Run the sorter to reduce code churn

pkg/analysis_server/lib/src/status/diagnostics.dart

Index: pkg/analysis_server/lib/src/status/diagnostics.dart
diff --git a/pkg/analysis_server/lib/src/status/diagnostics.dart b/pkg/analysis_server/lib/src/status/diagnostics.dart
index 5455a10fc88fe32b0d54a900c8ecbfb5f4d6d416..ef961c033841bd025ec52a9728d96123d448aa54 100644
--- a/pkg/analysis_server/lib/src/status/diagnostics.dart
+++ b/pkg/analysis_server/lib/src/status/diagnostics.dart
@@ -131,6 +131,18 @@ td.pre {
 }
 ''';
 
+String get _sdkVersion {
+  String version = Platform.version;
+  if (version.contains(' ')) {
+    version = version.substring(0, version.indexOf(' '));
+  }
+  return version;
+}
+
+String writeOption(String name, dynamic value) {
+  return '$name: <code>$value</code><br> ';
+}
+
 class AstPage extends DiagnosticPageWithNav {
   String _description;
 
@@ -141,17 +153,6 @@ class AstPage extends DiagnosticPageWithNav {
   String get description => _description ?? super.description;
 
   @override
-  Future<Null> generatePage(Map<String, String> params) async {
-    try {
-      String path = params['file'];
-      _description = path == null ? null : 'The AST for $path.';
-      await super.generatePage(params);
-    } finally {
-      _description = null;
-    }
-  }
-
-  @override
   Future<Null> generateContent(Map<String, String> params) async {
     String path = params['file'];
     if (path == null) {
@@ -174,421 +175,594 @@ class AstPage extends DiagnosticPageWithNav {
     AstWriter writer = new AstWriter(buf);
     result.unit.accept(writer);
   }
-}
 
-class DiagnosticsSite extends Site implements AbstractGetHandler {
-  /// An object that can handle either a WebSocket connection or a connection
-  /// to the client over stdio.
-  SocketServer socketServer;
-
-  /// The last few lines printed.
-  List<String> lastPrintedLines = <String>[];
+  @override
+  Future<Null> generatePage(Map<String, String> params) async {
+    try {
+      String path = params['file'];
+      _description = path == null ? null : 'The AST for $path.';
+      await super.generatePage(params);
+    } finally {
+      _description = null;
+    }
+  }
+}
 
-  DiagnosticsSite(this.socketServer, this.lastPrintedLines)
-      : super('Analysis Server') {
-    pages.add(new CompletionPage(this));
-    pages.add(new CommunicationsPage(this));
-    pages.add(new ContextsPage(this));
-    pages.add(new ExceptionsPage(this));
-    pages.add(new InstrumentationPage(this));
-    pages.add(new OverlaysPage(this));
-    pages.add(new PluginsPage(this));
-    pages.add(new ProfilePage(this));
-    pages.add(new SubscriptionsPage(this));
+class CommunicationsPage extends DiagnosticPageWithNav {
+  CommunicationsPage(DiagnosticsSite site)
+      : super(site, 'communications', 'Communications',
+            description:
+                'Latency statistics for analysis server communications.');
 
-    ProcessProfiler profiler = ProcessProfiler.getProfilerForPlatform();
-    if (profiler != null) {
-      pages.add(new MemoryAndCpuPage(this, profiler));
+  @override
+  void generateContent(Map<String, String> params) {
+    void writeRow(List<String> data, {List<String> classes}) {
+      buf.write("<tr>");
+      for (int i = 0; i < data.length; i++) {
+        String c = classes == null ? null : classes[i];
+        if (c != null) {
+          buf.write('<td class="$c">${escape(data[i])}</td>');
+        } else {
+          buf.write('<td>${escape(data[i])}</td>');
+        }
+      }
+      buf.writeln("</tr>");
     }
 
-    pages.sort(((Page a, Page b) =>
-        a.title.toLowerCase().compareTo(b.title.toLowerCase())));
-
-    // Add the status page at the beginning.
-    pages.insert(0, new StatusPage(this));
+    buf.writeln('<div class="columns">');
 
-    // Add non-nav pages.
-    pages.add(new FeedbackPage(this));
+    ServerPerformance perf = server.performanceAfterStartup;
+    if (perf != null) {
+      buf.writeln('<div class="column one-half">');
+      h3('Current');
 
-    secondaryPages.add(new AstPage(this));
-    secondaryPages.add(new ElementModelPage(this));
-  }
+      int requestCount = perf.requestCount;
+      int averageLatency =
+          requestCount > 0 ? (perf.requestLatency ~/ requestCount) : 0;
+      int maximumLatency = perf.maxLatency;
+      double slowRequestPercent =
+          requestCount > 0 ? (perf.slowRequestCount / requestCount) : 0.0;
 
-  String get customCss => kCustomCss;
+      buf.write('<table>');
+      writeRow([printInteger(requestCount), 'requests'],
+          classes: ["right", null]);
+      writeRow([printMilliseconds(averageLatency), 'average latency'],
+          classes: ["right", null]);
+      writeRow([printMilliseconds(maximumLatency), 'maximum latency'],
+          classes: ["right", null]);
+      writeRow([printPercentage(slowRequestPercent), '> 150 ms latency'],
+          classes: ["right", null]);
+      buf.write('</table>');
 
-  Page createUnknownPage(String unknownPath) =>
-      new NotFoundPage(this, unknownPath);
+      String time = server.uptime.toString();
+      if (time.contains('.')) {
+        time = time.substring(0, time.indexOf('.'));
+      }
+      buf.writeln(writeOption('Uptime', time));
 
-  Page createExceptionPage(String message, StackTrace trace) =>
-      new ExceptionPage(this, message, trace);
-}
+      buf.write('</div>');
+    }
 
-/// A page with a proscriptive notion of layout.
-abstract class DiagnosticPage extends Page {
-  final Site site;
+    buf.writeln('<div class="column one-half">');
+    h3('Startup');
+    perf = server.performanceDuringStartup;
 
-  DiagnosticPage(this.site, String id, String title, {String description})
-      : super(id, title, description: description);
+    int requestCount = perf.requestCount;
+    int averageLatency =
+        requestCount > 0 ? (perf.requestLatency ~/ requestCount) : 0;
+    int maximumLatency = perf.maxLatency;
+    double slowRequestPercent =
+        requestCount > 0 ? (perf.slowRequestCount / requestCount) : 0.0;
 
-  AnalysisServer get server =>
-      (site as DiagnosticsSite).socketServer.analysisServer;
+    buf.write('<table>');
+    writeRow([printInteger(requestCount), 'requests'],
+        classes: ["right", null]);
+    writeRow([printMilliseconds(averageLatency), 'average latency'],
+        classes: ["right", null]);
+    writeRow([printMilliseconds(maximumLatency), 'maximum latency'],
+        classes: ["right", null]);
+    writeRow([printPercentage(slowRequestPercent), '> 150 ms latency'],
+        classes: ["right", null]);
+    buf.write('</table>');
 
-  Future<Null> generatePage(Map<String, String> params) async {
-    buf.writeln('<!DOCTYPE html><html lang="en">');
-    buf.write('<head>');
-    buf.write('<meta charset="utf-8">');
-    buf.write('<meta name="viewport" content="width=device-width, '
-        'initial-scale=1.0">');
-    buf.writeln('<title>${site.title}</title>');
-    buf.writeln('<link rel="stylesheet" '
-        'href="https://cdnjs.cloudflare.com/ajax/libs/Primer/6.0.0/build.css">');
-    buf.writeln('<link rel="stylesheet" '
-        'href="https://cdnjs.cloudflare.com/ajax/libs/octicons/4.4.0/font/octicons.css">');
-    buf.writeln('<script type="text/javascript" '
-        'src="https://www.gstatic.com/charts/loader.js"></script>');
-    buf.writeln('<style>${site.customCss}</style>');
-    buf.writeln('</head>');
+    if (server.performanceAfterStartup != null) {
+      int startupTime =
+          server.performanceAfterStartup.startTime - perf.startTime;
+      buf.writeln(
+          writeOption('Initial analysis time', printMilliseconds(startupTime)));
+    }
+    buf.write('</div>');
 
