Implement A/B experiment for anti-DDoS.

chrome/browser/ui/webui/net_internals_ui.cc

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/net_internals_ui.h"
 
 #include <algorithm>
 #include <list>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/base64.h"
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/memory/singleton.h"
 #include "base/message_loop.h"
+#include "base/metrics/field_trial.h"  // TODO(joi): Remove after experiment.
 #include "base/path_service.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/io_thread.h"
 #include "chrome/browser/net/chrome_net_log.h"
@@ skipping 142 matching lines @@
                               const Value* value);
 
   // NotificationObserver implementation.
   virtual void Observe(NotificationType type,
                        const NotificationSource& source,
                        const NotificationDetails& details);
 
   // Javascript message handlers.
   void OnRendererReady(const ListValue* list);
   void OnEnableHttpThrottling(const ListValue* list);
+  void OnDisableThrottlingExperiments(const ListValue* list);
 #ifdef OS_CHROMEOS
   void OnRefreshSystemLogs(const ListValue* list);
   void OnGetSystemLog(const ListValue* list);
 #endif
 
   // SelectFileDialog::Listener implementation
   virtual void FileSelected(const FilePath& path, int index, void* params);
   virtual void FileSelectionCanceled(void* params);
 
   // The only callback handled on the UI thread.  As it needs to access fields
@@ skipping 75 matching lines @@
     CancelableRequestConsumer consumer_;
     // Libcros request handle.
     CancelableRequestProvider::Handle syslogs_request_id_;
   };
 #endif
 
   // The pref member about whether HTTP throttling is enabled, which needs to
   // be accessed on the UI thread.
   BooleanPrefMember http_throttling_enabled_;
 
+  // The pref member that determines whether experimentation on HTTP throttling
+  // is allowed (this becomes false once the user explicitly sets the
+  // feature to on or off).
+  BooleanPrefMember http_throttling_may_experiment_;
+
   // OnRendererReady invokes this callback to do the part of message handling
   // that needs to happen on the IO thread.
   scoped_ptr<WebUI::MessageCallback> renderer_ready_io_callback_;
 
   // This is the "real" message handler, which lives on the IO thread.
   scoped_refptr<IOThreadImpl> proxy_;
 
 #ifdef OS_CHROMEOS
   // Class that handles getting and filtering system logs.
   scoped_ptr<SystemLogsGetter> syslogs_getter_;
@@ skipping 253 matching lines @@
         NewRunnableMethod(proxy_.get(), &IOThreadImpl::Detach));
   }
   if (select_log_file_dialog_)
     select_log_file_dialog_->ListenerDestroyed();
 }
 
 WebUIMessageHandler* NetInternalsMessageHandler::Attach(WebUI* web_ui) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   PrefService* pref_service = web_ui->GetProfile()->GetPrefs();
-  http_throttling_enabled_.Init(prefs::kHttpThrottlingEnabled, pref_service,
-                                this);
+  http_throttling_enabled_.Init(
+      prefs::kHttpThrottlingEnabled, pref_service, this);
+  http_throttling_may_experiment_.Init(
+      prefs::kHttpThrottlingMayExperiment, pref_service, NULL);
 
   proxy_ = new IOThreadImpl(this->AsWeakPtr(), g_browser_process->io_thread(),
                             web_ui->GetProfile()->GetRequestContext());
 #ifdef OS_CHROMEOS
   syslogs_getter_.reset(new SystemLogsGetter(this,
       chromeos::SystemAccess::GetInstance()));
 #endif
   renderer_ready_io_callback_.reset(
       proxy_->CreateCallback(&IOThreadImpl::OnRendererReady));
 
@@ skipping 102 matching lines @@
       "getSystemLog",
       NewCallback(this, &NetInternalsMessageHandler::OnGetSystemLog));
 #endif
   web_ui_->RegisterMessageCallback(
       "setLogLevel",
       proxy_->CreateCallback(&IOThreadImpl::OnSetLogLevel));
 
   web_ui_->RegisterMessageCallback(
       "enableHttpThrottling",
       NewCallback(this, &NetInternalsMessageHandler::OnEnableHttpThrottling));
+  web_ui_->RegisterMessageCallback(
+      "disableThrottlingExperiments",
+      NewCallback(
+          this,
+          &NetInternalsMessageHandler::OnDisableThrottlingExperiments));
 }
 
 void NetInternalsMessageHandler::CallJavascriptFunction(
     const std::wstring& function_name,
     const Value* value) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (value) {
     web_ui_->CallJavascriptFunction(WideToASCII(function_name), *value);
   } else {
     web_ui_->CallJavascriptFunction(WideToASCII(function_name));
@@ skipping 31 matching lines @@
 
   bool enable = false;
   if (!list->GetBoolean(0, &enable)) {
     NOTREACHED();
     return;
   }
 
   http_throttling_enabled_.SetValue(enable);
 }
 
+void NetInternalsMessageHandler::OnDisableThrottlingExperiments(

[yzshen1, 2011/06/08 00:56:51]

The logic within this method can be put in the method OnEnableHttpThrottling, so
that you don't need to modify *.js files, and it is more clear.

[Jói, 2011/06/08 16:44:47]

You're right. I thought this method was also used at startup  (without user
action) but was confusing it with NetPrefObserver::ApplySettings().

I've removed the additional message and handler function.

+    const ListValue* list) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+
+  if (http_throttling_may_experiment_.GetValue()) {
+    http_throttling_may_experiment_.SetValue(false);
+
+    // Disable the ongoing trial so that histograms after this point
+    // show as being in the "Default" group of the trial.
+    base::FieldTrial* trial = base::FieldTrialList::Find("ThrottlingEnabled");
+    if (trial)
+      trial->Disable();

[yzshen1, 2011/06/08 00:56:51]

It may be better to move the part of disabling the trial to
NetPrefObserver::ApplySettings().

[Jói, 2011/06/08 16:44:47]

I can't do that because that method gets called not only on user action but also
just at the startup of Chrome - so it's not a signal that the user changed the
setting.

Strictly speaking, I _could_ do it there when pref_name is not NULL, but it
feels a bit brittle to do it this way.  The user gesture is much more apparent
in the NetInternalsMessageHandler::OnEnableHttpThrottling which is only used as
a handler for explicit user action.

[yzshen1, 2011/06/08 16:55:54]

Makes sense. Thanks for explaining.
On 2011/06/08 16:44:47, Jói wrote:

+  }
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 //
 // NetInternalsMessageHandler::ReadLogFileTask
 //
 ////////////////////////////////////////////////////////////////////////////////
 
 NetInternalsMessageHandler::ReadLogFileTask::ReadLogFileTask(
     IOThreadImpl* proxy, const FilePath& path)
     : proxy_(proxy), path_(path) {
 }
@@ skipping 899 matching lines @@
 ////////////////////////////////////////////////////////////////////////////////
 
 NetInternalsUI::NetInternalsUI(TabContents* contents) : ChromeWebUI(contents) {
   AddMessageHandler((new NetInternalsMessageHandler())->Attach(this));
 
   NetInternalsHTMLSource* html_source = new NetInternalsHTMLSource();
 
   // Set up the chrome://net-internals/ source.
   contents->profile()->GetChromeURLDataManager()->AddDataSource(html_source);
 }