timer: don't advance time_frameno when paused

This requires a bit of adjustment in the get_frame time_cond wait
loop so it still services the event loop when woken without advance

At least now get_frame has no explicit pause code, but it does
require the timer keep firing while paused so it signals time_cond.

2 files changed, 30 insertions, 17 deletions

diff --git a/src/rmd_get_frame.c b/src/rmd_get_frame.c
index 4f8343a..5c6e800 100644
--- a/src/rmd_get_frame.c
+++ b/src/rmd_get_frame.c
@@ -332,9 +332,22 @@ void *rmdGetFrame(ProgData *pdata) {
 		unsigned	time_frameno;
 
 		pthread_mutex_lock(&pdata->time_mutex);
-		while (pdata->capture_frameno >= pdata->time_frameno)
+		while (pdata->capture_frameno >= pdata->time_frameno) {
 			pthread_cond_wait(&pdata->time_cond, &pdata->time_mutex);
 
+			if (pdata->capture_frameno >= pdata->time_frameno) {
+				/* *Likely* paused, but could be a spurious wakeup.
+				 * either way, it's harmless to service the event loop
+				 * before waiting again.  This is how the timer keeps
+				 * the event loop serviced by signaling us without
+				 * advancing time_frameno.
+				 */
+				pthread_mutex_unlock(&pdata->time_mutex);
+				rmdEventLoop(pdata);
+				pthread_mutex_lock(&pdata->time_mutex);
+			}
+		}
+
 		time_frameno = pdata->time_frameno;
 		pthread_mutex_unlock(&pdata->time_mutex);
 
@@ -342,17 +355,6 @@ void *rmdGetFrame(ProgData *pdata) {
 		//events (if not full_shots)
 		rmdEventLoop(pdata);
 
-		if (pdata->paused) {
-			/* This is a bit janky, but there's need to service the event loop
-			 * when paused, so instead of blocking on pause_cond, a short sleep
-			 * is performed.
-			 * Since the timer keeps running currently when paused, the above
-			 * cond_wait() will never prevent us from reaching here.
-			 */
-			nanosleep(&(struct timespec){ .tv_nsec = 50000000 }, NULL);
-			continue;
-		}
-
 		//switch back and front buffers (full_shots only)
 		if (d_buff)
 			img_sel = img_sel ? 0 : 1;
diff --git a/src/rmd_timer.c b/src/rmd_timer.c
index f584bf2..a523166 100644
--- a/src/rmd_timer.c
+++ b/src/rmd_timer.c
@@ -113,14 +113,25 @@ void *rmdTimer(ProgData *pdata) {
 			}
 		}
 
+		/* When paused, stop advancing time_frameno, get_frame only progresses
+		 * when time_frameno > capture_frameno.  But get_frame needs to service
+		 * the event loop even when paused, so still signal time_cond just with
+		 * pdata->time_frameno frozen.  get_frame will then handle time_cond
+		 * wakeups where capture_frameno >= time_frameno as "poll events".
+		 */
+		if (pdata->paused)
+			frame_step = 0;
 		pthread_mutex_unlock(&pdata->pause_mutex);
 
-		if (!pdata->args.nosound)
-			sync_streams(pdata, &frame_step, &delay);
+		if (frame_step) {
+			if (!pdata->args.nosound)
+				sync_streams(pdata, &frame_step, &delay);
+
+			pthread_mutex_lock(&pdata->time_mutex);
+			pdata->time_frameno += frame_step;
+			pthread_mutex_unlock(&pdata->time_mutex);
+		}
 
-		pthread_mutex_lock(&pdata->time_mutex);
-		pdata->time_frameno += frame_step;
-		pthread_mutex_unlock(&pdata->time_mutex);
 		pthread_cond_signal(&pdata->time_cond);
 
 		nanosleep(&delay, NULL);