enhance code completion tracking and measurement

pkg/analysis_server/lib/src/services/completion/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.computer;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/protocol.dart';
 import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
@@ skipping 57 matching lines @@
       }
     }
     return new NoOpCompletionManager(source);
   }
 
   /**
    * Compute and cache information in preparation for a possible code
    * completion request sometime in the future. The default implementation
    * of this method does nothing. Subclasses may override but should not
    * count on this method being called before [computeSuggestions].
+   * Return a future that completes when the cache is computed with a bool
+   * indicating success.
    */
-  void computeCache() {
+  Future<bool> computeCache() {
+    return new Future.value(true);
   }
 
   /**
    * Compute completion results for the given reqeust and append them to the stream.
    * Clients should not call this method directly as it is automatically called
    * when a client listens to the stream returned by [results].
    * Subclasses should override this method, append at least one result
    * to the [controller], and close the controller stream once complete.
    */
   void computeSuggestions(CompletionRequest request);
@@ skipping 12 matching lines @@
 }
 
 /**
  * Overall performance of a code completion operation.
  */
 class CompletionPerformance {
   final Map<String, Duration> _startTimes = new Map<String, Duration>();
   final Stopwatch _stopwatch = new Stopwatch();
   final List<OperationPerformance> operations = <OperationPerformance>[];
 
+  Source source;
+  int offset;
+  String contents;
+  int notificationCount = -1;
+  int suggestionCount = -1;
+
   CompletionPerformance() {
     _stopwatch.start();
   }
 
-  void complete() {
+  int get elapsedInMilliseconds =>
+      operations.length > 0 ? operations.last.elapsed.inMilliseconds : 0;
+
+  String get snippet {
+    if (contents == null || offset < 0 || contents.length < offset) {
+      return '???';
+    }
+    int start = offset;
+    while (start > 0) {
+      String ch = contents[start - 1];
+      if (ch == '\r' || ch == '\n') {
+        break;
+      }
+      --start;
+    }
+    int end = offset;
+    while (end < contents.length) {
+      String ch = contents[end];
+      if (ch == '\r' || ch == '\n') {
+        break;
+      }
+      ++end;
+    }
+    String prefix = contents.substring(start, offset);
+    String suffix = contents.substring(offset, end);
+    return '$prefix^$suffix';
+  }
+
+  void complete([String tag = null]) {
     _stopwatch.stop();
-    _logDuration('total time', _stopwatch.elapsed);
+    _logDuration(tag != null ? tag : 'total time', _stopwatch.elapsed);
   }
 
   logElapseTime(String tag, [f() = null]) {
     Duration start;
     Duration end = _stopwatch.elapsed;
     var result;
     if (f == null) {
       start = _startTimes[tag];
       if (start == null) {
         _logDuration(tag, null);
@@ skipping 89 matching lines @@
    */
   final String name;
 
   /**
    * The elapse time or `null` if undefined.
    */
   final Duration elapsed;
 
   OperationPerformance(this.name, this.elapsed);
 }