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empty G_ATOMIC_MEMORY_BARRIER() definition for !G_THREADS_ENABLED

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2004-02-26  Sebastian Wilhelmi  <seppi@seppi.de>

	* glib/gatomic.h: empty G_ATOMIC_MEMORY_BARRIER() definition for
	!G_THREADS_ENABLED

	* glib/gthread.h: Define g_once and
	g_static_mutex_get_mutex_impl_shortcut in terms of
	G_MEMORY_BARRIER, if defined and if we can inline.

	* configure.in: Remove double checked locking feature check.
This commit is contained in:
Sebastian Wilhelmi 2004-02-26 16:53:55 +00:00 committed by Sebastian Wilhelmi
parent 76c213543a
commit ea9d13892e
9 changed files with 84 additions and 43 deletions
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9
ChangeLog
View File

@ -1,5 +1,14 @@
2004-02-26 Sebastian Wilhelmi <seppi@seppi.de>
* glib/gatomic.h: empty G_ATOMIC_MEMORY_BARRIER() definition for
!G_THREADS_ENABLED
* glib/gthread.h: Define g_once and
g_static_mutex_get_mutex_impl_shortcut in terms of
G_MEMORY_BARRIER, if defined and if we can inline.
* configure.in: Remove double checked locking feature check.
* configure.in, config.h.win32.in, glib/gthread.c: Removed the PID
niceness surrogate for thread priorities as requested by Tim. It
does more harm than good.

9
ChangeLog.pre-2-10
View File

@ -1,5 +1,14 @@
2004-02-26 Sebastian Wilhelmi <seppi@seppi.de>
* glib/gatomic.h: empty G_ATOMIC_MEMORY_BARRIER() definition for
!G_THREADS_ENABLED
* glib/gthread.h: Define g_once and
g_static_mutex_get_mutex_impl_shortcut in terms of
G_MEMORY_BARRIER, if defined and if we can inline.
* configure.in: Remove double checked locking feature check.
* configure.in, config.h.win32.in, glib/gthread.c: Removed the PID
niceness surrogate for thread priorities as requested by Tim. It
does more harm than good.

9
ChangeLog.pre-2-12
View File

@ -1,5 +1,14 @@
2004-02-26 Sebastian Wilhelmi <seppi@seppi.de>
* glib/gatomic.h: empty G_ATOMIC_MEMORY_BARRIER() definition for
!G_THREADS_ENABLED
* glib/gthread.h: Define g_once and
g_static_mutex_get_mutex_impl_shortcut in terms of
G_MEMORY_BARRIER, if defined and if we can inline.
* configure.in: Remove double checked locking feature check.
* configure.in, config.h.win32.in, glib/gthread.c: Removed the PID
niceness surrogate for thread priorities as requested by Tim. It
does more harm than good.

9
ChangeLog.pre-2-4
View File

@ -1,5 +1,14 @@
2004-02-26 Sebastian Wilhelmi <seppi@seppi.de>
* glib/gatomic.h: empty G_ATOMIC_MEMORY_BARRIER() definition for
!G_THREADS_ENABLED
* glib/gthread.h: Define g_once and
g_static_mutex_get_mutex_impl_shortcut in terms of
G_MEMORY_BARRIER, if defined and if we can inline.
* configure.in: Remove double checked locking feature check.
* configure.in, config.h.win32.in, glib/gthread.c: Removed the PID
niceness surrogate for thread priorities as requested by Tim. It
does more harm than good.

9
ChangeLog.pre-2-6
View File

@ -1,5 +1,14 @@
2004-02-26 Sebastian Wilhelmi <seppi@seppi.de>
* glib/gatomic.h: empty G_ATOMIC_MEMORY_BARRIER() definition for
!G_THREADS_ENABLED
* glib/gthread.h: Define g_once and
g_static_mutex_get_mutex_impl_shortcut in terms of
G_MEMORY_BARRIER, if defined and if we can inline.
* configure.in: Remove double checked locking feature check.
* configure.in, config.h.win32.in, glib/gthread.c: Removed the PID
niceness surrogate for thread priorities as requested by Tim. It
does more harm than good.

9
ChangeLog.pre-2-8
View File

@ -1,5 +1,14 @@
2004-02-26 Sebastian Wilhelmi <seppi@seppi.de>
* glib/gatomic.h: empty G_ATOMIC_MEMORY_BARRIER() definition for
!G_THREADS_ENABLED
* glib/gthread.h: Define g_once and
g_static_mutex_get_mutex_impl_shortcut in terms of
G_MEMORY_BARRIER, if defined and if we can inline.
* configure.in: Remove double checked locking feature check.
* configure.in, config.h.win32.in, glib/gthread.c: Removed the PID
niceness surrogate for thread priorities as requested by Tim. It
does more harm than good.

