]> granicus.if.org Git - postgresql/commit
Introduce latches. A latch is a boolean variable, with the capability to
authorHeikki Linnakangas <heikki.linnakangas@iki.fi>
Sat, 11 Sep 2010 15:48:04 +0000 (15:48 +0000)
committerHeikki Linnakangas <heikki.linnakangas@iki.fi>
Sat, 11 Sep 2010 15:48:04 +0000 (15:48 +0000)
commit2746e5f21d4dce07ee55c58b2035ff631470577f
tree421c208e30bc3ac7cae8c6282a1304595dfaa625
parent81624db39aa7501690aab71a68af689df78b71e8
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.
13 files changed:
configure
configure.in
src/backend/access/transam/twophase.c
src/backend/access/transam/xact.c
src/backend/port/Makefile
src/backend/port/unix_latch.c [new file with mode: 0644]
src/backend/port/win32_latch.c [new file with mode: 0644]
src/backend/replication/walsender.c
src/backend/storage/ipc/ipci.c
src/backend/storage/ipc/procsignal.c
src/include/replication/walsender.h
src/include/storage/latch.h [new file with mode: 0644]
src/tools/msvc/Mkvcbuild.pm