Store ViewSnapshots directly on the WebBackForwardListItem
authortimothy_horton@apple.com <timothy_horton@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Thu, 10 Jul 2014 20:33:05 +0000 (20:33 +0000)
committertimothy_horton@apple.com <timothy_horton@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Thu, 10 Jul 2014 20:33:05 +0000 (20:33 +0000)
commitb29cc1334b291125458c04595896128e526b083d
tree1f70e9b22f838945d127e9bfc682e417bf9ac659
parent4e7c2c3d38ba327f71f6ccd0d3e8fcf32a271329
Store ViewSnapshots directly on the WebBackForwardListItem
https://bugs.webkit.org/show_bug.cgi?id=134667
<rdar://problem/17082639>

Reviewed by Dan Bernstein.

Make ViewSnapshot a refcounted class. Store it directly on the back-forward item
instead of in a side map referenced by UUID. Switch to a very simple LRU eviction model for now.
This fixes a ton of snapshot management bugs; for example, we would start throwing out snapshots
in the page that was actively being interacted with *first* when evicting snapshots, instead of
preferring older snapshots. Additionally, we would not throw away snapshots when back forward items
became unreachable.

There is definitely room for improvement of the eviction mechanism, but this is closer to a time-tested implementation.

* Shared/SessionState.h:
Keep a ViewSnapshot instead of a UUID on the BackForwardListItemState.

* Shared/WebBackForwardListItem.h:
Fix some indented namespace contents.

(WebKit::WebBackForwardListItem::snapshot):
(WebKit::WebBackForwardListItem::setSnapshot):
(WebKit::WebBackForwardListItem::setSnapshotUUID): Deleted.
(WebKit::WebBackForwardListItem::snapshotUUID): Deleted.
Switch the snapshot getter/setter to operate on ViewSnapshots instead of UUIDs.

* UIProcess/API/Cocoa/WKWebView.mm:
(-[WKWebView _takeViewSnapshot]):
* UIProcess/API/Cocoa/WKWebViewInternal.h:
* UIProcess/API/mac/WKView.mm:
(-[WKView _takeViewSnapshot]):
* UIProcess/API/mac/WKViewInternal.h:
* UIProcess/PageClient.h:
* UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::takeViewSnapshot):
* UIProcess/WebPageProxy.h:
* UIProcess/ios/PageClientImplIOS.h:
* UIProcess/ios/PageClientImplIOS.mm:
(WebKit::PageClientImpl::takeViewSnapshot):
* UIProcess/mac/PageClientImpl.h:
* UIProcess/mac/PageClientImpl.mm:
(WebKit::PageClientImpl::takeViewSnapshot):
Adopt ViewSnapshot::create, return a PassRefPtr, and class-ify ViewSnapshot.

* UIProcess/ios/ViewGestureControllerIOS.mm:
(WebKit::ViewGestureController::beginSwipeGesture):
(WebKit::ViewGestureController::endSwipeGesture):
* UIProcess/mac/ViewGestureController.h:
* UIProcess/mac/ViewGestureControllerMac.mm:
(WebKit::ViewGestureController::shouldUseSnapshotForSize):
(WebKit::ViewGestureController::beginSwipeGesture):
(WebKit::ViewGestureController::endSwipeGesture):
Grab the ViewSnapshot directly from the WebBackForwardListItem, and adopt the new functions.

* UIProcess/ios/WebMemoryPressureHandlerIOS.mm:
(WebKit::WebMemoryPressureHandler::WebMemoryPressureHandler):
Rename discardSnapshots to discardSnapshotImages, because we're really only discarding
the images; the render tree size/background color "snapshot" remains and is useful.

