Show flags in Observatory.

Add vm support for setting flags through vm service (UI coming soon).
e.g.
  http://127.0.0.1:8181/#/flags/set?name=some_flag&value=100

--

I reworked the Flags class to use a growing array rather than a linked list to store flags.  This means that we don't need to go through the hassle of building an array and sorting every time that we print/printjson.

R=johnmccutchan@google.com

Review URL: https://codereview.chromium.org//299143007

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@36712 260f80e4-7a28-3924-810f-c04153c831b5

runtime/bin/vmservice/client/deployed/web/index.html._data

@@ -1 +1 @@
-{"experimental_bootstrap":false,"script_ids":[["observatory","lib/src/elements/curly_block.dart"],["observatory","lib/src/elements/observatory_element.dart"],["observatory","lib/src/elements/service_ref.dart"],["observatory","lib/src/elements/instance_ref.dart"],["observatory","lib/src/elements/action_link.dart"],["observatory","lib/src/elements/nav_bar.dart"],["observatory","lib/src/elements/breakpoint_list.dart"],["observatory","lib/src/elements/class_ref.dart"],["observatory","lib/src/elements/eval_box.dart"],["observatory","lib/src/elements/eval_link.dart"],["observatory","lib/src/elements/field_ref.dart"],["observatory","lib/src/elements/function_ref.dart"],["observatory","lib/src/elements/library_ref.dart"],["observatory","lib/src/elements/script_ref.dart"],["observatory","lib/src/elements/class_view.dart"],["observatory","lib/src/elements/code_ref.dart"],["observatory","lib/src/elements/code_view.dart"],["observatory","lib/src/elements/collapsible_content.dart"],["observatory","lib/src/elements/error_view.dart"],["observatory","lib/src/elements/field_view.dart"],["observatory","lib/src/elements/script_inset.dart"],["observatory","lib/src/elements/function_view.dart"],["observatory","lib/src/elements/heap_map.dart"],["observatory","lib/src/elements/io_view.dart"],["observatory","lib/src/elements/isolate_ref.dart"],["observatory","lib/src/elements/isolate_summary.dart"],["observatory","lib/src/elements/isolate_view.dart"],["observatory","lib/src/elements/instance_view.dart"],["observatory","lib/src/elements/json_view.dart"],["observatory","lib/src/elements/library_view.dart"],["observatory","lib/src/elements/heap_profile.dart"],["observatory","lib/src/elements/sliding_checkbox.dart"],["observatory","lib/src/elements/isolate_profile.dart"],["observatory","lib/src/elements/script_view.dart"],["observatory","lib/src/elements/stack_frame.dart"],["observatory","lib/src/elements/stack_trace.dart"],["observatory","lib/src/elements/vm_view.dart"],["observatory","lib/src/elements/service_view.dart"],["observatory","lib/src/elements/response_viewer.dart"],["observatory","lib/src/elements/observatory_application.dart"],["observatory","lib/src/elements/service_exception_view.dart"],["observatory","lib/src/elements/service_error_view.dart"],["observatory","lib/src/elements/vm_ref.dart"],["observatory","web/main.dart"]]}
+{"experimental_bootstrap":false,"script_ids":[["observatory","lib/src/elements/curly_block.dart"],["observatory","lib/src/elements/observatory_element.dart"],["observatory","lib/src/elements/service_ref.dart"],["observatory","lib/src/elements/instance_ref.dart"],["observatory","lib/src/elements/action_link.dart"],["observatory","lib/src/elements/nav_bar.dart"],["observatory","lib/src/elements/breakpoint_list.dart"],["observatory","lib/src/elements/class_ref.dart"],["observatory","lib/src/elements/eval_box.dart"],["observatory","lib/src/elements/eval_link.dart"],["observatory","lib/src/elements/field_ref.dart"],["observatory","lib/src/elements/function_ref.dart"],["observatory","lib/src/elements/library_ref.dart"],["observatory","lib/src/elements/script_ref.dart"],["observatory","lib/src/elements/class_view.dart"],["observatory","lib/src/elements/code_ref.dart"],["observatory","lib/src/elements/code_view.dart"],["observatory","lib/src/elements/collapsible_content.dart"],["observatory","lib/src/elements/error_view.dart"],["observatory","lib/src/elements/field_view.dart"],["observatory","lib/src/elements/stack_frame.dart"],["observatory","lib/src/elements/flag_list.dart"],["observatory","lib/src/elements/script_inset.dart"],["observatory","lib/src/elements/function_view.dart"],["observatory","lib/src/elements/heap_map.dart"],["observatory","lib/src/elements/io_view.dart"],["observatory","lib/src/elements/isolate_ref.dart"],["observatory","lib/src/elements/isolate_summary.dart"],["observatory","lib/src/elements/isolate_view.dart"],["observatory","lib/src/elements/instance_view.dart"],["observatory","lib/src/elements/json_view.dart"],["observatory","lib/src/elements/library_view.dart"],["observatory","lib/src/elements/heap_profile.dart"],["observatory","lib/src/elements/sliding_checkbox.dart"],["observatory","lib/src/elements/isolate_profile.dart"],["observatory","lib/src/elements/script_view.dart"],["observatory","lib/src/elements/stack_trace.dart"],["observatory","lib/src/elements/vm_view.dart"],["observatory","lib/src/elements/service_view.dart"],["observatory","lib/src/elements/response_viewer.dart"],["observatory","lib/src/elements/observatory_application.dart"],["observatory","lib/src/elements/service_exception_view.dart"],["observatory","lib/src/elements/service_error_view.dart"],["observatory","lib/src/elements/vm_ref.dart"],["observatory","web/main.dart"]]}

