Re: [PATCH] configure.ac: Link PSPPIRE explicitly against gthread.

[Ben Pfaff]

I added a call in the same commit that adds a call to
g_timer_new() to main(), because of the following note in the
documentation for GTimer:

    GTimer uses a higher-quality clock when thread support is
    available.  Therefore, calling g_thread_init() while timers
    are running may lead to unreliable results.  It is best to
    call g_thread_init() before starting any timers, if you are
    using threads at all.

Separately, the documentation for threads in Glib says:

    Calling g_thread_init() with a NULL argument is somewhat more
    relaxed.  You may call any other glib functions in the main
    thread before g_thread_init() as long as g_thread_init() is
    not called from a glib callback, or with any locks held.
    However, many libraries above glib does not support late
    initialization of threads, so doing this should be avoided if
    possible.

    Please note that since version 2.24 the GObject
    initialization function g_type_init() initializes threads
    (with a NULL argument), so most applications, including those
    using Gtk+ will run with threads enabled.  If you want a
    special thread implementation, make sure you call
    g_thread_init() before g_type_init() is called.

Taken together, it seemed to imply that I should call
g_thread_init() before g_timer_new(), or the timer might be
unreliable because glib would call it later for me.  But the
documentation doesn't seem entirely clear to me.

John Darrington <address@hidden> writes:

> This looks fine to me.
>
> However, I feel obliged to ask the question why are we actually
> calling g_thread_init.  The docs say this is necessary iff we are
> calling GLib from more than one thread.  So far as I'm aware, we're
> not doing that, are we?
>
> J'
>
> On Fri, May 04, 2012 at 09:33:32PM -0700, Ben Pfaff wrote:
>      Seems to be required on OpenSUSE.
>      
>      Reported by Mindaugas.
>      Bug #36396.
>      ---
>       configure.ac           |    3 +++
>       src/ui/gui/automake.mk |    1 +
>       2 files changed, 4 insertions(+), 0 deletions(-)
>      
>      diff --git a/configure.ac b/configure.ac
>      index 7d33ca2..2f3a8da 100644
>      --- a/configure.ac
>      +++ b/configure.ac
>      @@ -73,6 +73,9 @@ AC_ARG_WITH([gui],
>       AM_CONDITIONAL([HAVE_GUI], 
>                      [test "$with_cairo" != no && test "$with_gui" != "no"])
>       if test "$with_cairo" != no && test "$with_gui" != "no"; then
>      +  PKG_CHECK_MODULES([GTHREAD], [gthread-2.0], [],
>      +    [PSPP_REQUIRED_PREREQ([gthread 2.0 (or use --without-gui)])])
>      +
>         PKG_CHECK_MODULES([GTK], [gtk+-2.0 >= 2.16], [],
>           [PSPP_REQUIRED_PREREQ([gtk+ 2.0 version 2.16 or later (or use 
> --without-gui)])])
>       
>      diff --git a/src/ui/gui/automake.mk b/src/ui/gui/automake.mk
>      index 96209a0..a7cb1de 100644
>      --- a/src/ui/gui/automake.mk
>      +++ b/src/ui/gui/automake.mk
>      @@ -74,6 +74,7 @@ src_ui_gui_psppire_LDADD = \
>               src/libpspp.la \
>               src/libpspp-core.la \
>               $(GTK_LIBS) \
>      +        $(GTHREAD_LIBS) \
>               $(GTKSOURCEVIEW_LIBS) \
>               $(CAIRO_LIBS) \
>               $(LIBINTL) \
>      -- 
>      1.7.2.5
>      
>      
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