Re: getaddrinfo() for threading instead of gethostbyname()

OK, the thread test program is read for platform testing,
src/tools/thread_test. You will find the README, Makefile tests, and
program output to be very clear and almost error-proof.

Please run it on platforms we support and report back. Thanks.

---------------------------------------------------------------------------

Bruce Momjian wrote:
> When FreeBSD didn't have gethostbyname_r(), and gethostbyname() wasn't
> thread-safe, Marc asked around and found out that the threaded solution
> for this is to use getaddrinfo(). This makes sense because
> getaddrinfo() is described as:
>
> getaddrinfo () function is defined for protocol-independent nodename-
> to-address translation. It performs functionality of gethostbyname(3)
> and getservbyname(3), in more sophisticated manner.
>
> A number of platforms have getpwuid_r(), but not gethostbyname_r(). I
> now realize it is because they are assuming you arew using getaddrinfo(),
> which has freeaddrinfo() to free the allocated memory in a thread-safe
> manner.
>
> Right now, we call gethostname() from two places:
>
> port/getaddrinfo() (if backend)
> port/thread.c::pqGethostbyname()
>
> and pqGethostbyname() (thread-safe) is called only by:
>
> port/getaddrinfo() (if frontend)
> libpq/fe-secure.c
>
> If we convert fe-secure.c to use getaddrinfo(), then all host address
> lookups go through getaddrinfo().
>
> Then, if we don't need our port/getaddrinfo(), we don't care about a
> non-thread-safe gethostbyname() on that platform. This improves our
> thread-safe support. Specifically, it prevents host name lookups from
> be serialized by our pthread locks.
>
> Once everything goes through getaddrinfo(), I will modify my thread test
> program to test gethostbyname() threading _only_ if getaddrinfo()
> doesn't exist.
>
> --
> Bruce Momjian | http://candle.pha.pa.us
> pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
> + If your life is a hard drive, | 13 Roberts Road
> + Christ can be your backup. | Newtown Square, Pennsylvania 19073
>
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--
Bruce Momjian | http://candle.pha.pa.us
pgman(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073