-    buf.writeln('<body>');
-    generateHeader();
-    buf.writeln('<div class="container">');
-    await generateContainer(params);
-    generateFooter();
-    buf.writeln('</div>'); // div.container
-    buf.writeln('</body>');
-    buf.writeln('</html>');
+    buf.write('</div>');
   }
+}
 
-  void generateHeader() {
-    buf.writeln('''
-    <header class="masthead">
-    <div class="container">
-      <span class="masthead-logo">
-      <span class="mega-octicon octicon-database"></span>
-        ${site.title} Diagnostics
-      </span>
+class CompletionPage extends DiagnosticPageWithNav {
+  CompletionPage(DiagnosticsSite site)
+      : super(site, 'completion', 'Code Completion',
+            description: 'Latency statistics for code completion.');
 
-      <nav class="masthead-nav">
-        <a href="/status" ${isNavPage ? ' class="active"' : ''}>Diagnostics</a>
-        <a href="/feedback" ${isCurrentPage('/feedback') ? ' class="active"' : ''}>Feedback</a>
-        <a href="https://www.dartlang.org/tools/analyzer" target="_blank">Docs</a>
-        <a href="https://htmlpreview.github.io/?https://github.com/dart-lang/sdk/blob/master/pkg/analysis_server/doc/api.html" target="_blank">Spec</a>
-      </nav>
-    </div>
-    </header>
-''');
-  }
+  @override
+  void generateContent(Map<String, String> params) {
+    CompletionDomainHandler completionDomain = server.handlers
+        .firstWhere((handler) => handler is CompletionDomainHandler);
 
-  Future<Null> generateContainer(Map<String, String> params) async {
-    buf.writeln('<div class="columns docs-layout">');
-    buf.writeln('<div class="three-fourths column markdown-body">');
-    h1(title, classes: 'page-title');
-    await asyncDiv(() async {
-      p(description);
-      await generateContent(params);
-    }, classes: 'markdown-body');
-    buf.writeln('</div>');
-    buf.writeln('</div>');
-  }
+    List<CompletionPerformance> completions =
+        completionDomain.performanceList.items.toList();
 
-  void generateContent(Map<String, String> params);
+    if (completions.isEmpty) {
+      blankslate('No completions recorded.');
+      return;
+    }
 
-  void generateFooter() {
+    int fastCount =
+        completions.where((c) => c.elapsedInMilliseconds <= 100).length;
+    p('${completions.length} results; ${printPercentage(fastCount / completions.length)} within 100ms.');
+
+    // draw a chart
+    buf.writeln(
+        '<div id="chart-div" style="width: 700px; height: 300px;"></div>');
+    StringBuffer rowData = new StringBuffer();
+    for (int i = completions.length - 1; i >= 0; i--) {
+      // [' ', 101.5]
+      if (rowData.isNotEmpty) {
+        rowData.write(',');
+      }
+      rowData.write("[' ', ${completions[i].elapsedInMilliseconds}]");
+    }
     buf.writeln('''
-    <footer class="footer">
-      Dart ${site.title} <span style="float:right">SDK ${_sdkVersion}</span>
-    </footer>
+      <script type="text/javascript">
+      google.charts.load('current', {'packages':['bar']});
+      google.charts.setOnLoadCallback(drawChart);
+      function drawChart() {
+        var data = google.visualization.arrayToDataTable([
+          ['Completions', 'Time'],
+          $rowData
+        ]);
+        var options = { bars: 'vertical', vAxis: {format: 'decimal'}, height: 300 };
+        var chart = new google.charts.Bar(document.getElementById('chart-div'));
+        chart.draw(data, google.charts.Bar.convertOptions(options));
+      }
+      </script>
 ''');
-  }
-
-  bool get isNavPage => false;
-}
 
-abstract class DiagnosticPageWithNav extends DiagnosticPage {
-  DiagnosticPageWithNav(Site site, String id, String title,
-      {String description})
-      : super(site, id, title, description: description);
+    // emit the data as a table
+    buf.writeln('<table>');
+    buf.writeln(
+        '<tr><th>Time</th><th>Results</th><th>Source</th><th>Snippet</th></tr>');
+    for (CompletionPerformance completion in completions) {
+      buf.writeln('<tr>'
+          '<td class="pre right">${printMilliseconds(completion.elapsedInMilliseconds)}</td>'
+          '<td class="right">${completion.suggestionCount}</td>'
+          '<td>${escape(completion.source.shortName)}</td>'
+          '<td><code>${escape(completion.snippet)}</code></td>'
+          '</tr>');
+    }
+    buf.writeln('</table>');
+  }
+}
 
-  Future<Null> generateContainer(Map<String, String> params) async {
-    buf.writeln('<div class="columns docs-layout">');
+class ContextsPage extends DiagnosticPageWithNav {
+  ContextsPage(DiagnosticsSite site)
+      : super(site, 'contexts', 'Contexts',
+            description:
+                'An analysis context defines the options and the set of sources being analyzed.');
 
-    buf.writeln('<div class="one-fifth column">');
-    buf.writeln('<nav class="menu docs-menu">');
-    for (Page page in site.pages.where((p) => p is DiagnosticPageWithNav)) {
-      buf.write('<a class="menu-item ${page == this ? ' selected' : ''}" '
-          'href="${page.path}">${escape(page.title)}');
-      String detail = (page as DiagnosticPageWithNav).navDetail;
-      if (detail != null) {
-        buf.write('<span class="counter">$detail</span>');
+  String get navDetail => printInteger(server.driverMap.length);
+
+  String describe(AnalysisOptionsImpl options) {
+    StringBuffer b = new StringBuffer();
+
+    b.write(
+        writeOption('Analyze function bodies', options.analyzeFunctionBodies));
+    b.write(writeOption('Enable asserts in initializer lists',
+        options.enableAssertInitializer));
+    b.write(writeOption(
+        'Enable strict call checks', options.enableStrictCallChecks));
+    b.write(writeOption('Enable super mixins', options.enableSuperMixins));
+    b.write(writeOption('Generate dart2js hints', options.dart2jsHint));
+    b.write(writeOption(
+        'Generate errors in implicit files', options.generateImplicitErrors));
+    b.write(
+        writeOption('Generate errors in SDK files', options.generateSdkErrors));
+    b.write(writeOption('Generate hints', options.hint));
+    b.write(writeOption('Incremental resolution', options.incremental));
+    b.write(writeOption(
+        'Incremental resolution with API changes', options.incrementalApi));
+    b.write(writeOption('Preserve comments', options.preserveComments));
+    b.write(writeOption('Strong mode', options.strongMode));
+    b.write(writeOption('Strong mode hints', options.strongModeHints));
+
+    return b.toString();
+  }
+
+  @override
+  void generateContent(Map<String, String> params) {
+    Map<Folder, AnalysisDriver> driverMap = server.driverMap;
+    if (driverMap.isEmpty) {
+      blankslate('No contexts.');
+      return;
+    }
+
+    String contextPath = params['context'];
+    List<Folder> folders = driverMap.keys.toList();
+    folders
+        .sort((first, second) => first.shortName.compareTo(second.shortName));
+    Folder folder =
+        folders.firstWhere((f) => f.path == contextPath, orElse: () => null);
+
+    if (folder == null) {
+      folder = folders.first;
+      contextPath = folder.path;
+    }
+
+    AnalysisDriver driver = driverMap[folder];
+
+    buf.writeln('<div class="tabnav">');
+    buf.writeln('<nav class="tabnav-tabs">');
+    for (Folder f in folders) {
+      if (f == folder) {
+        buf.writeln(
+            '<a class="tabnav-tab selected">${escape(f.shortName)}</a>');
+      } else {
+        String p = '$path?context=${Uri.encodeQueryComponent(f.path)}';
+        buf.writeln(
+            '<a href="$p" class="tabnav-tab">${escape(f.shortName)}</a>');
       }
-      buf.writeln('</a>');
     }
     buf.writeln('</nav>');
     buf.writeln('</div>');
 
