Component updater on-demand logic with ResourceThrottle

chrome/browser/component_updater/component_updater_service.cc

 // Copyright (c) 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/stl_util.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.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/crx_update_item.h"
 #include "chrome/common/chrome_utility_messages.h"
 #include "chrome/common/chrome_version_info.h"
 #include "chrome/common/extensions/extension.h"
 #include "content/public/browser/browser_thread.h"
+#include "content/public/browser/resource_controller.h"
+#include "content/public/browser/resource_throttle.h"
 #include "content/public/browser/utility_process_host.h"
 #include "content/public/browser/utility_process_host_client.h"
 #include "net/base/escape.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
 #include "net/url_request/url_fetcher.h"
 #include "net/url_request/url_fetcher_delegate.h"
+#include "net/url_request/url_request.h"
 #include "net/url_request/url_request_status.h"
 #include "url/gurl.h"
 
 using content::BrowserThread;
 using content::UtilityProcessHost;
 using content::UtilityProcessHostClient;
 using extensions::Extension;
 
 // The component updater is designed to live until process shutdown, so
 // base::Bind() calls are not refcounted.
@@ skipping 179 matching lines @@
   return HexStringToID(StringToLowerASCII(base::HexEncode(&component.pk_hash[0],
                                           component.pk_hash.size()/2)));
 }
 
 CrxComponentInfo::CrxComponentInfo() {
 }
 
 CrxComponentInfo::~CrxComponentInfo() {
 }
 
+///////////////////////////////////////////////////////////////////////////////
+// In charge of blocking url requests until the |crx_id| component has been
+// updated. This class is touched solely from the IO thread. The UI thread
+// can post tasks to it via weak pointers. By default the request is blocked
+// unless the CrxUpdateService calls Unblock().
+class CUResourceThrottle
+    : public content::ResourceThrottle,
+      public base::SupportsWeakPtr<CUResourceThrottle> {
+ public:
+  explicit CUResourceThrottle(const net::URLRequest* request,
+                              const char* crx_id);
+  virtual ~CUResourceThrottle();
+  // Overriden from ResourceThrottle.
+  virtual void WillStartRequest(bool* defer) OVERRIDE;
+  virtual void WillRedirectRequest(const GURL& new_url, bool* defer) OVERRIDE;
+
+  void Unblock();
+
+ private:
+   enum State {
+     NEW,
+     BLOCKED,
+     UNBLOCKED
+   };
+

[cpu_(ooo_6.6-7.5), 2013/10/30 18:15:41]

it has 3 states because there is a strange requirement that triggers a DCHECK.
See 1192 for more information.

+   std::string crx_id_;
+   State state_;
+};
+
+void UnblockResourceThrottle(base::WeakPtr<CUResourceThrottle> rt) {
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&CUResourceThrottle::Unblock, rt));
+}
+
+void UnblockandReapAllThrottles(
+  std::vector<base::WeakPtr<CUResourceThrottle>>* throttles) {
+  std::vector<base::WeakPtr<CUResourceThrottle>>::iterator it =
+      throttles->begin();
+  while (it != throttles->end()) {
+    UnblockResourceThrottle(*it);
+    ++it;
+  }
+  throttles->clear();
+}
+
 //////////////////////////////////////////////////////////////////////////////
 // The one and only implementation of the ComponentUpdateService interface. In
 // charge of running the show. The main method is ProcessPendingItems() which
 // is called periodically to do the upgrades/installs or the update checks.
 // An important consideration here is to be as "low impact" as we can to the
 // rest of the browser, so even if we have many components registered and
 // eligible for update, we only do one thing at a time with pauses in between
 // the tasks. Also when we do network requests there is only one |url_fetcher_|
 // in flight at a time.
 // There are no locks in this code, the main structure |work_items_| is mutated
 // only from the UI thread. The unpack and installation is done in the file
 // thread and the network requests are done in the IO thread and in the file
 // thread.
 class CrxUpdateService : public ComponentUpdateService {
  public:
   explicit CrxUpdateService(ComponentUpdateService::Configurator* config);
 
   virtual ~CrxUpdateService();
 
   // Overrides for ComponentUpdateService.
   virtual Status Start() OVERRIDE;
   virtual Status Stop() OVERRIDE;
   virtual Status RegisterComponent(const CrxComponent& component) OVERRIDE;
   virtual Status OnDemandUpdate(const std::string& component_id) OVERRIDE;
   virtual void GetComponents(
       std::vector<CrxComponentInfo>* components) OVERRIDE;
+  virtual content::ResourceThrottle* GetResourceThrottle(
+      net::URLRequest* request, const char* crx_id) OVERRIDE;
 
