Add tests and fix error handling for stream callbacks

mpv.py

@@ -898,10 +898,13 @@ class MPV(object):
         try:
             yield
         except Exception as e:
-            try:
-                fut = next(iter(self._exception_futures))
-                fut.set_exception(e)
-            except StopIteration:
+            for fut in self._exception_futures:
+                try:
+                    fut.set_exception(e)
+                    break
+                except InvalidStateError:
+                    pass
+            else:
                 warn(f'Unhandled exception on python-mpv event loop: {e}\n{traceback.format_exc()}', RuntimeWarning)
 
     def _loop(self):
@@ -1087,7 +1090,6 @@ class MPV(object):
 
         @self.event_callback(*event_types)
         def target_handler(evt):
-
             try:
                 rv = cond(evt)
                 if rv:
@@ -1801,12 +1803,17 @@ class MPV(object):
                 except ValueError:
                     return ErrorCode.LOADING_FAILED
                 except Exception as e:
-                    try:
-                        fut = next(iter(self._exception_futures))
-                        fut.set_exception(e)
-                    except StopIteration:
+                    for fut in self._exception_futures:
+                        try:
+                            fut.set_exception(e)
+                            break
+                        except InvalidStateError:
+                            pass
+                    else:
                         warnings.warn(f'Unhandled exception {e} inside stream open callback for URI {uri}\n{traceback.format_exc()}')
 
+
+
                     return ErrorCode.LOADING_FAILED
 
                 cb_info.contents.cookie = None
@@ -1817,6 +1824,7 @@ class MPV(object):
                         for i in range(len(data)):
                             buf[i] = data[i]
                         return len(data)
+                    return -1
                 read = cb_info.contents.read = StreamReadFn(read_backend)
 
                 def close_backend(_userdata):
@@ -1832,12 +1840,14 @@ class MPV(object):
                     def seek_backend(_userdata, offx):
                         with self._enqueue_exceptions():
                             return frontend.seek(offx)
+                        return ErrorCode.GENERIC
                     seek = cb_info.contents.seek = StreamSeekFn(seek_backend)
 
                 if hasattr(frontend, 'size') and frontend.size is not None:
                     def size_backend(_userdata):
                         with self._enqueue_exceptions():
                             return frontend.size
+                        return 0
                     size = cb_info.contents.size = StreamSizeFn(size_backend)
 
                 if hasattr(frontend, 'cancel'):

tests/test_mpv.py

@@ -535,6 +535,115 @@ class TestStreams(unittest.TestCase):
         m.terminate()
         disp.stop()
 
+    def test_stream_open_exception(self):
+        disp = Xvfb()
+        disp.start()
+        m = mpv.MPV(vo=testvo, video=False)
+
+        @m.register_stream_protocol('raiseerror')
+        def open_fn(uri):
+            raise SystemError()
+
+        waiting = threading.Semaphore()
+        result = Future()
+        def run():
+            result.set_running_or_notify_cancel()
+            try:
+                waiting.release()
+                m.wait_for_playback()
+                result.set_result(False)
+            except SystemError:
+                result.set_result(True)
+            except Exception:
+                result.set_result(False)
+
+        t = threading.Thread(target=run, daemon=True)
+        t.start()
+
+        with waiting:
+            time.sleep(0.2)
+            m.play('raiseerror://foo')
+
+        m.wait_for_playback(catch_errors=False)
+        try:
+            assert result.result()
+        finally:
+            m.terminate()
+            disp.stop()
+
+    def test_python_stream_exception(self):
+        disp = Xvfb()
+        disp.start()
+        m = mpv.MPV(vo=testvo)
+
+        @m.python_stream('foo')
+        def foo_gen():
+            with open(TESTVID, 'rb') as f:
+                yield f.read(100)
+                raise SystemError()
+
+        waiting = threading.Semaphore()
+        result = Future()
+        def run():
+            result.set_running_or_notify_cancel()
+            try:
+                waiting.release()
+                m.wait_for_playback()
+                result.set_result(False)
+            except SystemError:
+                result.set_result(True)
+            except Exception:
+                result.set_result(False)
+
+        t = threading.Thread(target=run, daemon=True)
+        t.start()
+
+        with waiting:
+            time.sleep(0.2)
+            m.play('python://foo')
+
+        m.wait_for_playback(catch_errors=False)
+        try:
+            assert result.result()
+        finally:
+            m.terminate()
+            disp.stop()
+
+    def test_stream_open_forward(self):
+        disp = Xvfb()
+        disp.start()
+        m = mpv.MPV(vo=testvo, video=False)
+
+        @m.register_stream_protocol('raiseerror')
+        def open_fn(uri):
+            raise ValueError()
+
+        waiting = threading.Semaphore()
+        result = Future()
+        def run():
+            result.set_running_or_notify_cancel()
+            try:
+                waiting.release()
+                m.wait_for_playback()
+                result.set_result(True)
+            except Exception:
+                result.set_result(False)
+
+        t = threading.Thread(target=run, daemon=True)
+        t.start()
+
+        with waiting:
+            time.sleep(0.2)
+            m.play('raiseerror://foo')
+
+        m.wait_for_playback(catch_errors=False)
+        try:
+            assert result.result()
+        finally:
+            m.terminate()
+            disp.stop()
+
+
 
 class TestLifecycle(unittest.TestCase):
     def test_create_destroy(self):