August 2019 - webkit-dev - lists.webkit.org

PSA: Bit fields won't be packed on Windows if you mix types
by Ryosuke Niwa 04 Sep '20

04 Sep '20

Hi, Unlike gcc and clang, MSVC pads each consecutive member variables of the same type in bitfields. e.g. if you have: struct AB { unsigned m_1 : 31; bool m_2 : 1; } then *MSVC pads m_1 and allocates sizeof(unsigned) * 2 for AB* whereas gcc and clang only allocate sizeof(unsigned) * 1 for AB. This is *not a compiler bug*. It's a spec. compliant behavior, and may in fact have a better run-time performance in some situations. However, for core objects like RenderObject and InlineBox, allocating extra 4-8 bytes per each object is prohibitory expensive. In such cases, please *use the same POD type for all bitfield member variables*. (Storage class classifiers and variable qualifiers seem to have no effect on how variables are packed; e.g. mutable, const, etc...). For example, MSVC will allocate sizeof(unsigned) * 1 for AB if we rewrite the above code as: struct AB { unsigned m_1 : 31; unsigned m_2 : 1; } When you're making this change, *be sure to audit all code that assigns a non-boolean value to m_2* because implicit type coercion into boolean is no longer in effect. For example, AB ab; ab.m_2 = 2; puts(ab.m_2 ? "true" : "false"); will print "true" before the change and will print "false" after the change. An easy way to ensure you've audited all such code is to add getters and setters for all bitfield member variables or wrap them in a special structure or class as done in http://trac.webkit.org/changeset/103353 and http://trac.webkit.org/changeset/104254. Best regards, Ryosuke Niwa Software Engineer Google Inc.

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Support "registerProtocolHandler" in WebKit2
by Gyuyoung Kim 20 Apr '20

20 Apr '20

Hello, I would like to listen what do you think to support 'registerProtocolHandler' in WebKit2. This feature is to execute web content through registered custom protocol. - For example, web content can register "mailto" custom protocol using this feature, <script> navigator.registerProtocolHandler("mailto", "https://mail.naver.com/", "Web Mail"); </script> <html> <head> <title>Web Protocol Handler Sample - Test</title> </head> <body> <p>Send an email : <a href="mailto://">this !</a></p> </body> </html> Besides this feature has been supported by Mozilla and Chromium (From Mozilla 3.0, Chromium 13). - https://developer.mozilla.org/en-US/docs/Web/API/Navigator/registerProtocol… - https://developer.mozilla.org/en/docs/Web-based_protocol_handlers The feature is included in the W3C recommendation 28 released on Oct. 2014. - W3C spec : http://www.w3.org/TR/html5/webappapis.html#custom-handlers IIRC, some WebKit1 ports supported this feature though, those ports were deprecated. Now WebKit port supports this feature no more. There is a very old bug to support this feature though, it wasn't maintained so far. Recently I updated it based on latest WebKit. - https://bugs.webkit.org/show_bug.cgi?id=92749 Feel free to give me any feedback about this feature. Gyuyoung.

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Changing the svn commit hook to allow tabs for tests.
by Keith Miller 04 Apr '20

04 Apr '20

Hi all, I don’t know if this is possible but it would be great if some sub-directories could be excluded from the no-tabs pre-commit hook. For example, there are many test262 tests that contain tabs, either because they intentionally try to test parsing tab characters or because they were written by someone that used them. Regardless, it’s pretty inconvenient to add the svn attribute that allows tabs every time I update the tests. Since svn properties can’t apply to directories, as far as I know, there’s no way to add the “allow-tabs” property to the entire test262 directory. Alternatively, we could remove the pre-commit hook as tabs should be caught by the style-checker anyway. This is a more contentious choice so I’m not proposing it as the first option unless someone else wants to push for it. Cheers, Keith Miller

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Is anyone maintaining Nicosia scrolling code?
by Simon Fraser 27 Feb '20

27 Feb '20

There’s a bunch of code in Source/WebCore/page/scrolling/nicosia/ that I keep breaking with scrolling tree refactoring. Most of it it stubs. Is anyone maintaining this code, because it obviously doesn’t work, and I’d like to remove the maintenance burden. Simon

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[CSSOM View] Smooth scroll behavior via CSS property / DOM scroll* API
by Frédéric Wang 13 Feb '20

