add periodic delay in analysis to reduce request processing latency

pkg/analysis_server/lib/src/server/driver.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library driver;
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 
@@ skipping 90 matching lines @@
    */
   static const String HELP_OPTION = "help";
 
   /**
    * The name of the option used to specify if [print] should print to the
    * console instead of being intercepted.
    */
   static const String INTERNAL_PRINT_TO_CONSOLE = "internal-print-to-console";
 
   /**
+   * The name of the option used to specify if [print] should print to the
+   * console instead of being intercepted.
+   */
+  static const String INTERNAL_DELAY_FREQUENCY = 'internal-delay-freqency';
+
+  /**
    * The name of the option used to specify the port to which the server will
    * connect.
    */
   static const String PORT_OPTION = "port";
 
   /**
    * The path to the SDK.
    * TODO(paulberry): get rid of this once the 'analysis.updateSdks' request is
    * operational.
    */
@@ skipping 56 matching lines @@
 //      }
 //    } else {
 //      if (instrumentationServer != null) {
 //        print('Exiting server: providing an instrumentation server without enabling instrumentation');
 //        print('');
 //        _printUsage(parser);
 //        return;
 //      }
 //    }
 
+    // TODO (danrubel) Remove this workaround
+    // once the underlying VM and dart:io issue has been fixed.
+    if (results[INTERNAL_DELAY_FREQUENCY] != null) {
+      AnalysisServer.performOperationDelayFreqency =
+          int.parse(results[INTERNAL_DELAY_FREQUENCY], onError: (_) => 0);
+    }
+
     int port;
     bool serve_http = false;
     if (results[PORT_OPTION] != null) {
       serve_http = true;
       try {
         port = int.parse(results[PORT_OPTION]);
       } on FormatException {
         print('Invalid port number: ${results[PORT_OPTION]}');
         print('');
         _printUsage(parser);
@@ skipping 123 matching lines @@
         defaultsTo: false,
         negatable: false);
     parser.addFlag(
         INTERNAL_PRINT_TO_CONSOLE,
         help: "enable sending `print` output to the console",
         defaultsTo: false,
         negatable: false);
     parser.addOption(
         PORT_OPTION,
         help: "[port] the port on which the server will listen");
+    parser.addOption(INTERNAL_DELAY_FREQUENCY);
     parser.addOption(SDK_OPTION, help: "[path] the path to the sdk");
     parser.addFlag(
         NO_ERROR_NOTIFICATION,
         help: "disable sending all analysis error notifications to the server",
         defaultsTo: false,
         negatable: false);
     parser.addOption(
         FILE_READ_MODE,
         help: "an option of the ways files can be read from disk, " +
             "some clients normalize end of line characters which would make " +
@@ skipping 42 matching lines @@
       uuidFile.parent.createSync(recursive: true);
       uuidFile.writeAsStringSync(uuid);
     } catch (exception, stackTrace) {
       service.logPriorityException(exception, stackTrace);
       // Slightly alter the uuid to indicate it was not persisted
       uuid = 'temp-$uuid';
     }
     return uuid;
   }
 }