Status page for the new analysis driver.

pkg/analysis_server/lib/src/status/get_handler2.dart

+// Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file

[Brian Wilkerson, 2016/11/28 17:09:21]

"2014" --> "2016"

+// 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.
+
+import 'dart:convert';
+import 'dart:io';
+import 'dart:math';
+
+import 'package:analysis_server/plugin/protocol/protocol.dart' hide Element;
+import 'package:analysis_server/src/analysis_server.dart';
+import 'package:analysis_server/src/domain_completion.dart';
+import 'package:analysis_server/src/domain_diagnostic.dart';
+import 'package:analysis_server/src/domain_execution.dart';
+import 'package:analysis_server/src/services/completion/completion_performance.dart';
+import 'package:analysis_server/src/socket_server.dart';
+import 'package:analysis_server/src/status/get_handler.dart';
+import 'package:analyzer/exception/exception.dart';
+import 'package:analyzer/file_system/file_system.dart';
+import 'package:analyzer/source/error_processor.dart';
+import 'package:analyzer/source/sdk_ext.dart';
+import 'package:analyzer/src/context/source.dart';
+import 'package:analyzer/src/dart/analysis/driver.dart';
+import 'package:analyzer/src/dart/sdk/sdk.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/sdk.dart';
+import 'package:analyzer/src/generated/source.dart';
+import 'package:analyzer/src/generated/utilities_general.dart';
+import 'package:analyzer/src/services/lint.dart';
+import 'package:analyzer/task/model.dart';
+import 'package:plugin/plugin.dart';
+
+/**
+ * A function that can be used to generate HTML output into the given [buffer].
+ * The HTML that is generated must be valid (special characters must already be
+ * encoded).
+ */
+typedef void HtmlGenerator(StringBuffer buffer);
+
+/**
+ * Instances of the class [GetHandler2] handle GET requests.
+ */
+class GetHandler2 implements AbstractGetHandler {
+  /**
+   * The path used to request overall performance information.
+   */
+  static const String ANALYSIS_PERFORMANCE_PATH = '/perf/analysis';
+
+  /**
+   * The path used to request code completion information.
+   */
+  static const String COMPLETION_PATH = '/completion';
+
+  /**
+   * The path used to request communication performance information.
+   */
+  static const String COMMUNICATION_PERFORMANCE_PATH = '/perf/communication';
+
+  /**
+   * The path used to request information about a specific context.
+   */
+  static const String CONTEXT_PATH = '/context';
+
+  /**
+   * The path used to request an overlay contents.
+   */
+  static const String OVERLAY_PATH = '/overlay';
+
+  /**
+   * The path used to request overlays information.
+   */
+  static const String OVERLAYS_PATH = '/overlays';
+
+  /**
+   * The path used to request the status of the analysis server as a whole.
+   */
+  static const String STATUS_PATH = '/status';
+
+  /**
+   * Query parameter used to represent the context to search for.
+   */
+  static const String CONTEXT_QUERY_PARAM = 'context';
+
+  /**
+   * Query parameter used to represent the path of an overlayed file.
+   */
+  static const String PATH_PARAM = 'path';
+
+  static final ContentType _htmlContent =
+      new ContentType("text", "html", charset: "utf-8");
+
+  /**
+   * The socket server whose status is to be reported on.
+   */
+  SocketServer _server;
+
+  /**
+   * Buffer containing strings printed by the analysis server.
+   */
+  List<String> _printBuffer;
+
+  /**
+   * Contents of overlay files.
+   */
+  final Map<String, String> _overlayContents = <String, String>{};
+
+  /**
+   * Handler for diagnostics requests.
+   */
+  DiagnosticDomainHandler _diagnosticHandler;
+
+  /**
+   * Initialize a newly created handler for GET requests.
+   */
+  GetHandler2(this._server, this._printBuffer);
+
+  DiagnosticDomainHandler get diagnosticHandler {
+    if (_diagnosticHandler == null) {
+      _diagnosticHandler = new DiagnosticDomainHandler(_server.analysisServer);
+    }
+    return _diagnosticHandler;
+  }
+
+  /**
+   * Return the active [CompletionDomainHandler]
+   * or `null` if either analysis server is not running
+   * or there is no completion domain handler.
+   */
+  CompletionDomainHandler get _completionDomainHandler {
+    AnalysisServer analysisServer = _server.analysisServer;
+    if (analysisServer == null) {
+      return null;
+    }
+    return analysisServer.handlers
+        .firstWhere((h) => h is CompletionDomainHandler, orElse: () => null);
+  }
+
+  /**
+   * Handle a GET request received by the HTTP server.
+   */
+  void handleGetRequest(HttpRequest request) {
+    String path = request.uri.path;
+    if (path == '/' || path == STATUS_PATH) {
+      _returnServerStatus(request);
+    } else if (path == ANALYSIS_PERFORMANCE_PATH) {
+      _returnAnalysisPerformance(request);
+    } else if (path == COMPLETION_PATH) {
+      _returnCompletionInfo(request);
+    } else if (path == COMMUNICATION_PERFORMANCE_PATH) {
+      _returnCommunicationPerformance(request);
+    } else if (path == CONTEXT_PATH) {
+      _returnContextInfo(request);
+    } else if (path == OVERLAY_PATH) {
+      _returnOverlayContents(request);
+    } else if (path == OVERLAYS_PATH) {
+      _returnOverlaysInfo(request);
+    } else {
+      _returnUnknownRequest(request);
+    }
+  }
+
+  /**
+   * Return the folder being managed by the given [analysisServer] that matches
+   * the given [contextFilter], or `null` if there is none.