runtime/bin/vmservice/client/deployed/web/index_devtools.html._data

@@ -1 +1 @@
-{"experimental_bootstrap":false,"script_ids":[["observatory","lib/src/elements/curly_block.dart"],["observatory","lib/src/elements/observatory_element.dart"],["observatory","lib/src/elements/service_ref.dart"],["observatory","lib/src/elements/instance_ref.dart"],["observatory","lib/src/elements/action_link.dart"],["observatory","lib/src/elements/nav_bar.dart"],["observatory","lib/src/elements/breakpoint_list.dart"],["observatory","lib/src/elements/class_ref.dart"],["observatory","lib/src/elements/eval_box.dart"],["observatory","lib/src/elements/eval_link.dart"],["observatory","lib/src/elements/field_ref.dart"],["observatory","lib/src/elements/function_ref.dart"],["observatory","lib/src/elements/library_ref.dart"],["observatory","lib/src/elements/script_ref.dart"],["observatory","lib/src/elements/class_view.dart"],["observatory","lib/src/elements/code_ref.dart"],["observatory","lib/src/elements/code_view.dart"],["observatory","lib/src/elements/collapsible_content.dart"],["observatory","lib/src/elements/error_view.dart"],["observatory","lib/src/elements/field_view.dart"],["observatory","lib/src/elements/script_inset.dart"],["observatory","lib/src/elements/function_view.dart"],["observatory","lib/src/elements/heap_map.dart"],["observatory","lib/src/elements/io_view.dart"],["observatory","lib/src/elements/isolate_ref.dart"],["observatory","lib/src/elements/isolate_summary.dart"],["observatory","lib/src/elements/isolate_view.dart"],["observatory","lib/src/elements/instance_view.dart"],["observatory","lib/src/elements/json_view.dart"],["observatory","lib/src/elements/library_view.dart"],["observatory","lib/src/elements/heap_profile.dart"],["observatory","lib/src/elements/sliding_checkbox.dart"],["observatory","lib/src/elements/isolate_profile.dart"],["observatory","lib/src/elements/script_view.dart"],["observatory","lib/src/elements/stack_frame.dart"],["observatory","lib/src/elements/stack_trace.dart"],["observatory","lib/src/elements/vm_view.dart"],["observatory","lib/src/elements/service_view.dart"],["observatory","lib/src/elements/response_viewer.dart"],["observatory","lib/src/elements/observatory_application.dart"],["observatory","lib/src/elements/service_exception_view.dart"],["observatory","lib/src/elements/service_error_view.dart"],["observatory","lib/src/elements/vm_ref.dart"],["observatory","web/main.dart"]]}
+{"experimental_bootstrap":false,"script_ids":[["observatory","lib/src/elements/curly_block.dart"],["observatory","lib/src/elements/observatory_element.dart"],["observatory","lib/src/elements/service_ref.dart"],["observatory","lib/src/elements/instance_ref.dart"],["observatory","lib/src/elements/action_link.dart"],["observatory","lib/src/elements/nav_bar.dart"],["observatory","lib/src/elements/breakpoint_list.dart"],["observatory","lib/src/elements/class_ref.dart"],["observatory","lib/src/elements/eval_box.dart"],["observatory","lib/src/elements/eval_link.dart"],["observatory","lib/src/elements/field_ref.dart"],["observatory","lib/src/elements/function_ref.dart"],["observatory","lib/src/elements/library_ref.dart"],["observatory","lib/src/elements/script_ref.dart"],["observatory","lib/src/elements/class_view.dart"],["observatory","lib/src/elements/code_ref.dart"],["observatory","lib/src/elements/code_view.dart"],["observatory","lib/src/elements/collapsible_content.dart"],["observatory","lib/src/elements/error_view.dart"],["observatory","lib/src/elements/field_view.dart"],["observatory","lib/src/elements/stack_frame.dart"],["observatory","lib/src/elements/flag_list.dart"],["observatory","lib/src/elements/script_inset.dart"],["observatory","lib/src/elements/function_view.dart"],["observatory","lib/src/elements/heap_map.dart"],["observatory","lib/src/elements/io_view.dart"],["observatory","lib/src/elements/isolate_ref.dart"],["observatory","lib/src/elements/isolate_summary.dart"],["observatory","lib/src/elements/isolate_view.dart"],["observatory","lib/src/elements/instance_view.dart"],["observatory","lib/src/elements/json_view.dart"],["observatory","lib/src/elements/library_view.dart"],["observatory","lib/src/elements/heap_profile.dart"],["observatory","lib/src/elements/sliding_checkbox.dart"],["observatory","lib/src/elements/isolate_profile.dart"],["observatory","lib/src/elements/script_view.dart"],["observatory","lib/src/elements/stack_trace.dart"],["observatory","lib/src/elements/vm_view.dart"],["observatory","lib/src/elements/service_view.dart"],["observatory","lib/src/elements/response_viewer.dart"],["observatory","lib/src/elements/observatory_application.dart"],["observatory","lib/src/elements/service_exception_view.dart"],["observatory","lib/src/elements/service_error_view.dart"],["observatory","lib/src/elements/vm_ref.dart"],["observatory","web/main.dart"]]}

