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[cairo-atomic] Introduce atomic ops.
Test for the availability of the Intel __sync_* atomic primitives and use them to define a few operations useful for reference counting - providing a generic interface that may be targeted at more architectures in the future. If no atomic primitives are available, use a mutex based variant. If the contention on that mutex is too high, we can consider using an array of mutexes using the address of the atomic variable as the hash.
This commit is contained in:
Chris Wilson
parent
42de1a0a7f
commit
8b6c871c90
5 changed files with 181 additions and 0 deletions
16
configure.in
16
configure.in
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@ -89,6 +89,22 @@ dnl ===========================================================================
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AC_CHECK_FUNCS(vasnprintf)
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dnl ===========================================================================
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dnl
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dnl Test for native atomic operations.
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dnl
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AC_MSG_CHECKING([for native atomic primitives])
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cairo_atomic_primitives="none"
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AC_TRY_COMPILE([int atomic_add(int i) { return __sync_fetch_and_add (&i, 1); }], [],
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AC_DEFINE(CAIRO_HAS_INTEL_ATOMIC_PRIMITIVES, 1, [Enable if your compiler supports the Intel __sync_* atomic primitives])
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cairo_atomic_primitives="Intel"
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)
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AC_MSG_RESULT([$cairo_atomic_primitives])
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dnl ===========================================================================
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AC_CHECK_LIBM
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LIBS="$LIBS $LIBM"
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@ -172,6 +172,8 @@ libcairo_la_base_sources = \
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cairo-arc.c \
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cairo-arc-private.h \
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cairo-array.c \
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cairo-atomic.c \
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cairo-atomic-private.h \
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cairo-base85-stream.c \
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cairo-bentley-ottmann.c \
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cairo-cache.c \
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81
src/cairo-atomic-private.h
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81
src/cairo-atomic-private.h
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@ -0,0 +1,81 @@
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/* cairo - a vector graphics library with display and print output
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*
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* Copyright © 2007 Chris Wilson
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*
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* This library is free software; you can redistribute it and/or
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* modify it either under the terms of the GNU Lesser General Public
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* License version 2.1 as published by the Free Software Foundation
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* (the "LGPL") or, at your option, under the terms of the Mozilla
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* Public License Version 1.1 (the "MPL"). If you do not alter this
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* notice, a recipient may use your version of this file under either
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* the MPL or the LGPL.
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*
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* You should have received a copy of the LGPL along with this library
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* in the file COPYING-LGPL-2.1; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* You should have received a copy of the MPL along with this library
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* in the file COPYING-MPL-1.1
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.1 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
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* OF ANY KIND, either express or implied. See the LGPL or the MPL for
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* the specific language governing rights and limitations.
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*
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* The Original Code is the cairo graphics library.
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*
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* The Initial Developer of the Original Code is University of Southern
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* California.
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*
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* Contributor(s):
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* Chris Wilson <chris@chris-wilson.co.uk>
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*/
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#ifndef CAIRO_ATOMIC_PRIVATE_H
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#define CAIRO_ATOMIC_PRIVATE_H
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#if HAVE_CONFIG_H
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#include "config.h"
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#endif
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CAIRO_BEGIN_DECLS
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#define CAIRO_HAS_ATOMIC_OPS 1
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#if CAIRO_HAS_INTEL_ATOMIC_PRIMITIVES
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typedef int cairo_atomic_int_t;
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# define _cairo_atomic_int_inc(x) ((void) __sync_fetch_and_add(x, 1))
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# define _cairo_atomic_int_dec_and_test(x) (__sync_fetch_and_add(x, -1) == 1)
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# define _cairo_atomic_int_get(x) (*x)
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# define _cairo_atomic_int_set(x, value) ((*x) = value)
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#else
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# include "cairo-compiler-private.h"
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# undef CAIRO_HAS_ATOMIC_OPS
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typedef int cairo_atomic_int_t;
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cairo_private void
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_cairo_atomic_int_inc (int *x);
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cairo_private cairo_bool_t
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_cairo_atomic_int_dec_and_test (int *x);
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cairo_private int
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_cairo_atomic_int_get (int *x);
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cairo_private void
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_cairo_atomic_int_set (int *x, int value);
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#endif
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CAIRO_END_DECLS
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#endif
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79
src/cairo-atomic.c
Normal file
79
src/cairo-atomic.c
Normal file
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@ -0,0 +1,79 @@
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/* cairo - a vector graphics library with display and print output
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*
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* Copyright © 2007 Chris Wilson
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*
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* This library is free software; you can redistribute it and/or
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* modify it either under the terms of the GNU Lesser General Public
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* License version 2.1 as published by the Free Software Foundation
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* (the "LGPL") or, at your option, under the terms of the Mozilla
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* Public License Version 1.1 (the "MPL"). If you do not alter this
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* notice, a recipient may use your version of this file under either
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* the MPL or the LGPL.
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*
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* You should have received a copy of the LGPL along with this library
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* in the file COPYING-LGPL-2.1; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* You should have received a copy of the MPL along with this library
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* in the file COPYING-MPL-1.1
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.1 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
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* OF ANY KIND, either express or implied. See the LGPL or the MPL for
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* the specific language governing rights and limitations.
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*
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* The Original Code is the cairo graphics library.
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*
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* Contributor(s):
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* Chris Wilson <chris@chris-wilson.co.uk>
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*/
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#include "cairoint.h"
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#include "cairo-atomic-private.h"
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#include "cairo-mutex-private.h"
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#ifndef CAIRO_HAS_ATOMIC_OPS
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void
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_cairo_atomic_int_inc (int *x)
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{
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CAIRO_MUTEX_LOCK (_cairo_atomic_mutex);
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*x += 1;
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CAIRO_MUTEX_UNLOCK (_cairo_atomic_mutex);
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}
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cairo_bool_t
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_cairo_atomic_int_dec_and_test (int *x)
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{
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cairo_bool_t ret;
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CAIRO_MUTEX_LOCK (_cairo_atomic_mutex);
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ret = --*x == 0;
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CAIRO_MUTEX_UNLOCK (_cairo_atomic_mutex);
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return ret;
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}
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int
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_cairo_atomic_int_get (int *x)
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{
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int ret;
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CAIRO_MUTEX_LOCK (_cairo_atomic_mutex);
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ret = *x;
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CAIRO_MUTEX_UNLOCK (_cairo_atomic_mutex);
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return ret;
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}
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void
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_cairo_atomic_int_set (int *x, int value)
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{
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CAIRO_MUTEX_LOCK (_cairo_atomic_mutex);
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*x = value;
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CAIRO_MUTEX_UNLOCK (_cairo_atomic_mutex);
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}
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#endif
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@ -46,6 +46,9 @@ CAIRO_MUTEX_DECLARE (_cairo_ft_unscaled_font_map_mutex);
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CAIRO_MUTEX_DECLARE (_cairo_xlib_display_mutex);
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#endif
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#ifndef CAIRO_HAS_ATOMIC_OPS
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CAIRO_MUTEX_DECLARE (_cairo_atomic_mutex);
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#endif
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/* Undefine, to err on unintended inclusion */
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#undef CAIRO_MUTEX_DECLARE
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