[webkit-reviews] review granted: [Bug 31639] Add asserts to RefCounted to make sure ref/deref happens on the right thread. : [Attachment 91374] Patch

[bugzilla-daemon at webkit.org]

Darin Adler <darin at apple.com> has granted David Levin <levin at chromium.org>'s
request for review:
Bug 31639: Add asserts to RefCounted to make sure ref/deref happens on the
right thread.
https://bugs.webkit.org/show_bug.cgi?id=31639

Attachment 91374: Patch
https://bugs.webkit.org/attachment.cgi?id=91374&action=review

------- Additional Comments from Darin Adler <darin at apple.com>
View in context: https://bugs.webkit.org/attachment.cgi?id=91374&action=review

> Source/JavaScriptCore/wtf/RefCounted.h:77
> +	   UNUSED_PARAM(&mutex);
> +#ifndef NDEBUG
> +	   m_verifier.setMutexMode(mutex);
> +#endif

We should only use UNUSED_PARAM when it’s actually unused. So it should be in
an #else. But, better, I suggest writing it like this:

    void setMutexForVerifier(Mutex&);

    ...

    #ifdef NDEBUG
    inline void RefCountedBase::setMutexForVerifier(Mutex&)
    {
    }
    #else
    inline void RefCountedBase::setMutexForVerifier(Mutex& mutex)
    {
	m_verifier.setMutexMode(mutex);
    }
    #endif

Or like this:


    #ifdef NDEBUG
    void setMutexForVerifier(Mutex&) { }
    #else
    void setMutexForVerifier(Mutex& mutex)
    {
	m_verifier.setMutexMode(mutex);
    }
    #endif

> Source/JavaScriptCore/wtf/ThreadRestrictionVerifier.h:95
> +    // Is it ok to use the object at this moment on the current thread?

Normally "ok" is spelled "OK".

> Source/JavaScriptCore/wtf/ThreadRestrictionVerifier.h:104
> +	       // isMainThread() is way faster than currentThread() on many
platforms, so use it first.
> +	       return (m_isOwnedByMainThread && isMainThread()) ||
(m_owningThread == currentThread());

If m_isOwnedByMainThread is false, then m_owningThread is not something we
should look at; sure, it’s initialized to 0, but I’m not sure that’s even
meaningful. So I suggest writing:

    return m_isOwnedByMainThread ? isMainThread() : (m_owningThread ==
currentThread());

Or factoring the code some other way, but doing that same effective check. I
don’t think it’s good to look at m_owningThread at all if it wasn’t set to a
thread.