[RFC] Use mutexes by default in db_open()

[Amitay Isaacs]

On Wed, May 31, 2017 at 5:11 PM, Ralph Böhme <slow at samba.org> wrote:

> On Wed, May 31, 2017 at 04:12:18PM +1000, Amitay Isaacs wrote:
> > On Wed, May 31, 2017 at 3:29 PM, Ralph Böhme <slow at samba.org> wrote:
> >
> > > Hi Amitay
> > >
> > > On Mon, May 29, 2017 at 12:21:50PM +1000, Amitay Isaacs wrote:
> > > > Here's the summary of what I would like to propose:
> > > >  1. CTDB ignores tdb_flags specified in DB_ATTACH controls, tdb
> flags are
> > > > calculated based on the database model (or specific DB_ATTACH
> control)
> > > >  2. For volatile databases, mutexes will be enabled by default
> > > > (TDBMutexEnabled=1) when samba enables mutexes by default
> > > > (dbwrap_tdb_mutexes:*=true)
> > >
> > > sorry, but I fail to understand how 1 and 2 could work together. If,
> > > according
> > > to 1, ctdb ignores the tdb_flags in the DB_ATTACH control, how is
> > > disabling of
> > > mutexes handled in step 2 when dbwrap_tdb_mutexes:*=false is set in
> > > smb.conf
> > > (while TDBMutexEnabled=1 still set for ctdb) ?
> > >
> > > *scratches head*
> > >
> >
> > Obviously you have not ready my fully. Here's the statement you missed
> from
> > previous email.
> >
> > -------
> > As a result, in clustered samba case, dbwrap_tdb_mutexes settings will be
> > ignored for clustered (volatile) databases.
> > ------
>
> huh, sorry but for me this still doesn't combine with clause 2. Let me try
> to
> rephrase it:
>
> 2. Whether mutexes are enabled or disabled for volatile databases is
> determined by
> 2.1. smb.conf dbwrap_tdb_mutexes setting on a standalone Samba server, or
> 2.2. ctdb tunable TDBMutexEnabled in a ctdb cluster
>
> With 4.7 we change both defaults to yes and 1 respectively.
>

Correct.


>
> Got it? :)
>
>
Yes, I understand the confusion now. :-)

Amitay.