8b1b68d31
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/126405
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Mike Fairhurst <mfairhurst@google.com>

Author: MichaelRFairhurst

pkg/analysis_server/lib/src/plugin/plugin_manager.dart

@@ -13,6 +13,7 @@ import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/instrumentation/instrumentation.dart';
 import 'package:analyzer/src/context/context_root.dart' as analyzer;
 import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/util/glob.dart';
 import 'package:analyzer/src/workspace/bazel.dart';
 import 'package:analyzer/src/workspace/gn.dart';
@@ -438,7 +439,11 @@ class PluginManager {
     Map<PluginInfo, Future<Response>> responseMap =
         <PluginInfo, Future<Response>>{};
     for (PluginInfo plugin in plugins) {
-      responseMap[plugin] = plugin.currentSession?.sendRequest(params);
+      final request = plugin.currentSession?.sendRequest(params);
+      // Only add an entry to the map if we have sent a request.
+      if (request != null) {
+        responseMap[plugin] = request;
+      }
     }
     return responseMap;
   }
@@ -675,7 +680,13 @@ class PluginManager {
    * Stop all of the plugins that are currently running.
    */
   Future<List<void>> stopAll() {
-    return Future.wait(_pluginMap.values.map((PluginInfo info) => info.stop()));
+    return Future.wait(_pluginMap.values.map((PluginInfo info) async {
+      try {
+        await info.stop();
+      } catch (e, st) {
+        AnalysisEngine.instance.instrumentationService.logException(e, st);
+      }
+    }));
   }
 
   /**

pkg/analysis_server/test/src/plugin/plugin_manager_test.dart

@@ -292,6 +292,31 @@ class PluginManagerFromDiskTest extends PluginTestSupport {
     pkg1Dir.deleteSync(recursive: true);
   }
 
+  @SkippedTest(
+      reason: 'flaky timeouts',
+      issue: 'https://github.com/dart-lang/sdk/issues/38629')
+  test_broadcastRequest_noCurrentSession() async {
+    io.Directory pkg1Dir = io.Directory.systemTemp.createTempSync('pkg1');
+    String pkgPath = pkg1Dir.resolveSymbolicLinksSync();
+    await withPlugin(
+        pluginName: 'plugin1',
+        content: '(invalid content here)',
+        test: (String plugin1Path) async {
+          ContextRoot contextRoot = _newContextRoot(pkgPath);
+          await manager.addPluginToContextRoot(contextRoot, plugin1Path);
+
+          Map<PluginInfo, Future<Response>> responses =
+              manager.broadcastRequest(
+                  new CompletionGetSuggestionsParams(
+                      '/pkg1/lib/pkg1.dart', 100),
+                  contextRoot: contextRoot);
+          expect(responses, hasLength(0));
+
+          await manager.stopAll();
+        });
+    pkg1Dir.deleteSync(recursive: true);
+  }
+
   @SkippedTest(
       reason: 'flaky timeouts',
       issue: 'https://github.com/dart-lang/sdk/issues/38629')