update computeFast/Full now that completion manager is long lived

pkg/analysis_server/lib/src/services/completion/dart_completion_manager.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // 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.
 
 library services.completion.dart;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/completion/arglist_computer.dart';
@@ skipping 60 matching lines @@
     return new DartCompletionManager(
         context,
         searchEngine,
         source,
         new DartCompletionCache(context, source));
   }
 
   /**
    * Compute suggestions based upon cached information only
    * then send an initial response to the client.
+   * Return a list of computers for which [computeFull] should be called
    */
-  void computeFast(DartCompletionRequest request) {
-    request.performance.logElapseTime('computeFast', () {
+  List<DartCompletionComputer> computeFast(DartCompletionRequest request) {
+    return request.performance.logElapseTime('computeFast', () {
       CompilationUnit unit = context.parseCompilationUnit(source);
       request.unit = unit;
       request.node = new NodeLocator.con1(request.offset).searchWithin(unit);
       request.node.accept(new _ReplacementOffsetBuilder(request));
-      computers.removeWhere((DartCompletionComputer c) {
+      List<DartCompletionComputer> todo = new List.from(computers);
+      todo.removeWhere((DartCompletionComputer c) {
         return request.performance.logElapseTime(
             'computeFast ${c.runtimeType}',
             () {
           return c.computeFast(request);
         });
       });
-      sendResults(request, computers.isEmpty);
+      sendResults(request, todo.isEmpty);
+      return todo;
     });
   }
 
   /**
    * If there is remaining work to be done, then wait for the unit to be
    * resolved and request that each remaining computer finish their work.
    */
-  void computeFull(DartCompletionRequest request) {
+  void computeFull(DartCompletionRequest request,
+      List<DartCompletionComputer> todo) {
     request.performance.logStartTime('waitForAnalysis');
     waitForAnalysis().then((CompilationUnit unit) {
       request.performance.logElapseTime('waitForAnalysis');
       if (unit == null) {
         sendResults(request, true);
         return;
       }
       request.performance.logElapseTime('computeFull', () {
         request.unit = unit;
         request.node = new NodeLocator.con1(request.offset).searchWithin(unit);
-        int count = computers.length;
-        computers.forEach((DartCompletionComputer c) {
+        int count = todo.length;
+        todo.forEach((DartCompletionComputer c) {
           String name = c.runtimeType.toString();
           String completeTag = 'computeFull $name complete';
           request.performance.logStartTime(completeTag);
           request.performance.logElapseTime('computeFull $name', () {
             c.computeFull(request).then((bool changed) {
               request.performance.logElapseTime(completeTag);
               bool last = --count == 0;
               if (changed || last) {
                 sendResults(request, last);
               }
             });
           });
         });
       });
     });
   }
 
   @override
   void computeSuggestions(CompletionRequest completionRequest) {
     DartCompletionRequest request = new DartCompletionRequest(
         context,
         searchEngine,
         source,
         completionRequest.offset,
         cache,
         completionRequest.performance);
     request.performance.logElapseTime('compute', () {
-      computeFast(request);
-      if (!computers.isEmpty) {
-        computeFull(request);
+      List<DartCompletionComputer> todo = computeFast(request);
+      if (!todo.isEmpty) {
+        computeFull(request, todo);
       }
     });
   }
 
   /**
    * Send the current list of suggestions to the client.
    */
   void sendResults(DartCompletionRequest request, bool last) {
     controller.add(
         new CompletionResult(
@@ skipping 98 matching lines @@
   _ReplacementOffsetBuilder(this.request) {
     request.replacementOffset = request.offset;
     request.replacementLength = 0;
   }
 
   visitSimpleIdentifier(SimpleIdentifier node) {
     request.replacementOffset = node.offset;
     request.replacementLength = node.length;
   }
 }