[PATCH 6/7] Provide pthread-based alternative implementation
Keith Packard
keithp at keithp.com
Wed Nov 20 11:56:00 PST 2013
This uses pthread mutexes and condition variables instead of futexes.
Signed-off-by: Keith Packard <keithp at keithp.com>
---
configure.ac | 25 +++++++++
src/Makefile.am | 10 +++-
src/xshmfence_pthread.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++
src/xshmfence_pthread.h | 39 ++++++++++++++
src/xshmfenceint.h | 7 +++
test/Makefile.am | 2 +-
xshmfence.pc.in | 1 +
7 files changed, 214 insertions(+), 2 deletions(-)
create mode 100644 src/xshmfence_pthread.c
create mode 100644 src/xshmfence_pthread.h
diff --git a/configure.ac b/configure.ac
index ee09faf..0c8a325 100644
--- a/configure.ac
+++ b/configure.ac
@@ -46,6 +46,31 @@ dnl
dnl Locate a suitable tmp file system for creating shared memeory files
dnl
+AC_ARG_ENABLE(futex, AS_HELP_STRING([--enable-futex], [Enable futexes (default: auto)]),
+ [FUTEX=$enableval], [FUTEX=auto])
+
+if test "x$FUTEX" = "xauto"; then
+ AC_CHECK_HEADER([linux/futex.h], [FUTEX=yes], [FUTEX=no])
+fi
+
+if test "x$FUTEX" = "xyes"; then
+ PTHREAD=no
+ AC_DEFINE(HAVE_FUTEX,1,[Use futexes])
+else
+ PTHREAD=yes
+ AC_DEFINE(HAVE_PTHREAD,1,[Use pthread primitives])
+fi
+
+PTHREAD_LIBS=
+if test "x$PTHREAD" = "xyes"; then
+ AC_CHECK_LIB(pthread,pthread_create,[PTHREAD_LIBS=-lpthread],[PTHREAD_LIBS=])
+fi
+
+AC_SUBST([PTHREAD_LIBS])
+
+AM_CONDITIONAL([FUTEX], [test x"$FUTEX" = xyes])
+AM_CONDITIONAL([PTHREAD], [test x"$PTHREAD" = xyes])
+
AC_ARG_WITH(shared-memory-dir, AS_HELP_STRING([--with-shared-memory-dir=PATH], [Path to directory in a world-writable temporary directory for anonymous shared memory (default: auto)]),
[],
[with_shared_memory_dir=yes])
diff --git a/src/Makefile.am b/src/Makefile.am
index d817326..cac6de5 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,14 +1,22 @@
lib_LTLIBRARIES = libxshmfence.la
+if PTHREAD
+PTHREAD_SOURCES=xshmfence_pthread.c
+endif
+
+if FUTEX
FUTEX_SOURCES=xshmfence_futex.c
+endif
libxshmfence_la_SOURCES = \
xshmfence_alloc.c \
+ $(PTHREAD_SOURCES) \
$(FUTEX_SOURCES)
-noinst_HEADERS = xshmfence_futex.h xshmfenceint.h
+noinst_HEADERS = xshmfence_pthread.h xshmfence_futex.h xshmfenceint.h
libxshmfence_la_LDFLAGS = -version-number 1:0:0 -no-undefined
+libxshmfence_la_LIBADD = @PTHREAD_LIBS@
libxshmfenceincludedir = $(includedir)/X11
libxshmfenceinclude_HEADERS = xshmfence.h
diff --git a/src/xshmfence_pthread.c b/src/xshmfence_pthread.c
new file mode 100644
index 0000000..6324b31
--- /dev/null
+++ b/src/xshmfence_pthread.c
@@ -0,0 +1,132 @@
+/*
+ * Copyright © 2013 Keith Packard
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission. The copyright holders make no representations
+ * about the suitability of this software for any purpose. It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "xshmfenceint.h"
+
+/**
+ * xshmfence_trigger:
+ * @f: An X fence
+ *
+ * Set @f to triggered, waking all waiters.
+ *
+ * Return value: 0 on success and -1 on error (in which case, errno
+ * will be set as appropriate).
+ **/
+int
+xshmfence_trigger(struct xshmfence *f) {
+ pthread_mutex_lock(&f->lock);
+ if (f->value == 0) {
+ f->value = 1;
+ if (f->waiting) {
+ f->waiting = 0;
+ pthread_cond_broadcast(&f->wakeup);
+ }
+ }
+ pthread_mutex_unlock(&f->lock);
+ return 0;
+}
+
+/**
+ * xshmfence_await:
+ * @f: An X fence
+ *
+ * Wait for @f to be triggered. If @f is already triggered, this
+ * function returns immediately.
+ *
+ * Return value: 0 on success and -1 on error (in which case, errno
+ * will be set as appropriate).
