qemu-thread: Add qemu_cond_timedwait

The new function is needed to implement conditional sleep for CPU
throttling. It's possible to reuse qemu_sem_timedwait, but it's more
difficult than just add qemu_cond_timedwait.

Also moved compute_abs_deadline function up the code to reuse it in
qemu_cond_timedwait_impl win32.

Signed-off-by: Yury Kotov <yury-kotov@yandex-team.ru>
Message-Id: <20190909131335.16848-2-yury-kotov@yandex-team.ru>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 66 insertions, 12 deletions

diff --git a/util/qemu-thread-posix.c b/util/qemu-thread-posix.c
index 1bf5e65..838980a 100644
--- a/util/qemu-thread-posix.c
+++ b/util/qemu-thread-posix.c
@@ -36,6 +36,18 @@ static void error_exit(int err, const char *msg)
     abort();
 }
 
+static void compute_abs_deadline(struct timespec *ts, int ms)
+{
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    ts->tv_nsec = tv.tv_usec * 1000 + (ms % 1000) * 1000000;
+    ts->tv_sec = tv.tv_sec + ms / 1000;
+    if (ts->tv_nsec >= 1000000000) {
+        ts->tv_sec++;
+        ts->tv_nsec -= 1000000000;
+    }
+}
+
 void qemu_mutex_init(QemuMutex *mutex)
 {
     int err;
@@ -164,6 +176,23 @@ void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const char *file, con
         error_exit(err, __func__);
 }
 
+bool qemu_cond_timedwait_impl(QemuCond *cond, QemuMutex *mutex, int ms,
+                              const char *file, const int line)
+{
+    int err;
+    struct timespec ts;
+
+    assert(cond->initialized);
+    trace_qemu_mutex_unlock(mutex, file, line);
+    compute_abs_deadline(&ts, ms);
+    err = pthread_cond_timedwait(&cond->cond, &mutex->lock, &ts);
+    trace_qemu_mutex_locked(mutex, file, line);
+    if (err && err != ETIMEDOUT) {
+        error_exit(err, __func__);
+    }
+    return err != ETIMEDOUT;
+}
+
 void qemu_sem_init(QemuSemaphore *sem, int init)
 {
     int rc;
@@ -238,18 +267,6 @@ void qemu_sem_post(QemuSemaphore *sem)
 #endif
 }
 
-static void compute_abs_deadline(struct timespec *ts, int ms)
-{
-    struct timeval tv;
-    gettimeofday(&tv, NULL);
-    ts->tv_nsec = tv.tv_usec * 1000 + (ms % 1000) * 1000000;
-    ts->tv_sec = tv.tv_sec + ms / 1000;
-    if (ts->tv_nsec >= 1000000000) {
-        ts->tv_sec++;
-        ts->tv_nsec -= 1000000000;
-    }
-}
-
 int qemu_sem_timedwait(QemuSemaphore *sem, int ms)
 {
     int rc;
diff --git a/util/qemu-thread-win32.c b/util/qemu-thread-win32.c
index 572f885..56a8333 100644
--- a/util/qemu-thread-win32.c
+++ b/util/qemu-thread-win32.c
@@ -145,6 +145,23 @@ void qemu_cond_wait_impl(QemuCond *cond, QemuMutex *mutex, const char *file, con
     qemu_mutex_post_lock(mutex, file, line);
 }
 
+bool qemu_cond_timedwait_impl(QemuCond *cond, QemuMutex *mutex, int ms,
+                              const char *file, const int line)
+{
+    int rc = 0;
+
+    assert(cond->initialized);
+    trace_qemu_mutex_unlock(mutex, file, line);
+    if (!SleepConditionVariableSRW(&cond->var, &mutex->lock, ms, 0)) {
+        rc = GetLastError();
+    }
+    trace_qemu_mutex_locked(mutex, file, line);
+    if (rc && rc != ERROR_TIMEOUT) {
+        error_exit(rc, __func__);
+    }
+    return rc != ERROR_TIMEOUT;
+}
+
 void qemu_sem_init(QemuSemaphore *sem, int init)
 {
     /* Manual reset.  */
diff --git a/util/qsp.c b/util/qsp.c
index 5264c97..6226541 100644
--- a/util/qsp.c
+++ b/util/qsp.c
@@ -131,6 +131,7 @@ QemuRecMutexLockFunc qemu_rec_mutex_lock_func = qemu_rec_mutex_lock_impl;
 QemuRecMutexTrylockFunc qemu_rec_mutex_trylock_func =
     qemu_rec_mutex_trylock_impl;
 QemuCondWaitFunc qemu_cond_wait_func = qemu_cond_wait_impl;
+QemuCondTimedWaitFunc qemu_cond_timedwait_func = qemu_cond_timedwait_impl;
 
 /*
  * It pays off to _not_ hash callsite->file; hashing a string is slow, and
@@ -412,6 +413,23 @@ qsp_cond_wait(QemuCond *cond, QemuMutex *mutex, const char *file, int line)
     qsp_entry_record(e, t1 - t0);
 }
 
+static bool
+qsp_cond_timedwait(QemuCond *cond, QemuMutex *mutex, int ms,
+                   const char *file, int line)
+{
+    QSPEntry *e;
+    int64_t t0, t1;
+    bool ret;
+
+    t0 = get_clock();
+    ret = qemu_cond_timedwait_impl(cond, mutex, ms, file, line);
+    t1 = get_clock();
+
+    e = qsp_entry_get(cond, file, line, QSP_CONDVAR);
+    qsp_entry_record(e, t1 - t0);
+    return ret;
+}
+
 bool qsp_is_enabled(void)
 {
     return atomic_read(&qemu_mutex_lock_func) == qsp_mutex_lock;
@@ -425,6 +443,7 @@ void qsp_enable(void)
     atomic_set(&qemu_rec_mutex_lock_func, qsp_rec_mutex_lock);
     atomic_set(&qemu_rec_mutex_trylock_func, qsp_rec_mutex_trylock);
     atomic_set(&qemu_cond_wait_func, qsp_cond_wait);
+    atomic_set(&qemu_cond_timedwait_func, qsp_cond_timedwait);
 }
 
 void qsp_disable(void)
@@ -435,6 +454,7 @@ void qsp_disable(void)
     atomic_set(&qemu_rec_mutex_lock_func, qemu_rec_mutex_lock_impl);
     atomic_set(&qemu_rec_mutex_trylock_func, qemu_rec_mutex_trylock_impl);
     atomic_set(&qemu_cond_wait_func, qemu_cond_wait_impl);
+    atomic_set(&qemu_cond_timedwait_func, qemu_cond_timedwait_impl);
 }
 
 static gint qsp_tree_cmp(gconstpointer ap, gconstpointer bp, gpointer up)