From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 23 Jan 2017 21:11:48 GMT
Subject: Re: [PATCH v2 22/27] attr: eliminate global check_all_attr array
Message-ID: <xmqq7f5lqy5n.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <20170123203525.185058-23-bmwill@google.com>

Brandon Williams <bmwill@google.com> writes:

> Currently there is a reliance on 'check_all_attr' which is a global
> array of 'attr_check_item' items which is used to store the value of
> each attribute during the collection process.
>
> This patch eliminates this global and instead creates an array per
> 'attr_check' instance which is then used in the attribute collection
> process.  This brings the attribute system one step closer to being
> thread-safe.

Hmph, how close is "closer"?  

My understanding of this is that a codepath that has a single
"attr_check" can be executing simultaneously by multiple threads,
and "attr_check" is meant to contain read-only stuff sharable by
them.  Unless this check_all_attr is tied to the attr_result (which
in turn is tied to each invocation and typically is on stack), the
resulting code would not be safe, right?