[PATCH] [cairo-atomic] Introduce atomic ops.
Chris Wilson
chris at chris-wilson.co.uk
Fri Sep 21 02:45:55 PDT 2007
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.
---
configure.in | 11 +++++
src/Makefile.am | 2 +
src/cairo-atomic-private.h | 80 ++++++++++++++++++++++++++++++++++++++++
src/cairo-atomic.c | 79 +++++++++++++++++++++++++++++++++++++++
src/cairo-mutex-list-private.h | 3 +
5 files changed, 175 insertions(+), 0 deletions(-)
diff --git a/configure.in b/configure.in
index aa7c1e7..5c49f66 100644
--- a/configure.in
+++ b/configure.in
@@ -89,6 +89,17 @@ dnl ===========================================================================
AC_CHECK_FUNCS(vasnprintf)
+AC_ARG_ENABLE(atomics,
+ AS_HELP_STRING([--disable-atomics],
+ [Do not use atomic operations]),
+ [use_atomic=$enableval], [use_atomic=auto])
+if test "x$use_atomic" != "xno"; then
+ AC_TRY_COMPILE([int atomic_add(int i) { return __sync_fetch_and_add (&i, 1); }], [],
+ AC_DEFINE(CAIRO_HAS_ATOMIC_OPS, 1, [Enable if your platform has native atomic operations])
+ AC_DEFINE(CAIRO_HAS_INTEL_ATOMIC_PRIMITIVES, 1, [Enable if your compiler supports the Intel __sync_* atomic primitives])
+ )
+fi
+
AC_CHECK_LIBM
LIBS="$LIBS $LIBM"
diff --git a/src/Makefile.am b/src/Makefile.am
index 85964e3..2e6d2c6 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -172,6 +172,8 @@ libcairo_la_base_sources = \
cairo-arc.c \
cairo-arc-private.h \
cairo-array.c \
+ cairo-atomic.c \
+ cairo-atomic-private.h \
cairo-base85-stream.c \
cairo-bentley-ottmann.c \
cairo-cache.c \
diff --git a/src/cairo-atomic-private.h b/src/cairo-atomic-private.h
new file mode 100644
index 0000000..c027c13
--- /dev/null
+++ b/src/cairo-atomic-private.h
@@ -0,0 +1,80 @@
+/* cairo - a vector graphics library with display and print output
+ *
+ * Copyright © 2007 Chris Wilson
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ * The Original Code is the cairo graphics library.
+ *
+ * The Initial Developer of the Original Code is University of Southern
+ * California.
+ *
+ * Contributor(s):
+ * Chris Wilson <chris at chris-wilson.co.uk>
+ */
+
+#ifndef CAIRO_ATOMIC_PRIVATE_H
+#define CAIRO_ATOMIC_PRIVATE_H
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+CAIRO_BEGIN_DECLS
+
+#if CAIRO_HAS_ATOMIC_OPS
+
+#if CAIRO_HAS_INTEL_ATOMIC_PRIMITIVES
+typedef int cairo_atomic_int_t;
+#define _cairo_atomic_int_inc(x) ((void) __sync_fetch_and_add(x, 1))
+#define _cairo_atomic_int_dec_and_test(x) (__sync_fetch_and_add(x, -1) == 1)
+#define _cairo_atomic_int_get(x) (*x)
+#define _cairo_atomic_int_set(x, value) ((*x) = value)
+#else
+#error "Cairo tried to use native atomic operations without a valid architectural implementation"
+#endif
+
+#else
+
+#include "cairo-compiler-private.h"
+
+typedef int cairo_atomic_int_t;
+
+cairo_private void
+_cairo_atomic_int_inc (int *x);
+
+cairo_private cairo_bool_t
+_cairo_atomic_int_dec_and_test (int *x);
+
+cairo_private int
+_cairo_atomic_int_get (int *x);
+
+cairo_private void
+_cairo_atomic_int_set (int *x, int value);
+
+#endif
+
+CAIRO_END_DECLS
+
+#endif
diff --git a/src/cairo-atomic.c b/src/cairo-atomic.c
new file mode 100644
index 0000000..9941548
--- /dev/null
+++ b/src/cairo-atomic.c
@@ -0,0 +1,79 @@
+/* cairo - a vector graphics library with display and print output
+ *
+ * Copyright © 2007 Chris Wilson
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ * The Original Code is the cairo graphics library.
+ *
+ * Contributor(s):
+ * Chris Wilson <chris at chris-wilson.co.uk>
+ */
+
+#include "cairoint.h"
+
+#include "cairo-atomic-private.h"
+#include "cairo-mutex-private.h"
+
+#ifndef CAIRO_HAS_ATOMIC_OPS
+void
+_cairo_atomic_int_inc (int *x)
+{
+ CAIRO_MUTEX_LOCK (_cairo_atomic_mutex);
+ *x += 1;
+ CAIRO_MUTEX_UNLOCK (_cairo_atomic_mutex);
+}
+
+cairo_bool_t
+_cairo_atomic_int_dec_and_test (int *x)
+{
+ cairo_bool_t ret;
+
+ CAIRO_MUTEX_LOCK (_cairo_atomic_mutex);
+ ret = --*x == 0;
+ CAIRO_MUTEX_UNLOCK (_cairo_atomic_mutex);
+
+ return ret;
+}
+
+int
+_cairo_atomic_int_get (int *x)
+{
+ int ret;
+
+ CAIRO_MUTEX_LOCK (_cairo_atomic_mutex);
+ ret = *x;
+ CAIRO_MUTEX_UNLOCK (_cairo_atomic_mutex);
+
+ return ret;
+}
+
+void
+_cairo_atomic_int_set (int *x, int value)
+{
+ CAIRO_MUTEX_LOCK (_cairo_atomic_mutex);
+ *x = value;
+ CAIRO_MUTEX_UNLOCK (_cairo_atomic_mutex);
+}
+#endif
diff --git a/src/cairo-mutex-list-private.h b/src/cairo-mutex-list-private.h
index abb4a9a..9960797 100644
--- a/src/cairo-mutex-list-private.h
+++ b/src/cairo-mutex-list-private.h
@@ -46,6 +46,9 @@ CAIRO_MUTEX_DECLARE (_cairo_ft_unscaled_font_map_mutex);
CAIRO_MUTEX_DECLARE (_cairo_xlib_display_mutex);
#endif
+#ifndef CAIRO_HAS_ATOMIC_OPS
+CAIRO_MUTEX_DECLARE (_cairo_atomic_mutex);
+#endif
/* Undefine, to err on unintended inclusion */
#undef CAIRO_MUTEX_DECLARE
--
1.4.4.2
--df+09Je9rNq3P+GE
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