-    buf.writeln('<div class="four-fifths column markdown-body">');
-    h1(title, classes: 'page-title');
-    await asyncDiv(() async {
-      p(description);
-      await generateContent(params);
-    }, classes: 'markdown-body');
-    buf.writeln('</div>');
+    buf.writeln(writeOption('Context location', escape(contextPath)));
+    buf.writeln(writeOption('Analysis options path',
+        escape(driver.contextRoot.optionsFilePath ?? 'none')));
+
+    buf.writeln('<div class="columns">');
 
+    buf.writeln('<div class="column one-half">');
+    h3('Analysis options');
+    p(describe(driver.analysisOptions), raw: true);
+    buf.writeln(
+        writeOption('Has .packages file', folder.getChild('.packages').exists));
+    buf.writeln(writeOption(
+        'Has pubspec.yaml file', folder.getChild('pubspec.yaml').exists));
     buf.writeln('</div>');
-  }
 
-  String get navDetail => null;
+    buf.writeln('<div class="column one-half">');
+    DartSdk sdk = driver?.sourceFactory?.dartSdk;
+    AnalysisOptionsImpl sdkOptions = sdk?.context?.analysisOptions;
+    if (sdkOptions != null) {
+      h3('SDK analysis options');
+      p(describe(sdkOptions), raw: true);
 
-  bool get isNavPage => true;
-}
+      if (sdk is FolderBasedDartSdk) {
+        p(writeOption('Use summaries', sdk.useSummary), raw: true);
+      }
+    }
+    buf.writeln('</div>');
 
-class ElementModelPage extends DiagnosticPageWithNav {
-  String _description;
+    buf.writeln('</div>');
 
-  ElementModelPage(DiagnosticsSite site)
-      : super(site, 'element', 'Element model',
-            description: 'The element model for a file.');
+    h3('Lints');
+    p(driver.analysisOptions.lintRules.map((l) => l.name).join(', '));
 
-  @override
-  String get description => _description ?? super.description;
+    h3('Error processors');
+    p(driver.analysisOptions.errorProcessors
+        .map((e) => e.description)
+        .join(', '));
 
-  @override
-  Future<Null> generatePage(Map<String, String> params) async {
-    try {
-      String path = params['file'];
-      _description = path == null ? null : 'The element model for $path.';
-      await super.generatePage(params);
-    } finally {
-      _description = null;
-    }
-  }
+    List<String> priorityFiles = driver.priorityFiles;
+    List<String> addedFiles = driver.addedFiles.toList();
+    List<String> implicitFiles =
+        driver.knownFiles.difference(driver.addedFiles).toList();
+    addedFiles.sort();
+    implicitFiles.sort();
 
-  @override
-  Future<Null> generateContent(Map<String, String> params) async {
-    String path = params['file'];
-    if (path == null) {
-      p('No file path provided.');
-      return;
+    String lenCounter(List list) {
+      return '<span class="counter" style="float: right;">${list.length}</span>';
     }
-    AnalysisDriver driver = server.getAnalysisDriver(path);
-    if (driver == null) {
-      p('The file <code>${escape(path)}</code> is not being analyzed.',
-          raw: true);
-      return;
+
+    h3('Context files');
+
+    void writeFile(String file) {
+      String astPath = '/ast?file=${Uri.encodeQueryComponent(file)}';
+      String elementPath = '/element?file=${Uri.encodeQueryComponent(file)}';
+
+      buf.write(file);
+      buf.write(' (');
+      buf.writeln('<a href="$astPath">ast</a>');
+      buf.write(' ');
+      buf.writeln('<a href="$elementPath">element</a>');
+      buf.write(')');
     }
-    AnalysisResult result = await driver.getResult(path);
-    if (result == null) {
-      p('An element model could not be produced for the file <code>${escape(path)}</code>.',
-          raw: true);
-      return;
+
+    h4('Priority files ${lenCounter(priorityFiles)}', raw: true);
+    ul(priorityFiles, writeFile, classes: 'scroll-table');
+
+    h4('Added files ${lenCounter(addedFiles)}', raw: true);
+    ul(addedFiles, writeFile, classes: 'scroll-table');
+
+    h4('ImplicitFiles files ${lenCounter(implicitFiles)}', raw: true);
+    ul(implicitFiles, writeFile, classes: 'scroll-table');
+
+    SourceFactory sourceFactory = driver.sourceFactory;
+    if (sourceFactory is SourceFactoryImpl) {
+      h3('Resolvers');
+      for (UriResolver resolver in sourceFactory.resolvers) {
+        h4(resolver.runtimeType.toString());
+        buf.write('<p class="scroll-table">');
+        if (resolver is DartUriResolver) {
+          DartSdk sdk = resolver.dartSdk;
+          buf.write(' (sdk = ');
+          buf.write(sdk.runtimeType);
+          if (sdk is FolderBasedDartSdk) {
+            buf.write(' (path = ');
+            buf.write(sdk.directory.path);
+            buf.write(')');
+          } else if (sdk is EmbedderSdk) {
+            buf.write(' (map = ');
+            writeMap(sdk.urlMappings);
+            buf.write(')');
+          }
+          buf.write(')');
+        } else if (resolver is SdkExtUriResolver) {
+          buf.write(' (map = ');
+          writeMap(resolver.urlMappings);
+          buf.write(')');
+        } else if (resolver is PackageMapUriResolver) {
+          writeMap(resolver.packageMap);
+        }
+        buf.write('</p>');
+      }
     }
+  }
 
-    ElementWriter writer = new ElementWriter(buf);
-    result.unit.element.accept(writer);
+  void writeList<E>(List<E> list) {
+    buf.writeln('[${list.join(', ')}]');
   }
-}
 
-class NotFoundPage extends DiagnosticPage {
-  final String path;
+  void writeMap<V>(Map<String, V> map) {
+    List<String> keys = map.keys.toList();
+    keys.sort();
+    int length = keys.length;
+    buf.write('{');
+    for (int i = 0; i < length; i++) {
+      buf.write('<br>');
+      String key = keys[i];
+      V value = map[key];
+      buf.write(key);
+      buf.write(' = ');
+      if (value is List) {
+        writeList(value);
+      } else {
+        buf.write(value);
+      }
+      buf.write(',');
+    }
+    buf.write('<br>}');
+  }
+}
 
-  NotFoundPage(Site site, this.path)
-      : super(site, '', '404 Not found', description: "'$path' not found.");
+/// A page with a proscriptive notion of layout.
+abstract class DiagnosticPage extends Page {
+  final Site site;
 
-  void generateContent(Map<String, String> params) {}
-}
+  DiagnosticPage(this.site, String id, String title, {String description})
+      : super(id, title, description: description);
 
-class ExceptionPage extends DiagnosticPage {
-  final StackTrace trace;
+  bool get isNavPage => false;
 
-  ExceptionPage(Site site, String message, this.trace)
-      : super(site, '', '500 Oops', description: message);
+  AnalysisServer get server =>
+      (site as DiagnosticsSite).socketServer.analysisServer;
 
-  void generateContent(Map<String, String> params) {
-    p(trace.toString(), style: 'white-space: pre');
+  Future<Null> generateContainer(Map<String, String> params) async {
+    buf.writeln('<div class="columns docs-layout">');
+    buf.writeln('<div class="three-fourths column markdown-body">');
+    h1(title, classes: 'page-title');
+    await asyncDiv(() async {
+      p(description);
+      await generateContent(params);
+    }, classes: 'markdown-body');
+    buf.writeln('</div>');
+    buf.writeln('</div>');
   }
-}
 
