<html><head></head><body>The case of spurious wake-ups is already covered by the existing Doxygen text. I think that's a much better place to document API semantics that git commit messages.<br><br><div class="gmail_quote">Le 17 février 2020 14:39:08 GMT+02:00, Thomas Guillem <thomas@gllm.fr> a écrit :<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<pre class="k9mail"><br><br>On Sun, Feb 16, 2020, at 18:50, Rémi Denis-Courmont wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;"><hr> src/Makefile.am  |   3 ++<br> src/posix/wait.c | 128 +++++++++++++++++++++++++++++++++++++++++++++++<br> 2 files changed, 131 insertions(+)<br> create mode 100644 src/posix/wait.c<br><br>diff --git a/src/Makefile.am b/src/Makefile.am<br>index f2adf61095..0ad47fc105 100644<br>--- a/src/Makefile.am<br>+++ b/src/Makefile.am<br>@@ -482,6 +482,9 @@ libvlccore_la_SOURCES += \<br>    posix/plugin.c \<br>      posix/rand.c \<br>        posix/timer.c<br>+if !HAVE_LINUX<br>+libvlccore_la_SOURCES += posix/wait.c<br>+endif<br> if !HAVE_ANDROID<br> libvlccore_la_SOURCES += posix/sort.c<br> if !HAVE_DARWIN<br>diff --git a/src/posix/wait.c b/src/posix/wait.c<br>new file mode 100644<br>index 0000000000..60f9c7626f<br>--- /dev/null<br>+++ b/src/posix/wait.c<br>@@ -0,0 +1,128 @@<br>+/*****************************************************************************<br>+ * wait.c : pthread back-end for vlc_atomic_wait<br>+ *****************************************************************************<br>+ * Copyright (C) 2019-2020 Rémi Denis-Courmont<br>+ *<br>+ * This program is free software; you can redistribute it and/or modify it<br>+ * under the terms of the GNU Lesser General Public License as published by<br>+ * the Free Software Foundation; either version 2.1 of the License, or<br>+ * (at your option) any later version.<br>+ *<br>+ * This program is distributed in the hope that it will be useful,<br>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of<br>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the<br>+ * GNU Lesser General Public License for more details.<br>+ *<br>+ * You should have received a copy of the GNU Lesser General Public License<br>+ * along with this program; if not, write to the Free Software Foundation,<br>+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.<br>+ *****************************************************************************/<br>+<br>+#ifdef HAVE_CONFIG_H<br>+# include "config.h"<br>+#endif<br>+<br>+#include <vlc_common.h><br>+<br>+#include <stdalign.h><br>+#include <stdatomic.h><br>+#include <errno.h><br>+#include <time.h><br>+<br>+#include <sys/types.h><br>+#include <pthread.h><br>+<br>+#define WAIT_BUCKET_INIT \<br>+     { PTHREAD_MUTEX_INITIALIZER, PTHREAD_COND_INITIALIZER, 0 }<br>+#define WAIT_BUCKET_INIT_2 WAIT_BUCKET_INIT, WAIT_BUCKET_INIT<br>+#define WAIT_BUCKET_INIT_4 WAIT_BUCKET_INIT_2, WAIT_BUCKET_INIT_2<br>+#define WAIT_BUCKET_INIT_8 WAIT_BUCKET_INIT_4, WAIT_BUCKET_INIT_4<br>+#define WAIT_BUCKET_INIT_16 WAIT_BUCKET_INIT_8, WAIT_BUCKET_INIT_8<br>+#define WAIT_BUCKET_INIT_32 WAIT_BUCKET_INIT_16, WAIT_BUCKET_INIT_16<br></blockquote><br><br>If I understand correctly, this bucket is here to minimize the number of spurious wake, but it doesn't prevent it from happening, which is fine ?