[DVDnav-discuss] [PATCH] Fix parallel jobs; sources need version.h

[Dan Nicholson]

On Wed, Apr 30, 2008 at 9:01 AM, Nico Sabbi <Nicola.Sabbi at poste.it> wrote:
>
> On Wednesday 30 April 2008 14:55:06 Dan Nicholson wrote:
>  > On Wed, Apr 30, 2008 at 12:57 AM, Nico Sabbi <Nicola.Sabbi at poste.it>
>  wrote:
>  > > On Monday 28 April 2008 23:53:38 Dan Nicholson wrote:
>  > >  > ---
>  > >  >  Makefile |    2 ++
>  > >  >  1 files changed, 2 insertions(+), 0 deletions(-)
>  > >  >
>  > >  > diff --git a/Makefile b/Makefile
>  > >  > index fcc3940..85108e5 100644
>  > >  > --- a/Makefile
>  > >  > +++ b/Makefile
>  > >  > @@ -81,6 +81,8 @@ endif
>  > >  >  version.h:
>  > >  >       sh $(SRC_PATH)/version.sh $(SRC_PATH)
>  > >  >
>  > >  > +$(SRCS) $(DVDREAD_SRCS): version.h
>  > >  > +
>  > >  >
>  > >  >  # General targets
>  > >
>  > >  can you explain, please?
>  > >  If I read the dependencies all .c files already depend on
>  > > version.h
>  >
>  > They don't. The library $(SHLIB) depends on version.h. Since that's
>  > the first target, version.h gets built immediately. However, if you
>  > have multiple jobs (-j3 or whatever), make will also begin building
>  > the .c files without waiting for version.h to be built. This causes
>  > a race condition if any .c file including config.h or version.h is
>  > built before version.h is created.
>  >
>  > You can see if the .c files depend on version.h pretty easily. Run
>  > `make -d dvdnav.o' and redirect the log somewhere. It will show in
>  > detail the prerequisites for the target dvdnav.o. For me, version.h
>  > never comes up until after the patch above. If this is a clean
>  > checkout (i.e., you've only run configure2), `mkdir obj && make
>  > dvdnav.o' will bomb like this:
>  >
>  > cd obj && gcc -MD -g -O2 -march=i686 -pipe  -Wall -funsigned-char
>  > -I/home/dan/scm/libdvdnav -I"/home/dan/scm/libdvdnav"/src
>  > -I"/home/dan/scm/libdvdnav"/src/vm -DDVDNAV_COMPILE
>  > -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -DHAVE_CONFIG_H
>  > -DHAVE_DLFCN_H -I"/home/dan/scm/libdvdnav"/src/dvdread -c -o
>  > dvdnav.o /home/dan/scm/libdvdnav/src/dvdnav.c
>  > In file included from /home/dan/scm/libdvdnav/src/dvdnav.c:25:
>  > /home/dan/scm/libdvdnav/config.h:2:21: error: version.h: No such
>  > file or directory
>  >
>  > With the patch, it properly generates version.h first, and this
>  > works.
>  >
>
>  ok and sorry for the delay: I've been busy all week. Today or tomorrow
>  I'll commit your patch(es)

No problem. Sorry for not giving many details initially.

--
Dan