runtime/bin/vmservice/client/deployed/web/packages/observatory/elements.html

@@ -14,6 +14,7 @@
   <link rel="import" href="src/elements/eval_link.html">
   <link rel="import" href="src/elements/field_ref.html">
   <link rel="import" href="src/elements/field_view.html">
+  <link rel="import" href="src/elements/flag_list.html">
   <link rel="import" href="src/elements/function_ref.html">
   <link rel="import" href="src/elements/function_view.html">
   <link rel="import" href="src/elements/heap_map.html">

runtime/bin/vmservice/client/deployed/web/packages/observatory/src/elements/css/shared.css

@@ -56,7 +56,12 @@ a:hover {
 
 em {
   color: inherit;
-  font-style:italic;
+  font-style: italic;
+}
+
+b {
+  color: inherit;
+  font-weight: bold;
 }
 
 hr {

runtime/bin/vmservice/client/deployed/web/packages/observatory/src/elements/flag_list.html

@@ -0,0 +1,55 @@
+<head>
+  <link rel="import" href="nav_bar.html">
+  <link rel="import" href="observatory_element.html">
+  <link rel="import" href="stack_frame.html">
+</head>
+
+<polymer-element name="flag-list" extends="observatory-element">
+  <template>
+    <link rel="stylesheet" href="css/shared.css">
+    <nav-bar>
+      <top-nav-menu></top-nav-menu>
+      <nav-menu link="{{ flagList.isolate.relativeHashLink('flags') }}" anchor="flags" last="{{ true }}"></nav-menu>
+      <nav-refresh callback="{{ refresh }}"></nav-refresh>
+    </nav-bar>
+
+    <div class="content-centered">
+      <template if="{{ flagList['modifiedFlags'].isNotEmpty }}">
+        <h1>Modified Flags</h1>
+        <br>
+        <template repeat="{{ flag in flagList['modifiedFlags'] }}">
+          <flag-item flag="{{ flag }}"></flag-item>
+          <br>
+        </template>
+        <hr>
+      </template>
+
+      <h1>Unmodified Flags</h1>
+      <br>
+      <template if="{{ flagList['unmodifiedFlags'].isEmpty }}">
+        <em>None</em>
+      </template>
+      <template if="{{ flagList['unmodifiedFlags'].isNotEmpty }}">
+        <template repeat="{{ flag in flagList['unmodifiedFlags'] }}">
+          <flag-item flag="{{ flag }}"></flag-item>
+          <br>
+        </template>
+      </template>
+    </div>
+
+  </template>
+</polymer-element>
+
+<polymer-element name="flag-item" extends="observatory-element">
+  <template>
+    <link rel="stylesheet" href="css/shared.css">
+    <span style="color:#aaa">// {{ flag['comment'] }}</span>
+    <div style="padding: 3px 0">
+      <b>{{ flag['name'] }}</b>
+      &nbsp;=&nbsp;
+      {{ flag['valueAsString'] }}
+    </div>
+  </template>
+</polymer-element>
+
+<script type="application/dart" src="flag_list.dart"></script>

runtime/bin/vmservice/client/deployed/web/packages/observatory/src/elements/io_view.html

@@ -61,6 +61,21 @@
   </template>
 </polymer-element>
 
+<polymer-element name="io-ref" extends="service-ref">
+  <template>
+    <link rel="stylesheet" href="css/shared.css">
+    <template if="{{ ref.serviceType == 'Socket' }}">
+      <io-socket-ref ref="{{ ref }}"></io-socket-ref>
+    </template>
+    <template if="{{ ref.serviceType == 'HttpServer' }}">
+      <io-http-server-ref ref="{{ ref }}"></io-http-server-ref>
+    </template>
+    <template if="{{ ref.serviceType == 'WebSocket' }}">
+      <io-web-socket-ref ref="{{ ref }}"></io-web-socket-ref>
+    </template>
+  </template>
+</polymer-element>
+
 <polymer-element name="io-http-server-list-view" extends="observatory-element">
   <template>
     <link rel="stylesheet" href="css/shared.css">
@@ -186,6 +201,12 @@
       <br>
 
       <div class="memberList">
+        <template if="{{ socket['owner'] != null }}">
+          <div class="memberItem">
+            <div class="memberName">Owner</div>
+            <div class="memberValue"><io-ref ref="{{ socket['owner'] }}"></io-ref></div>
+          </div>
+        </template>
         <div class="memberItem">
           <div class="memberName">Address</div>
           <div class="memberValue">{{ socket['address'] }}</div>

runtime/bin/vmservice/client/deployed/web/packages/observatory/src/elements/vm_view.html