   // The only purpose of this class is to forward the
   // UtilityProcessHostClient callbacks so CrxUpdateService does
   // not have to derive from it because that is refcounted.
   class ManifestParserBridge : public UtilityProcessHostClient {
    public:
     explicit ManifestParserBridge(CrxUpdateService* service)
         : service_(service) {}
 
     virtual bool OnMessageReceived(const IPC::Message& message) OVERRIDE {
@@ skipping 60 matching lines @@
   };
 
   // See ManifestParserBridge.
   void OnParseUpdateManifestSucceeded(const UpdateManifest::Results& results);
 
   // See ManifestParserBridge.
   void OnParseUpdateManifestFailed(const std::string& error_message);
 
   bool AddItemToUpdateCheck(CrxUpdateItem* item, std::string* query);
 
+  Status OnDemandUpdateInternal(CrxUpdateItem* item);
+
   void ProcessPendingItems();
 
   CrxUpdateItem* FindReadyComponent();
 
   void UpdateComponent(CrxUpdateItem* workitem);
 
   void AddUpdateCheckItems(std::string* query);
 
   void DoUpdateCheck(const std::string& query);
 
@@ skipping 12 matching lines @@
   size_t ChangeItemStatus(CrxUpdateItem::Status from,
                           CrxUpdateItem::Status to);
 
   CrxUpdateItem* FindUpdateItemById(const std::string& id);
 
   void NotifyComponentObservers(ComponentObserver::Events event,
                                 int extra) const;
 
   bool HasOnDemandItems() const;
 
+  void OnNewResourceThrottle(base::WeakPtr<CUResourceThrottle> rt,
+                             const char* crx_id);
+
   scoped_ptr<ComponentUpdateService::Configurator> config_;
 
   scoped_ptr<ComponentPatcher> component_patcher_;
 
   scoped_ptr<net::URLFetcher> url_fetcher_;
 
   scoped_ptr<component_updater::PingManager> ping_manager_;
 
   // A collection of every work item.
   typedef std::vector<CrxUpdateItem*> UpdateItems;
@@ skipping 144 matching lines @@
     switch (to) {
       case CrxUpdateItem::kCanUpdate:
         observer->OnEvent(ComponentObserver::COMPONENT_UPDATE_FOUND, 0);
         break;
       case CrxUpdateItem::kUpdatingDiff:
       case CrxUpdateItem::kUpdating:
         observer->OnEvent(ComponentObserver::COMPONENT_UPDATE_READY, 0);
         break;
       case CrxUpdateItem::kUpdated:
         observer->OnEvent(ComponentObserver::COMPONENT_UPDATED, 0);
+        UnblockandReapAllThrottles(&item->throttles);

[jvoung (off chromium), 2013/10/30 18:50:41]

is there a missing file in the patch (crx_update_item.h)?

         break;
       case CrxUpdateItem::kUpToDate:
       case CrxUpdateItem::kNoUpdate:
         observer->OnEvent(ComponentObserver::COMPONENT_NOT_UPDATED, 0);
+        UnblockandReapAllThrottles(&item->throttles);
         break;
       case CrxUpdateItem::kNew:
       case CrxUpdateItem::kChecking:
       case CrxUpdateItem::kDownloading:
       case CrxUpdateItem::kDownloadingDiff:
       case CrxUpdateItem::kLastStatus:
         // No notification for these states.
         break;

[cpu_(ooo_6.6-7.5), 2013/10/30 18:15:41]

Did I got all the cases in 599 and 604? I think so. Only these two calls delete
the weak pointers to throttles so if I got it wrong then we keep accumulating
dead weakptrs.

     }
   }
 }
 
 // Changes all the components in |work_items_| that have |from| status to
 // |to| status and returns how many have been changed.
 size_t CrxUpdateService::ChangeItemStatus(CrxUpdateItem::Status from,
                                           CrxUpdateItem::Status to) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   size_t count = 0;
@@ skipping 71 matching lines @@
   item->diff_error_code = 0;
   item->diff_extra_code1 = 0;
   return true;
 }
 
