Add --x-perf-report flag to the dartanalyzer command

pkg/analyzer_cli/lib/src/driver.dart

Index: pkg/analyzer_cli/lib/src/driver.dart
diff --git a/pkg/analyzer_cli/lib/src/driver.dart b/pkg/analyzer_cli/lib/src/driver.dart
index f69e935f5dd49b5fa33944eed2c51ab043a17303..f190b78e43a9220af3f6ca95664327a546a1f3bf 100644
--- a/pkg/analyzer_cli/lib/src/driver.dart
+++ b/pkg/analyzer_cli/lib/src/driver.dart
@@ -25,6 +25,8 @@ import 'package:analyzer/src/generated/java_io.dart';
 import 'package:analyzer/src/generated/sdk_io.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/generated/source_io.dart';
+import 'package:analyzer/src/generated/utilities_general.dart'
+    show PerformanceTag;
 import 'package:analyzer/src/services/lint.dart';
 import 'package:analyzer/src/task/options.dart';
 import 'package:analyzer_cli/src/analyzer_impl.dart';
@@ -88,6 +90,8 @@ class Driver {
 
   /// Use the given command-line [args] to start this analysis driver.
   void start(List<String> args) {
+    int startTime = new DateTime.now().millisecondsSinceEpoch;
+
     StringUtilities.INTERNER = new MappedInterner();
 
     _processPlugins();
@@ -111,10 +115,23 @@ class Driver {
         exitCode = severity.ordinal;
       }
     }
+
+    if (options.perfLog != null) {
+      _writePerfLog(options.perfLog, startTime);
+    }
   }
 
-  /// Perform analysis according to the given [options].
   ErrorSeverity _analyzeAll(CommandLineOptions options) {
+    return _analyzeAllTag.makeCurrentWhile(() {
+      return _analyzeAllImpl(options);
+    });
+  }
+
+  static final PerformanceTag _analyzeAllTag =
+      new PerformanceTag("Driver._analyzeAll");
+
+  /// Perform analysis according to the given [options].
+  ErrorSeverity _analyzeAllImpl(CommandLineOptions options) {
     if (!options.machineFormat) {
       outSink.writeln("Analyzing ${options.sourceFiles}...");
     }
@@ -190,6 +207,38 @@ class Driver {
     return allResult;
   }
 
+  static _writePerfLog(String filename, int startTime) {
+    int totalTime = currentTimeMillis() - startTime;
+    int otherTime = totalTime;
+
+    // Convert performance tags to JSON representation.
+    var json = <String, dynamic>{};
+    for (PerformanceTag tag in PerformanceTag.all) {
+      if (tag != PerformanceTag.UNKNOWN) {
+        int tagTime = tag.elapsedMs;
+        json[tag.label] = tagTime;
+        otherTime -= tagTime;
+      }
+    }
+    json['other'] = otherTime;
+    json['total'] = totalTime;
+
+    // Pretty-print the JSON, one line per value for readability.
+    var buf = new StringBuffer();

[Paul Berry, 2015/12/16 15:11:26]

There's already library code available to pretty-print the JSON.  Just do this:

var encoded = new JsonEncoder.withIndent('  ').encode(json);

[skybrian, 2015/12/16 18:48:10]

Thanks!

+    buf.writeln("{");
+    var firstLine = true;
+    for (var key in json.keys) {
+      if (!firstLine) buf.writeln(",");

[Brian Wilkerson, 2015/12/16 15:08:43]

style nit: we always use blocks for 'if's.

+      var val = json[key];
+      buf.write('  "$key": ${JSON.encode(val)}');
+      firstLine = false;
+    }
+    buf.writeln("\n}");

[Brian Wilkerson, 2015/12/16 15:08:43]

nit: seems strange to have a newline explicitly in the string rather than

buf.writeln();
buf.writeln('}');

+
+    // Save to disk.
+    new File(filename).writeAsStringSync(buf.toString());
+  }
+
   /// Determine whether the context created during a previous call to
   /// [_analyzeAll] can be re-used in order to analyze using [options].
   bool _canContextBeReused(CommandLineOptions options) {