-class FeedbackPage extends DiagnosticPage {
-  FeedbackPage(DiagnosticsSite site)
-      : super(site, 'feedback', 'Feedback',
-            description: 'Providing feedback and filing issues.');
+  void generateContent(Map<String, String> params);
 
-  @override
-  void generateContent(Map<String, String> params) {
-    final String issuesUrl = 'https://github.com/dart-lang/sdk/issues';
-    p(
-      'To file issues or feature requests, see our '
-          '<a href="$issuesUrl">bug tracker</a>. When filing an issue, please describe:',
-      raw: true,
-    );
-    ul([
-      'what you were doing',
-      'what occured',
-      'what you think the expected behavior should have been',
-    ], (line) => buf.writeln(line));
+  void generateFooter() {
+    buf.writeln('''
+    <footer class="footer">
+      Dart ${site.title} <span style="float:right">SDK ${_sdkVersion}</span>
+    </footer>
+''');
+  }
 
-    List<String> ideInfo = [];
-    if (server.options.clientId != null) {
-      ideInfo.add(server.options.clientId);
-    }
-    if (server.options.clientVersion != null) {
-      ideInfo.add(server.options.clientVersion);
-    }
-    String ideText = ideInfo.map((str) => '<code>$str</code>').join(', ');
+  void generateHeader() {
+    buf.writeln('''
+    <header class="masthead">
+    <div class="container">
+      <span class="masthead-logo">
+      <span class="mega-octicon octicon-database"></span>
+        ${site.title} Diagnostics
+      </span>
 
-    p('Other data to include:');
-    ul([
-      "the IDE you are using and it's version${ideText.isEmpty ? '' : ' ($ideText)'}",
-      'the Dart SDK version (<code>${escape(_sdkVersion)}</code>)',
-      'your operating system (<code>${escape(Platform.operatingSystem)}</code>)',
-    ], (line) => buf.writeln(line));
+      <nav class="masthead-nav">
+        <a href="/status" ${isNavPage ? ' class="active"' : ''}>Diagnostics</a>
+        <a href="/feedback" ${isCurrentPage('/feedback') ? ' class="active"' : ''}>Feedback</a>
+        <a href="https://www.dartlang.org/tools/analyzer" target="_blank">Docs</a>
+        <a href="https://htmlpreview.github.io/?https://github.com/dart-lang/sdk/blob/master/pkg/analysis_server/doc/api.html" target="_blank">Spec</a>
+      </nav>
+    </div>
+    </header>
+''');
+  }
 
-    p('Thanks!');
+  Future<Null> generatePage(Map<String, String> params) async {
+    buf.writeln('<!DOCTYPE html><html lang="en">');
+    buf.write('<head>');
+    buf.write('<meta charset="utf-8">');
+    buf.write('<meta name="viewport" content="width=device-width, '
+        'initial-scale=1.0">');
+    buf.writeln('<title>${site.title}</title>');
+    buf.writeln('<link rel="stylesheet" '
+        'href="https://cdnjs.cloudflare.com/ajax/libs/Primer/6.0.0/build.css">');
+    buf.writeln('<link rel="stylesheet" '
+        'href="https://cdnjs.cloudflare.com/ajax/libs/octicons/4.4.0/font/octicons.css">');
+    buf.writeln('<script type="text/javascript" '
+        'src="https://www.gstatic.com/charts/loader.js"></script>');
+    buf.writeln('<style>${site.customCss}</style>');
+    buf.writeln('</head>');
+
+    buf.writeln('<body>');
+    generateHeader();
+    buf.writeln('<div class="container">');
+    await generateContainer(params);
+    generateFooter();
+    buf.writeln('</div>'); // div.container
+    buf.writeln('</body>');
+    buf.writeln('</html>');
   }
 }
 
-class StatusPage extends DiagnosticPageWithNav {
-  StatusPage(DiagnosticsSite site)
-      : super(site, 'status', 'Status',
-            description:
-                'General status and diagnostics for the analysis server.');
+abstract class DiagnosticPageWithNav extends DiagnosticPage {
+  DiagnosticPageWithNav(Site site, String id, String title,
+      {String description})
+      : super(site, id, title, description: description);
 
-  @override
-  void generateContent(Map<String, String> params) {
-    buf.writeln('<div class="columns">');
+  bool get isNavPage => true;
 
-    buf.writeln('<div class="column one-half">');
-    h3('Status');
-    buf.writeln(writeOption(
-        'New analysis driver enabled', server.options.enableNewAnalysisDriver));
-    buf.writeln(writeOption('Instrumentation enabled',
-        AnalysisEngine.instance.instrumentationService.isActive));
-    buf.writeln(writeOption('Server process ID', pid));
-    buf.writeln('</div>');
+  String get navDetail => null;
 
-    buf.writeln('<div class="column one-half">');
-    h3('Versions');
-    buf.writeln(writeOption('Analysis server version', AnalysisServer.VERSION));
-    buf.writeln(writeOption('Dart SDK', Platform.version));
+  Future<Null> generateContainer(Map<String, String> params) async {
+    buf.writeln('<div class="columns docs-layout">');
+
+    buf.writeln('<div class="one-fifth column">');
+    buf.writeln('<nav class="menu docs-menu">');
+    for (Page page in site.pages.where((p) => p is DiagnosticPageWithNav)) {
+      buf.write('<a class="menu-item ${page == this ? ' selected' : ''}" '
+          'href="${page.path}">${escape(page.title)}');
+      String detail = (page as DiagnosticPageWithNav).navDetail;
+      if (detail != null) {
+        buf.write('<span class="counter">$detail</span>');
+      }
+      buf.writeln('</a>');
+    }
+    buf.writeln('</nav>');
     buf.writeln('</div>');
 
+    buf.writeln('<div class="four-fifths column markdown-body">');
+    h1(title, classes: 'page-title');
+    await asyncDiv(() async {
+      p(description);
+      await generateContent(params);
+    }, classes: 'markdown-body');
     buf.writeln('</div>');
 
-    List<String> lines = (site as DiagnosticsSite).lastPrintedLines;
-    if (lines.isNotEmpty) {
-      h3('Debug output');
-      p(lines.join('\n'), style: 'white-space: pre');
-    }
+    buf.writeln('</div>');
   }
 }
 
-class InstrumentationPage extends DiagnosticPageWithNav {
-  InstrumentationPage(DiagnosticsSite site)
-      : super(site, 'instrumentation', 'Instrumentation',
-            description:
-                'Verbose instrumentation data from the analysis server.');
+class DiagnosticsSite extends Site implements AbstractGetHandler {
+  /// An object that can handle either a WebSocket connection or a connection
+  /// to the client over stdio.
+  SocketServer socketServer;
 
-  @override
-  void generateContent(Map<String, String> params) {
-    p(
-        'Instrumentation can be enabled by starting the analysis server with the '
-        '<code>--instrumentation-log-file=path/to/file</code> flag.',
-        raw: true);
+  /// The last few lines printed.
+  List<String> lastPrintedLines = <String>[];
+
+  DiagnosticsSite(this.socketServer, this.lastPrintedLines)
+      : super('Analysis Server') {
+    pages.add(new CompletionPage(this));
+    pages.add(new CommunicationsPage(this));
+    pages.add(new ContextsPage(this));
+    pages.add(new ExceptionsPage(this));
+    pages.add(new InstrumentationPage(this));
+    pages.add(new OverlaysPage(this));
+    pages.add(new PluginsPage(this));
+    pages.add(new ProfilePage(this));
+    pages.add(new SubscriptionsPage(this));
 
