Bug 519590. Don't interrupt reflow until some time has passed. r=roc

docshell/base/nsDocShell.cpp

@@ -4375,10 +4375,14 @@ nsDocShell::GetPositionAndSize(PRInt32 * x, PRInt32 * y, PRInt32 * cx,
 {
     // We should really consider just getting this information from
     // our window instead of duplicating the storage and code...
-    nsCOMPtr<nsIDOMDocument> document(do_GetInterface(GetAsSupports(mParent)));
-    nsCOMPtr<nsIDocument> doc(do_QueryInterface(document));
-    if (doc) {
-        doc->FlushPendingNotifications(Flush_Layout);
+    if (cx || cy) {
+        // Caller wants to know our size; make sure to give them up to
+        // date information.
+        nsCOMPtr<nsIDOMDocument> document(do_GetInterface(GetAsSupports(mParent)));
+        nsCOMPtr<nsIDocument> doc(do_QueryInterface(document));
+        if (doc) {
+            doc->FlushPendingNotifications(Flush_Layout);
+        }
     }
     
     DoGetPositionAndSize(x, y, cx, cy);

layout/base/nsPresContext.cpp

@@ -112,6 +112,9 @@
 //needed for resetting of image service color
 #include "nsLayoutCID.h"
 
+using mozilla::TimeDuration;
+using mozilla::TimeStamp;
+
 static nscolor
 MakeColorPref(const char *colstr)
 {
@@ -2062,18 +2065,33 @@ nsPresContext::HasCachedStyleData()
   return mShell && mShell->StyleSet()->HasCachedStyleData();
 }
 
-static NS_DEFINE_CID(kAppShellCID, NS_APPSHELL_CID);
 static PRBool sGotInterruptEnv = PR_FALSE;
-static PRUint32 sInterruptSeed = 1;
-static PRUint32 sInterruptChecksToSkip = 200;
 enum InterruptMode {
   ModeRandom,
   ModeCounter,
   ModeEvent
 };
+// Controlled by the GECKO_REFLOW_INTERRUPT_MODE env var; allowed values are
+// "random" (except on Windows) or "counter".  If neither is used, the mode is
+// ModeEvent.
 static InterruptMode sInterruptMode = ModeEvent;
-static PRUint32 sInterruptCounter;
+// Used for the "random" mode.  Controlled by the GECKO_REFLOW_INTERRUPT_SEED
+// env var.
+static PRUint32 sInterruptSeed = 1;
+// Used for the "counter" mode.  This is the number of unskipped interrupt
+// checks that have to happen before we interrupt.  Controlled by the
+// GECKO_REFLOW_INTERRUPT_FREQUENCY env var.
 static PRUint32 sInterruptMaxCounter = 10;
+// Used for the "counter" mode.  This counts up to sInterruptMaxCounter and is
+// then reset to 0.
+static PRUint32 sInterruptCounter;
+// Number of interrupt checks to skip before really trying to interrupt.
+// Controlled by the GECKO_REFLOW_INTERRUPT_CHECKS_TO_SKIP env var.
+static PRUint32 sInterruptChecksToSkip = 200;
+// Number of milliseconds that a reflow should be allowed to run for before we
+// actually allow interruption.  Controlled by the
+// GECKO_REFLOW_MIN_NOINTERRUPT_DURATION env var.
+static TimeDuration sInterruptTimeout = TimeDuration::FromMilliseconds(100);
 
 static void GetInterruptEnv()
 {
@@ -2102,6 +2120,11 @@ static void GetInterruptEnv()
   if (ev) {
     sInterruptChecksToSkip = atoi(ev);
   }
+
+  ev = PR_GetEnv("GECKO_REFLOW_MIN_NOINTERRUPT_DURATION");
+  if (ev) {
+    sInterruptTimeout = TimeDuration::FromMilliseconds(atoi(ev));
+  }
 }
 
 PRBool
@@ -2136,6 +2159,11 @@ nsPresContext::HavePendingInputEvent()
 void
 nsPresContext::ReflowStarted(PRBool aInterruptible)
 {
+#ifdef NOISY_INTERRUPTIBLE_REFLOW
+  if (!aInterruptible) {
+    printf("STARTING NONINTERRUPTIBLE REFLOW\n");
+  }
+#endif
   // We don't support interrupting in paginated contexts, since page
   // sequences only handle initial reflow
   mInterruptsEnabled = aInterruptible && !IsPaginated();
@@ -2149,6 +2177,10 @@ nsPresContext::ReflowStarted(PRBool aInterruptible)
   mHasPendingInterrupt = PR_FALSE;
 
   mInterruptChecksToSkip = sInterruptChecksToSkip;
+
+  if (mInterruptsEnabled) {
+    mReflowStartTime = TimeStamp::Now();
+  }
 }
 
 PRBool
@@ -2174,7 +2206,12 @@ nsPresContext::CheckForInterrupt(nsIFrame* aFrame)
   }
   mInterruptChecksToSkip = sInterruptChecksToSkip;
 
-  mHasPendingInterrupt = HavePendingInputEvent();
+  // Don't interrupt if it's been less than sInterruptTimeout since we started
+  // the reflow.
+  mHasPendingInterrupt =
+    TimeStamp::Now() - mReflowStartTime > sInterruptTimeout &&
+    HavePendingInputEvent() &&
+    !IsChrome();
   if (mHasPendingInterrupt) {
 #ifdef NOISY_INTERRUPTIBLE_REFLOW
     printf("*** DETECTED pending interrupt (time=%lld)\n", PR_Now());

layout/base/nsPresContext.h

@@ -71,6 +71,7 @@
 #include "nsThreadUtils.h"
 #include "nsContentUtils.h"
 #include "nsIWidget.h"
+#include "mozilla/TimeStamp.h"
 
 class nsImageLoader;
 #ifdef IBMBIDI
@@ -1015,6 +1016,8 @@ protected:
 
   PRUint32              mInterruptChecksToSkip;
 
+  mozilla::TimeStamp    mReflowStartTime;
+
   unsigned              mHasPendingInterrupt : 1;
   unsigned              mInterruptsEnabled : 1;
   unsigned              mUseDocumentFonts : 1;

layout/base/nsPresShell.cpp

@@ -7229,6 +7229,11 @@ PresShell::PostReflowEventOffTimer()
 PRBool
 PresShell::DoReflow(nsIFrame* target, PRBool aInterruptible)
 {
+  if (mReflowContinueTimer) {
+    mReflowContinueTimer->Cancel();
+    mReflowContinueTimer = nsnull;
+  }
+
   nsIFrame* rootFrame = FrameManager()->GetRootFrame();
 
   nsCOMPtr<nsIRenderingContext> rcx;