Bug 215535 – Use std::call_once + LazyNeverDestroyed to initialize complex data structures

• Component: New Bugs
• Status: RESOLVED FIXED

[Yusuke Suzuki]

Use std::call_once + LazyNeverDestroyed to initialize complex data structures

[Yusuke Suzuki]

Created attachment 406657 [details]
Patch

[Yusuke Suzuki]

Created attachment 406658 [details]
Patch

[Yusuke Suzuki]

<rdar://problem/66774266>

[Yusuke Suzuki]

Created attachment 406659 [details]
Patch

[Mark Lam]

Comment on attachment 406659 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=406659&action=review

r=me if EWS bots are happy.

> Source/WTF/wtf/Logger.cpp:35
> +Lock loggerObserverLock { };

Don't need the { }.

[Yusuke Suzuki]

Created attachment 406660 [details]
Patch

[Yusuke Suzuki]

Committed r265735: <https://trac.webkit.org/changeset/265735>

[Darin Adler]

Comment on attachment 406660 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=406660&action=review

> Source/WTF/wtf/Language.cpp:87
> -    static NeverDestroyed<Vector<String>> override;
> +    static LazyNeverDestroyed<Vector<String>> override;
> +    static std::once_flag onceKey;
> +    std::call_once(onceKey, [&] {
> +        override.construct();
> +    });
>      return override;

This doesn't seem like a useful change. The reference counts on the strings aren’t thread safe either. Same might apply for some of the other examples in this patch, but this one is clear cut case. Unless I am missing something?

[Yusuke Suzuki]

Comment on attachment 406660 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=406660&action=review

>> Source/WTF/wtf/Language.cpp:87
>>      return override;
> 
> This doesn't seem like a useful change. The reference counts on the strings aren’t thread safe either. Same might apply for some of the other examples in this patch, but this one is clear cut case. Unless I am missing something?

The goal of this patch is fixing <rdar://problem/66774266> (RunLoop). So the other part is mechanical change.
I changed all `NeverDestroyed<ComplexData>` code in WTF mechanically to prevent the above type of issues.
If some of them are proven that this is not thread-related, I think we can change it to MainThreadNeverDestroyed<> etc.

[Yusuke Suzuki]

Comment on attachment 406660 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=406660&action=review

>>> Source/WTF/wtf/Language.cpp:87
>>>      return override;
>> 
>> This doesn't seem like a useful change. The reference counts on the strings aren’t thread safe either. Same might apply for some of the other examples in this patch, but this one is clear cut case. Unless I am missing something?
> 
> The goal of this patch is fixing <rdar://problem/66774266> (RunLoop). So the other part is mechanical change.
> I changed all `NeverDestroyed<ComplexData>` code in WTF mechanically to prevent the above type of issues.
> If some of them are proven that this is not thread-related, I think we can change it to MainThreadNeverDestroyed<> etc.

Filed in https://bugs.webkit.org/show_bug.cgi?id=215546