+   */
+  Folder _findFolder(AnalysisServer analysisServer, String contextFilter) {
+    return analysisServer.driverMap.keys.firstWhere(
+        (Folder folder) => folder.path == contextFilter,
+        orElse: () => null);
+  }
+
+  /**
+   * Return `true` if the given analysis [driver] has at least one entry with
+   * an exception.
+   */
+  bool _hasException(AnalysisDriver driver) {
+//    if (driver == null) {
+//      return false;
+//    }
+//    MapIterator<AnalysisTarget, CacheEntry> iterator =
+//        context.analysisCache.iterator();
+//    while (iterator.moveNext()) {
+//      CacheEntry entry = iterator.value;
+//      if (entry == null || entry.exception != null) {
+//        return true;
+//      }
+//    }
+    // TODO(scheglov)
+    return false;
+  }
+
+  /**
+   * Return a response displaying overall performance information.
+   */
+  void _returnAnalysisPerformance(HttpRequest request) {
+    AnalysisServer analysisServer = _server.analysisServer;
+    if (analysisServer == null) {
+      return _returnFailure(request, 'Analysis server is not running');
+    }
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(buffer, 'Analysis Server - Analysis Performance', [],
+          (StringBuffer buffer) {
+        buffer.write('<h3>Analysis Performance</h3>');
+        _writeTwoColumns(buffer, (StringBuffer buffer) {
+          //
+          // Write performance tags.
+          //
+          buffer.write('<p><b>Performance tag data</b></p>');
+          buffer.write(
+              '<table style="border-collapse: separate; border-spacing: 10px 5px;">');
+          _writeRow(buffer, ['Time (in ms)', 'Percent', 'Tag name'],
+              header: true);
+          // prepare sorted tags
+          List<PerformanceTag> tags = PerformanceTag.all.toList();
+          tags.remove(ServerPerformanceStatistics.idle);
+          tags.sort((a, b) => b.elapsedMs - a.elapsedMs);
+          // prepare total time
+          int totalTagTime = 0;
+          tags.forEach((PerformanceTag tag) {
+            totalTagTime += tag.elapsedMs;
+          });
+          // write rows
+          void writeRow(PerformanceTag tag) {
+            double percent = (tag.elapsedMs * 100) / totalTagTime;
+            String percentStr = '${percent.toStringAsFixed(2)}%';
+            _writeRow(buffer, [tag.elapsedMs, percentStr, tag.label],
+                classes: ["right", "right", null]);
+          }
+
+          tags.forEach(writeRow);
+          buffer.write('</table>');
+        }, (StringBuffer buffer) {
+          //
+          // Write task model timing information.
+          //
+          buffer.write('<p><b>Task performance data</b></p>');
+          buffer.write(
+              '<table style="border-collapse: separate; border-spacing: 10px 5px;">');
+          _writeRow(
+              buffer,
+              [
+                'Task Name',
+                'Count',
+                'Total Time (in ms)',
+                'Average Time (in ms)'
+              ],
+              header: true);
+
+          Map<Type, int> countMap = AnalysisTask.countMap;
+          Map<Type, Stopwatch> stopwatchMap = AnalysisTask.stopwatchMap;
+          List<Type> taskClasses = stopwatchMap.keys.toList();
+          taskClasses.sort((Type first, Type second) =>
+              first.toString().compareTo(second.toString()));
+          int totalTaskTime = 0;
+          taskClasses.forEach((Type taskClass) {
+            int count = countMap[taskClass];
+            if (count == null) {
+              count = 0;
+            }
+            int taskTime = stopwatchMap[taskClass].elapsedMilliseconds;
+            totalTaskTime += taskTime;
+            _writeRow(buffer, [
+              taskClass.toString(),
+              count,
+              taskTime,
+              count <= 0 ? '-' : (taskTime / count).toStringAsFixed(3)
+            ], classes: [
+              null,
+              "right",
+              "right",
+              "right"
+            ]);
+          });
+          _writeRow(buffer, ['Total', '-', totalTaskTime, '-'],
+              classes: [null, "right", "right", "right"]);
+          buffer.write('</table>');
+        });
+      });
+    });
+  }
+
+  /**
+   * Return a response displaying overall performance information.
+   */
+  void _returnCommunicationPerformance(HttpRequest request) {
+    AnalysisServer analysisServer = _server.analysisServer;
+    if (analysisServer == null) {
+      return _returnFailure(request, 'Analysis server is not running');
+    }
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(buffer, 'Analysis Server - Communication Performance', [],
+          (StringBuffer buffer) {
+        buffer.write('<h3>Communication Performance</h3>');
+        _writeTwoColumns(buffer, (StringBuffer buffer) {
+          ServerPerformance perf = analysisServer.performanceDuringStartup;
+          int requestCount = perf.requestCount;
+          num averageLatency = requestCount > 0
+              ? (perf.requestLatency / requestCount).round()
+              : 0;
+          int maximumLatency = perf.maxLatency;
+          num slowRequestPercent = requestCount > 0
+              ? (perf.slowRequestCount * 100 / requestCount).round()
+              : 0;
+          buffer.write('<h4>Startup</h4>');
+          buffer.write('<table>');
+          _writeRow(buffer, [requestCount, 'requests'],
+              classes: ["right", null]);
+          _writeRow(buffer, [averageLatency, 'ms average latency'],
+              classes: ["right", null]);
+          _writeRow(buffer, [maximumLatency, 'ms maximum latency'],
+              classes: ["right", null]);
+          _writeRow(buffer, [slowRequestPercent, '% > 150 ms latency'],
+              classes: ["right", null]);
+          if (analysisServer.performanceAfterStartup != null) {
+            int startupTime = analysisServer.performanceAfterStartup.startTime -
+                perf.startTime;
+            _writeRow(
+                buffer, [startupTime, 'ms for initial analysis to complete']);
+          }
+          buffer.write('</table>');
+        }, (StringBuffer buffer) {
+          ServerPerformance perf = analysisServer.performanceAfterStartup;
+          if (perf == null) {
+            return;
+          }
+          int requestCount = perf.requestCount;
+          num averageLatency = requestCount > 0
+              ? (perf.requestLatency * 10 / requestCount).round() / 10
+              : 0;
+          int maximumLatency = perf.maxLatency;
+          num slowRequestPercent = requestCount > 0
+              ? (perf.slowRequestCount * 100 / requestCount).round()
+              : 0;
+          buffer.write('<h4>Current</h4>');
+          buffer.write('<table>');
+          _writeRow(buffer, [requestCount, 'requests'],
+              classes: ["right", null]);
+          _writeRow(buffer, [averageLatency, 'ms average latency'],
+              classes: ["right", null]);
+          _writeRow(buffer, [maximumLatency, 'ms maximum latency'],
+              classes: ["right", null]);
+          _writeRow(buffer, [slowRequestPercent, '% > 150 ms latency'],
+              classes: ["right", null]);
+          buffer.write('</table>');
+        });
+      });
+    });
+  }
+
+  /**
+   * Return a response displaying code completion information.