13 Feb '20

Hi all, This email is to announce that I have started to work on (programmatic) smooth scrolling in WebKit from the CSSOM View specification [1]. To use this effect, web developers can pass a behavior parameter (auto, smooth, or instant) to Element.scroll, Element.scrollTo, Element.scrollBy, Element.scrollIntoView, Window.scroll, Window.scrollTo or Window.scrollBy [2]. When behavior is auto, the instant/smooth characteristic is actually taken from the value of a new CSS scroll-behavior property [3]. This new feature will be protected by a compile flag (enabled by default) and a runtime flag (an experimental feature). If you are interested, you can follow advancement on Bugzilla [4]. Incidentally (and since that was convenient to do it before) I also added some basic support for new ScrollIntoView options [5] [6] that allow to specify how you want the revealed element to be aligned with respect to its scrollable ancestors. Cheers, Frédéric [1] https://drafts.csswg.org/cssom-view [2] https://drafts.csswg.org/cssom-view/#dictdef-scrolloptions [3] https://drafts.csswg.org/cssom-view/#propdef-scroll-behavior [4] https://bugs.webkit.org/show_bug.cgi?id=188043 [5] https://bugs.webkit.org/show_bug.cgi?id=189258 [6] https://drafts.csswg.org/cssom-view/#dictdef-scrollintoviewoptions

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WebKit project in Coverity
by Carlos Alberto Lopez Perez 09 Jan '20

09 Jan '20

Hi, Coverity is an static analysis tool that allows to find bugs and vulnerabilities on the source code via static analysis. For open source projects, they offer free usage of their platform. The WebKit project is already registered there since a while. [1] To read the reports in detail or run new scans you have to be member of the WebKit project in Coverity. I happen to be one of the admins there, and I will happily grant you access to this platform if you are a WebKit committer (listed in contributors.json). So if you are interested in this, just send me an email requesting access. Regards ------- [1] https://scan.coverity.com/projects/webkit

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Moving to Python 3
by Jonathan Bedard 09 Oct '19

09 Oct '19

Hello WebKit developers, Now that the Catalina developer seeds are available, it is official that the new Mac developer tools come with Python 3. As a result, we need to continue the ongoing discussion about migrating our Python 2.7 scripts to Python 3. I propose that, over the next 9 months, we do the following: 1. Make any no-cost Python 3 compatibility changes, in particular - print foo -> print(foo) - import .foo -> import webkitpy.foo 2. Convert any scripts not used in automation to Python 3 ASAP (scripts like bisect-builds, block-spammers, compare-results) 3. Make most Python 3 compatibility changes which sacrifice efficiency, subject to a case-by-case audit. These would be things like: - dict.iteritems() -> dict.items() - dict.items() -> list(dict.items()) 4. Install Python 3 on macOS Sierra and Mojave bots 5. Convert peripheral automation scripts to Python 3 1-by-1 (scripts like clean-webkit, merge-results-json, webkit-patch) 6. Convert testing scripts and webkitpy to Python 3 in a single change The trouble I foresee us encountering with any scheme which attempts a conversion which retains both Python 2.7 and Python 3 compatibility is code like this: for expectation_string, expectation_enum in test_expectations.TestExpectations.EXPECTATIONS.iteritems(): ... In this code, the EXPECTATIONS dictionary is thousands of elements long. In Python 2.7, iteritems() gives us an iterator instead of creating a new list, like items() would. In Python 3, iteritems() doesn’t exist, but items() does, and now gives us an iterator instead of creating a new list. The trouble here is that, in this case, creating a new list will be very expensive, expensive enough that we might manage to impact the testing run. There isn’t really an elegant way around this problem if we want to support both Python 2.7 and Python 3, other than defining different code paths for each language. There are other small gotchas as well. For example, ‘%’ is no longer a protected character, which can actually change the behavior of regexes. That’s why I think it’s better to just try and directly convert things instead of attempting to be compatible with both Python 2.7 and Python 3. Jonathan

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Requesting feedback about EWS comments on Bugzilla bugs
by Aakash Jain 26 Sep '19

