Changeset 232356 in webkit

Timestamp:

May 31, 2018 10:55:43 AM (6 years ago)

Author:

Antti Koivisto

Message:

WebKit memory management: Safari jetsams on some websites when zooming and scrolling
​https://bugs.webkit.org/show_bug.cgi?id=186091
<rdar://problem/36315010>

Reviewed by Geoff Garen.

When zooming a page rapidly the visible rect and the page zoom level may get momentarily out of sync.
When this happens we may generate tiles for a much larger area than needed and run out of memory
building the next layer tree transaction. Running out of memory is more likely if the page has lots of
tiled layers in addition to the main content layer.

We already have code for dealing with the scale mismatch for zoom-out case (where this would cause
visibly missing tiles). This patch enables the same exact adjustment for zoom-in case (where the
symptom is creating too many tiles).

• WebProcess/WebPage/ios/WebPageIOS.mm:

(WebKit::adjustExposedRectForNewScale):

Do some renames to make it clear that this can both expand and contract the visible rect.
Bail out if there is nothing to do.

(WebKit::WebPage::updateVisibleContentRects):

Call adjustExposedRectForNewScale directly and unconditionally.

(WebKit::adjustExposedRectForBoundedScale): Deleted.

Location:

trunk/Source/WebKit

Files:

• ChangeLog (modified) (1 diff)
• WebProcess/WebPage/ios/WebPageIOS.mm (modified) (3 diffs)

trunk/Source/WebKit/ChangeLog

@@ +1 @@
+2018-05-31  Antti Koivisto  <antti@apple.com>
+
+        WebKit memory management: Safari jetsams on some websites when zooming and scrolling
+        https://bugs.webkit.org/show_bug.cgi?id=186091
+        <rdar://problem/36315010>
+
+        Reviewed by Geoff Garen.
+
+        When zooming a page rapidly the visible rect and the page zoom level may get momentarily out of sync.
+        When this happens we may generate tiles for a much larger area than needed and run out of memory
+        building the next layer tree transaction. Running out of memory is more likely if the page has lots of
+        tiled layers in addition to the main content layer.
+
+        We already have code for dealing with the scale mismatch for zoom-out case (where this would cause
+        visibly missing tiles). This patch enables the same exact adjustment for zoom-in case (where the
+        symptom is creating too many tiles).
+
+        * WebProcess/WebPage/ios/WebPageIOS.mm:
+        (WebKit::adjustExposedRectForNewScale):
+
+        Do some renames to make it clear that this can both expand and contract the visible rect.
+        Bail out if there is nothing to do.
+
+        (WebKit::WebPage::updateVisibleContentRects):
+
+        Call adjustExposedRectForNewScale directly and unconditionally.
+
+        (WebKit::adjustExposedRectForBoundedScale): Deleted.
+
 2018-05-30  Yusuke Suzuki  <utatane.tea@gmail.com>
 

trunk/Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm

@@ -300 +300 @@
 static inline FloatRect adjustExposedRectForNewScale(const FloatRect& exposedRect, double exposedRectScale, double newScale)
 {
-    double overscaledWidth = exposedRect.width();
-    double missingHorizonalMargin = exposedRect.width() * exposedRectScale / newScale - overscaledWidth;
-
-    double overscaledHeight = exposedRect.height();
-    double missingVerticalMargin = exposedRect.height() * exposedRectScale / newScale - overscaledHeight;
-
-    return FloatRect(exposedRect.x() - missingHorizonalMargin / 2, exposedRect.y() - missingVerticalMargin / 2, exposedRect.width() + missingHorizonalMargin, exposedRect.height() + missingVerticalMargin);
+    if (exposedRectScale == newScale)
+        return exposedRect;
+
+    float horizontalChange = exposedRect.width() * exposedRectScale / newScale - exposedRect.width();
+    float verticalChange = exposedRect.height() * exposedRectScale / newScale - exposedRect.height();
+
+    auto adjustedRect = exposedRect;
+    adjustedRect.inflate({ horizontalChange / 2, verticalChange / 2 });
+    return adjustedRect;
 }
 
@@ -2809 +2811 @@
 }
 
-static inline FloatRect adjustExposedRectForBoundedScale(const FloatRect& exposedRect, double exposedRectScale, double newScale)
-{
-    if (exposedRectScale < newScale)
-        return exposedRect;
-
-    return adjustExposedRectForNewScale(exposedRect, exposedRectScale, newScale);
-}
-
 std::optional<float> WebPage::scaleFromUIProcess(const VisibleContentRectUpdateInfo& visibleContentRectUpdateInfo) const
 {
@@ -2887 +2881 @@
     float scaleToUse = scaleFromUIProcess.value_or(m_page->pageScaleFactor());
     FloatRect exposedContentRect = visibleContentRectUpdateInfo.exposedContentRect();
-    FloatRect adjustedExposedContentRect = adjustExposedRectForBoundedScale(exposedContentRect, visibleContentRectUpdateInfo.scale(), scaleToUse);
+    FloatRect adjustedExposedContentRect = adjustExposedRectForNewScale(exposedContentRect, visibleContentRectUpdateInfo.scale(), scaleToUse);
     m_drawingArea->setExposedContentRect(adjustedExposedContentRect);