dummy: fix deadlock when pause called from write_callback

src/dummy.cpp

@@ -44,6 +44,12 @@ static void playback_thread_run(void *arg) {
             continue;
         }
 
+        if (osd->pause_requested.load()) {
+            start_time = now;
+            frames_consumed = 0;
+            continue;
+        }
+
         int fill_bytes = soundio_ring_buffer_fill_count(&osd->ring_buffer);
         int fill_frames = fill_bytes / outstream->bytes_per_frame;
         int free_bytes = soundio_ring_buffer_capacity(&osd->ring_buffer) - fill_bytes;
@@ -86,6 +92,12 @@ static void capture_thread_run(void *arg) {
         double relative_time = next_period - now;
         soundio_os_cond_timed_wait(isd->cond, nullptr, relative_time);
 
+        if (isd->pause_requested.load()) {
+            start_time = now;
+            frames_consumed = 0;
+            continue;
+        }
+
         int fill_bytes = soundio_ring_buffer_fill_count(&isd->ring_buffer);
         int free_bytes = soundio_ring_buffer_capacity(&isd->ring_buffer) - fill_bytes;
         int fill_frames = fill_bytes / instream->bytes_per_frame;
@@ -166,6 +178,7 @@ static int outstream_open_dummy(SoundIoPrivate *si, SoundIoOutStreamPrivate *os)
     SoundIoDevice *device = outstream->device;
 
     osd->clear_buffer_flag.test_and_set();
+    osd->pause_requested.store(false);
 
     if (outstream->software_latency == 0.0)
         outstream->software_latency = clamp(device->software_latency_min, 1.0, device->software_latency_max);
@@ -192,17 +205,15 @@ static int outstream_open_dummy(SoundIoPrivate *si, SoundIoOutStreamPrivate *os)
 }
 
 static int outstream_pause_dummy(struct SoundIoPrivate *si, struct SoundIoOutStreamPrivate *os, bool pause) {
+    SoundIoOutStreamDummy *osd = &os->backend_data.dummy;
+    osd->pause_requested.store(pause);
+    return 0;
+}
+
+static int outstream_start_dummy(SoundIoPrivate *si, SoundIoOutStreamPrivate *os) {
     SoundIoOutStreamDummy *osd = &os->backend_data.dummy;
     SoundIo *soundio = &si->pub;
-    if (pause) {
+    assert(!osd->thread);
-        if (osd->thread) {
-            osd->abort_flag.clear();
-            soundio_os_cond_signal(osd->cond, nullptr);
-            soundio_os_thread_destroy(osd->thread);
-            osd->thread = nullptr;
-        }
-    } else {
-        if (!osd->thread) {
     osd->abort_flag.test_and_set();
     int err;
     if ((err = soundio_os_thread_create(playback_thread_run, os,
@@ -210,15 +221,9 @@ static int outstream_pause_dummy(struct SoundIoPrivate *si, struct SoundIoOutStr
     {
         return err;
     }
-        }
-    }
     return 0;
 }
 
-static int outstream_start_dummy(SoundIoPrivate *si, SoundIoOutStreamPrivate *os) {
-    return outstream_pause_dummy(si, os, false);
-}
-
 static int outstream_begin_write_dummy(SoundIoPrivate *si,
         SoundIoOutStreamPrivate *os, SoundIoChannelArea **out_areas, int *frame_count)
 {
@@ -284,6 +289,7 @@ static int instream_open_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is) {
     SoundIoInStream *instream = &is->pub;
     SoundIoDevice *device = instream->device;
 
+    isd->pause_requested.store(false);
 
     if (instream->software_latency == 0.0)
         instream->software_latency = clamp(device->software_latency_min, 1.0, device->software_latency_max);
@@ -312,17 +318,15 @@ static int instream_open_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is) {
 }
 
 static int instream_pause_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is, bool pause) {
+    SoundIoInStreamDummy *isd = &is->backend_data.dummy;
+    isd->pause_requested.store(pause);
+    return 0;
+}
+
+static int instream_start_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is) {
     SoundIoInStreamDummy *isd = &is->backend_data.dummy;
     SoundIo *soundio = &si->pub;
-    if (pause) {
+    assert(!isd->thread);
-        if (isd->thread) {
-            isd->abort_flag.clear();
-            soundio_os_cond_signal(isd->cond, nullptr);
-            soundio_os_thread_destroy(isd->thread);
-            isd->thread = nullptr;
-        }
-    } else {
-        if (!isd->thread) {
     isd->abort_flag.test_and_set();
     int err;
     if ((err = soundio_os_thread_create(capture_thread_run, is,
@@ -330,15 +334,9 @@ static int instream_pause_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is,
     {
         return err;
     }
-        }
-    }
     return 0;
 }
 
-static int instream_start_dummy(SoundIoPrivate *si, SoundIoInStreamPrivate *is) {
-    return instream_pause_dummy(si, is, false);
-}
-
 static int instream_begin_read_dummy(SoundIoPrivate *si,
         SoundIoInStreamPrivate *is, SoundIoChannelArea **out_areas, int *frame_count)
 {

src/dummy.hpp

@@ -34,6 +34,7 @@ struct SoundIoOutStreamDummy {
     struct SoundIoRingBuffer ring_buffer;
     double playback_start_time;
     atomic_flag clear_buffer_flag;
+    atomic_bool pause_requested;
     SoundIoChannelArea areas[SOUNDIO_MAX_CHANNELS];
 };
 
@@ -46,6 +47,7 @@ struct SoundIoInStreamDummy {
     int read_frame_count;
     int buffer_frame_count;
     struct SoundIoRingBuffer ring_buffer;
+    atomic_bool pause_requested;
     SoundIoChannelArea areas[SOUNDIO_MAX_CHANNELS];
 };