@@ -36,6 +36,12 @@
           <div class="memberName">asserts enabled</div>
           <div class="memberValue">{{ vm.assertsEnabled }}</div>
         </div>
+        <br>
+        <div class="memberItem">
+          <div class="memberValue">
+            See <a href="#/flags">flags</a>
+          </div>
+        </div>
       </div>
     </div>
 

runtime/bin/vmservice/client/lib/elements.dart

@@ -14,6 +14,7 @@ export 'package:observatory/src/elements/eval_box.dart';
 export 'package:observatory/src/elements/eval_link.dart';
 export 'package:observatory/src/elements/field_ref.dart';
 export 'package:observatory/src/elements/field_view.dart';
+export 'package:observatory/src/elements/flag_list.dart';
 export 'package:observatory/src/elements/function_ref.dart';
 export 'package:observatory/src/elements/function_view.dart';
 export 'package:observatory/src/elements/heap_map.dart';

runtime/bin/vmservice/client/lib/elements.html

@@ -14,6 +14,7 @@
   <link rel="import" href="src/elements/eval_link.html">
   <link rel="import" href="src/elements/field_ref.html">
   <link rel="import" href="src/elements/field_view.html">
+  <link rel="import" href="src/elements/flag_list.html">
   <link rel="import" href="src/elements/function_ref.html">
   <link rel="import" href="src/elements/function_view.html">
   <link rel="import" href="src/elements/heap_map.html">

runtime/bin/vmservice/client/lib/src/elements/css/shared.css

@@ -56,7 +56,12 @@ a:hover {
 
 em {
   color: inherit;
-  font-style:italic;
+  font-style: italic;
+}
+
+b {
+  color: inherit;
+  font-weight: bold;
 }
 
 hr {

runtime/bin/vmservice/client/lib/src/elements/flag_list.dart

@@ -0,0 +1,27 @@
+// Copyright (c) 2013, 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 flag_list_element;
+
+import 'package:polymer/polymer.dart';
+import 'observatory_element.dart';
+import 'package:observatory/service.dart';
+
+@CustomTag('flag-list')
+class FlagListElement extends ObservatoryElement {
+  @published ServiceMap flagList;
+
+  FlagListElement.created() : super.created();
+
+  void refresh(var done) {
+    flagList.reload().whenComplete(done);
+  }
+}
+
+@CustomTag('flag-item')
+class FlagItemElement extends ObservatoryElement {
+  @published ObservableMap flag;
+
+  FlagItemElement.created() : super.created();
+}

runtime/bin/vmservice/client/lib/src/elements/flag_list.html

@@ -0,0 +1,55 @@
+<head>
+  <link rel="import" href="nav_bar.html">
+  <link rel="import" href="observatory_element.html">
+  <link rel="import" href="stack_frame.html">
+</head>
+
+<polymer-element name="flag-list" extends="observatory-element">
+  <template>
+    <link rel="stylesheet" href="css/shared.css">
+    <nav-bar>
+      <top-nav-menu></top-nav-menu>
+      <nav-menu link="{{ flagList.isolate.relativeHashLink('flags') }}" anchor="flags" last="{{ true }}"></nav-menu>
+      <nav-refresh callback="{{ refresh }}"></nav-refresh>
+    </nav-bar>
+
+    <div class="content-centered">
+      <template if="{{ flagList['modifiedFlags'].isNotEmpty }}">
+        <h1>Modified Flags</h1>
+        <br>
+        <template repeat="{{ flag in flagList['modifiedFlags'] }}">
+          <flag-item flag="{{ flag }}"></flag-item>
+          <br>
+        </template>
+        <hr>
+      </template>
+
+      <h1>Unmodified Flags</h1>
+      <br>
+      <template if="{{ flagList['unmodifiedFlags'].isEmpty }}">
+        <em>None</em>
+      </template>
+      <template if="{{ flagList['unmodifiedFlags'].isNotEmpty }}">
+        <template repeat="{{ flag in flagList['unmodifiedFlags'] }}">
+          <flag-item flag="{{ flag }}"></flag-item>
+          <br>
+        </template>
+      </template>
+    </div>
+
+  </template>
+</polymer-element>
+
+<polymer-element name="flag-item" extends="observatory-element">
+  <template>
+    <link rel="stylesheet" href="css/shared.css">
+    <span style="color:#aaa">// {{ flag['comment'] }}</span>
+    <div style="padding: 3px 0">
+      <b>{{ flag['name'] }}</b>
+      &nbsp;=&nbsp;
+      {{ flag['valueAsString'] }}
+    </div>
+  </template>
+</polymer-element>
+
+<script type="application/dart" src="flag_list.dart"></script>

runtime/bin/vmservice/client/lib/src/elements/service_view.dart

@@ -44,6 +44,10 @@ class ServiceObjectViewElement extends ObservatoryElement {
         FieldViewElement element = new Element.tag('field-view');
         element.field = object;
         return element;
+      case 'FlagList':
+        FlagListElement element = new Element.tag('flag-list');
+        element.flagList = object;
+        return element;
       case 'Function':
         FunctionViewElement element = new Element.tag('function-view');
         element.function = object;

runtime/bin/vmservice/client/lib/src/elements/vm_view.html

@@ -36,6 +36,12 @@
           <div class="memberName">asserts enabled</div>
           <div class="memberValue">{{ vm.assertsEnabled }}</div>
         </div>
+        <br>
+        <div class="memberItem">
+          <div class="memberValue">
+            See <a href="#/flags">flags</a>
+          </div>
+        </div>
       </div>
     </div>
 

runtime/bin/vmservice/client/lib/src/service/object.dart

@@ -27,7 +27,7 @@ abstract class ServiceObject extends Observable {
   String _serviceType;
 
