commit 048059405ddca0dc8d102a4d5d283c141339d496
author wenson_hsieh@apple.com <wenson_hsieh@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> Wed Jul 18 17:08:46 2018 +0000
committer wenson_hsieh@apple.com <wenson_hsieh@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> Wed Jul 18 17:08:46 2018 +0000
tree 8a7ef7e8888eb9419afc759014c22c0cc504dee2
parent e487e8d27c09feff5c187176d4f5b5df4b66147b

Add SPI to defer running async script until after document load
https://bugs.webkit.org/show_bug.cgi?id=187748
<rdar://problem/42317378>

Reviewed by Ryosuke Niwa and Tim Horton.

Source/WebCore:

On watchOS, we currently observe that time-consuming async scripts can block the first paint of Reader, leaving
the user with a blank screen for tens of seconds. One way to mitigate this is to defer async script execution
until after document load (i.e. the same timing as DOMContentLoaded).

This patch introduces an SPI configuration allowing internal clients to defer execution of asynchronous script
until after document load; this, in combination with the parser yielding token introduced in r233891, allows
Safari on watchOS to avoid being blocked on slow script execution before the first paint of the Reader page on
most article-like pages. See below for more details.

Test: RunScriptAfterDocumentLoad.ExecutionOrderOfScriptsInDocument

* dom/Document.cpp:
(WebCore::Document::shouldDeferAsynchronousScriptsUntilParsingFinishes const):
(WebCore::Document::finishedParsing):

Notify ScriptRunner when the Document has finished parsing, and is about to fire DOMContentLoaded.

* dom/Document.h:
* dom/ScriptRunner.cpp:
(WebCore::ScriptRunner::documentFinishedParsing):

When the document is finished parsing, kick off the script execution timer if needed to run any async script
that has been deferred.

(WebCore::ScriptRunner::notifyFinished):
(WebCore::ScriptRunner::timerFired):

Instead of always taking from the list of async scripts to execute, check our document to see whether we should
defer this until after document load. If so, ignore `m_scriptsToExecuteSoon`.

* dom/ScriptRunner.h:
* page/Settings.yaml:

Add a WebCore setting for this behavior.

Source/WebKit:

Add plumbing for a new ShouldDeferAsynchronousScriptsUntilAfterDocumentLoad configuration that determines
whether async script execution should be deferred until document load (i.e. DOMContentLoaded). This
configuration defaults to NO on all platforms. See WebCore ChangeLog for more detail.

* Shared/WebPreferences.yaml:
* UIProcess/API/Cocoa/WKWebView.mm:
(-[WKWebView _initializeWithConfiguration:]):
* UIProcess/API/Cocoa/WKWebViewConfiguration.mm:
(-[WKWebViewConfiguration init]):
(-[WKWebViewConfiguration copyWithZone:]):
(-[WKWebViewConfiguration _shouldDeferAsynchronousScriptsUntilAfterDocumentLoad]):
(-[WKWebViewConfiguration _setShouldDeferAsynchronousScriptsUntilAfterDocumentLoad:]):
* UIProcess/API/Cocoa/WKWebViewConfigurationPrivate.h:

Tools:

Add an API test to verify that when the deferred async script configuration is set, async scripts will be
executed after the DOMContentLoaded event.

* TestWebKitAPI/TestWebKitAPI.xcodeproj/project.pbxproj:
* TestWebKitAPI/Tests/WebKitCocoa/RunScriptAfterDocumentLoad.mm: Added.
(TEST):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@233915 268f45cc-cd09-0410-ab3c-d52691b4dbfc