[PATCH RFCv3 25/51] mainloop: Clear wakeup pipe only when necessary

[pmeerw@xxxxxxxxxx (Peter Meerwald)]

From: Peter Meerwald <p.meerwald@xxxxxxxxxxxxxxxxxx>

when the wakeup pipe became ready, and poll() returned
just one descriptor, we can stop scanning io_events

Signed-off-by: Peter Meerwald <pmeerw at pmeerw.net>
---
 src/pulse/mainloop.c | 24 ++++++++++++++----------
 1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/src/pulse/mainloop.c b/src/pulse/mainloop.c
index c7a5236..a7a3c48 100644
--- a/src/pulse/mainloop.c
+++ b/src/pulse/mainloop.c
@@ -635,6 +635,15 @@ static void rebuild_pollfds(pa_mainloop *m) {
     m->rebuild_pollfds = false;
 }
 
+static void clear_wakeup(pa_mainloop *m) {
+    char c[10];
+
+    pa_assert(m);
+
+    while (pa_read(m->wakeup_pipe[0], &c, sizeof(c), &m->wakeup_pipe_type) == sizeof(c))
+        ;
+}
+
 static unsigned dispatch_pollfds(pa_mainloop *m) {
     pa_io_event *e;
     unsigned r = 0, k;
@@ -642,6 +651,11 @@ static unsigned dispatch_pollfds(pa_mainloop *m) {
     pa_assert(m->poll_func_ret > 0);
 
     k = m->poll_func_ret;
+    if (m->pollfds[0].revents) {
+        clear_wakeup(m);
+        m->pollfds[0].revents = 0;
+        k--;
+    }
 
     PA_LLIST_FOREACH(e, m->io_events) {
 
@@ -775,20 +789,10 @@ void pa_mainloop_wakeup(pa_mainloop *m) {
         pa_log("pa_write() failed while trying to wake up the mainloop: %s", pa_cstrerror(errno));
 }
 
-static void clear_wakeup(pa_mainloop *m) {
-    char c[10];
-
-    pa_assert(m);
-
-    while (pa_read(m->wakeup_pipe[0], &c, sizeof(c), &m->wakeup_pipe_type) == sizeof(c))
-        ;
-}
-
 int pa_mainloop_prepare(pa_mainloop *m, int timeout) {
     pa_assert(m);
     pa_assert(m->state == STATE_PASSIVE);
 
-    clear_wakeup(m);
     scan_dead(m);
 
     if (m->quit)
-- 
1.9.1