Component updater on-demand logic with ResourceThrottle

chrome/browser/component_updater/component_updater_service.cc

Index: chrome/browser/component_updater/component_updater_service.cc
===================================================================
--- chrome/browser/component_updater/component_updater_service.cc	(revision 231370)
+++ chrome/browser/component_updater/component_updater_service.cc	(working copy)
@@ -15,6 +15,7 @@
 #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"
@@ -30,6 +31,8 @@
 #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"
@@ -37,6 +40,7 @@
 #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"
 
@@ -236,6 +240,52 @@
 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().
+// The lifetime is controlled by Chrome's resource loader so the component
+// updater cannot touch objects from this class except via weak pointers.
+class CUResourceThrottle
+    : public content::ResourceThrottle,
+      public base::SupportsWeakPtr<CUResourceThrottle> {
+ public:
+  explicit CUResourceThrottle(const net::URLRequest* request);
+  virtual ~CUResourceThrottle();
+  // Overriden from ResourceThrottle.
+  virtual void WillStartRequest(bool* defer) OVERRIDE;
+  virtual void WillRedirectRequest(const GURL& new_url, bool* defer) OVERRIDE;
+
+  // Component updater calls this function via PostTask to unblock the request.
+  void Unblock();
+
+  typedef std::vector<base::WeakPtr<CUResourceThrottle> > WeakPtrVector;
+
+ private:
+   enum State {

[waffles, 2013/11/01 19:16:56]

I think this is indented by 3 spaces.

+     NEW,
+     BLOCKED,
+     UNBLOCKED
+   };
+
+   State state_;
+};
+
+void UnblockResourceThrottle(base::WeakPtr<CUResourceThrottle> rt) {
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&CUResourceThrottle::Unblock, rt));
+}
+
+void UnblockandReapAllThrottles(CUResourceThrottle::WeakPtrVector* throttles) {
+  CUResourceThrottle::WeakPtrVector::iterator it;
+  for (it = throttles->begin(); it != throttles->end(); ++it)
+    UnblockResourceThrottle(*it);
+  throttles->clear();
+}
+
 //////////////////////////////////////////////////////////////////////////////
 // The one and only implementation of the ComponentUpdateService interface. In
 // charge of running the show. The main method is ProcessPendingItems() which
@@ -262,6 +312,8 @@
   virtual Status OnDemandUpdate(const std::string& component_id) OVERRIDE;
   virtual void GetComponents(
       std::vector<CrxComponentInfo>* components) OVERRIDE;
+  virtual content::ResourceThrottle* GetOnDemandResourceThrottle(
+      net::URLRequest* request, const std::string& crx_id) OVERRIDE;
 
   // The only purpose of this class is to forward the
   // UtilityProcessHostClient callbacks so CrxUpdateService does
@@ -342,6 +394,8 @@
 
   bool AddItemToUpdateCheck(CrxUpdateItem* item, std::string* query);
 
+  Status OnDemandUpdateInternal(CrxUpdateItem* item);
+
   void ProcessPendingItems();
 
   CrxUpdateItem* FindReadyComponent();
@@ -374,6 +428,9 @@
 
   bool HasOnDemandItems() const;
 
+  void OnNewResourceThrottle(base::WeakPtr<CUResourceThrottle> rt,
+                             const std::string& crx_id);
+
   scoped_ptr<ComponentUpdateService::Configurator> config_;
 
   scoped_ptr<ComponentPatcher> component_patcher_;
@@ -552,6 +609,13 @@
         break;
     }
   }
+
+  // Free possible pending network requests.
+  if ((to == CrxUpdateItem::kUpdated) ||
+      (to == CrxUpdateItem::kUpToDate) ||
+      (to == CrxUpdateItem::kNoUpdate)) {
+    UnblockandReapAllThrottles(&item->throttles);
+  }
 }
 
 // Changes all the components in |work_items_| that have |from| status to
@@ -641,11 +705,13 @@
 // |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()))
@@ -1069,6 +1135,66 @@
   }
 }
 
+content::ResourceThrottle* CrxUpdateService::GetOnDemandResourceThrottle(
+     net::URLRequest* request, const std::string& 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);
+  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 std::string& 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)
+    : 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;
+}
+
 // The component update factory. Using the component updater as a singleton
 // is the job of the browser process.
 ComponentUpdateService* ComponentUpdateServiceFactory(