 // Start the process of checking for an update, for a particular component
 // that was previously registered.
 // |component_id| is a value returned from GetCrxComponentID().
 ComponentUpdateService::Status CrxUpdateService::OnDemandUpdate(
     const std::string& component_id) {
-  CrxUpdateItem* uit;
-  uit = FindUpdateItemById(component_id);
+  return OnDemandUpdateInternal(FindUpdateItemById(component_id));
+}
+
+ComponentUpdateService::Status CrxUpdateService::OnDemandUpdateInternal(
+    CrxUpdateItem* uit) {
   if (!uit)
     return kError;
-
   // Check if the request is too soon.
   base::TimeDelta delta = base::Time::Now() - uit->last_check;
   if (delta < base::TimeDelta::FromSeconds(config_->OnDemandDelay()))
     return kError;
 
   switch (uit->status) {
     // If the item is already in the process of being updated, there is
     // no point in this call, so return kInProgress.
     case CrxUpdateItem::kChecking:
     case CrxUpdateItem::kCanUpdate:
@@ skipping 17 matching lines @@
 
   // In case the current delay is long, set the timer to a shorter value
   // to get the ball rolling.
   if (timer_.IsRunning()) {
     timer_.Stop();
     timer_.Start(FROM_HERE, base::TimeDelta::FromSeconds(config_->StepDelay()),
                  this, &CrxUpdateService::ProcessPendingItems);
   }
 
   return kOk;
+
 }
 
 void CrxUpdateService::GetComponents(
     std::vector<CrxComponentInfo>* components) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   for (UpdateItems::const_iterator it = work_items_.begin();
        it != work_items_.end(); ++it) {
     const CrxUpdateItem* item = *it;
     CrxComponentInfo info;
     info.id = GetCrxComponentID(item->component);
@@ skipping 366 matching lines @@
 void CrxUpdateService::NotifyComponentObservers(
     ComponentObserver::Events event, int extra) const {
   for (UpdateItems::const_iterator it = work_items_.begin();
        it != work_items_.end(); ++it) {
     ComponentObserver* observer = (*it)->component.observer;
     if (observer)
       observer->OnEvent(event, 0);
   }
 }
 
+content::ResourceThrottle* CrxUpdateService::GetResourceThrottle(
+     net::URLRequest* request, const char* crx_id) {
+  // We give the raw pointer to the caller, who will delete it at will
+  // and we keep for ourselves a weak pointer to it so we can post tasks
+  // from the UI thread without having to track lifetime directly.
+  CUResourceThrottle* rt = new CUResourceThrottle(request, crx_id);
+  BrowserThread::PostTask(
+      BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&CrxUpdateService::OnNewResourceThrottle,
+                 base::Unretained(this),
+                 rt->AsWeakPtr(),
+                 crx_id));
+  return rt;
+}
+
+void CrxUpdateService::OnNewResourceThrottle(
+    base::WeakPtr<CUResourceThrottle> rt, const char* crx_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  // Check if we can on-demand update, else unblock the request anyway.
+  CrxUpdateItem* item = FindUpdateItemById(crx_id);
+  Status status = OnDemandUpdateInternal(item);
+  if (status == kOk || status == kInProgress) {
+    item->throttles.push_back(rt);
+    return;
+  }
+  UnblockResourceThrottle(rt);
+}
+
+///////////////////////////////////////////////////////////////////////////////
+
+CUResourceThrottle::CUResourceThrottle(
+    const net::URLRequest* request, const char* crx_id)
+    : crx_id_(crx_id), state_(NEW) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+}
+
+CUResourceThrottle::~CUResourceThrottle() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+}
+
+void CUResourceThrottle::WillStartRequest(bool* defer) {
+  if (state_ != UNBLOCKED) {
+    state_ = BLOCKED;
+    *defer = true;
+  } else {
+    *defer = false;
+  }
+}
+
+void CUResourceThrottle::WillRedirectRequest(const GURL& new_url, bool* defer) {
+  WillStartRequest(defer);
+}
+
+void CUResourceThrottle::Unblock() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (state_ == BLOCKED)
+    controller()->Resume();
+  state_ = UNBLOCKED;

[cpu_(ooo_6.6-7.5), 2013/10/30 18:15:41]

if I Resume() without have been blocked it triggers a DCHECK in:

void ThrottlingResourceHandler::Resume() {
  DCHECK(!cancelled_by_resource_throttle_);

  DeferredStage last_deferred_stage = deferred_stage_;
  deferred_stage_ = DEFERRED_NONE;
  switch (last_deferred_stage) {
    case DEFERRED_NONE:
      NOTREACHED();                  <----- this one
      break;
    case DEFERRED_START:
      ResumeStart();
      break;
    case DEFERRED_REDIRECT:
      ResumeRedirect();
      break;
    case DEFERRED_RESPONSE:
      ResumeResponse();
      break;
  }
}

+}
+
 // 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);
 }