-    if (!AnalysisEngine.instance.instrumentationService.isActive) {
-      blankslate('Instrumentation not active.');
-      return;
+    ProcessProfiler profiler = ProcessProfiler.getProfilerForPlatform();
+    if (profiler != null) {
+      pages.add(new MemoryAndCpuPage(this, profiler));
     }
 
-    h3('Instrumentation');
+    pages.sort(((Page a, Page b) =>
+        a.title.toLowerCase().compareTo(b.title.toLowerCase())));
 
-    p('Instrumentation active.');
+    // Add the status page at the beginning.
+    pages.insert(0, new StatusPage(this));
 
-    InstrumentationServer instrumentation =
-        AnalysisEngine.instance.instrumentationService.instrumentationServer;
-    String description = instrumentation.describe;
-    HtmlEscape htmlEscape = new HtmlEscape(HtmlEscapeMode.ELEMENT);
-    description = htmlEscape.convert(description);
-    // Convert http(s): references to hyperlinks.
-    final RegExp urlRegExp = new RegExp(r'[http|https]+:\/*(\S+)');
-    description = description.replaceAllMapped(urlRegExp, (Match match) {
-      return '<a href="${match.group(0)}">${match.group(1)}</a>';
-    });
-    p(description.replaceAll('\n', '<br>'), raw: true);
+    // Add non-nav pages.
+    pages.add(new FeedbackPage(this));
+
+    secondaryPages.add(new AstPage(this));
+    secondaryPages.add(new ElementModelPage(this));
   }
-}
 
-class ProfilePage extends DiagnosticPageWithNav {
-  ProfilePage(DiagnosticsSite site)
-      : super(site, 'profile', 'Profiling Info',
-            description: 'Profiling performance tag data.');
+  String get customCss => kCustomCss;
 
-  @override
-  void generateContent(Map<String, String> params) {
-    // prepare sorted tags
-    List<PerformanceTag> tags = PerformanceTag.all.toList();
-    tags.remove(ServerPerformanceStatistics.idle);
-    tags.remove(PerformanceTag.unknown);
-    tags.removeWhere((tag) => tag.elapsedMs == 0);
-    tags.sort((a, b) => b.elapsedMs - a.elapsedMs);
+  Page createExceptionPage(String message, StackTrace trace) =>
+      new ExceptionPage(this, message, trace);
 
-    // draw a pie chart
-    String rowData =
-        tags.map((tag) => "['${tag.label}', ${tag.elapsedMs}]").join(',');
-    buf.writeln(
-        '<div id="chart-div" style="width: 700px; height: 300px;"></div>');
-    buf.writeln('''
-      <script type="text/javascript">
-        google.charts.load('current', {'packages':['corechart']});
-        google.charts.setOnLoadCallback(drawChart);
+  Page createUnknownPage(String unknownPath) =>
+      new NotFoundPage(this, unknownPath);
+}
 
-        function drawChart() {
-          var data = new google.visualization.DataTable();
-          data.addColumn('string', 'Tag');
-          data.addColumn('number', 'Time (ms)');
-          data.addRows([$rowData]);
-          var options = {'title': 'Performance Tag Data', 'width': 700, 'height': 300};
-          var chart = new google.visualization.PieChart(document.getElementById('chart-div'));
-          chart.draw(data, options);
-        }
-      </script>
-''');
+class ElementModelPage extends DiagnosticPageWithNav {
+  String _description;
 
-    // print total time
-    int totalTime =
-        tags.fold<int>(0, (int a, PerformanceTag tag) => a + tag.elapsedMs);
-    p('Total measured time: ${printMilliseconds(totalTime)}');
+  ElementModelPage(DiagnosticsSite site)
+      : super(site, 'element', 'Element model',
+            description: 'The element model for a file.');
 
-    // write out a table
-    void _writeRow(List<String> data, {bool header: false}) {
-      buf.write('<tr>');
-      if (header) {
-        for (String d in data) {
-          buf.write('<th>$d</th>');
-        }
-      } else {
-        buf.write('<td>${data[0]}</td>');
+  @override
+  String get description => _description ?? super.description;
 
-        for (String d in data.sublist(1)) {
-          buf.write('<td class="right">$d</td>');
-        }
-      }
-      buf.writeln('</tr>');
+  @override
+  Future<Null> generateContent(Map<String, String> params) async {
+    String path = params['file'];
+    if (path == null) {
+      p('No file path provided.');
+      return;
+    }
+    AnalysisDriver driver = server.getAnalysisDriver(path);
+    if (driver == null) {
+      p('The file <code>${escape(path)}</code> is not being analyzed.',
+          raw: true);
+      return;
+    }
+    AnalysisResult result = await driver.getResult(path);
+    if (result == null) {
+      p('An element model could not be produced for the file <code>${escape(path)}</code>.',
+          raw: true);
+      return;
     }
 
-    buf.write('<table>');
-    _writeRow(['Tag name', 'Time (in ms)', 'Percent'], header: true);
-    void writeRow(PerformanceTag tag) {
-      double percent = tag.elapsedMs / totalTime;
-      _writeRow([
-        tag.label,
-        printMilliseconds(tag.elapsedMs),
-        printPercentage(percent)
-      ]);
+    ElementWriter writer = new ElementWriter(buf);
+    result.unit.element.accept(writer);
+  }
+
+  @override
+  Future<Null> generatePage(Map<String, String> params) async {
+    try {
+      String path = params['file'];
+      _description = path == null ? null : 'The element model for $path.';
+      await super.generatePage(params);
+    } finally {
+      _description = null;
     }
+  }
+}
 
-    tags.forEach(writeRow);
-    buf.write('</table>');
+class ExceptionPage extends DiagnosticPage {
+  final StackTrace trace;
+
+  ExceptionPage(Site site, String message, this.trace)
+      : super(site, '', '500 Oops', description: message);
+
+  void generateContent(Map<String, String> params) {
+    p(trace.toString(), style: 'white-space: pre');
   }
 }
 
@@ -597,6 +771,8 @@ class ExceptionsPage extends DiagnosticPageWithNav {
       : super(site, 'exceptions', 'Exceptions',
             description: 'Exceptions from the analysis server.');
 
+  Iterable<ServerException> get exceptions => server.exceptions.items;
+
   String get navDetail => printInteger(exceptions.length);
 
   @override
@@ -614,208 +790,80 @@ class ExceptionsPage extends DiagnosticPageWithNav {
       }
     }
   }
-
-  Iterable<ServerException> get exceptions => server.exceptions.items;
 }
 
-class ContextsPage extends DiagnosticPageWithNav {
-  ContextsPage(DiagnosticsSite site)
-      : super(site, 'contexts', 'Contexts',
-            description:
-                'An analysis context defines the options and the set of sources being analyzed.');
-
-  String get navDetail => printInteger(server.driverMap.length);
+class FeedbackPage extends DiagnosticPage {
+  FeedbackPage(DiagnosticsSite site)
+      : super(site, 'feedback', 'Feedback',
+            description: 'Providing feedback and filing issues.');
 