40
configure.in
View File

@ -1188,27 +1188,6 @@ esac
AC_MSG_RESULT($GIO)
AC_SUBST(GIO)
dnl check for cpu to enable double checked locking when possible
dnl ************************************************************
if test x"$have_threads" != xno; then
AC_MSG_CHECKING(whether double checked locking is safe)
# According to glibc/linuxthreads the following platforms do
# not have the notion of a read or write memory barrier and
# therefore the double checked locking should be safe. Have a
# look at pthread_once in glibc/linuxthreads/mutex.c to see,
# what this means.
case $host_cpu in
arm|hppa|i386|i686|ia64|m68k|sh|cris|x86_64)
g_use_double_checked_locking=yes
;;
*)
g_use_double_checked_locking=no
;;
esac
AC_MSG_RESULT($g_use_double_checked_locking)
fi
dnl ****************************************
dnl *** platform dependent source checks ***
dnl ****************************************
@ -2233,24 +2212,6 @@ typedef struct _GMutex* GStaticMutex;
_______EOF
fi
if test x$g_use_double_checked_locking = xyes; then
cat >>$outfile <<_______EOF
/* double checked locking can be used on this platform */
#define g_once(once, func, arg) \\
((once)->status == G_ONCE_STATUS_READY ? (once)->retval : \\
g_once_impl (once, func, arg))
#define g_static_mutex_get_mutex_impl_shortcut(mutex) \\
(*(mutex) ? *(mutex) : g_static_mutex_get_mutex_impl (mutex))
_______EOF
else
cat >>$outfile <<_______EOF
/* double checked locking is unsafe to use on this platform, do full locking */
#define g_once(once, func, arg) (g_once_impl(once, func, arg))
#define g_static_mutex_get_mutex_impl_shortcut(mutex) \\
(g_static_mutex_get_mutex_impl (mutex))
_______EOF
fi
cat >>$outfile <<_______EOF
/* This represents a system thread as used by the implementation. An
* alien implementaion, as loaded by g_thread_init can only count on
@ -2565,7 +2526,6 @@ xno) g_enable_threads_def="#undef";;
esac
g_threads_impl_def=$g_threads_impl
g_use_double_checked_locking=$g_use_double_checked_locking
g_mutex_has_default="$mutex_has_default"
g_mutex_sizeof="$glib_cv_sizeof_gmutex"

7
glib/gatomic.h
View File

@ -341,7 +341,7 @@ g_atomic_pointer_compare_and_exchange (gpointer *atomic,
return result == oldval;
}
# define G_ATOMIC_MEMORY_BARRIER() /* Not needed */
# define G_ATOMIC_MEMORY_BARRIER() /* Not needed */
# elif defined(G_ATOMIC_INLINED_IMPLEMENTATION_POWERPC)
/* Adapted from CVS version 1.12 of glibc's sysdeps/powerpc/bits/atomic.h
@ -450,7 +450,7 @@ g_atomic_pointer_compare_and_exchange (gpointer *atomic,
# error "Your system has an unsupported pointer size"
# endif /* GLIB_SIZEOF_VOID_P */
# define G_ATOMIC_MEMORY_BARRIER() __asm ("sync" : : : "memory")
# define G_ATOMIC_MEMORY_BARRIER() __asm ("sync" : : : "memory")
# elif defined(G_ATOMIC_INLINED_IMPLEMENTATION_IA64)
/* Adapted from CVS version 1.8 of glibc's sysdeps/ia64/bits/atomic.h
@ -486,7 +486,7 @@ g_atomic_pointer_compare_and_exchange (gpointer *atomic,
(long)oldval, (long)newval);
}
# define G_ATOMIC_MEMORY_BARRIER() __sync_synchronize ()
# define G_ATOMIC_MEMORY_BARRIER() __sync_synchronize ()
# else /* !G_ATOMIC_INLINED_IMPLEMENTATION_... */
# define G_ATOMIC_USE_FALLBACK_IMPLEMENTATION
@ -503,6 +503,7 @@ gint32 g_atomic_int_exchange_and_add (gint32 *atomic, gint32 val);
(*(atomic) == (oldval) ? (*(atomic) = (newval), TRUE) : FALSE)
# define g_atomic_int_get(atomic) (*(atomic))
# define g_atomic_pointer_get(atomic) (*(atomic))
# define G_ATOMIC_MEMORY_BARRIER() /* Not needed */
#endif /* G_THREADS_ENABLED */
#ifdef G_ATOMIC_USE_FALLBACK_IMPLEMENTATION

26
glib/gthread.h
View File

@ -29,6 +29,8 @@
#include <glib/gerror.h>
#include <glib/gtypes.h>
#include <glib/gutils.h> /* for G_CAN_INLINE */
#include <glib/gatomic.h> /* for G_ATOMIC_MEMORY_BARRIER */
G_BEGIN_DECLS
@ -302,6 +304,30 @@ struct _GOnce
gpointer g_once_impl (GOnce *once, GThreadFunc func, gpointer arg);
#if defined (G_CAN_INLINE) && defined (G_ATOMIC_MEMORY_BARRIER)
static inline gpointer
g_once (GOnce *once, GThreadFunc func, gpointer arg)
{
if (once->status != G_ONCE_STATUS_READY)
return g_once_impl (once, func, arg);
G_ATOMIC_MEMORY_BARRIER ();
return once->retval;
}
static inline GMutex*
g_static_mutex_get_mutex_impl_shortcut (GMutex **mutex)
{
if (! *mutex)
return g_static_mutex_get_mutex_impl (mutex);
G_ATOMIC_MEMORY_BARRIER ();
return *mutex;
}
#else /* !G_CAN_INLINE || !G_ATOMIC_MEMORY_BARRIER */
# define g_once g_once_impl
# define g_static_mutex_get_mutex_impl_shortcut g_static_mutex_get_mutex_impl
#endif /* G_CAN_INLINE && G_ATOMIC_MEMORY_BARRIER*/
/* these are some convenience macros that expand to nothing if GLib
* was configured with --disable-threads. for using StaticMutexes,
* you define them with G_LOCK_DEFINE_STATIC (name) or G_LOCK_DEFINE (name)