+   */
+  void _returnCompletionInfo(HttpRequest request) {
+    String value = request.requestedUri.queryParameters['index'];
+    int index = value != null ? int.parse(value, onError: (_) => 0) : 0;
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(buffer, 'Analysis Server - Completion Stats', [],
+          (StringBuffer buffer) {
+        _writeCompletionPerformanceDetail(buffer, index);
+        _writeCompletionPerformanceList(buffer);
+      });
+    });
+  }
+
+  /**
+   * Return a response containing information about a single source file in the
+   * cache.
+   */
+  void _returnContextInfo(HttpRequest request) {
+    AnalysisServer analysisServer = _server.analysisServer;
+    if (analysisServer == null) {
+      return _returnFailure(request, 'Analysis server not running');
+    }
+    String contextFilter = request.uri.queryParameters[CONTEXT_QUERY_PARAM];
+    if (contextFilter == null) {
+      return _returnFailure(
+          request, 'Query parameter $CONTEXT_QUERY_PARAM required');
+    }
+    AnalysisDriver driver = null;
+    Folder folder = _findFolder(analysisServer, contextFilter);
+    if (folder == null) {
+      return _returnFailure(request, 'Invalid context: $contextFilter');
+    } else {
+      driver = analysisServer.driverMap[folder];
+    }
+
+    // TODO(scheglov) Show priority files.
+//    List<String> priorityNames = <String>[];
+    List<String> addedFiles = driver.addedFiles.toList();
+    List<String> implicitFiles =
+        driver.knownFiles.difference(driver.addedFiles).toList();
+    addedFiles.sort();
+    implicitFiles.sort();
+
+    // TODO(scheglov) Use file overlays.
+//    _overlayContents.clear();
+//    context.visitContentCache((String fullName, int stamp, String contents) {
+//      _overlayContents[fullName] = contents;
+//    });
+
+    void _writeFiles(StringBuffer buffer, String title, List<String> files) {
+      buffer.write('<h3>$title</h3>');
+      if (files == null || files.isEmpty) {
+        buffer.write('<p>None</p>');
+      } else {
+        buffer.write('<p><table style="width: 100%">');
+        for (String file in files) {
+          buffer.write('<tr><td>');
+          buffer.write(file);
+          buffer.write('</td><td>');
+          if (_overlayContents.containsKey(files)) {
+            buffer.write(makeLink(OVERLAY_PATH, {PATH_PARAM: file}, 'overlay'));
+          }
+          buffer.write('</td></tr>');
+        }
+        buffer.write('</table></p>');
+      }
+    }
+
+    void writeOptions(StringBuffer buffer, AnalysisOptionsImpl options,
+        {void writeAdditionalOptions(StringBuffer buffer)}) {
+      if (options == null) {
+        buffer.write('<p>No option information available.</p>');
+        return;
+      }
+      buffer.write('<p>');
+      _writeOption(
+          buffer, 'Analyze functon bodies', options.analyzeFunctionBodies);
+      _writeOption(
+          buffer, 'Enable strict call checks', options.enableStrictCallChecks);
+      _writeOption(buffer, 'Enable super mixins', options.enableSuperMixins);
+      _writeOption(buffer, 'Generate dart2js hints', options.dart2jsHint);
+      _writeOption(buffer, 'Generate errors in implicit files',
+          options.generateImplicitErrors);
+      _writeOption(
+          buffer, 'Generate errors in SDK files', options.generateSdkErrors);
+      _writeOption(buffer, 'Generate hints', options.hint);
+      _writeOption(buffer, 'Incremental resolution', options.incremental);
+      _writeOption(buffer, 'Incremental resolution with API changes',
+          options.incrementalApi);
+      _writeOption(buffer, 'Preserve comments', options.preserveComments);
+      _writeOption(buffer, 'Strong mode', options.strongMode);
+      _writeOption(buffer, 'Strong mode hints', options.strongModeHints);
+      if (writeAdditionalOptions != null) {
+        writeAdditionalOptions(buffer);
+      }
+      buffer.write('</p>');
+    }
+
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(
+          buffer, 'Analysis Server - Context', ['Context: $contextFilter'],
+          (StringBuffer buffer) {
+        buffer.write('<h3>Configuration</h3>');
+
+        _writeColumns(buffer, <HtmlGenerator>[
+          (StringBuffer buffer) {
+            buffer.write('<p><b>Context Options</b></p>');
+            writeOptions(buffer, driver.analysisOptions);
+          },
+          (StringBuffer buffer) {
+            buffer.write('<p><b>SDK Context Options</b></p>');
+            DartSdk sdk = driver?.sourceFactory?.dartSdk;
+            writeOptions(buffer, sdk?.context?.analysisOptions,
+                writeAdditionalOptions: (StringBuffer buffer) {
+              if (sdk is FolderBasedDartSdk) {
+                _writeOption(buffer, 'Use summaries', sdk.useSummary);
+              }
+            });
+          },
+          (StringBuffer buffer) {
+            List<Linter> lints = driver.analysisOptions.lintRules;
+            buffer.write('<p><b>Lints</b></p>');
+            if (lints.isEmpty) {
+              buffer.write('<p>none</p>');
