Sprinkle some thread safety over event loop, add *wait_for_event

1 files changed, 91 insertions, 56 deletions

diff --git a/mpv.py b/mpv.py
index aded4a9..a2950ce 100644
--- a/mpv.py
+++ b/mpv.py
@@ -23,6 +23,7 @@ import os
 import sys
 from warnings import warn
 from functools import partial, wraps
+from contextlib import contextmanager
 import collections
 import re
 import traceback
@@ -636,37 +637,6 @@ def _event_generator(handle):
         yield event
 
 
-def _event_loop(event_handle, event_callbacks, message_handlers, property_handlers, log_handler):
-    for event in _event_generator(event_handle):
-        try:
-            devent = event.as_dict(decoder=lazy_decoder) # copy data from ctypes
-            eid = devent['event_id']
-            for callback in event_callbacks:
-                callback(devent)
-
-            if eid == MpvEventID.PROPERTY_CHANGE:
-                pc = devent['event']
-                name, value, _fmt = pc['name'], pc['value'], pc['format']
-                for handler in property_handlers[name]:
-                    handler(name, value)
-
-            if eid == MpvEventID.LOG_MESSAGE and log_handler is not None:
-                ev = devent['event']
-                log_handler(ev['level'], ev['prefix'], ev['text'])
-
-            if eid == MpvEventID.CLIENT_MESSAGE:
-                # {'event': {'args': ['key-binding', 'foo', 'u-', 'g']}, 'reply_userdata': 0, 'error': 0, 'event_id': 16}
-                target, *args = devent['event']['args']
-                if target in message_handlers:
-                    message_handlers[target](*args)
-
-            if eid == MpvEventID.SHUTDOWN:
-                _mpv_detach_destroy(event_handle)
-                return
-
-        except Exception as e:
-            traceback.print_exc()
-
 _py_to_mpv = lambda name: name.replace('_', '-')
 _mpv_to_py = lambda name: name.replace('-', '_')
 
@@ -857,13 +827,13 @@ class MPV(object):
         self.lazy   = _DecoderPropertyProxy(self, lazy_decoder)
 
         self._event_callbacks = []
+        self._event_handler_lock = threading.Lock()
         self._property_handlers = collections.defaultdict(lambda: [])
         self._quit_handlers = set()
         self._message_handlers = {}
         self._key_binding_handlers = {}
         self._event_handle = _mpv_create_client(self.handle, b'py_event_handler')
-        self._loop = partial(_event_loop, self._event_handle, self._event_callbacks,
-                self._message_handlers, self._property_handlers, log_handler)
+        self._log_handler = log_handler
         self._stream_protocol_cbs = {}
         self._stream_protocol_frontends = collections.defaultdict(lambda: {})
         self.register_stream_protocol('python', self._python_stream_open)
@@ -881,36 +851,68 @@ class MPV(object):
             self._event_thread = None
 
         self._core_shutdown = False
-        # This is the first callback in line, so other event callback-based mechanisms can use core_shutdown
-        @self.event_callback('shutdown')
-        def shutdown_event_callback(event):
-            nonlocal self
-            self._core_shutdown = True
+
+    def _loop(self):
+        for event in _event_generator(self._event_handle):
+            try:
+                devent = event.as_dict(decoder=lazy_decoder) # copy data from ctypes
+                eid = devent['event_id']
+
+                with self._event_handler_lock:
+                    if eid == MpvEventID.SHUTDOWN:
+                        self._core_shutdown = True
+
+                for callback in self._event_callbacks:
+                    callback(devent)
+
+                if eid == MpvEventID.PROPERTY_CHANGE:
+                    pc = devent['event']
+                    name, value, _fmt = pc['name'], pc['value'], pc['format']
+                    for handler in self._property_handlers[name]:
+                        handler(name, value)
+
+                if eid == MpvEventID.LOG_MESSAGE and self._log_handler is not None:
+                    ev = devent['event']
+                    self._log_handler(ev['level'], ev['prefix'], ev['text'])
+
+                if eid == MpvEventID.CLIENT_MESSAGE:
+                    # {'event': {'args': ['key-binding', 'foo', 'u-', 'g']}, 'reply_userdata': 0, 'error': 0, 'event_id': 16}
+                    target, *args = devent['event']['args']
+                    if target in self._message_handlers:
+                        self._message_handlers[target](*args)
+
+                if eid == MpvEventID.SHUTDOWN:
+                    _mpv_detach_destroy(self._event_handle)
+                    return
+
+            except Exception as e:
+                print('Exception inside python-mpv event loop:', file=sys.stderr)
+                traceback.print_exc()
 
