On Fri, 4 Dec 2009 10:03:54 +0100, Jens Rehsack
<rehs...@googlemail.com> wrote:
> 2009/12/3 H.Merijn Brand <h.m.br...@xs4all.nl>:
> > Any objections to me committing below change?
>
> While the originator of this request updates his ticket, maybe a smarter
> implementation is reasonable:
>
> I could modify S::S opentable () to request opening for reading/writing,
> so you could differ between LOCK_SH and LOCK_EX automatically.
That can still be done. You can set a localized $data->{Database}{f_lock}
What I have now done (and committed) is create support and
documentation for locking control. How this will be used is up to the
higher levels.
> Further, it could be suitable to or LOCK_NB, which allows to avoid deadlocks.
LOCK_NB?
Apply or remove an advisory lock on the open file specified by fd. The
argument operation is one of the following:
LOCK_SH Place a shared lock. More than one process may hold a
shared lock for a given file at a given time.
LOCK_EX Place an exclusive lock. Only one process may hold an
exclusive lock for a given file at a given time.
LOCK_UN Remove an existing lock held by this process.
> Sorry for generating extra wishes ;)
No need to be sorry. Wishes keep us sharp!
> /Jens
>
> > --8<---
> > --- DBI-svn/lib/DBD/File.pm 2009-12-03 17:47:15.000000000 +0100
> > +++ DBI-svn/lib/DBD/File.pm 2009-12-03 17:49:20.000000000 +0100
> > @@ -162,6 +162,7 @@ sub connect ($$;$$$)
> > f_ext => 1, # file extension
> > f_schema => 1, # schema name
> > f_tables => 1, # base directory
> > + f_lock => 1, # Table locking mode
> > };
> > $this->{sql_valid_attrs} = {
> > sql_handler => 1, # Nano or S:S
> > @@ -725,12 +726,17 @@ sub open_table ($$$$$)
> > }
> > $fh and binmode $fh;
> > if ($locking and $fh) {
> > - if ($lockMode) {
> > + my $lm = defined $data->{Database}{f_lock}
> > + && $data->{Database}{f_lock} =~ m/^[012]$/
> > + ? $data->{Database}{f_lock}
> > + : $lockMode ? 2 : 1;
> > + if ($lm == 2) {
> > flock $fh, 2 or croak "Cannot obtain exclusive lock on $file:
> > $!";
> > }
> > - else {
> > + elsif ($lm == 1) {
> > flock $fh, 1 or croak "Cannot obtain shared lock on $file: $!";
> > }
> > + # $lm = 0 is forced no locking at all
> > }
> > my $columns = {};
> > my $array = [];
> > @@ -929,6 +935,29 @@ tables into the same (or no) schema:
> > Defining f_schema to the empty string is equal to setting it to C<undef>,
> > this to enable the DSN to be C<dbi:CSV:f_schema=;f_dir=.>.
> >
> > +=item f_lock
> > +
> > +With this attribute, you can force locking mode (if locking is supported
> > +at all) for opening tables. By default, tables are opened with a shared
> > +lock for reading, and with an exclusive lock for writing. The supported
> > +modes are:
> > +
> > +=over 2
> > +
> > +=item 0
> > +
> > +Force no locking at all.
> > +
> > +=item 1
> > +
> > +Only shared locks will be used.
> > +
> > +=item 2
> > +
> > +Only exclusive locks will be used.
> > +
> > +=back
> > +
> > =back
> >
> > =head2 Driver private methods
> > -->8---
--
H.Merijn Brand http://tux.nl Perl Monger http://amsterdam.pm.org/
using & porting perl 5.6.2, 5.8.x, 5.10.x, 5.11.x on HP-UX 10.20, 11.00,
11.11, 11.23, and 11.31, OpenSuSE 10.3, 11.0, and 11.1, AIX 5.2 and 5.3.
http://mirrors.develooper.com/hpux/ http://www.test-smoke.org/
http://qa.perl.org http://www.goldmark.org/jeff/stupid-disclaimers/
