Re: pgsql: Introduce latches.

Portions Copyright (c) 1994, Regents of the University of California

Is that line needed for new files introduced by the Community?

Regards,

On Sat, Sep 11, 2010 at 11:48 AM, Heikki Linnakangas
<heikki(at)postgresql(dot)org>wrote:

> Log Message:
> -----------
> Introduce latches. A latch is a boolean variable, with the capability to
> wait until it is set. Latches can be used to reliably wait until a signal
> arrives, which is hard otherwise because signals don't interrupt select()
> on some platforms, and even when they do, there's race conditions.
>
> On Unix, latches use the so called self-pipe trick under the covers to
> implement the sleep until the latch is set, without race conditions. On
> Windows, Windows events are used.
>
> Use the new latch abstraction to sleep in walsender, so that as soon as
> a transaction finishes, walsender is woken up to immediately send the WAL
> to the standby. This reduces the latency between master and standby, which
> is good.
>
> Preliminary work by Fujii Masao. The latch implementation is by me, with
> helpful comments from many people.
>
> Modified Files:
> --------------
> pgsql:
> configure (r1.685 -> r1.686)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure?r1=1.685&r2=1.686
> )
> configure.in (r1.633 -> r1.634)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/configure.in?r1=1.633&r2=1.634
> )
> pgsql/src/backend/access/transam:
> twophase.c (r1.63 -> r1.64)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/twophase.c?r1=1.63&r2=1.64
> )
> xact.c (r1.298 -> r1.299)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/access/transam/xact.c?r1=1.298&r2=1.299
> )
> pgsql/src/backend/port:
> Makefile (r1.28 -> r1.29)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/Makefile?r1=1.28&r2=1.29
> )
> pgsql/src/backend/replication:
> walsender.c (r1.29 -> r1.30)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/replication/walsender.c?r1=1.29&r2=1.30
> )
> pgsql/src/backend/storage/ipc:
> ipci.c (r1.104 -> r1.105)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/ipci.c?r1=1.104&r2=1.105
> )
> procsignal.c (r1.7 -> r1.8)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/storage/ipc/procsignal.c?r1=1.7&r2=1.8
> )
> pgsql/src/include/replication:
> walsender.h (r1.4 -> r1.5)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/replication/walsender.h?r1=1.4&r2=1.5
> )
> pgsql/src/tools/msvc:
> Mkvcbuild.pm (r1.59 -> r1.60)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/tools/msvc/Mkvcbuild.pm?r1=1.59&r2=1.60
> )
>
> Added Files:
> -----------
> pgsql/src/backend/port:
> unix_latch.c (r1.1)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/unix_latch.c?rev=1.1&content-type=text/x-cvsweb-markup
> )
> win32_latch.c (r1.1)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/port/win32_latch.c?rev=1.1&content-type=text/x-cvsweb-markup
> )
> pgsql/src/include/storage:
> latch.h (r1.1)
> (
> http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/include/storage/latch.h?rev=1.1&content-type=text/x-cvsweb-markup
> )
>
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