Randomize order in which ready component updates are applied. On demand updates

chrome/browser/component_updater/component_updater_service.cc

 // Copyright 2012 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/component_updater/component_updater_service.h"
 
 #include <algorithm>
 #include <set>
 #include <vector>
 
 #include "base/at_exit.h"
 #include "base/bind.h"
 #include "base/compiler_specific.h"
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequenced_task_runner.h"
 #include "base/stl_util.h"
+#include "base/strings/stringprintf.h"

[Sorin Jianu, 2014/02/11 22:10:23]

What is the reason for including this header?

[bartekn, 2014/02/13 22:51:30]

Whoops, sorry, I used it for printing some debug messages, that I removed, but
forgot to remove the include.

 #include "base/threading/sequenced_worker_pool.h"
 #include "base/timer/timer.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/component_updater/component_patcher.h"
 #include "chrome/browser/component_updater/component_unpacker.h"
 #include "chrome/browser/component_updater/component_updater_ping_manager.h"
 #include "chrome/browser/component_updater/component_updater_utils.h"
 #include "chrome/browser/component_updater/crx_downloader.h"
 #include "chrome/browser/component_updater/crx_update_item.h"
 #include "chrome/browser/component_updater/update_checker.h"
@@ skipping 536 matching lines @@
   if (ready_upgrade) {
     UpdateComponent(ready_upgrade);
     return;
   }
 
   if (!CheckForUpdates())
     ScheduleNextRun(kStepDelayLong);
 }
 
 CrxUpdateItem* CrxUpdateService::FindReadyComponent() const {
-  class Helper {
-   public:
-    static bool IsReadyOnDemand(CrxUpdateItem* item) {
-      return item->on_demand && IsReady(item);
+  std::vector<CrxUpdateItem*> ready;

[Sorin Jianu, 2014/02/11 22:10:23]

One idea to filter the work_items_ is by using std::copy_if and eventually a
helper function that takes a predicate as an argument and returns a vector, as
in:

std::vector<CrxUpdateItem*> ready_items(Helper::FilterWorkItems(IsReady));

[bartekn, 2014/02/13 22:51:30]

I tried it, but for some reason copy_if doesn't seem to exist. It says that
copy_if isn't in std, despite I include <algorithm>

+  std::vector<CrxUpdateItem*> ready_on_demand;
+  for (std::vector<CrxUpdateItem*>::const_iterator it = work_items_.begin();
+       it != work_items_.end();
+       ++it) {
+    CrxUpdateItem* item = *it;
+    if (item->status == CrxUpdateItem::kCanUpdate) {
+      if (item->on_demand) {

[Sorin Jianu, 2014/02/11 22:10:23]

the chrome style guide prefers not fully bracing statements such as the inner if
in this case.

[bartekn, 2014/02/13 22:51:30]

Done.

+        ready_on_demand.push_back(item);
+      } else {
+        ready.push_back(item);
+      }
     }
-    static bool IsReady(CrxUpdateItem* item) {
-      return item->status == CrxUpdateItem::kCanUpdate;
-    }
-  };
+  }
 
-  std::vector<CrxUpdateItem*>::const_iterator it = std::find_if(
-      work_items_.begin(), work_items_.end(), Helper::IsReadyOnDemand);
-  if (it != work_items_.end())
-    return *it;
-  it = std::find_if(work_items_.begin(), work_items_.end(), Helper::IsReady);
-  if (it != work_items_.end())
-    return *it;
+  if (ready_on_demand.size() > 0) {
+    int r = rand();

[Sorin Jianu, 2014/02/11 22:10:23]

I suggest using a function from base/rand_util.h and also paying attention to
how long the types are.

[bartekn, 2014/02/13 22:51:30]

Done.

+    return ready_on_demand[r % ready_on_demand.size()];
+  }
+  if (ready.size() > 0) {
+    int r = rand();
+    return ready[r % ready.size()];
+  }
   return NULL;
 }
 
 // Prepares the components for an update check and initiates the request.
 bool CrxUpdateService::CheckForUpdates() {
   // All components are selected for the update check, regardless of when they
   // were last checked. More selective algorithms could be implemented in the
   // future.
   std::vector<CrxUpdateItem*> items_to_check;
   for (size_t i = 0; i != work_items_.size(); ++i) {
@@ skipping 397 matching lines @@
 // The component update factory. Using the component updater as a singleton
 // is the job of the browser process.
 ComponentUpdateService* ComponentUpdateServiceFactory(
     ComponentUpdateService::Configurator* config) {
   DCHECK(config);
   return new CrxUpdateService(config);
 }
 
 }  // namespace component_updater