Re: [PATCH] V3: Idle in transaction cancellation

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Robert Haas <robertmhaas(at)gmail(dot)com>
Cc: Greg Smith <greg(at)2ndquadrant(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, Alvaro Herrera <alvherre(at)commandprompt(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>, Kevin Grittner <kevin(dot)grittner(at)wicourts(dot)gov>
Subject: Re: [PATCH] V3: Idle in transaction cancellation
Date: 2010-12-16 20:18:58
Message-ID: 11435.1292530738@sss.pgh.pa.us
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Robert Haas <robertmhaas(at)gmail(dot)com> writes:
> Hmm. It's seeming to me that what we want to do is something like this:

> 1. If an error is thrown while DoingCommandRead, it gets upgraded to
> FATAL. I don't think we have much choice about this because, per your
> previous comments, we can't longjmp() here without risking protocol
> breakage, and we certainly can't return from an elog(ERROR) or
> ereport(ERROR).

Um, if that's the ground rules then we have no advance over the current
situation.

I guess you misunderstood what I said. What I meant was that we cannot
longjmp *out to the outer level*, ie we cannot take control away from
the input stack. We could however have a TRY block inside the interrupt
handler that catches and handles (queues) any errors occurring during
transaction abort. As long as we eventually return control to openssl
I think it should work. (Hm, but I wonder whether there are any hard
timing constraints in the ssl protocol ... although hopefully xact abort
won't ever take long enough that that's a real problem.)

regards, tom lane

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