+            } else {
+              for (Linter lint in lints) {
+                buffer.write('<p>');
+                buffer.write(lint.runtimeType);
+                buffer.write('</p>');
+              }
+            }
+
+            List<ErrorProcessor> errorProcessors =
+                driver.analysisOptions.errorProcessors;
+            int processorCount = errorProcessors?.length ?? 0;
+            buffer
+                .write('<p><b>Error Processor count</b>: $processorCount</p>');
+          }
+        ]);
+
+        SourceFactory sourceFactory = driver.sourceFactory;
+        if (sourceFactory is SourceFactoryImpl) {
+          buffer.write('<h3>Resolvers</h3>');
+          for (UriResolver resolver in sourceFactory.resolvers) {
+            buffer.write('<p>');
+            buffer.write(resolver.runtimeType);
+            if (resolver is DartUriResolver) {
+              DartSdk sdk = resolver.dartSdk;
+              buffer.write(' (sdk = ');
+              buffer.write(sdk.runtimeType);
+              if (sdk is FolderBasedDartSdk) {
+                buffer.write(' (path = ');
+                buffer.write(sdk.directory.path);
+                buffer.write(')');
+              } else if (sdk is EmbedderSdk) {
+                buffer.write(' (map = ');
+                _writeMapOfStringToString(buffer, sdk.urlMappings);
+                buffer.write(')');
+              }
+              buffer.write(')');
+            } else if (resolver is SdkExtUriResolver) {
+              buffer.write(' (map = ');
+              _writeMapOfStringToString(buffer, resolver.urlMappings);
+              buffer.write(')');
+            }
+            buffer.write('</p>');
+          }
+        }
+
+        // TODO(scheglov) Show priority files.
+//        _writeFiles(
+//            buffer, 'Priority Files (${priorityNames.length})', priorityNames);
+        _writeFiles(buffer, 'Added Files (${addedFiles.length})', addedFiles);
+        _writeFiles(
+            buffer,
+            'Implicitly Analyzed Files (${implicitFiles.length})',
+            implicitFiles);
+
+        // TODO(scheglov) Show exceptions.
+//        buffer.write('<h3>Exceptions</h3>');
+//        if (exceptions.isEmpty) {
+//          buffer.write('<p>none</p>');
+//        } else {
+//          exceptions.forEach((CaughtException exception) {
+//            _writeException(buffer, exception);
+//          });
+//        }
+      });
+    });
+  }
+
+  void _returnFailure(HttpRequest request, String message) {
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(buffer, 'Analysis Server - Failure', [],
+          (StringBuffer buffer) {
+        buffer.write(HTML_ESCAPE.convert(message));
+      });
+    });
+  }
+
+  void _returnOverlayContents(HttpRequest request) {
+    String path = request.requestedUri.queryParameters[PATH_PARAM];
+    if (path == null) {
+      return _returnFailure(request, 'Query parameter $PATH_PARAM required');
+    }
+    String contents = _overlayContents[path];
+
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(buffer, 'Analysis Server - Overlay', [],
+          (StringBuffer buffer) {
+        buffer.write('<pre>${HTML_ESCAPE.convert(contents)}</pre>');
+      });
+    });
+  }
+
+  /**
+   * Return a response displaying overlays information.
+   */
+  void _returnOverlaysInfo(HttpRequest request) {
+    AnalysisServer analysisServer = _server.analysisServer;
+    if (analysisServer == null) {
+      return _returnFailure(request, 'Analysis server is not running');
+    }
+
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(buffer, 'Analysis Server - Overlays', [],
+          (StringBuffer buffer) {
+        buffer.write('<table border="1">');
+        _overlayContents.clear();
+        ContentCache overlayState = analysisServer.overlayState;
+        overlayState.accept((String fullName, int stamp, String contents) {
+          buffer.write('<tr>');
+          String link =
+              makeLink(OVERLAY_PATH, {PATH_PARAM: fullName}, fullName);
+          DateTime time = new DateTime.fromMillisecondsSinceEpoch(stamp);
+          _writeRow(buffer, [link, time]);
+          _overlayContents[fullName] = contents;
+        });
+        int count = _overlayContents.length;
+        buffer.write('<tr><td colspan="2">Total: $count entries.</td></tr>');
+        buffer.write('</table>');
+      });
+    });
+  }
+
+  /**
+   * Return a response indicating the status of the analysis server.
+   */
+  void _returnServerStatus(HttpRequest request) {
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(buffer, 'Analysis Server - Status', [], (StringBuffer buffer) {
+        if (_writeServerStatus(buffer)) {
+          _writeAnalysisStatus(buffer);
+          _writeEditStatus(buffer);
+          _writeExecutionStatus(buffer);
+          _writePluginStatus(buffer);
+          _writeRecentOutput(buffer);
+        }
+      });
+    });
+  }
+
+  /**
+   * Return an error in response to an unrecognized request received by the HTTP
+   * server.
