threads: use mpv time for mpthread_cond_timedwait wrapper

Use the time as returned by mp_time_us() for mpthread_cond_timedwait(),
instead of calculating the struct timespec value based on a timeout.
This (probably) makes it easier to wait for a specific deadline.

audio/out/push.c

@@ -274,7 +274,7 @@ static void *playthread(void *arg)
         MP_STATS(ao, "start audio wait");
         pthread_mutex_lock(&p->wakeup_lock);
         if (!p->need_wakeup)
-            mpthread_cond_timedwait(&p->wakeup, &p->wakeup_lock, timeout);
+            mpthread_cond_timedwait_rel(&p->wakeup, &p->wakeup_lock, timeout);
         p->need_wakeup = false;
         pthread_mutex_unlock(&p->wakeup_lock);
         MP_STATS(ao, "end audio wait");

misc/dispatch.c

@@ -20,6 +20,7 @@
 
 #include "common/common.h"
 #include "osdep/threads.h"
+#include "osdep/timer.h"
 
 #include "dispatch.h"
 
@@ -175,11 +176,12 @@ void mp_dispatch_run(struct mp_dispatch_queue *queue,
 // still process the remaining queue items, and wait for unsuspend.)
 void mp_dispatch_queue_process(struct mp_dispatch_queue *queue, double timeout)
 {
+    int64_t wait = timeout > 0 ? mp_add_timeout(mp_time_us(), timeout) : 0;
     pthread_mutex_lock(&queue->lock);
     queue->suspended = true;
     // Wake up thread which called mp_dispatch_suspend().
     pthread_cond_broadcast(&queue->cond);
-    while (queue->head || queue->suspend_requested || timeout > 0) {
+    while (queue->head || queue->suspend_requested || wait > 0) {
         if (queue->head) {
             struct mp_dispatch_item *item = queue->head;
             queue->head = item->next;
@@ -203,13 +205,13 @@ void mp_dispatch_queue_process(struct mp_dispatch_queue *queue, double timeout)
                 pthread_cond_broadcast(&queue->cond);
             }
         } else {
-            if (timeout > 0) {
-                mpthread_cond_timedwait(&queue->cond, &queue->lock, timeout);
+            if (wait > 0) {
+                mpthread_cond_timedwait(&queue->cond, &queue->lock, wait);
             } else {
                 pthread_cond_wait(&queue->cond, &queue->lock);
             }
         }
-        timeout = 0;
+        wait = 0;
     }
     queue->suspended = false;
     pthread_mutex_unlock(&queue->lock);

osdep/threads.c

@@ -15,61 +15,22 @@
  * with mpv.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include <time.h>
-#include <unistd.h>
-#include <sys/time.h>
-#include <limits.h>
-
-#include "common/common.h"
 #include "threads.h"
+#include "timer.h"
 
-static void get_pthread_time(struct timespec *out_ts)
-{
-#if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
-    clock_gettime(CLOCK_REALTIME, out_ts);
-#else
-    // OSX
-    struct timeval tv;
-    gettimeofday(&tv, NULL);
-    out_ts->tv_sec = tv.tv_sec;
-    out_ts->tv_nsec = tv.tv_usec * 1000UL;
-#endif
-}
-
-static void timespec_add_seconds(struct timespec *ts, double seconds)
-{
-    // clamp to 1 week to avoid tv_sec overflows
-    seconds = MPMIN(seconds, 60 * 60 * 24 * 7);
-    unsigned long secs = (int)seconds;
-    unsigned long nsecs = (seconds - secs) * 1000000000UL;
-    if (nsecs + ts->tv_nsec >= 1000000000UL) {
-        secs += 1;
-        nsecs -= 1000000000UL;
-    }
-    ts->tv_sec += secs;
-    ts->tv_nsec += nsecs;
-}
-
-// Return the argument to pass to e.g. pthread_cond_timedwait().
-// (Note that pthread_cond_t supports multiple clocks; this function computes
-// the time value needed by the default clock.)
-struct timespec mpthread_get_deadline(double timeout)
-{
-    struct timespec ts;
-    get_pthread_time(&ts);
-    timespec_add_seconds(&ts, timeout);
-    return ts;
-}
-
-// Call pthread_cond_timedwait() with a relative timeout in seconds
 int mpthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
-                            double timeout)
+                            int64_t abstime)
 {
-    struct timespec ts = mpthread_get_deadline(timeout);
+    struct timespec ts = mp_time_us_to_timespec(abstime);
     return pthread_cond_timedwait(cond, mutex, &ts);
 }
 
