display completion performance in new server status page

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';
 import 'package:analysis_server/src/services/search/search_engine.dart';
-import 'package:analysis_server/src/services/completion/dart_completion_manager.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/source.dart';
 
 /**
  * Manages `CompletionComputer`s for a given completion request.
  */
 abstract class CompletionManager {
 
   StreamController<CompletionResult> controller;
 
@@ skipping 13 matching lines @@
     controller = new StreamController<CompletionResult>(onListen: () {
       scheduleMicrotask(compute);
     });
     return controller.stream;
   }
 
   /**
    * Create a manager for the given request.
    */
   static CompletionManager create(AnalysisContext context, Source source,
-      int offset, SearchEngine searchEngine) {
+      int offset, SearchEngine searchEngine, CompletionPerformance performance) {
     if (context != null) {
       if (AnalysisEngine.isDartFileName(source.shortName)) {
-        return new DartCompletionManager(context, searchEngine, source, offset);
+        return new DartCompletionManager(
+            context,
+            searchEngine,
+            source,
+            offset,
+            performance);
       }
       if (AnalysisEngine.isHtmlFileName(source.shortName)) {
         //TODO (danrubel) implement
 //        return new HtmlCompletionManager(context, searchEngine, source, offset);
       }
     }
     return new NoOpCompletionManager(source, offset);
   }
 }
 
 /**
+ * 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 = [];
+
+  CompletionPerformance() {
+    _stopwatch.start();
+  }
+
+  void complete() {
+    _stopwatch.stop();
+    _logDuration('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);
+        return null;
+      }
+    } else {
+      result = f();
+      start = end;
+      end = _stopwatch.elapsed;
+    }
+    _logDuration(tag, end - start);
+    return result;
+  }
+
+  void logStartTime(String tag) {
+    _startTimes[tag] = _stopwatch.elapsed;
+  }
+
+  void _logDuration(String tag, Duration elapsed) {
+    operations.add(new OperationPerformance(tag, elapsed));
+  }
+}
+
+/**
  * Code completion result generated by an [CompletionManager].
  */
 class CompletionResult {
 
   /**
    * The length of the text to be replaced if the remainder of the identifier
    * containing the cursor is to be replaced when the suggestion is applied
    * (that is, the number of characters in the existing identifier).
    */
   final int replacementLength;
@@ skipping 25 matching lines @@
   final Source source;
   final int offset;
 
   NoOpCompletionManager(this.source, this.offset);
 
   @override
   void compute() {
     controller.add(new CompletionResult(offset, 0, [], true));
   }
 }
+
+/**
+ * The performance of an operation when computing code completion.
+ */
+class OperationPerformance {
+
+  /**
+   * The name of the operation
+   */
+  final String name;
+
+  /**
+   * The elapse time or `null` if undefined.
+   */
+  final Duration elapsed;
+
+  OperationPerformance(this.name, this.elapsed);
+}