+   */
+  void _returnUnknownRequest(HttpRequest request) {
+    _writeResponse(request, (StringBuffer buffer) {
+      _writePage(buffer, 'Analysis Server', [], (StringBuffer buffer) {
+        buffer.write('<h3>Unknown page: ');
+        buffer.write(request.uri.path);
+        buffer.write('</h3>');
+        buffer.write('''
+        <p>
+        You have reached an un-recognized page. If you reached this page by
+        following a link from a status page, please report the broken link to
+        the Dart analyzer team:
+        <a>https://github.com/dart-lang/sdk/issues/new</a>.
+        </p><p>
+        If you mistyped the URL, you can correct it or return to
+        ${makeLink(STATUS_PATH, {}, 'the main status page')}.
+        </p>''');
+      });
+    });
+  }
+
+  /**
+   * Return a two digit decimal representation of the given non-negative integer
+   * [value].
+   */
+  String _twoDigit(int value) {
+    if (value < 10) {
+      return '0$value';
+    }
+    return value.toString();
+  }
+
+  /**
+   * Write the status of the analysis domain (on the main status page) to the
+   * given [buffer] object.
+   */
+  void _writeAnalysisStatus(StringBuffer buffer) {
+    AnalysisServer analysisServer = _server.analysisServer;
+    Map<Folder, AnalysisDriver> driverMap = analysisServer.driverMap;
+    List<Folder> folders = driverMap.keys.toList();
+    folders.sort((Folder first, Folder second) =>
+        first.shortName.compareTo(second.shortName));
+
+    buffer.write('<h3>Analysis Domain</h3>');
+    _writeTwoColumns(buffer, (StringBuffer buffer) {
+      buffer.write('<p>Using package resolver provider: ');
+      buffer.write(_server.packageResolverProvider != null);
+      buffer.write('</p>');
+      buffer.write('<p>');
+      buffer.write(makeLink(OVERLAYS_PATH, {}, 'All overlay information'));
+      buffer.write('</p>');
+
+      buffer.write('<p><b>Analysis Contexts</b></p>');
+      buffer.write('<p>');
+      bool first = true;
+      folders.forEach((Folder folder) {
+        if (first) {
+          first = false;
+        } else {
+          buffer.write('<br>');
+        }
+        String key = folder.shortName;
+        buffer.write(makeLink(CONTEXT_PATH, {CONTEXT_QUERY_PARAM: folder.path},
+            key, _hasException(driverMap[folder])));
+        if (!folder.getChild('.packages').exists) {
+          buffer.write(' <small>[no .packages file]</small>');
+        }
+      });
+      buffer.write('</p>');
+
+      int freq = AnalysisServer.performOperationDelayFrequency;
+      String delay = freq > 0 ? '1 ms every $freq ms' : 'off';
+
+      buffer.write('<p><b>Performance Data</b></p>');
+      buffer.write('<p>Perform operation delay: $delay</p>');
+      buffer.write('<p>');
+      buffer.write(makeLink(ANALYSIS_PERFORMANCE_PATH, {}, 'Task data'));
+      buffer.write('</p>');
+    }, (StringBuffer buffer) {
+      _writeSubscriptionMap(
+          buffer, AnalysisService.VALUES, analysisServer.analysisServices);
+    });
+  }
+
+  /**
+   * Write multiple columns of information to the given [buffer], where the list
+   * of [columns] functions are used to generate the content of those columns.
+   */
+  void _writeColumns(StringBuffer buffer, List<HtmlGenerator> columns) {
+    buffer
+        .write('<table class="column"><tr class="column"><td class="column">');
+    int count = columns.length;
+    for (int i = 0; i < count; i++) {
+      if (i > 0) {
+        buffer.write('</td><td class="column">');
+      }
+      columns[i](buffer);
+    }
+    buffer.write('</td></tr></table>');
+  }
+
+  /**
+   * Write performance information about a specific completion request
+   * to the given [buffer] object.
+   */
+  void _writeCompletionPerformanceDetail(StringBuffer buffer, int index) {
+    CompletionDomainHandler handler = _completionDomainHandler;
+    CompletionPerformance performance;
+    if (handler != null) {
+      List<CompletionPerformance> list = handler.performanceList;
+      if (list != null && list.isNotEmpty) {
+        performance = list[max(0, min(list.length - 1, index))];
+      }
+    }
+    if (performance == null) {
+      buffer.write('<h3>Completion Performance Detail</h3>');
+      buffer.write('<p>No completions yet</p>');
+      return;
+    }
+    buffer.write('<h3>Completion Performance Detail</h3>');
+    buffer.write('<p>${performance.startTimeAndMs} for ${performance.source}');
+    buffer.write('<table>');
+    _writeRow(buffer, ['Elapsed', '', 'Operation'], header: true);
+    performance.operations.forEach((OperationPerformance op) {
+      String elapsed = op.elapsed != null ? op.elapsed.toString() : '???';
+      _writeRow(buffer, [elapsed, '&nbsp;&nbsp;', op.name]);
+    });
+    buffer.write('</table>');
+    buffer.write('<p><b>Compute Cache Performance</b>: ');
+    if (handler.computeCachePerformance == null) {
+      buffer.write('none');
+    } else {
+      int elapsed = handler.computeCachePerformance.elapsedInMilliseconds;
+      Source source = handler.computeCachePerformance.source;
+      buffer.write(' $elapsed ms for $source');
+    }
+    buffer.write('</p>');
+  }
+
+  /**
+   * Write a table showing summary information for the last several
+   * completion requests to the given [buffer] object.