-// Helper to reduce boiler plate.
+int mpthread_cond_timedwait_rel(pthread_cond_t *cond, pthread_mutex_t *mutex,
+                                double s)
+{
+    return mpthread_cond_timedwait(cond, mutex, mp_add_timeout(mp_time_us(), s));
+}
+
 int mpthread_mutex_init_recursive(pthread_mutex_t *mutex)
 {
     pthread_mutexattr_t attr;

osdep/threads.h

@@ -2,12 +2,18 @@
 #define MP_OSDEP_THREADS_H_
 
 #include <pthread.h>
+#include <inttypes.h>
 
-struct timespec mpthread_get_deadline(double timeout);
-
+// Call pthread_cond_timedwait() with an absolute timeout using the same
+// time source/unit as mp_time_us() (microseconds).
 int mpthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
-                            double timeout);
+                            int64_t abstime);
 
+// Wait by a relative amount of time in seconds.
+int mpthread_cond_timedwait_rel(pthread_cond_t *cond, pthread_mutex_t *mutex,
+                                double seconds);
+
+// Helper to reduce boiler plate.
 int mpthread_mutex_init_recursive(pthread_mutex_t *mutex);
 
 #endif

osdep/timer.c

@@ -17,9 +17,15 @@
 
 #include <stdlib.h>
 #include <pthread.h>
+#include <time.h>
+#include <unistd.h>
+#include <sys/time.h>
+#include <limits.h>
+#include <assert.h>
 
-#include "timer.h"
+#include "common/common.h"
 #include "common/msg.h"
+#include "timer.h"
 
 static uint64_t raw_time_offset;
 pthread_once_t timer_init_once = PTHREAD_ONCE_INIT;
@@ -60,21 +66,75 @@ int64_t mp_time_relative_us(int64_t *t)
     return r;
 }
 
+int64_t mp_add_timeout(int64_t time_us, double timeout_sec)
+{
+    assert(time_us > 0); // mp_time_us() returns strictly positive values
+    double t = timeout_sec * 1000 * 1000;
+    if (t >= (double)(INT64_MAX - time_us))
+        return INT64_MAX;
+    if (t <= (double)time_us)
+        return 1;
+    return time_us + (int64_t)t;
+}
+
+static void get_realtime(struct timespec *out_ts)
+{
+#if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
+    clock_gettime(CLOCK_REALTIME, out_ts);
+#else
+    // OSX
+    struct timeval tv;
+    gettimeofday(&tv, NULL);
+    out_ts->tv_sec = tv.tv_sec;
+    out_ts->tv_nsec = tv.tv_usec * 1000UL;
+#endif
+}
+
+struct timespec mp_time_us_to_timespec(int64_t time_us)
+{
+    struct timespec ts;
+    get_realtime(&ts);
+    // We don't know what time source mp_time_us() uses, but usually it's not
+    // CLOCK_REALTIME - so we have to remap the times.
+    int64_t unow = mp_time_us();
+    int64_t diff_us = time_us - unow;
+    long diff_secs = diff_us / (1000L * 1000L);
+    unsigned long diff_nsecs = (diff_us - diff_secs * (1000L * 1000L)) * 1000UL;
+    if (diff_nsecs + ts.tv_nsec >= 1000000000UL) {
+        diff_secs += 1;
+        diff_nsecs -= 1000000000UL;
+    }
+    ts.tv_sec += diff_secs;
+    ts.tv_nsec += diff_nsecs;
+    return ts;
+}
+
 #if 0
 #include <stdio.h>
+#include "threads.h"
+
+#define TEST_SLEEP 1
 
