Make it possible to safely access CALayers and PlatformCALayerCocoa objects on the scrolling thread

[Simon Fraser (smfr)]

Make it possible to safely access CALayers and PlatformCALayerCocoa objects on the scrolling thread

[Simon Fraser (smfr)]

Created attachment 392644 [details]
Patch

[Radar WebKit Bug Importer]

<rdar://problem/60106163>

[Tim Horton]

Comment on attachment 392644 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=392644&action=review

> Source/WebCore/ChangeLog:13
> +        when pushing GraphicsLayer changes to CA, and when destroying GraphicsLayers which tears down their associated

What about PlatformCALayerCustom... are we sure they're not mutated in other cases than these?

> Source/WebCore/page/scrolling/ScrollingTree.h:220
> +private:

Why? This was already the case

[Antti Koivisto]

Comment on attachment 392644 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=392644&action=review

> Source/WebCore/platform/graphics/ca/cocoa/PlatformCALayerCocoa.mm:88
> +static Lock& layerToPlatformLayerMapMutex()
> +{
> +    static LazyNeverDestroyed<Lock> mutex;
> +    static std::once_flag initializeMutex;
> +    std::call_once(initializeMutex, [] {
> +        mutex.construct();
> +    });
> +    return mutex.get();
> +}

I think you can just do 

static Lock lock;

[Simon Fraser (smfr)]

https://trac.webkit.org/changeset/258006/webkit