   /// The complete service url of this object.
-  @reflectable String get link => isolate.relativeLink(_id);
+  @reflectable String get link => _owner.relativeLink(_id);
 
   /// The complete service url of this object with a '#/' prefix.
   // TODO(turnidge): Figure out why using a getter here messes up polymer.
@@ -179,6 +179,7 @@ abstract class VM extends ServiceObjectOwner {
   @reflectable Iterable<Isolate> get isolates => _isolateCache.values;
 
   @reflectable String get link => '$id';
+  @reflectable String relativeLink(String id) => '$id';
 
   @observable String version = 'unknown';
   @observable String architecture = 'unknown';

runtime/vm/flags.cc

@@ -5,6 +5,7 @@
 #include "vm/flags.h"
 
 #include "platform/assert.h"
+#include "vm/json_stream.h"
 #include "vm/os.h"
 
 namespace dart {
@@ -13,11 +14,13 @@ DEFINE_FLAG(bool, print_flags, false, "Print flags as they are being parsed.");
 DEFINE_FLAG(bool, ignore_unrecognized_flags, false,
     "Ignore unrecognized flags.");
 
-// List of registered flags.
-Flag* Flags::flags_ = NULL;
-
 bool Flags::initialized_ = false;
 
+// List of registered flags.
+Flag** Flags::flags_ = NULL;
+intptr_t Flags::capacity_ = 0;
+intptr_t Flags::num_flags_ = 0;
+
 class Flag {
  public:
   enum FlagType {
@@ -72,7 +75,6 @@ class Flag {
     return (type_ == kBoolean) && (bool_ptr_ == NULL);
   }
 
-  Flag* next_;
   const char* name_;
   const char* comment_;
   union {
@@ -83,16 +85,16 @@ class Flag {
     FlagHandler handler_;
   };
   FlagType type_;
+  bool changed_;
 };
 
 
 Flag* Flags::Lookup(const char* name) {
-  Flag* cur = Flags::flags_;
+  for (intptr_t i = 0; i < num_flags_; i++) {
-  while (cur != NULL) {
+    Flag* flag = flags_[i];
-    if (strcmp(cur->name_, name) == 0) {
+    if (strcmp(flag->name_, name) == 0) {
-      return cur;
+      return flag;
     }
-    cur = cur->next_;
   }
   return NULL;
 }
@@ -107,6 +109,27 @@ bool Flags::IsSet(const char* name) {
 }
 
 
+void Flags::AddFlag(Flag* flag) {
+  ASSERT(!initialized_);
+  if (num_flags_ == capacity_) {
+    if (flags_ == NULL) {
+      capacity_ = 256;
+      flags_ = new Flag*[capacity_];
+    } else {
+      intptr_t new_capacity = capacity_ * 2;
+      Flag** new_flags = new Flag*[new_capacity];
+      for (intptr_t i = 0; i < num_flags_; i++) {
+        new_flags[i] = flags_[i];
+      }
+      delete [] flags_;
+      flags_ = new_flags;
+      capacity_ = new_capacity;
+    }
+  }
+  flags_[num_flags_++] = flag;
+}
+
+
 bool Flags::Register_bool(bool* addr,
                           const char* name,
                           bool default_value,
@@ -117,9 +140,7 @@ bool Flags::Register_bool(bool* addr,
     return default_value;
   }
   flag = new Flag(name, comment, addr, Flag::kBoolean);
-  flag->next_ = Flags::flags_;
+  AddFlag(flag);
-  Flags::flags_ = flag;
-
   return default_value;
 }
 
@@ -131,8 +152,7 @@ int Flags::Register_int(int* addr,
   ASSERT(Lookup(name) == NULL);
 
   Flag* flag = new Flag(name, comment, addr, Flag::kInteger);
-  flag->next_ = Flags::flags_;
+  AddFlag(flag);
-  Flags::flags_ = flag;
 
   return default_value;
 }
@@ -144,8 +164,7 @@ const char* Flags::Register_charp(charp* addr,
                                   const char* comment) {
   ASSERT(Lookup(name) == NULL);
   Flag* flag = new Flag(name, comment, addr, Flag::kString);
-  flag->next_ = Flags::flags_;
+  AddFlag(flag);
-  Flags::flags_ = flag;
   return default_value;
 }
 
@@ -155,8 +174,7 @@ bool Flags::Register_func(FlagHandler handler,
                           const char* comment) {
   ASSERT(Lookup(name) == NULL);
   Flag* flag = new Flag(name, comment, handler);
-  flag->next_ = Flags::flags_;
+  AddFlag(flag);
-  Flags::flags_ = flag;
   return false;
 }
 