+   */
+  void _writeCompletionPerformanceList(StringBuffer buffer) {
+    CompletionDomainHandler handler = _completionDomainHandler;
+    buffer.write('<h3>Completion Performance List</h3>');
+    if (handler == null) {
+      return;
+    }
+    buffer.write('<table>');
+    _writeRow(
+        buffer,
+        [
+          'Start Time',
+          '',
+          'First (ms)',
+          '',
+          'Complete (ms)',
+          '',
+          '# Notifications',
+          '',
+          '# Suggestions',
+          '',
+          'Snippet'
+        ],
+        header: true);
+    int index = 0;
+    for (CompletionPerformance performance in handler.performanceList) {
+      String link = makeLink(COMPLETION_PATH, {'index': '$index'},
+          '${performance.startTimeAndMs}');
+      _writeRow(buffer, [
+        link,
+        '&nbsp;&nbsp;',
+        performance.firstNotificationInMilliseconds,
+        '&nbsp;&nbsp;',
+        performance.elapsedInMilliseconds,
+        '&nbsp;&nbsp;',
+        performance.notificationCount,
+        '&nbsp;&nbsp;',
+        performance.suggestionCount,
+        '&nbsp;&nbsp;',
+        HTML_ESCAPE.convert(performance.snippet)
+      ]);
+      ++index;
+    }
+
+    buffer.write('</table>');
+    buffer.write('''
+      <p><strong>First (ms)</strong> - the number of milliseconds
+        from when completion received the request until the first notification
+        with completion results was queued for sending back to the client.
+      <p><strong>Complete (ms)</strong> - the number of milliseconds
+        from when completion received the request until the final notification
+        with completion results was queued for sending back to the client.
+      <p><strong># Notifications</strong> - the total number of notifications
+        sent to the client with completion results for this request.
+      <p><strong># Suggestions</strong> - the number of suggestions
+        sent to the client in the first notification, followed by a comma,
+        followed by the number of suggestions send to the client
+        in the last notification. If there is only one notification,
+        then there will be only one number in this column.''');
+  }
+
+  /**
+   * Write the status of the edit domain (on the main status page) to the given
+   * [buffer].
+   */
+  void _writeEditStatus(StringBuffer buffer) {
+    buffer.write('<h3>Edit Domain</h3>');
+    _writeTwoColumns(buffer, (StringBuffer buffer) {
+      buffer.write('<p><b>Performance Data</b></p>');
+      buffer.write('<p>');
+      buffer.write(makeLink(COMPLETION_PATH, {}, 'Completion data'));
+      buffer.write('</p>');
+    }, (StringBuffer buffer) {});
+  }
+
+  /**
+   * Write a representation of the given [caughtException] to the given
+   * [buffer]. If [isCause] is `true`, then the exception was a cause for
+   * another exception.
+   */
+  void _writeException(StringBuffer buffer, CaughtException caughtException,
+      {bool isCause: false}) {
+    Object exception = caughtException.exception;
+
+    if (exception is AnalysisException) {
+      buffer.write('<p>');
+      if (isCause) {
+        buffer.write('Caused by ');
+      }
+      buffer.write(exception.message);
+      buffer.write('</p>');
+      _writeStackTrace(buffer, caughtException.stackTrace);
+      CaughtException cause = exception.cause;
+      if (cause != null) {
+        buffer.write('<blockquote>');
+        _writeException(buffer, cause, isCause: true);
+        buffer.write('</blockquote>');
+      }
+    } else {
+      buffer.write('<p>');
+      if (isCause) {
+        buffer.write('Caused by ');
+      }
+      buffer.write(exception.toString());
+      buffer.write('<p>');
+      _writeStackTrace(buffer, caughtException.stackTrace);
+    }
+  }
+
+  /**
+   * Write the status of the execution domain (on the main status page) to the
+   * given [buffer].
+   */
+  void _writeExecutionStatus(StringBuffer buffer) {
+    AnalysisServer analysisServer = _server.analysisServer;
+    ExecutionDomainHandler handler = analysisServer.handlers.firstWhere(
+        (RequestHandler handler) => handler is ExecutionDomainHandler,
+        orElse: () => null);
+    Set<ExecutionService> services = new Set<ExecutionService>();
+    if (handler.onFileAnalyzed != null) {
+      services.add(ExecutionService.LAUNCH_DATA);
+    }
+
+    if (handler != null) {
+      buffer.write('<h3>Execution Domain</h3>');
+      _writeTwoColumns(buffer, (StringBuffer buffer) {
+        _writeSubscriptionList(buffer, ExecutionService.VALUES, services);
+      }, (StringBuffer buffer) {});
+    }
+  }
+
+  /**
+   * Write to the given [buffer] a representation of the given [map] of strings
+   * to strings.
+   */
+  void _writeMapOfStringToString(StringBuffer buffer, Map<String, String> map) {
+    List<String> keys = map.keys.toList();
+    keys.sort();
+    int length = keys.length;
+    buffer.write('{');
+    for (int i = 0; i < length; i++) {
+      buffer.write('<br>');
+      String key = keys[i];
+      if (i > 0) {
+        buffer.write(', ');
+      }
+      buffer.write(key);
+      buffer.write(' = ');
+      buffer.write(map[key]);
+    }
+    buffer.write('<br>}');
+  }
+
+  /**
+   * Write a representation of an analysis option with the given [name] and
+   * [value] to the given [buffer]. The option should be separated from other
+   * options unless the [last] flag is true, indicating that this is the last
+   * option in the list of options.
+   */
+  void _writeOption(StringBuffer buffer, String name, Object value,
+      {bool last: false}) {
+    buffer.write(name);
+    buffer.write(' = ');
+    buffer.write(value.toString());
+    if (!last) {
+      buffer.write('<br>');
+    }
+  }
+
+  /**
+   * Write a standard HTML page to the given [buffer]. The page will have the
+   * given [title] and a body that is generated by the given [body] generator.
