Bug 166778 – The ObjC API's JSVirtualMachine's map tables needs to be guarded by a lock.

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Mark Lam]

Now that we have a concurrent GC, access to JSVirtualMachine's m_externalObjectGraph and m_externalRememberedSet needs to guarded by a lock since both the GC marker thread and the mutator thread may access them at the same time.

[Mark Lam]

<rdar://problem/29759165>

[Mark Lam]

<rdar://problem/29761198>

This is the correct radar.  The previous one was a mistake.

[Mark Lam]

Created attachment 298230 [details]
proposed patch.

[Filip Pizlo]

Comment on attachment 298230 [details]
proposed patch.

View in context: https://bugs.webkit.org/attachment.cgi?id=298230&action=review

LGTM

> Source/JavaScriptCore/API/JSVirtualMachine.mm:160
> +    std::lock_guard<Lock> lock(m_externalDataMutex);

It's cool to use std::lock_guard, though I've been using:

auto locker = holdLock(m_externalDataMutex);

recently, since holdLock() is generic over the lock type without requiring you to say what the lock type is.

I don't think it's a big deal, though.

[Mark Lam]

Thanks for the review.  I've updated it to use holdLock instead.

Patch landed in r210458: <http://trac.webkit.org/r210458>.