   @override
   void generateContent(Map<String, String> params) {
-    Map<Folder, AnalysisDriver> driverMap = server.driverMap;
-    if (driverMap.isEmpty) {
-      blankslate('No contexts.');
-      return;
-    }
-
-    String contextPath = params['context'];
-    List<Folder> folders = driverMap.keys.toList();
-    folders
-        .sort((first, second) => first.shortName.compareTo(second.shortName));
-    Folder folder =
-        folders.firstWhere((f) => f.path == contextPath, orElse: () => null);
-
-    if (folder == null) {
-      folder = folders.first;
-      contextPath = folder.path;
-    }
-
-    AnalysisDriver driver = driverMap[folder];
-
-    buf.writeln('<div class="tabnav">');
-    buf.writeln('<nav class="tabnav-tabs">');
-    for (Folder f in folders) {
-      if (f == folder) {
-        buf.writeln(
-            '<a class="tabnav-tab selected">${escape(f.shortName)}</a>');
-      } else {
-        String p = '$path?context=${Uri.encodeQueryComponent(f.path)}';
-        buf.writeln(
-            '<a href="$p" class="tabnav-tab">${escape(f.shortName)}</a>');
-      }
-    }
-    buf.writeln('</nav>');
-    buf.writeln('</div>');
-
-    buf.writeln(writeOption('Context location', escape(contextPath)));
-    buf.writeln(writeOption('Analysis options path',
-        escape(driver.contextRoot.optionsFilePath ?? 'none')));
-
-    buf.writeln('<div class="columns">');
-
-    buf.writeln('<div class="column one-half">');
-    h3('Analysis options');
-    p(describe(driver.analysisOptions), raw: true);
-    buf.writeln(
-        writeOption('Has .packages file', folder.getChild('.packages').exists));
-    buf.writeln(writeOption(
-        'Has pubspec.yaml file', folder.getChild('pubspec.yaml').exists));
-    buf.writeln('</div>');
-
-    buf.writeln('<div class="column one-half">');
-    DartSdk sdk = driver?.sourceFactory?.dartSdk;
-    AnalysisOptionsImpl sdkOptions = sdk?.context?.analysisOptions;
-    if (sdkOptions != null) {
-      h3('SDK analysis options');
-      p(describe(sdkOptions), raw: true);
-
-      if (sdk is FolderBasedDartSdk) {
-        p(writeOption('Use summaries', sdk.useSummary), raw: true);
-      }
-    }
-    buf.writeln('</div>');
-
-    buf.writeln('</div>');
-
-    h3('Lints');
-    p(driver.analysisOptions.lintRules.map((l) => l.name).join(', '));
-
-    h3('Error processors');
-    p(driver.analysisOptions.errorProcessors
-        .map((e) => e.description)
-        .join(', '));
-
-    List<String> priorityFiles = driver.priorityFiles;
-    List<String> addedFiles = driver.addedFiles.toList();
-    List<String> implicitFiles =
-        driver.knownFiles.difference(driver.addedFiles).toList();
-    addedFiles.sort();
-    implicitFiles.sort();
+    final String issuesUrl = 'https://github.com/dart-lang/sdk/issues';
+    p(
+      'To file issues or feature requests, see our '
+          '<a href="$issuesUrl">bug tracker</a>. When filing an issue, please describe:',
+      raw: true,
+    );
+    ul([
+      'what you were doing',
+      'what occured',
+      'what you think the expected behavior should have been',
+    ], (line) => buf.writeln(line));
 
-    String lenCounter(List list) {
-      return '<span class="counter" style="float: right;">${list.length}</span>';
+    List<String> ideInfo = [];
+    if (server.options.clientId != null) {
+      ideInfo.add(server.options.clientId);
     }
-
-    h3('Context files');
-
-    void writeFile(String file) {
-      String astPath = '/ast?file=${Uri.encodeQueryComponent(file)}';
-      String elementPath = '/element?file=${Uri.encodeQueryComponent(file)}';
-
-      buf.write(file);
-      buf.write(' (');
-      buf.writeln('<a href="$astPath">ast</a>');
-      buf.write(' ');
-      buf.writeln('<a href="$elementPath">element</a>');
-      buf.write(')');
+    if (server.options.clientVersion != null) {
+      ideInfo.add(server.options.clientVersion);
     }
+    String ideText = ideInfo.map((str) => '<code>$str</code>').join(', ');
 
-    h4('Priority files ${lenCounter(priorityFiles)}', raw: true);
-    ul(priorityFiles, writeFile, classes: 'scroll-table');
-
-    h4('Added files ${lenCounter(addedFiles)}', raw: true);
-    ul(addedFiles, writeFile, classes: 'scroll-table');
-
-    h4('ImplicitFiles files ${lenCounter(implicitFiles)}', raw: true);
-    ul(implicitFiles, writeFile, classes: 'scroll-table');
+    p('Other data to include:');
+    ul([
+      "the IDE you are using and it's version${ideText.isEmpty ? '' : ' ($ideText)'}",
+      'the Dart SDK version (<code>${escape(_sdkVersion)}</code>)',
+      'your operating system (<code>${escape(Platform.operatingSystem)}</code>)',
+    ], (line) => buf.writeln(line));
 
-    SourceFactory sourceFactory = driver.sourceFactory;
-    if (sourceFactory is SourceFactoryImpl) {
-      h3('Resolvers');
-      for (UriResolver resolver in sourceFactory.resolvers) {
-        h4(resolver.runtimeType.toString());
-        buf.write('<p class="scroll-table">');
-        if (resolver is DartUriResolver) {
-          DartSdk sdk = resolver.dartSdk;
-          buf.write(' (sdk = ');
-          buf.write(sdk.runtimeType);
-          if (sdk is FolderBasedDartSdk) {
-            buf.write(' (path = ');
-            buf.write(sdk.directory.path);
-            buf.write(')');
-          } else if (sdk is EmbedderSdk) {
-            buf.write(' (map = ');
-            writeMap(sdk.urlMappings);
-            buf.write(')');
-          }
-          buf.write(')');
-        } else if (resolver is SdkExtUriResolver) {
-          buf.write(' (map = ');
-          writeMap(resolver.urlMappings);
-          buf.write(')');
-        } else if (resolver is PackageMapUriResolver) {
-          writeMap(resolver.packageMap);
-        }
-        buf.write('</p>');
-      }
-    }
+    p('Thanks!');
   }
+}
 
-  String describe(AnalysisOptionsImpl options) {
-    StringBuffer b = new StringBuffer();
+class InstrumentationPage extends DiagnosticPageWithNav {
+  InstrumentationPage(DiagnosticsSite site)
+      : super(site, 'instrumentation', 'Instrumentation',
+            description:
+                'Verbose instrumentation data from the analysis server.');
 
-    b.write(
-        writeOption('Analyze function bodies', options.analyzeFunctionBodies));
-    b.write(writeOption('Enable asserts in initializer lists',
-        options.enableAssertInitializer));
-    b.write(writeOption(
-        'Enable strict call checks', options.enableStrictCallChecks));
-    b.write(writeOption('Enable super mixins', options.enableSuperMixins));
-    b.write(writeOption('Generate dart2js hints', options.dart2jsHint));
-    b.write(writeOption(
-        'Generate errors in implicit files', options.generateImplicitErrors));
-    b.write(
-        writeOption('Generate errors in SDK files', options.generateSdkErrors));
-    b.write(writeOption('Generate hints', options.hint));
-    b.write(writeOption('Incremental resolution', options.incremental));
-    b.write(writeOption(
-        'Incremental resolution with API changes', options.incrementalApi));
-    b.write(writeOption('Preserve comments', options.preserveComments));
-    b.write(writeOption('Strong mode', options.strongMode));
-    b.write(writeOption('Strong mode hints', options.strongModeHints));
+  @override
+  void generateContent(Map<String, String> params) {
+    p(
+        'Instrumentation can be enabled by starting the analysis server with the '
+        '<code>--instrumentation-log-file=path/to/file</code> flag.',
+        raw: true);
 
-    return b.toString();
-  }
+    if (!AnalysisEngine.instance.instrumentationService.isActive) {
+      blankslate('Instrumentation not active.');
+      return;
+    }
 
-  void writeList<E>(List<E> list) {
-    buf.writeln('[${list.join(', ')}]');
-  }
+    h3('Instrumentation');
 