+ **/
+int
+xshmfence_await(struct xshmfence *f) {
+ int ret;
+ pthread_mutex_lock(&f->lock);
+ while (f->value == 0) {
+ f->waiting = 1;
+ pthread_cond_wait(&f->wakeup, &f->lock);
+ }
+ pthread_mutex_unlock(&f->lock);
+ return 0;
+}
+
+/**
+ * xshmfence_query:
+ * @f: An X fence
+ *
+ * Return value: 1 if @f is triggered, else returns 0.
+ **/
+int
+xshmfence_query(struct xshmfence *f) {
+ int value;
+
+ pthread_mutex_lock(&f->lock);
+ value = f->value;
+ pthread_mutex_unlock(&f->lock);
+ return value;
+}
+
+/**
+ * xshmfence_reset:
+ * @f: An X fence
+ *
+ * Reset @f to untriggered. If @f is already untriggered,
+ * this function has no effect.
+ **/
+void
+xshmfence_reset(struct xshmfence *f) {
+
+ pthread_mutex_lock(&f->lock);
+ f->value = 0;
+ pthread_mutex_unlock(&f->lock);
+}
+
+/**
+ * xshmfence_init:
+ * @fd: An fd for an X fence
+ *
+ * Initialize the fence when first allocated
+ **/
+
+void
+xshmfence_init(int fd)
+{
+ struct xshmfence *f = xshmfence_map_shm(fd);
+ pthread_mutexattr_t mutex_attr;
+ pthread_condattr_t cond_attr;
+
+ if (!f)
+ return;
+
+ pthread_mutexattr_init(&mutex_attr);
+ pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED);
+ pthread_mutex_init(&f->lock, &mutex_attr);
+
+ pthread_condattr_init(&cond_attr);
+ pthread_condattr_setpshared(&cond_attr, PTHREAD_PROCESS_SHARED);
+ pthread_cond_init(&f->wakeup, &cond_attr);
+ f->value = 0;
+ f->waiting = 0;
+ xshmfence_unmap_shm(f);
+}
diff --git a/src/xshmfence_pthread.h b/src/xshmfence_pthread.h
new file mode 100644
index 0000000..9d6b0c8
--- /dev/null
+++ b/src/xshmfence_pthread.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright © 2013 Keith Packard
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that copyright
+ * notice and this permission notice appear in supporting documentation, and
+ * that the name of the copyright holders not be used in advertising or
+ * publicity pertaining to distribution of the software without specific,
+ * written prior permission. The copyright holders make no representations
+ * about the suitability of this software for any purpose. It is provided "as
+ * is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+ * OF THIS SOFTWARE.
+ */
+
+#ifndef _XSHMFENCE_PTHREAD_H_
+#define _XSHMFENCE_PTHREAD_H_
+
+#include <pthread.h>
+#include <sys/types.h>
+
+struct xshmfence {
+ pthread_mutex_t lock;
+ pthread_cond_t wakeup;
+ int value;
+ int waiting;
+};
+
+void
+xshmfence_init(int fd);
+
+#endif /* _XSHMFENCE_PTHREAD_H_ */
diff --git a/src/xshmfenceint.h b/src/xshmfenceint.h
index 3452a55..178cbdd 100644
--- a/src/xshmfenceint.h
+++ b/src/xshmfenceint.h
@@ -27,6 +27,13 @@
#include <unistd.h>
#include <sys/mman.h>
#include "xshmfence.h"
+
+#if HAVE_FUTEX
#include "xshmfence_futex.h"
+#endif
+
+#if HAVE_PTHREAD
+#include "xshmfence_pthread.h"
+#endif
#endif /* _XSHMFENCEINT_H_ */
diff --git a/test/Makefile.am b/test/Makefile.am
index c67014a..57bf1ae 100644
--- a/test/Makefile.am
+++ b/test/Makefile.am
@@ -5,5 +5,5 @@ TESTS=$(check_PROGRAMS)
xshmfence_test_SOURCES = xshmfence_test.c
xshmfence_test_CFLAGS = -I$(top_srcdir)/src
-xshmfence_test_LDADD = $(top_builddir)/src/libxshmfence.la
+xshmfence_test_LDADD = $(top_builddir)/src/libxshmfence.la @PTHREAD_LIBS@
diff --git a/xshmfence.pc.in b/xshmfence.pc.in
index cfc1860..579af0b 100644
--- a/xshmfence.pc.in
+++ b/xshmfence.pc.in
@@ -8,3 +8,4 @@ Description: The X Shared Memory Fence Library
Version: @PACKAGE_VERSION@
Cflags: -I${includedir}
Libs: -L${libdir} -lxshmfence
+Libs.private: @PTHREAD_LIBS@
--
1.8.4.2
More information about the xorg-devel
mailing list