Bug 1378966 - Don't cause immediate throttling of the refresh driver on repeat transactions. r=mattwoodrow

MozReview-Commit-ID: 8orAmdpIRTF

--HG--
extra : rebase_source : 2988a9faced2648cd182ebe8adff791634af519f

gfx/layers/TransactionIdAllocator.h

@@ -24,9 +24,11 @@ public:
    * only be called while IsInRefresh().
    *
    * If too many id's are allocated without being returned then
-   * the refresh driver will suspend until they catch up.
+   * the refresh driver will suspend until they catch up. This
+   * "throttling" behaviour can be skipped by passing aThrottle=false.
+   * Otherwise call sites should generally be passing aThrottle=true.
    */
-  virtual uint64_t GetTransactionId() = 0;
+  virtual uint64_t GetTransactionId(bool aThrottle) = 0;
 
   /**
    * Return the transaction id that for the last non-revoked transaction.

gfx/layers/client/ClientLayerManager.cpp

@@ -726,7 +726,7 @@ ClientLayerManager::ForwardTransaction(bool aScheduleComposite)
 
   mPhase = PHASE_FORWARD;
 
-  mLatestTransactionId = mTransactionIdAllocator->GetTransactionId();
+  mLatestTransactionId = mTransactionIdAllocator->GetTransactionId(!mIsRepeatTransaction);
   TimeStamp transactionStart;
   if (!mTransactionIdAllocator->GetTransactionStart().IsNull()) {
     transactionStart = mTransactionIdAllocator->GetTransactionStart();

gfx/layers/wr/WebRenderLayerManager.cpp

@@ -520,7 +520,7 @@ WebRenderLayerManager::EndTransactionInternal(DrawPaintedLayerCallback aCallback
   }
 
   bool sync = mTarget != nullptr;
-  mLatestTransactionId = mTransactionIdAllocator->GetTransactionId();
+  mLatestTransactionId = mTransactionIdAllocator->GetTransactionId(/*aThrottle*/ true);
 
   {
     AutoProfilerTracing

layout/base/nsRefreshDriver.cpp

@@ -2161,11 +2161,12 @@ nsRefreshDriver::FinishedWaitingForTransaction()
 }
 
 uint64_t
-nsRefreshDriver::GetTransactionId()
+nsRefreshDriver::GetTransactionId(bool aThrottle)
 {
   ++mPendingTransaction;
 
-  if (mPendingTransaction >= mCompletedTransaction + 2 &&
+  if (aThrottle &&
+      mPendingTransaction >= mCompletedTransaction + 2 &&
       !mWaitingForTransaction &&
       !mTestControllingRefreshes) {
     mWaitingForTransaction = true;

layout/base/nsRefreshDriver.h

@@ -317,7 +317,7 @@ public:
   static bool GetJankLevels(mozilla::Vector<uint64_t>& aJank);
 
   // mozilla::layers::TransactionIdAllocator
-  uint64_t GetTransactionId() override;
+  uint64_t GetTransactionId(bool aThrottle) override;
   uint64_t LastTransactionId() const override;
   void NotifyTransactionCompleted(uint64_t aTransactionId) override;
   void RevokeTransactionId(uint64_t aTransactionId) override;