Bug 1357318 - remember previous priority boost request in imgRequest. r=tnikkel

MozReview-Commit-ID: IieWWUw8EIB

--HG--
extra : rebase_source : 2a4fcc625f6f44833533b524bb388bedfeceecaa

image/imgIRequest.idl

@@ -208,5 +208,23 @@ interface imgIRequest : nsIRequest
    * underlying call.
    */
   void decrementAnimationConsumers();
+
+  /**
+   * Request loading priority boost to requested category, each category
+   * of request increases priority only one time..
+   *
+   * CATEGORY_FRAME_INIT: increase priority when the imgRequest is associated
+   * with an nsImageFrame.
+   *
+   * CATEGORY_SIZE_QUERY: increase priority when size decoding is necessary to
+   * determine the layout size of the associated nsImageFrame.
+   *
+   * CATEGORY_DISPLAY: increase priority when the image is about to be displayed
+   * in the viewport.
+   */
+  const uint32_t CATEGORY_FRAME_INIT = 1 << 0;
+  const uint32_t CATEGORY_SIZE_QUERY = 1 << 1;
+  const uint32_t CATEGORY_DISPLAY    = 1 << 2;
+  void boostPriority(in uint32_t aCategory);
 };
 

image/imgRequest.cpp

@@ -541,12 +541,50 @@ imgRequest::AdjustPriority(imgRequestProxy* proxy, int32_t delta)
     return;
   }
 
+  AdjustPriorityInternal(delta);
+}
+
+void
+imgRequest::AdjustPriorityInternal(int32_t aDelta)
+{
   nsCOMPtr<nsISupportsPriority> p = do_QueryInterface(mChannel);
   if (p) {
-    p->AdjustPriority(delta);
+    p->AdjustPriority(aDelta);
   }
 }
 
+void
+imgRequest::BoostPriority(uint32_t aCategory)
+{
+  uint32_t newRequestedCategory =
+    (mBoostCategoriesRequested & aCategory) ^ aCategory;
+  if (!newRequestedCategory) {
+    // priority boost for each category can only apply once.
+    return;
+  }
+
+  MOZ_LOG(gImgLog, LogLevel::Debug,
+         ("[this=%p] imgRequest::BoostPriority for category %x",
+          this, newRequestedCategory));
+
+  int32_t delta = 0;
+
+  if (newRequestedCategory & imgIRequest::CATEGORY_FRAME_INIT) {
+    --delta;
+  }
+
+  if (newRequestedCategory & imgIRequest::CATEGORY_SIZE_QUERY) {
+    --delta;
+  }
+
+  if (newRequestedCategory & imgIRequest::CATEGORY_DISPLAY) {
+    delta += nsISupportsPriority::PRIORITY_HIGH;
+  }
+
+  AdjustPriorityInternal(delta);
+  mBoostCategoriesRequested |= newRequestedCategory;
+}
+
 bool
 imgRequest::HasTransferredData() const
 {

image/imgRequest.h

@@ -171,6 +171,8 @@ public:
   /// of @aProxy.
   void AdjustPriority(imgRequestProxy* aProxy, int32_t aDelta);
 
+  void BoostPriority(uint32_t aCategory);
+
   /// Returns a weak pointer to the underlying request.
   nsIRequest* GetRequest() const { return mRequest; }
 
@@ -223,6 +225,8 @@ private:
   /// Returns true if StartDecoding() was called.
   bool IsDecodeRequested() const;
 
+  void AdjustPriorityInternal(int32_t aDelta);
+
   // Weak reference to parent loader; this request cannot outlive its owner.
   imgLoader* mLoader;
   nsCOMPtr<nsIRequest> mRequest;
@@ -275,6 +279,9 @@ private:
 
   nsresult mImageErrorCode;
 
+  // The categories of prioritization strategy that have been requested.
+  uint32_t mBoostCategoriesRequested = 0;
+
   mutable mozilla::Mutex mMutex;
 
   // Member variables protected by mMutex. Note that *all* flags in our bitfield

image/imgRequestProxy.cpp

@@ -718,6 +718,14 @@ imgRequestProxy::GetCORSMode(int32_t* aCorsMode)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+imgRequestProxy::BoostPriority(uint32_t aCategory)
+{
+  NS_ENSURE_STATE(GetOwner() && !mCanceled);
+  GetOwner()->BoostPriority(aCategory);
+  return NS_OK;
+}
+
 /** nsISupportsPriority methods **/
 
 NS_IMETHODIMP