     @property
     def core_shutdown(self):
         return self._core_shutdown
 
     def wait_until_paused(self):
-        """Waits until playback of the current title is paused or done."""
+        """Waits until playback of the current title is paused or done. Raises a ShutdownError if the core is shutdown while
+        waiting."""
         self.wait_for_property('core-idle')
 
     def wait_for_playback(self):
-        """Waits until playback of the current title is paused or done.
-
-        NOTE: This function changed from an event-based implementation to a property observer-based implementation in
-        v0.5.0. This may cause different results in certain cases. If you find one such case, for documentation please
-        tell the world in an issue on the github project."""
-        self.wait_until_playing()
-        self.wait_until_paused()
+        """Waits until playback of the current title is finished. Raises a ShutdownError if the core is shutdown while
+        waiting.
+        """
+        self.wait_for_event('end_file')
 
     def wait_until_playing(self):
-        """Waits until playback of the current title has started."""
+        """Waits until playback of the current title has started. Raises a ShutdownError if the core is shutdown while
+        waiting."""
         self.wait_for_property('core-idle', lambda idle: not idle)
 
     def wait_for_property(self, name, cond=lambda val: val, level_sensitive=True):
         """Waits until ``cond`` evaluates to a truthy value on the named property. This can be used to wait for
-        properties such as ``idle_active`` indicating the player is done with regular playback and just idling around
+        properties such as ``idle_active`` indicating the player is done with regular playback and just idling around.
+        Raises a ShutdownError when the core is shutdown while waiting.
         """
         sema = threading.Semaphore(value=0)
 
@@ -929,8 +931,38 @@ class MPV(object):
         if self._core_shutdown:
             raise ShutdownError('libmpv core has been shutdown')
 
+        shutdown_handler.unregister_mpv_events()
         self.unobserve_property(name, observer)
 
+    def wait_for_event(self, *event_types, cond=lambda evt: True):
+        with self.prepare_and_wait_for_event(*event_types, cond=cond):
+            pass
+
+    @contextmanager
+    def prepare_and_wait_for_event(self, *event_types, cond=lambda evt: True):
+        """Waits for the indicated event(s). If cond is given, waits until cond(event) is true. Raises a ShutdownError
+        if the core is shutdown while waiting. This also happens when 'shutdown' is in event_types.
+        """
+        sema = threading.Semaphore(value=0)
+
+        @self.event_callback('shutdown')
+        def shutdown_handler(event):
+            sema.release()
+
+        @self.event_callback(*event_types)
+        def target_handler(evt):
+            if cond(evt):
+                sema.release()
+
+        yield
+        sema.acquire()
+
+        if self._core_shutdown:
+            raise ShutdownError('libmpv core has been shutdown')
+
+        shutdown_handler.unregister_mpv_events()
+        target_handler.unregister_mpv_events()
+
     def __del__(self):
         if self.handle:
             self.terminate()
@@ -1369,14 +1401,17 @@ class MPV(object):
             my_handler.unregister_mpv_events()
         """
         def register(callback):
-            types = [MpvEventID.from_str(t) if isinstance(t, str) else t for t in event_types] or MpvEventID.ANY
-            @wraps(callback)
-            def wrapper(event, *args, **kwargs):
-                if event['event_id'] in types:
-                    callback(event, *args, **kwargs)
-            self._event_callbacks.append(wrapper)
-            wrapper.unregister_mpv_events = partial(self.unregister_event_callback, wrapper)
-            return wrapper
+            with self._event_handler_lock:
+                if self._core_shutdown:
+                    raise ShutdownError('libmpv core has been shutdown')
+                types = [MpvEventID.from_str(t) if isinstance(t, str) else t for t in event_types] or MpvEventID.ANY
+                @wraps(callback)
+                def wrapper(event, *args, **kwargs):
+                    if event['event_id'] in types:
+                        callback(event, *args, **kwargs)
+                self._event_callbacks.append(wrapper)
+                wrapper.unregister_mpv_events = partial(self.unregister_event_callback, wrapper)
+                return wrapper
         return register
 
     @staticmethod