@@ -171,6 +189,51 @@ static void Normalize(char* s) {
 }
 
 
+bool Flags::SetFlagFromString(Flag* flag, const char* argument) {
+  ASSERT(!flag->IsUnrecognized());
+  switch (flag->type_) {
+    case Flag::kBoolean: {
+      if (strcmp(argument, "true") == 0) {
+        *flag->bool_ptr_ = true;
+      } else if (strcmp(argument, "false") == 0) {
+        *flag->bool_ptr_ = false;
+      } else {
+        return false;
+      }
+      break;
+    }
+    case Flag::kString: {
+      *flag->charp_ptr_ = argument == NULL ? NULL : strdup(argument);
+      break;
+    }
+    case Flag::kInteger: {
+      char* endptr = NULL;
+      int val = strtol(argument, &endptr, 10);
+      if (endptr != argument) {
+        *flag->int_ptr_ = val;
+      }
+      break;
+    }
+    case Flag::kFunc: {
+      if (strcmp(argument, "true") == 0) {
+        (flag->handler_)(true);
+      } else if (strcmp(argument, "false") == 0) {
+        (flag->handler_)(false);
+      } else {
+        return false;
+      }
+      break;
+    }
+    default: {
+      UNREACHABLE();
+      return false;
+    }
+  }
+  flag->changed_ = true;
+  return true;
+}
+
+
 void Flags::Parse(const char* option) {
   // Find the beginning of the option argument, if it exists.
   const char* equals = option;
@@ -220,43 +283,9 @@ void Flags::Parse(const char* option) {
     // Only set values for recognized flags, skip collected
     // unrecognized flags.
     if (!flag->IsUnrecognized()) {
-      switch (flag->type_) {
+      if (!SetFlagFromString(flag, argument)) {
-        case Flag::kBoolean: {
+        OS::Print("Ignoring flag: %s is an invalid value for flag %s\n",
-          if (strcmp(argument, "true") == 0) {
+                  argument, name);
-            *flag->bool_ptr_ = true;
-          } else if (strcmp(argument, "false") == 0) {
-            *flag->bool_ptr_ = false;
-          } else {
-            OS::Print("Ignoring flag: %s is a bool flag.\n", name);
-          }
-          break;
-        }
-        case Flag::kString: {
-          *flag->charp_ptr_ = argument == NULL ? NULL : strdup(argument);
-          break;
-        }
-        case Flag::kInteger: {
-          char* endptr = NULL;
-          int val = strtol(argument, &endptr, 10);
-          if (endptr != argument) {
-            *flag->int_ptr_ = val;
-          }
-          break;
-        }
-        case Flag::kFunc: {
-          if (strcmp(argument, "true") == 0) {
-            (flag->handler_)(true);
-          } else if (strcmp(argument, "false") == 0) {
-            (flag->handler_)(false);
-          } else {
-            OS::Print("Ignoring flag: %s is a bool flag.\n", name);
-          }
-          break;
-        }
-        default: {
-          UNREACHABLE();
-          break;
-        }
       }
     }
   }
@@ -274,13 +303,20 @@ static bool IsValidFlag(const char* name,
 }
 
 
+int Flags::CompareFlagNames(const void* left, const void* right) {
+  const Flag* left_flag = *reinterpret_cast<const Flag* const *>(left);
+  const Flag* right_flag = *reinterpret_cast<const Flag* const *>(right);
+  return strcmp(left_flag->name_, right_flag->name_);
+}
+
+
 bool Flags::ProcessCommandLineFlags(int number_of_vm_flags,
                                     const char** vm_flags) {
   if (initialized_) {
     return false;
   }
 
-  initialized_ = true;
+  qsort(flags_, num_flags_, sizeof flags_[0], CompareFlagNames);
 
   const char* kPrefix = "--";
   const intptr_t kPrefixLen = strlen(kPrefix);
@@ -295,8 +331,8 @@ bool Flags::ProcessCommandLineFlags(int number_of_vm_flags,
 
   if (!FLAG_ignore_unrecognized_flags) {
     int unrecognized_count = 0;
-    Flag* flag = Flags::flags_;
+    for (intptr_t j = 0; j < num_flags_; j++) {
-    while (flag != NULL) {
+      Flag* flag = flags_[j];
       if (flag->IsUnrecognized()) {
         if (unrecognized_count == 0) {
           OS::PrintErr("Unrecognized flags: %s", flag->name_);
@@ -305,7 +341,6 @@ bool Flags::ProcessCommandLineFlags(int number_of_vm_flags,
         }
         unrecognized_count++;
       }
-      flag = flag->next_;
     }
     if (unrecognized_count > 0) {
       OS::PrintErr("\n");
@@ -315,36 +350,93 @@ bool Flags::ProcessCommandLineFlags(int number_of_vm_flags,
   if (FLAG_print_flags) {
     PrintFlags();
   }
+
+  initialized_ = true;
+  return true;
+}
+
+bool Flags::SetFlag(const char* name,
+                    const char* value,
+                    const char** error) {
+  Flag* flag = Lookup(name);
+  if (flag == NULL) {
+    *error = "Cannot set flag: flag not found";
+    return false;
+  }
+  if (!SetFlagFromString(flag, value)) {
+    *error = "Cannot set flag: invalid value";
+    return false;
+  }
   return true;
 }
 
