When navigating, discard decoded image data that is only live due to page cache.

[WebKit-https.git] / Source / WebCore / ChangeLog

diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
index c412cf8..e2a8e2b 100644 (file)
--- a/Source/WebCore/ChangeLog
+++ b/Source/WebCore/ChangeLog
@@ -1,3 +1,44 @@
+2016-06-20  Andreas Kling  <akling@apple.com>
+
+        When navigating, discard decoded image data that is only live due to page cache.
+        <https://webkit.org/b/158941>
+
+        Reviewed by Antti Koivisto.
+
+        A resource is "live" if it's currently in use by a web page, and "dead" if it's
+        only kept alive by the memory cache.
+
+        This patch adds a mechanism that looks at CachedImage resources to see if all the
+        clients that make them appear "live" are actually pages in the page cache.
+
+        If so, we let the "jettison expensive objects on top-level navigation" mechanism
+        discard the decoded data for such half-live images. This can reduce the peak
+        memory usage during navigations quite a bit.
+
+        * loader/FrameLoader.cpp:
+        (WebCore::FrameLoader::commitProvisionalLoad): Move the call to MemoryPressureHandler
+        before we add the outgoing page to the page cache. This allows the jettisoning code
+        to make decisions based on which pages were cached *before* the navigation.
+
+        * loader/cache/CachedImageClient.h:
+        (WebCore::CachedImageClient::inPageCache):
+        * loader/ImageLoader.h:
+        * loader/ImageLoader.cpp:
+        (WebCore::ImageLoader::inPageCache):
+        * rendering/RenderObject.h:
+        (WebCore::RenderObject::inPageCache): Added a CachedImageClient::inPageCache() virtual
+        to determine which clients are currently in page cache (answered by their Document.)
+
+        * loader/cache/CachedImage.h:
+        * loader/cache/CachedImage.cpp:
+        (WebCore::CachedImage::areAllClientsInPageCache): Walks all CachedImageClient clients
+        and returns true if all of them are inPageCache().
+
+        * platform/MemoryPressureHandler.cpp:
+        (WebCore::MemoryPressureHandler::jettisonExpensiveObjectsOnTopLevelNavigation):
+        Walk all the known CachedImages and nuke decoded data for those that have some but
+        are only considered live due to clients in the page cache.
+
 2016-06-20  Chris Dumez  <cdumez@apple.com>
 
         Unreviewed, fix post-landing review comment from Darin on r202188.