-  void writeMap<V>(Map<String, V> map) {
-    List<String> keys = map.keys.toList();
-    keys.sort();
-    int length = keys.length;
-    buf.write('{');
-    for (int i = 0; i < length; i++) {
-      buf.write('<br>');
-      String key = keys[i];
-      V value = map[key];
-      buf.write(key);
-      buf.write(' = ');
-      if (value is List) {
-        writeList(value);
-      } else {
-        buf.write(value);
-      }
-      buf.write(',');
-    }
-    buf.write('<br>}');
+    p('Instrumentation active.');
+
+    InstrumentationServer instrumentation =
+        AnalysisEngine.instance.instrumentationService.instrumentationServer;
+    String description = instrumentation.describe;
+    HtmlEscape htmlEscape = new HtmlEscape(HtmlEscapeMode.ELEMENT);
+    description = htmlEscape.convert(description);
+    // Convert http(s): references to hyperlinks.
+    final RegExp urlRegExp = new RegExp(r'[http|https]+:\/*(\S+)');
+    description = description.replaceAllMapped(urlRegExp, (Match match) {
+      return '<a href="${match.group(0)}">${match.group(1)}</a>';
+    });
+    p(description.replaceAll('\n', '<br>'), raw: true);
   }
 }
 
@@ -826,6 +874,11 @@ class MemoryAndCpuPage extends DiagnosticPageWithNav {
       : super(site, 'memory', 'Memory and CPU Usage',
             description: 'Memory and CPU usage for the analysis server.');
 
+  DiagnosticDomainHandler get diagnosticDomain {
+    return server.handlers
+        .firstWhere((handler) => handler is DiagnosticDomainHandler);
+  }
+
   @override
   void generateContent(Map<String, String> params) {
     UsageInfo usage = profiler.getProcessUsageSync(pid);
@@ -838,11 +891,15 @@ class MemoryAndCpuPage extends DiagnosticPageWithNav {
       p('Error retreiving the memory and cpu usage information.');
     }
   }
+}
 
-  DiagnosticDomainHandler get diagnosticDomain {
-    return server.handlers
-        .firstWhere((handler) => handler is DiagnosticDomainHandler);
-  }
+class NotFoundPage extends DiagnosticPage {
+  final String path;
+
+  NotFoundPage(Site site, this.path)
+      : super(site, '', '404 Not found', description: "'$path' not found.");
+
+  void generateContent(Map<String, String> params) {}
 }
 
 class OverlaysPage extends DiagnosticPageWithNav {
@@ -867,56 +924,166 @@ class OverlaysPage extends DiagnosticPageWithNav {
         p('<code>${escape(overlayPath)}</code> not found.', raw: true);
       }
 
-      return;
-    }
+      return;
+    }
+
+    if (paths.isEmpty) {
+      blankslate('No overlays.');
+    } else {
+      String lenCounter(List list) {
+        return '<span class="counter" style="float: right;">${list.length}</span>';
+      }
+
+      h3('Overlays ${lenCounter(paths)}', raw: true);
+      ul(paths, (String overlayPath) {
+        String uri = '$path?overlay=${Uri.encodeQueryComponent(overlayPath)}';
+        buf.writeln('<a href="$uri">${escape(overlayPath)}</a>');
+      });
+    }
+  }
+}
+
+class PluginsPage extends DiagnosticPageWithNav {
+  PluginsPage(DiagnosticsSite site)
+      : super(site, 'plugins', 'Plugins', description: 'Plugins in use.');
+
+  @override
+  void generateContent(Map<String, String> params) {
+    h3('Analysis plugins');
+    List<PluginInfo> analysisPlugins = server.pluginManager.plugins;
+
+    if (analysisPlugins.isEmpty) {
+      blankslate('No analysis plugins active.');
+    } else {
+      ul(analysisPlugins, (PluginInfo p) {
+        buf.writeln('${p.data.name} ${p.pluginId} (${p.data.version})');
+      });
+    }
+
+    h3('Analyzer plugins');
+    void writePlugin(Plugin plugin) {
+      buf.write(plugin.uniqueIdentifier);
+      buf.write(' (');
+      buf.write(plugin.runtimeType);
+      buf.write(')');
+    }
+
+    List<Plugin> plugins = [
+      AnalysisEngine.instance.enginePlugin,
+      server.serverPlugin
+    ];
+    plugins.addAll(server.userDefinedPlugins);
+    ul(plugins, writePlugin);
+  }
+}
+
+// TODO(devoncarew): Show the last x requests and responses.
+class ProfilePage extends DiagnosticPageWithNav {
+  ProfilePage(DiagnosticsSite site)
+      : super(site, 'profile', 'Profiling Info',
+            description: 'Profiling performance tag data.');
+
+  @override
+  void generateContent(Map<String, String> params) {
+    // prepare sorted tags
+    List<PerformanceTag> tags = PerformanceTag.all.toList();
+    tags.remove(ServerPerformanceStatistics.idle);
+    tags.remove(PerformanceTag.unknown);
+    tags.removeWhere((tag) => tag.elapsedMs == 0);
+    tags.sort((a, b) => b.elapsedMs - a.elapsedMs);
+
+    // draw a pie chart
+    String rowData =
+        tags.map((tag) => "['${tag.label}', ${tag.elapsedMs}]").join(',');
+    buf.writeln(
+        '<div id="chart-div" style="width: 700px; height: 300px;"></div>');
+    buf.writeln('''
+      <script type="text/javascript">
+        google.charts.load('current', {'packages':['corechart']});
+        google.charts.setOnLoadCallback(drawChart);
+
+        function drawChart() {
+          var data = new google.visualization.DataTable();
+          data.addColumn('string', 'Tag');
+          data.addColumn('number', 'Time (ms)');
+          data.addRows([$rowData]);
+          var options = {'title': 'Performance Tag Data', 'width': 700, 'height': 300};
+          var chart = new google.visualization.PieChart(document.getElementById('chart-div'));
+          chart.draw(data, options);
+        }
+      </script>
+''');
+
+    // print total time
+    int totalTime =
+        tags.fold<int>(0, (int a, PerformanceTag tag) => a + tag.elapsedMs);
+    p('Total measured time: ${printMilliseconds(totalTime)}');
+
+    // write out a table
+    void _writeRow(List<String> data, {bool header: false}) {
+      buf.write('<tr>');
+      if (header) {
+        for (String d in data) {
+          buf.write('<th>$d</th>');
+        }
+      } else {
+        buf.write('<td>${data[0]}</td>');
 
-    if (paths.isEmpty) {
-      blankslate('No overlays.');
-    } else {
-      String lenCounter(List list) {
-        return '<span class="counter" style="float: right;">${list.length}</span>';
+        for (String d in data.sublist(1)) {
+          buf.write('<td class="right">$d</td>');
+        }
       }
+      buf.writeln('</tr>');
+    }
 
-      h3('Overlays ${lenCounter(paths)}', raw: true);
-      ul(paths, (String overlayPath) {
-        String uri = '$path?overlay=${Uri.encodeQueryComponent(overlayPath)}';
-        buf.writeln('<a href="$uri">${escape(overlayPath)}</a>');
-      });
+    buf.write('<table>');
+    _writeRow(['Tag name', 'Time (in ms)', 'Percent'], header: true);
+    void writeRow(PerformanceTag tag) {
+      double percent = tag.elapsedMs / totalTime;
+      _writeRow([
+        tag.label,
+        printMilliseconds(tag.elapsedMs),
+        printPercentage(percent)
+      ]);
     }
+
+    tags.forEach(writeRow);
+    buf.write('</table>');
   }
 }
 
-class PluginsPage extends DiagnosticPageWithNav {
-  PluginsPage(DiagnosticsSite site)
-      : super(site, 'plugins', 'Plugins', description: 'Plugins in use.');
+class StatusPage extends DiagnosticPageWithNav {
+  StatusPage(DiagnosticsSite site)
+      : super(site, 'status', 'Status',
+            description:
+                'General status and diagnostics for the analysis server.');
 
   @override
   void generateContent(Map<String, String> params) {
-    h3('Analysis plugins');
-    List<PluginInfo> analysisPlugins = server.pluginManager.plugins;
+    buf.writeln('<div class="columns">');
 