 int main(void) {
-    int c = 200;
+    int c = 2000000;
     int64_t j, r, t = 0;
+    pthread_mutex_t mtx;
+    pthread_mutex_init(&mtx, NULL);
+    pthread_cond_t cnd;
+    pthread_cond_init(&cnd, NULL);
 
     mp_time_init();
 
     for (int i = 0; i < c; i++) {
         const int delay = rand() / (RAND_MAX / 1e5);
         r = mp_time_us();
+#if TEST_SLEEP
         mp_sleep_us(delay);
+#else
+        mpthread_cond_timedwait(&cnd, &mtx, r + delay);
+#endif
         j = (mp_time_us() - r) - delay;
-        printf("sleep time: sleep=%8i err=%5i\n", delay, (int)j);
+        printf("sleep time: t=%"PRId64" sleep=%8i err=%5i\n", r, delay, (int)j);
         t += j;
     }
     fprintf(stderr, "average error:\t%i\n", (int)(t / c));

osdep/timer.h

@@ -44,4 +44,11 @@ void mp_sleep_us(int64_t us);
 // first call will return 0, instead of the absolute current time.)
 int64_t mp_time_relative_us(int64_t *t);
 
+// Add a time in seconds to the given time in microseconds, and return it.
+// Takes care of possible overflows. Never returns a negative or 0 time.
+int64_t mp_add_timeout(int64_t time_us, double timeout_sec);
+
+// Convert the mp time in microseconds to a timespec using CLOCK_REALTIME.
+struct timespec mp_time_us_to_timespec(int64_t time_us);
+
 #endif /* MPLAYER_TIMER_H */

player/client.c

@@ -477,7 +477,7 @@ mpv_event *mpv_wait_event(mpv_handle *ctx, double timeout)
 {
     mpv_event *event = ctx->cur_event;
 
-    struct timespec deadline = mpthread_get_deadline(timeout);
+    int64_t deadline = mp_add_timeout(mp_time_us(), timeout);
 
     pthread_mutex_lock(&ctx->lock);
 
@@ -519,7 +519,7 @@ mpv_event *mpv_wait_event(mpv_handle *ctx, double timeout)
             break;
         if (timeout <= 0)
             break;
-        int r = pthread_cond_timedwait(&ctx->wakeup, &ctx->lock, &deadline);
+        int r = mpthread_cond_timedwait(&ctx->wakeup, &ctx->lock, deadline);
         if (r == ETIMEDOUT)
             break;
     }

stream/cache.c

@@ -167,7 +167,7 @@ static int cache_wakeup_and_wait(struct priv *s, double *retry_time)
     }
 
     pthread_cond_signal(&s->wakeup);
-    mpthread_cond_timedwait(&s->wakeup, &s->mutex, CACHE_WAIT_TIME);
+    mpthread_cond_timedwait_rel(&s->wakeup, &s->mutex, CACHE_WAIT_TIME);
 
     *retry_time += mp_time_sec() - start;
 
@@ -529,7 +529,7 @@ static void *cache_thread(void *arg)
             s->control = CACHE_CTRL_NONE;
         }
         if (s->idle && s->control == CACHE_CTRL_NONE)
-            mpthread_cond_timedwait(&s->wakeup, &s->mutex, CACHE_IDLE_SLEEP_TIME);
+            mpthread_cond_timedwait_rel(&s->wakeup, &s->mutex, CACHE_IDLE_SLEEP_TIME);
     }
     pthread_cond_signal(&s->wakeup);
     pthread_mutex_unlock(&s->mutex);