<br><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;">+<br>+static struct wait_bucket<br>+{<br>+    pthread_mutex_t lock;<br>+    pthread_cond_t wait;<br>+    unsigned waiters;<br>+} wait_buckets[32] = { WAIT_BUCKET_INIT_32 };<br>+<br>+static struct wait_bucket *wait_bucket_get(atomic_uint *addr)<br>+{<br>+    uintptr_t u = (uintptr_t)addr;<br>+    size_t idx = (u / alignof (*addr)) % ARRAY_SIZE(wait_buckets);<br>+<br>+    return &wait_buckets[idx];<br>+}<br>+<br>+static struct wait_bucket *wait_bucket_enter(atomic_uint *addr)<br>+{<br>+    struct wait_bucket *bucket = wait_bucket_get(addr);<br>+<br>+    pthread_mutex_lock(&bucket->lock);<br>+    bucket->waiters++;<br>+    return bucket;<br>+}<br>+<br>+static void wait_bucket_leave(void *data)<br>+{<br>+    struct wait_bucket *bucket = data;<br>+<br>+    bucket->waiters--;<br>+    pthread_mutex_unlock(&bucket->lock);<br>+}<br>+<br>+void vlc_atomic_wait(void *addr, unsigned value)<br>+{<br>+    atomic_uint *futex = addr;<br>+    struct wait_bucket *bucket = wait_bucket_enter(futex);<br>+<br>+    pthread_cleanup_push(wait_bucket_leave, bucket);<br>+<br>+    if (value == atomic_load_explicit(futex, memory_order_relaxed))<br>+        pthread_cond_wait(&bucket->wait, &bucket->lock);<br>+<br>+    pthread_cleanup_pop(1);<br>+}<br>+<br>+bool vlc_atomic_timedwait(void *addr, unsigned value, vlc_tick_t delay)<br>+{<br>+    atomic_uint *futex = addr;<br>+    struct wait_bucket *bucket;<br>+    struct timespec ts;<br>+    lldiv_t d = lldiv(delay, CLOCK_FREQ);<br>+    int ret = 0;<br>+<br>+    clock_gettime(CLOCK_MONOTONIC, &ts);<br>+    ts.tv_sec += d.quot;<br>+    ts.tv_nsec += NS_FROM_VLC_TICK(d.rem);<br>+<br>+    if (ts.tv_nsec >= 1000000000) {<br>+        ts.tv_sec++;<br>+        ts.tv_nsec -= 1000000000;<br>+    }<br>+<br>+    bucket = wait_bucket_enter(futex);<br>+    pthread_cleanup_push(wait_bucket_leave, bucket);<br>+<br>+    if (value == atomic_load_explicit(futex, memory_order_relaxed))<br>+        ret = pthread_cond_timedwait(&bucket->wait, &bucket->lock, &ts);<br>+<br>+    pthread_cleanup_pop(1);<br>+    return ret == 0;<br>+}<br>+<br>+void vlc_atomic_notify_one(void *addr)<br>+{<br>+    vlc_atomic_notify_all(addr);<br>+}<br>+<br>+void vlc_atomic_notify_all(void *addr)<br>+{<br>+    struct wait_bucket *bucket = wait_bucket_get(addr);<br>+<br>+    pthread_mutex_lock(&bucket->lock);<br>+    if (bucket->waiters > 0)<br>+        pthread_cond_broadcast(&bucket->wait);<br>+    pthread_mutex_unlock(&bucket->lock);<br>+}<br></blockquote><br>OK for me, but it deserves a git message and/or few comments. It took me some time to understand what you wanted to do.<br><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 1ex 0.8ex; border-left: 1px solid #729fcf; padding-left: 1ex;">-- <br>2.25.0<hr>vlc-devel mailing list<br>To unsubscribe or modify your subscription options:<br><a href="https://mailman.videolan.org/listinfo/vlc-devel">https://mailman.videolan.org/listinfo/vlc-devel</a><br></blockquote><hr>vlc-devel mailing list<br>To unsubscribe or modify your subscription options:<br><a href="https://mailman.videolan.org/listinfo/vlc-devel">https://mailman.videolan.org/listinfo/vlc-devel</a></pre></blockquote></div><br>-- <br>Envoyé de mon appareil Android avec Courriel K-9 Mail. Veuillez excuser ma brièveté.</body></html>