 
-int Flags::CompareFlagNames(const void* left, const void* right) {
+void Flags::PrintFlags() {
-  const Flag* left_flag = *reinterpret_cast<const Flag* const *>(left);
+  OS::Print("Flag settings:\n");
-  const Flag* right_flag = *reinterpret_cast<const Flag* const *>(right);
+  for (intptr_t i = 0; i < num_flags_; ++i) {
-  return strcmp(left_flag->name_, right_flag->name_);
+    flags_[i]->Print();
+  }
 }
 
 
-void Flags::PrintFlags() {
+void Flags::PrintFlagToJSONArray(JSONArray* jsarr, const Flag* flag) {
-    OS::Print("Flag settings:\n");
+  if (flag->IsUnrecognized() || flag->type_ == Flag::kFunc) {
-    Flag* flag = Flags::flags_;
+    return;
-    int num_flags = 0;
-    while (flag != NULL) {
-      num_flags++;
-      flag = flag->next_;
-    }
-    Flag** flag_array = new Flag*[num_flags];
-    flag = Flags::flags_;
-    for (int i = 0; i < num_flags; ++i, flag = flag->next_) {
-      flag_array[i] = flag;
-    }
-
-    qsort(flag_array, num_flags, sizeof flag_array[0], CompareFlagNames);
-
-    for (int i = 0; i < num_flags; ++i) {
-      flag_array[i]->Print();
-    }
-    delete[] flag_array;
   }
+  JSONObject jsflag(jsarr);
+  jsflag.AddProperty("name", flag->name_);
+  jsflag.AddProperty("comment", flag->comment_);
+  switch (flag->type_) {
+    case Flag::kBoolean: {
+      jsflag.AddProperty("flagType", "bool");
+      jsflag.AddProperty("valueAsString",
+                         (*flag->bool_ptr_ ? "true" : "false"));
+      break;
+    }
+    case Flag::kInteger: {
+      jsflag.AddProperty("flagType", "int");
+      jsflag.AddPropertyF("valueAsString", "%d", *flag->int_ptr_);
+      break;
+    }
+    case Flag::kString: {
+      jsflag.AddProperty("flagType", "string");
+      if (flag->charp_ptr_ != NULL) {
+        jsflag.AddPropertyF("valueAsString", "%s", *flag->charp_ptr_);
+      } else {
+        // valueAsString missing means NULL.
+      }
+      break;
+    }
+    default:
+      UNREACHABLE();
+      break;
+  }
+}
+
+
+void Flags::PrintJSON(JSONStream* js) {
+  JSONObject jsobj(js);
+  jsobj.AddProperty("type", "FlagList");
+  jsobj.AddProperty("id", "flags");
+
+  {
+    JSONArray jsarr(&jsobj, "unmodifiedFlags");
+    for (intptr_t i = 0; i < num_flags_; ++i) {
+      Flag* flag = flags_[i];
+      if (!flag->changed_) {
+        PrintFlagToJSONArray(&jsarr, flag);
+      }
+    }
+  }
+  {
+    JSONArray jsarr(&jsobj, "modifiedFlags");
+    for (intptr_t i = 0; i < num_flags_; ++i) {
+      Flag* flag = flags_[i];
+      if (flag->changed_) {
+        PrintFlagToJSONArray(&jsarr, flag);
+      }
+    }
+  }
+}
+
 }  // namespace dart

runtime/vm/flags.h

@@ -36,8 +36,10 @@ namespace dart {
 
 typedef void (*FlagHandler)(bool value);
 
-// Forward declaration.
+// Forward declarations.
 class Flag;
+class JSONArray;
+class JSONStream;
 
 class Flags {
  public:
@@ -68,17 +70,31 @@ class Flags {
 
   static bool Initialized() { return initialized_; }
 
+  static void PrintJSON(JSONStream* js);
+
+  static bool SetFlag(const char* name,
+                      const char* value,
+                      const char** error);
+
  private:
-  static Flag* flags_;
+  static Flag** flags_;
+  static intptr_t capacity_;
+  static intptr_t num_flags_;
 
   static bool initialized_;
 
+  static void AddFlag(Flag* flag);
+
+  static bool SetFlagFromString(Flag* flag, const char* argument);
+
   static void Parse(const char* option);
 
   static int CompareFlagNames(const void* left, const void* right);
 
   static void PrintFlags();
 
+  static void PrintFlagToJSONArray(JSONArray* jsarr, const Flag* flag);
+
   // Testing needs direct access to private methods.
   friend void Dart_TestParseFlags();
 

runtime/vm/service.cc

@@ -1933,7 +1933,8 @@ static bool HandleVM(JSONStream* js) {
   JSONObject jsobj(js);
   jsobj.AddProperty("type", "VM");
   jsobj.AddProperty("id", "vm");
-  jsobj.AddProperty("architecture", CPU::Id());
+  jsobj.AddProperty("targetCPU", CPU::Id());
+  jsobj.AddProperty("hostCPU", HostCPUFeatures::hardware());
   jsobj.AddProperty("version", Version::String());
   jsobj.AddProperty("assertsEnabled", FLAG_enable_asserts);
   jsobj.AddProperty("typeChecksEnabled", FLAG_enable_type_checks);
@@ -1953,9 +1954,47 @@ static bool HandleVM(JSONStream* js) {
 }
 