-    if (analysisPlugins.isEmpty) {
-      blankslate('No analysis plugins active.');
-    } else {
-      ul(analysisPlugins, (PluginInfo p) {
-        buf.writeln('${p.data.name} ${p.pluginId} (${p.data.version})');
-      });
-    }
+    buf.writeln('<div class="column one-half">');
+    h3('Status');
+    buf.writeln(writeOption(
+        'New analysis driver enabled', server.options.enableNewAnalysisDriver));
+    buf.writeln(writeOption('Instrumentation enabled',
+        AnalysisEngine.instance.instrumentationService.isActive));
+    buf.writeln(writeOption('Server process ID', pid));
+    buf.writeln('</div>');
 
-    h3('Analyzer plugins');
-    void writePlugin(Plugin plugin) {
-      buf.write(plugin.uniqueIdentifier);
-      buf.write(' (');
-      buf.write(plugin.runtimeType);
-      buf.write(')');
-    }
+    buf.writeln('<div class="column one-half">');
+    h3('Versions');
+    buf.writeln(writeOption('Analysis server version', AnalysisServer.VERSION));
+    buf.writeln(writeOption('Dart SDK', Platform.version));
+    buf.writeln('</div>');
 
-    List<Plugin> plugins = [
-      AnalysisEngine.instance.enginePlugin,
-      server.serverPlugin
-    ];
-    plugins.addAll(server.userDefinedPlugins);
-    ul(plugins, writePlugin);
+    buf.writeln('</div>');
+
+    List<String> lines = (site as DiagnosticsSite).lastPrintedLines;
+    if (lines.isNotEmpty) {
+      h3('Debug output');
+      p(lines.join('\n'), style: 'white-space: pre');
+    }
   }
 }
 
@@ -961,170 +1128,3 @@ class SubscriptionsPage extends DiagnosticPageWithNav {
     });
   }
 }
-
-class CompletionPage extends DiagnosticPageWithNav {
-  CompletionPage(DiagnosticsSite site)
-      : super(site, 'completion', 'Code Completion',
-            description: 'Latency statistics for code completion.');
-
-  @override
-  void generateContent(Map<String, String> params) {
-    CompletionDomainHandler completionDomain = server.handlers
-        .firstWhere((handler) => handler is CompletionDomainHandler);
-
-    List<CompletionPerformance> completions =
-        completionDomain.performanceList.items.toList();
-
-    if (completions.isEmpty) {
-      blankslate('No completions recorded.');
-      return;
-    }
-
-    int fastCount =
-        completions.where((c) => c.elapsedInMilliseconds <= 100).length;
-    p('${completions.length} results; ${printPercentage(fastCount / completions.length)} within 100ms.');
-
-    // draw a chart
-    buf.writeln(
-        '<div id="chart-div" style="width: 700px; height: 300px;"></div>');
-    StringBuffer rowData = new StringBuffer();
-    for (int i = completions.length - 1; i >= 0; i--) {
-      // [' ', 101.5]
-      if (rowData.isNotEmpty) {
-        rowData.write(',');
-      }
-      rowData.write("[' ', ${completions[i].elapsedInMilliseconds}]");
-    }
-    buf.writeln('''
-      <script type="text/javascript">
-      google.charts.load('current', {'packages':['bar']});
-      google.charts.setOnLoadCallback(drawChart);
-      function drawChart() {
-        var data = google.visualization.arrayToDataTable([
-          ['Completions', 'Time'],
-          $rowData
-        ]);
-        var options = { bars: 'vertical', vAxis: {format: 'decimal'}, height: 300 };
-        var chart = new google.charts.Bar(document.getElementById('chart-div'));
-        chart.draw(data, google.charts.Bar.convertOptions(options));
-      }
-      </script>
-''');
-
-    // emit the data as a table
-    buf.writeln('<table>');
-    buf.writeln(
-        '<tr><th>Time</th><th>Results</th><th>Source</th><th>Snippet</th></tr>');
-    for (CompletionPerformance completion in completions) {
-      buf.writeln('<tr>'
-          '<td class="pre right">${printMilliseconds(completion.elapsedInMilliseconds)}</td>'
-          '<td class="right">${completion.suggestionCount}</td>'
-          '<td>${escape(completion.source.shortName)}</td>'
-          '<td><code>${escape(completion.snippet)}</code></td>'
-          '</tr>');
-    }
-    buf.writeln('</table>');
-  }
-}
-
-// TODO(devoncarew): Show the last x requests and responses.
-class CommunicationsPage extends DiagnosticPageWithNav {
-  CommunicationsPage(DiagnosticsSite site)
-      : super(site, 'communications', 'Communications',
-            description:
-                'Latency statistics for analysis server communications.');
-
-  @override
-  void generateContent(Map<String, String> params) {
-    void writeRow(List<String> data, {List<String> classes}) {
-      buf.write("<tr>");
-      for (int i = 0; i < data.length; i++) {
-        String c = classes == null ? null : classes[i];
-        if (c != null) {
-          buf.write('<td class="$c">${escape(data[i])}</td>');
-        } else {
-          buf.write('<td>${escape(data[i])}</td>');
-        }
-      }
-      buf.writeln("</tr>");
-    }
-
-    buf.writeln('<div class="columns">');
-
-    ServerPerformance perf = server.performanceAfterStartup;
-    if (perf != null) {
-      buf.writeln('<div class="column one-half">');
-      h3('Current');
-
-      int requestCount = perf.requestCount;
-      int averageLatency =
-          requestCount > 0 ? (perf.requestLatency ~/ requestCount) : 0;
-      int maximumLatency = perf.maxLatency;
-      double slowRequestPercent =
-          requestCount > 0 ? (perf.slowRequestCount / requestCount) : 0.0;
-
-      buf.write('<table>');
-      writeRow([printInteger(requestCount), 'requests'],
-          classes: ["right", null]);
-      writeRow([printMilliseconds(averageLatency), 'average latency'],
-          classes: ["right", null]);
-      writeRow([printMilliseconds(maximumLatency), 'maximum latency'],
-          classes: ["right", null]);
-      writeRow([printPercentage(slowRequestPercent), '> 150 ms latency'],
-          classes: ["right", null]);
-      buf.write('</table>');
-
-      String time = server.uptime.toString();
-      if (time.contains('.')) {
-        time = time.substring(0, time.indexOf('.'));
-      }
-      buf.writeln(writeOption('Uptime', time));
-
-      buf.write('</div>');
-    }
-
-    buf.writeln('<div class="column one-half">');
-    h3('Startup');
-    perf = server.performanceDuringStartup;
-
-    int requestCount = perf.requestCount;
-    int averageLatency =
-        requestCount > 0 ? (perf.requestLatency ~/ requestCount) : 0;
-    int maximumLatency = perf.maxLatency;
-    double slowRequestPercent =
-        requestCount > 0 ? (perf.slowRequestCount / requestCount) : 0.0;
-
-    buf.write('<table>');
-    writeRow([printInteger(requestCount), 'requests'],
-        classes: ["right", null]);
-    writeRow([printMilliseconds(averageLatency), 'average latency'],
-        classes: ["right", null]);
-    writeRow([printMilliseconds(maximumLatency), 'maximum latency'],
-        classes: ["right", null]);
-    writeRow([printPercentage(slowRequestPercent), '> 150 ms latency'],
-        classes: ["right", null]);
-    buf.write('</table>');
-
-    if (server.performanceAfterStartup != null) {
-      int startupTime =
-          server.performanceAfterStartup.startTime - perf.startTime;
-      buf.writeln(
-          writeOption('Initial analysis time', printMilliseconds(startupTime)));
-    }
-    buf.write('</div>');
-
-    buf.write('</div>');
-  }
-}
-
-String writeOption(String name, dynamic value) {
-  return '$name: <code>$value</code><br> ';
-}
-
-String get _sdkVersion {
-  String version = Platform.version;
-  if (version.contains(' ')) {
-    version = version.substring(0, version.indexOf(' '));
-  }
-  return version;
-}