Re: pgsql: Make WaitLatch's WL_POSTMASTER_DEATH result trustworthy; simplif

Peter Geoghegan <peter(at)2ndquadrant(dot)com> writes:
> On 10 May 2012 19:35, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Remove weasel wording about falsely-set result bits from
>> WaitLatch's API contract.

> Aren't those weasel words still applicable to the case where sock !=
> PGINVALID_SOCKET ?

I don't think so. WaitLatch is honestly reporting the result of select
or poll; code that doesn't work with it wouldn't work with the native
OS facilities either. The only case that is really a problem here is
where we make the logical leap from "socket possibly readable" to
"postmaster is dead".

I think what that Linux man page is advising is that you not assume that
a blocking-mode read() won't block, which AFAIK is something we don't
do; we always use non-block mode on sockets we don't wish to block on.

regards, tom lane