 
+static bool HandleFlags(JSONStream* js) {
+  if (js->num_arguments() == 1) {
+    Flags::PrintJSON(js);
+    return true;
+  } else if (js->num_arguments() == 2) {
+    const char* arg = js->GetArgument(1);
+    if (strcmp(arg, "set") == 0) {
+      if (js->num_arguments() > 2) {
+        PrintError(js, "expected at most 2 arguments but found %" Pd "\n",
+                   js->num_arguments());
+      } else {
+        if (js->HasOption("name") && js->HasOption("value")) {
+          JSONObject jsobj(js);
+          const char* flag_name = js->LookupOption("name");
+          const char* flag_value = js->LookupOption("value");
+          const char* error = NULL;
+          if (Flags::SetFlag(flag_name, flag_value, &error)) {
+            jsobj.AddProperty("type", "Success");
+            jsobj.AddProperty("id", "");
+          } else {
+            jsobj.AddProperty("type", "Failure");
+            jsobj.AddProperty("id", "");
+            jsobj.AddProperty("message", error);
+          }
+        } else {
+          PrintError(js, "expected to find 'name' and 'value' options");
+        }
+      }
+    }
+    return true;
+  } else {
+    PrintError(js, "Command too long");
+    return true;
+  }
+}
+
+
 static RootMessageHandlerEntry root_handlers[] = {
   { "_echo", HandleRootEcho },
   { "vm", HandleVM },
+  { "flags", HandleFlags },
 };
 
 

runtime/vm/service_test.cc

@@ -18,6 +18,9 @@
 
 namespace dart {
 
+// This flag is used in the Service_Flags test below.
+DEFINE_FLAG(bool, service_testing_flag, false, "Comment");
+
 class ServiceTestMessageHandler : public MessageHandler {
  public:
   ServiceTestMessageHandler() : _msg(NULL) {}
@@ -1065,13 +1068,63 @@ TEST_CASE(Service_VM) {
   Service::HandleRootMessage(service_msg);
   handler.HandleNextMessage();
   EXPECT_SUBSTRING("\"type\":\"VM\",\"id\":\"vm\"", handler.msg());
-  EXPECT_SUBSTRING("\"architecture\"", handler.msg());
+  EXPECT_SUBSTRING("\"targetCPU\"", handler.msg());
+  EXPECT_SUBSTRING("\"hostCPU\"", handler.msg());
   EXPECT_SUBSTRING("\"version\"", handler.msg());
   EXPECT_SUBSTRING("\"uptime\"", handler.msg());
   EXPECT_SUBSTRING("\"isolates\"", handler.msg());
 }
 
 
+TEST_CASE(Service_Flags) {
+  const char* kScript =
+      "var port;\n"  // Set to our mock port by C++.
+      "\n"
+      "main() {\n"
+      "}";
+
+  Isolate* isolate = Isolate::Current();
+  Dart_Handle lib = TestCase::LoadTestScript(kScript, NULL);
+  EXPECT_VALID(lib);
+
+  // Build a mock message handler and wrap it in a dart port.
+  ServiceTestMessageHandler handler;
+  Dart_Port port_id = PortMap::CreatePort(&handler);
+  Dart_Handle port = Api::NewHandle(isolate, SendPort::New(port_id));
+  EXPECT_VALID(port);
+  EXPECT_VALID(Dart_SetField(lib, NewString("port"), port));
+
+  Instance& service_msg = Instance::Handle();
+  service_msg = Eval(lib, "[port, ['flags'], [], []]");
+
+  // Make sure we can get the FlagList.
+  Service::HandleRootMessage(service_msg);
+  handler.HandleNextMessage();
+  EXPECT_SUBSTRING("\"type\":\"FlagList\",\"id\":\"flags\"", handler.msg());
+  EXPECT_SUBSTRING(
+      "\"name\":\"service_testing_flag\",\"comment\":\"Comment\","
+      "\"flagType\":\"bool\",\"valueAsString\":\"false\"",
+      handler.msg());
+
+  // Modify a flag through the vm service.
+  service_msg = Eval(lib,
+                     "[port, ['flags', 'set'], "
+                     "['name', 'value'], ['service_testing_flag', 'true']]");
+  Service::HandleRootMessage(service_msg);
+  handler.HandleNextMessage();
+  EXPECT_SUBSTRING("Success", handler.msg());
+
+  // Make sure that the flag changed.
+  service_msg = Eval(lib, "[port, ['flags'], [], []]");
+  Service::HandleRootMessage(service_msg);
+  handler.HandleNextMessage();
+  EXPECT_SUBSTRING(
+      "\"name\":\"service_testing_flag\",\"comment\":\"Comment\","
+      "\"flagType\":\"bool\",\"valueAsString\":\"true\"",
+      handler.msg());
+}
+
+
 TEST_CASE(Service_Scripts) {
   const char* kScript =
       "var port;\n"  // Set to our mock port by C++.