26 Sep '19

Hi Everyone, I am gathering feedback about EWS - specially about the comments which EWS makes on the Bugzilla bugs. Currently, the comments are not very user-friendly/polished/readable and are sometimes very noisy (e.g.: 72 comments and 36 attachments by EWS in https://bugs.webkit.org/show_bug.cgi?id=177484 <https://bugs.webkit.org/show_bug.cgi?id=177484>). I am working on improving them and looking for specific ideas/feedback. Few ideas which I am considering: 1) Do not upload archive (for layout-test-results) on bugzilla, instead upload it to another server, unzip it and post a link to the results.html. Pros: a) Engineers won't have to download the attachment, unzip it, look for failures, and then delete it from their disk. They can simply click the url to view the results. b) This approach will also reduce 2 comments per failure to 1 comment. Currently there are two comments per failure, one for failure details, second for bugzilla attachment. 2) Aggregate comments from multiple queues. Pros: less noise Cons: comments would get delayed while waiting for results from other queues. (Also might be little complex to implement) 3) Improve the text of the comments to make them more readable (specific ideas are welcome). 4) When a patch becomes 'obsolete', tag the corresponding EWS comments as 'obsolete', so that they will be hidden. 5) Do not comment on bugzilla bug at all, instead send email to the author of the patch. Pros: less noisy, also this will allow to include more detailed information about the failure in email. Cons: reviewers would have to click status-bubbles to see the failures, failure information is not immediately present in the comments. What do you guys think? Thanks Aakash

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Introducing brand new EWS
by Aakash Jain 04 Sep '19

04 Sep '19

Introducing brand new EWS with EWS for API Tests (for macOS and iOS) and EWS for WebKitPerl Tests! Starting today, when you upload a patch to bugs.webkit.org <http://bugs.webkit.org/>, you will see few more bubbles (for API tests and webkitperl tests). You might also see additional button 'Submit to new EWS' (if the patch doesn't have r? flag). The new EWS comes with many new features and there are lot more I want to add. But, I don't want you guys to wait more to start getting the benefits. That's why I am rolling it out in phases, starting with EWS for API Tests and WebKitPerl Tests. These are tests which are not currently covered by the existing EWS. Next step would be to move queues from existing EWS to new EWS one by one, with the eventual goal of moving over everything to new EWS. Why new EWS? The existing EWS has certain architectural limitations. One of the prominent limitation is that there is no concept of building and testing the patch on different queues. If we have three queues: WK1 tests, WK2 tests and API tests, all three queues would need to compile WebKit independently. So WebKit would be compiled thrice instead of once. This is inefficient and thereby require more hardware. The new EWS has separate builder and tester queues. Builder queues build once and upload the archive. Multiple tester queues download that same archive and run tests on that. That way WebKit is compiled only once, and re-used on multiple tester queues. This improves system efficiency and allows us to add new test queues with substantially less hardware. The new EWS uses Buildbot at the back-end, which is a production-level CI system. It is easier to maintain and automatically provide various features like historical build logs, real-time log streaming, easier bot management, ability to retry a build etc. Plus, it’s a system most of you are already familiar with (build.webkit.org <http://build.webkit.org/>). How can you contribute: If you are interested in contributing, the source code is located at: ews-build (Buildbot): Tools/BuildSlaveSupport/ews-build ews-app (web-app): Tools/BuildSlaveSupport/ews-app Detailed instructions are at: https://trac.webkit.org/wiki/EarlyWarningSystem#ContributingtoEarlyWarningS… <https://trac.webkit.org/wiki/EarlyWarningSystem#ContributingtoEarlyWarningS…> Upcoming features: - status-bubble should display position in queue https://bugs.webkit.org/show_bug.cgi?id=196607 <https://bugs.webkit.org/show_bug.cgi?id=196607> - EWS should comment on Bugzilla bugs about failures https://bugs.webkit.org/show_bug.cgi?id=196598 <https://bugs.webkit.org/show_bug.cgi?id=196598> - EWS should have a way to retry a patch https://bugs.webkit.org/show_bug.cgi?id=196599 <https://bugs.webkit.org/show_bug.cgi?id=196599> - Security EWS https://bugs.webkit.org/show_bug.cgi?id=196605 <https://bugs.webkit.org/show_bug.cgi?id=196605> If you notice any issue, please feel free to file bugs (and assign to me). Thanks & Regards Aakash Jain

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Logging in iOS simulator
by Ken Russell 03 Sep '19

03 Sep '19

Hi WebKit developers, Is it possible to log from the WebKit build for the iOS Simulator? I've had difficulty getting LOG() statements to work even on macOS, so just tried NSLog, but the result didn't show up in the system log when opened from the simulator. Thanks, -Ken

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