* UIProcess/mac/ViewSnapshotStore.h:
(WebKit::ViewSnapshot::setRenderTreeSize):
(WebKit::ViewSnapshot::renderTreeSize):
(WebKit::ViewSnapshot::setBackgroundColor):
(WebKit::ViewSnapshot::backgroundColor):
(WebKit::ViewSnapshot::setDeviceScaleFactor):
(WebKit::ViewSnapshot::deviceScaleFactor):
(WebKit::ViewSnapshot::imageSizeInBytes):
(WebKit::ViewSnapshot::surface):
(WebKit::ViewSnapshot::size):
(WebKit::ViewSnapshot::creationTime):
Make ViewSnapshot a refcounted class.
Add create functions which take an image (or slot ID), and relevant sizes.
It is expected that a ViewSnapshot is created with an image, and it is only possible
to remove that image, never to replace it. A new ViewSnapshot is required in that case.
Add setters for things that ViewSnapshotStore sets on the snapshot after the PageClient
retrieves it from the view. Add getters for things that the ViewGestureControllers need.

Remove removeSnapshotImage, getSnapshot, and the snapshot map.

* UIProcess/mac/ViewSnapshotStore.mm:
(WebKit::ViewSnapshotStore::~ViewSnapshotStore):
(WebKit::ViewSnapshotStore::didAddImageToSnapshot):
(WebKit::ViewSnapshotStore::willRemoveImageFromSnapshot):
Manage m_snapshotCacheSize and m_snapshotsWithImages via didAddImageToSnapshot and willRemoveImageFromSnapshot.
willRemoveImageFromSnapshot will -always- be called before the ViewSnapshot is destroyed.

(WebKit::ViewSnapshotStore::pruneSnapshots):
Switch to a simple LRU eviction model. As previously mentioned, it's possible to do better, but
this is much less broken than the previous implementation.

(WebKit::ViewSnapshotStore::recordSnapshot):
(WebKit::ViewSnapshotStore::discardSnapshotImages):
(WebKit::ViewSnapshot::create):
(WebKit::ViewSnapshot::ViewSnapshot):
(WebKit::ViewSnapshot::~ViewSnapshot):
(WebKit::ViewSnapshot::hasImage):
(WebKit::ViewSnapshot::clearImage):
(WebKit::ViewSnapshot::asLayerContents):
If a surface is Empty when it comes back from being volatile, throw away the surface
and notify the Store to remove it from m_snapshotCacheSize (via clearImage()).

(WebKit::ViewSnapshotStore::removeSnapshotImage): Deleted.
(WebKit::ViewSnapshotStore::getSnapshot): Deleted.
(WebKit::ViewSnapshotStore::discardSnapshots): Deleted.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@170974 268f45cc-cd09-0410-ab3c-d52691b4dbfc
20 files changed:
Source/WebKit2/ChangeLog
Source/WebKit2/Shared/SessionState.h
Source/WebKit2/Shared/WebBackForwardListItem.h
Source/WebKit2/UIProcess/API/Cocoa/WKWebView.mm
Source/WebKit2/UIProcess/API/Cocoa/WKWebViewInternal.h
Source/WebKit2/UIProcess/API/mac/WKView.mm
Source/WebKit2/UIProcess/API/mac/WKViewInternal.h
Source/WebKit2/UIProcess/PageClient.h
Source/WebKit2/UIProcess/WebPageProxy.cpp
Source/WebKit2/UIProcess/WebPageProxy.h
Source/WebKit2/UIProcess/ios/PageClientImplIOS.h
Source/WebKit2/UIProcess/ios/PageClientImplIOS.mm
Source/WebKit2/UIProcess/ios/ViewGestureControllerIOS.mm
Source/WebKit2/UIProcess/ios/WebMemoryPressureHandlerIOS.mm
Source/WebKit2/UIProcess/mac/PageClientImpl.h
Source/WebKit2/UIProcess/mac/PageClientImpl.mm
Source/WebKit2/UIProcess/mac/ViewGestureController.h
Source/WebKit2/UIProcess/mac/ViewGestureControllerMac.mm
Source/WebKit2/UIProcess/mac/ViewSnapshotStore.h
Source/WebKit2/UIProcess/mac/ViewSnapshotStore.mm