+   */
+  void _writePage(StringBuffer buffer, String title, List<String> subtitles,
+      HtmlGenerator body) {
+    DateTime now = new DateTime.now();
+    String date = "${now.month}/${now.day}/${now.year}";
+    String time =
+        "${now.hour}:${_twoDigit(now.minute)}:${_twoDigit(now.second)}.${now.millisecond}";
+
+    buffer.write('<!DOCTYPE html>');
+    buffer.write('<html>');
+    buffer.write('<head>');
+    buffer.write('<meta charset="utf-8">');
+    buffer.write(
+        '<meta name="viewport" content="width=device-width, initial-scale=1.0">');
+    buffer.write('<title>$title</title>');
+    buffer.write('<style>');
+    buffer.write('a {color: #0000DD; text-decoration: none;}');
+    buffer.write('a:link.error {background-color: #FFEEEE;}');
+    buffer.write('a:visited.error {background-color: #FFEEEE;}');
+    buffer.write('a:hover.error {background-color: #FFEEEE;}');
+    buffer.write('a:active.error {background-color: #FFEEEE;}');
+    buffer.write(
+        'h3 {background-color: #DDDDDD; margin-top: 0em; margin-bottom: 0em;}');
+    buffer.write('p {margin-top: 0.5em; margin-bottom: 0.5em;}');
+    buffer.write(
+        'p.commentary {margin-top: 1em; margin-bottom: 1em; margin-left: 2em; font-style: italic;}');
+//    response.write('span.error {text-decoration-line: underline; text-decoration-color: red; text-decoration-style: wavy;}');
+    buffer.write(
+        'table.column {border: 0px solid black; width: 100%; table-layout: fixed;}');
+    buffer.write('td.column {vertical-align: top; width: 50%;}');
+    buffer.write('td.right {text-align: right;}');
+    buffer.write('th {text-align: left; vertical-align:top;}');
+    buffer.write('tr {vertical-align:top;}');
+    buffer.write('</style>');
+    buffer.write('</head>');
+
+    buffer.write('<body>');
+    buffer.write(
+        '<h2>$title <small><small>(as of $time on $date)</small></small></h2>');
+    if (subtitles != null && subtitles.isNotEmpty) {
+      buffer.write('<blockquote>');
+      bool first = true;
+      for (String subtitle in subtitles) {
+        if (first) {
+          first = false;
+        } else {
+          buffer.write('<br>');
+        }
+        buffer.write('<b>');
+        buffer.write(subtitle);
+        buffer.write('</b>');
+      }
+      buffer.write('</blockquote>');
+    }
+    try {
+      body(buffer);
+    } catch (exception, stackTrace) {
+      buffer.write('<h3>Exception while creating page</h3>');
+      _writeException(buffer, new CaughtException(exception, stackTrace));
+    }
+    buffer.write('</body>');
+    buffer.write('</html>');
+  }
+
+  /**
+   * Write the recent output section (on the main status page) to the given
+   * [buffer] object.
+   */
+  void _writePluginStatus(StringBuffer buffer) {
+    void writePlugin(Plugin plugin) {
+      buffer.write(plugin.uniqueIdentifier);
+      buffer.write(' (');
+      buffer.write(plugin.runtimeType);
+      buffer.write(')<br>');
+    }
+
+    buffer.write('<h3>Plugin Status</h3><p>');
+    writePlugin(AnalysisEngine.instance.enginePlugin);
+    writePlugin(_server.serverPlugin);
+    for (Plugin plugin in _server.analysisServer.userDefinedPlugins) {
+      writePlugin(plugin);
+    }
+    buffer.write('<p>');
+  }
+
+  /**
+   * Write the recent output section (on the main status page) to the given
+   * [buffer] object.
+   */
+  void _writeRecentOutput(StringBuffer buffer) {
+    buffer.write('<h3>Recent Output</h3>');
+    String output = HTML_ESCAPE.convert(_printBuffer.join('\n'));
+    if (output.isEmpty) {
+      buffer.write('<i>none</i>');
+    } else {
+      buffer.write('<pre>');
+      buffer.write(output);
+      buffer.write('</pre>');
+    }
+  }
+
+  void _writeResponse(HttpRequest request, HtmlGenerator writePage) {
+    HttpResponse response = request.response;
+    response.statusCode = HttpStatus.OK;
+    response.headers.contentType = _htmlContent;
+    try {
+      StringBuffer buffer = new StringBuffer();
+      try {
+        writePage(buffer);
+      } catch (exception, stackTrace) {
+        buffer.clear();
+        _writePage(buffer, 'Internal Exception', [], (StringBuffer buffer) {
+          _writeException(buffer, new CaughtException(exception, stackTrace));
+        });
+      }
+      response.write(buffer.toString());
+    } finally {
+      response.close();
+    }
+  }
+
+  /**
+   * Write a single row within a table to the given [buffer]. The row will have
+   * one cell for each of the [columns], and will be a header row if [header] is
+   * `true`.
+   */
+  void _writeRow(StringBuffer buffer, List<Object> columns,
+      {bool header: false, List<String> classes}) {
+    buffer.write('<tr>');
+    int count = columns.length;
+    int maxClassIndex = classes == null ? 0 : classes.length - 1;
+    for (int i = 0; i < count; i++) {
+      String classAttribute = '';
+      if (classes != null) {
+        String className = classes[min(i, maxClassIndex)];
+        if (className != null) {
+          classAttribute = ' class="$className"';
+        }
+      }
+      if (header) {
+        buffer.write('<th$classAttribute>');
+      } else {
+        buffer.write('<td$classAttribute>');
+      }
+      buffer.write(columns[i]);
+      if (header) {
+        buffer.write('</th>');
+      } else {
+        buffer.write('</td>');
+      }
+    }
+    buffer.write('</tr>');
+  }
+
+  /**
+   * Write the status of the service domain (on the main status page) to the
+   * given [response] object.
