[webkit-changes] [WebKit/WebKit] 7f170e: The first RemoteLayerTreeDrawingAreaProxy::commitL...

[mattwoodrow]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 7f170efe52d7a390011fb9434c7c7f220ceb03e4
      https://github.com/WebKit/WebKit/commit/7f170efe52d7a390011fb9434c7c7f220ceb03e4
  Author: Matt Woodrow <mattwoodrow at apple.com>
  Date:   2023-05-25 (Thu, 25 May 2023)

  Changed paths:
    M Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.h
    M Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.messages.in
    M Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.mm
    M Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.mm

  Log Message:
  -----------
  The first RemoteLayerTreeDrawingAreaProxy::commitLayerTree after being idle is always considered 'missed'.
https://bugs.webkit.org/show_bug.cgi?id=257005
<rdar://problem/109543927>

Reviewed by Simon Fraser.

 Each RemoteLayerTreeDrawingAreaProxy::commitLayerTree IPC messages results in a reply displayDidRefresh message being sent back to the WebProcess (once the display link fires) to trigger the next rendering update.

If the next commitLayerTree isn't received before the following display link callback, it goes into a 'missed commit' state, assuming the rendering update took more than one interval to render. In missed commit state, when the commitLayerTree eventually arrives, the displayDidRefresh reply is sent immediately, rather than waiting for the next display link callback.

This can't differentiate between a slow rendering update, and an idle WebContent process that decided it didn't need to do a rendering update at all. When we do resume from idle, we'll always be in missed commit state, and do a second rendering update (attempt) immediately, for no real benefit.

This patch adds a new 'commitLayerTreeNotTriggered' message so the WebContent process can notify the UI process that it isn't going to do a rendering update, and to go into an idle state.
It also renames DidUpdateMessageState a bit to more accurately match the IPC message/function names that are being waited on.

* Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.h:
* Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.messages.in:
* Source/WebKit/UIProcess/RemoteLayerTree/RemoteLayerTreeDrawingAreaProxy.mm:
(WebKit::RemoteLayerTreeDrawingAreaProxy::commitLayerTreeNotTriggered):
(WebKit::RemoteLayerTreeDrawingAreaProxy::commitLayerTreeTransaction):
(WebKit::RemoteLayerTreeDrawingAreaProxy::didRefreshDisplay):
(WebKit::RemoteLayerTreeDrawingAreaProxy::waitForDidUpdateActivityState):
* Source/WebKit/WebProcess/WebPage/RemoteLayerTree/RemoteLayerTreeDrawingArea.mm:
(WebKit::RemoteLayerTreeDrawingArea::displayDidRefresh):

Canonical link: https://commits.webkit.org/264538@main