Re: Resource Owner reassign Locks

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Andres Freund <andres(at)anarazel(dot)de>
Cc: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Resource Owner reassign Locks
Date: 2015-08-25 18:53:07
Message-ID: 16303.1440528787@sss.pgh.pa.us
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Andres Freund <andres(at)anarazel(dot)de> writes:
> On 2015-08-25 14:33:25 -0400, Tom Lane wrote:
>> (IOW, yeah, certainly third-party code could create a new *instance* of
>> the ResourceOwner data structure, but they would not have any knowledge of
>> what's inside unless they had hacked the core code.)

> What I was thinking is that somebody created a new resowner, did
> something, and then called LockReleaseCurrentOwner() (because no locks
> are needed anymore), or LockReassignCurrentOwner() (say you want to
> abort a subtransaction, but do *not* want the locks to be released).

> Anyway, I slightly lean towards having wrappers, you strongly against,
> so that makes it an easy call.

Well, I'm not "strongly" against them, just trying to understand whether
there's a plausible argument that someone is calling these functions from
extensions. I'm not hearing one ... for one thing, I don't believe there
are any extensions playing games with transaction/lock semantics. (My
Salesforce colleagues have done some of that, and no you can't get far
without changing the core code.)

regards, tom lane

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