+   */
+  bool _writeServerStatus(StringBuffer buffer) {
+    AnalysisServer analysisServer = _server.analysisServer;
+    Set<ServerService> services = analysisServer.serverServices;
+
+    buffer.write('<h3>Server Domain</h3>');
+    _writeTwoColumns(buffer, (StringBuffer buffer) {
+      if (analysisServer == null) {
+        buffer.write('Status: <span style="color:red">Not running</span>');
+        return;
+      }
+      buffer.write('<p>');
+      buffer.write('Status: Running<br>');
+      buffer.write('New analysis driver: ');
+      buffer.write(analysisServer.options.enableNewAnalysisDriver);
+      buffer.write('<br>');
+      buffer.write('Instrumentation: ');
+      if (AnalysisEngine.instance.instrumentationService.isActive) {
+        buffer.write('<span style="color:red">Active</span>');
+      } else {
+        buffer.write('Inactive');
+      }
+      buffer.write('<br>');
+      buffer.write('Version: ');
+      buffer.write(AnalysisServer.VERSION);
+      buffer.write('<br>');
+      buffer.write('Process ID: ');
+      buffer.write(pid);
+      buffer.write('</p>');
+
+      buffer.write('<p><b>Performance Data</b></p>');
+      buffer.write('<p>');
+      buffer.write(makeLink(
+          COMMUNICATION_PERFORMANCE_PATH, {}, 'Communication performance'));
+      buffer.write('</p>');
+    }, (StringBuffer buffer) {
+      _writeSubscriptionList(buffer, ServerService.VALUES, services);
+    });
+    return analysisServer != null;
+  }
+
+  /**
+   * Write a representation of the given [stackTrace] to the given [buffer].
+   */
+  void _writeStackTrace(StringBuffer buffer, StackTrace stackTrace) {
+    if (stackTrace != null) {
+      String trace = stackTrace.toString().replaceAll('#', '<br>#');
+      if (trace.startsWith('<br>#')) {
+        trace = trace.substring(4);
+      }
+      buffer.write('<p>');
+      buffer.write(trace);
+      buffer.write('</p>');
+    }
+  }
+
+  /**
+   * Given a [service] that could be subscribed to and a set of the services
+   * that are actually subscribed to ([subscribedServices]), write a
+   * representation of the service to the given [buffer].
+   */
+  void _writeSubscriptionInList(
+      StringBuffer buffer, Enum service, Set<Enum> subscribedServices) {
+    if (subscribedServices.contains(service)) {
+      buffer.write('<code>+ </code>');
+    } else {
+      buffer.write('<code>- </code>');
+    }
+    buffer.write(service.name);
+    buffer.write('<br>');
+  }
+
+  /**
+   * Given a [service] that could be subscribed to and a set of paths that are
+   * subscribed to the services ([subscribedPaths]), write a representation of
+   * the service to the given [buffer].
+   */
+  void _writeSubscriptionInMap(
+      StringBuffer buffer, Enum service, Set<String> subscribedPaths) {
+    buffer.write('<p>');
+    buffer.write(service.name);
+    buffer.write('</p>');
+    if (subscribedPaths == null || subscribedPaths.isEmpty) {
+      buffer.write('none');
+    } else {
+      List<String> paths = subscribedPaths.toList();
+      paths.sort();
+      for (String path in paths) {
+        buffer.write('<p>');
+        buffer.write(path);
+        buffer.write('</p>');
+      }
+    }
+  }
+
+  /**
+   * Given a list containing all of the services that can be subscribed to in a
+   * single domain ([allServices]) and a set of the services that are actually
+   * subscribed to ([subscribedServices]), write a representation of the
+   * subscriptions to the given [buffer].
+   */
+  void _writeSubscriptionList(StringBuffer buffer, List<Enum> allServices,
+      Set<Enum> subscribedServices) {
+    buffer.write('<p><b>Subscriptions</b></p>');
+    buffer.write('<p>');
+    for (Enum service in allServices) {
+      _writeSubscriptionInList(buffer, service, subscribedServices);
+    }
+    buffer.write('</p>');
+  }
+
+  /**
+   * Given a list containing all of the services that can be subscribed to in a
+   * single domain ([allServices]) and a set of the services that are actually
+   * subscribed to ([subscribedServices]), write a representation of the
+   * subscriptions to the given [buffer].
+   */
+  void _writeSubscriptionMap(StringBuffer buffer, List<Enum> allServices,
+      Map<Enum, Set<String>> subscribedServices) {
+    buffer.write('<p><b>Subscriptions</b></p>');
+    for (Enum service in allServices) {
+      _writeSubscriptionInMap(buffer, service, subscribedServices[service]);
+    }
+  }
+
+  /**
+   * Write two columns of information to the given [buffer], where the
+   * [leftColumn] and [rightColumn] functions are used to generate the content
+   * of those columns.
+   */
+  void _writeTwoColumns(StringBuffer buffer, HtmlGenerator leftColumn,
+      HtmlGenerator rightColumn) {
+    buffer
+        .write('<table class="column"><tr class="column"><td class="column">');
+    leftColumn(buffer);
+    buffer.write('</td><td class="column">');
+    rightColumn(buffer);
+    buffer.write('</td></tr></table>');
+  }
+
+  /**
+   * Create a link to [path] with query parameters [params], with inner HTML
+   * [innerHtml]. If [hasError] is `true`, then the link will have the class
+   * 'error'.
+   */
+  static String makeLink(
+      String path, Map<String, String> params, String innerHtml,
+      [bool hasError = false]) {
+    Uri uri = params.isEmpty
+        ? new Uri(path: path)
+        : new Uri(path: path, queryParameters: params);
+    String href = HTML_ESCAPE.convert(uri.toString());
+    String classAttribute = hasError ? ' class="error"' : '';
+    return '<a href="$href"$classAttribute>$innerHtml</a>';
+  }
+}