sink,source: Avoid unnecessary call to pa_rtclock_now()

pa_{sink,source}_volume_change_apply were being called by the ALSA I/O
thread on every iteration, causing a pa_rtclock_now() call, which can
sometimes be heavy. We avoid this call by making sure there actually are
changes to apply before proceeding into the function.

While we're at it, also dropping a redundant check on s->write_volume.

2 files changed, 10 insertions, 6 deletions

diff --git a/src/pulsecore/sink.c b/src/pulsecore/sink.c
index 21c672364..05b08aaf5 100644
--- a/src/pulsecore/sink.c
+++ b/src/pulsecore/sink.c
@@ -3400,12 +3400,12 @@ static void pa_sink_volume_change_flush(pa_sink *s) {
 
 /* Called from the IO thread. */
 pa_bool_t pa_sink_volume_change_apply(pa_sink *s, pa_usec_t *usec_to_next) {
-    pa_usec_t now = pa_rtclock_now();
+    pa_usec_t now;
     pa_bool_t ret = FALSE;
 
     pa_assert(s);
 
-    if (!PA_SINK_IS_LINKED(s->state)) {
+    if (!s->thread_info.volume_changes || !PA_SINK_IS_LINKED(s->state)) {
         if (usec_to_next)
             *usec_to_next = 0;
         return ret;
@@ -3413,6 +3413,8 @@ pa_bool_t pa_sink_volume_change_apply(pa_sink *s, pa_usec_t *usec_to_next) {
 
     pa_assert(s->write_volume);
 
+    now = pa_rtclock_now();
+
     while (s->thread_info.volume_changes && now >= s->thread_info.volume_changes->at) {
         pa_sink_volume_change *c = s->thread_info.volume_changes;
         PA_LLIST_REMOVE(pa_sink_volume_change, s->thread_info.volume_changes, c);
@@ -3423,7 +3425,7 @@ pa_bool_t pa_sink_volume_change_apply(pa_sink *s, pa_usec_t *usec_to_next) {
         pa_sink_volume_change_free(c);
     }
 
-    if (s->write_volume && ret)
+    if (ret)
         s->write_volume(s);
 
     if (s->thread_info.volume_changes) {
diff --git a/src/pulsecore/source.c b/src/pulsecore/source.c
index 523961010..d47280ce8 100644
--- a/src/pulsecore/source.c
+++ b/src/pulsecore/source.c
@@ -2575,12 +2575,12 @@ static void pa_source_volume_change_flush(pa_source *s) {
 
 /* Called from the IO thread. */
 pa_bool_t pa_source_volume_change_apply(pa_source *s, pa_usec_t *usec_to_next) {
-    pa_usec_t now = pa_rtclock_now();
+    pa_usec_t now;
     pa_bool_t ret = FALSE;
 
     pa_assert(s);
 
-    if (!PA_SOURCE_IS_LINKED(s->state)) {
+    if (!s->thread_info.volume_changes || !PA_SOURCE_IS_LINKED(s->state)) {
         if (usec_to_next)
             *usec_to_next = 0;
         return ret;
@@ -2588,6 +2588,8 @@ pa_bool_t pa_source_volume_change_apply(pa_source *s, pa_usec_t *usec_to_next) {
 
     pa_assert(s->write_volume);
 
+    now = pa_rtclock_now();
+
     while (s->thread_info.volume_changes && now >= s->thread_info.volume_changes->at) {
         pa_source_volume_change *c = s->thread_info.volume_changes;
         PA_LLIST_REMOVE(pa_source_volume_change, s->thread_info.volume_changes, c);
@@ -2598,7 +2600,7 @@ pa_bool_t pa_source_volume_change_apply(pa_source *s, pa_usec_t *usec_to_next) {
         pa_source_volume_change_free(c);
     }
 
-    if (s->write_volume && ret)
+    if (ret)
         s->write_volume(s);
 
     if (s->thread_info.volume_changes) {