fix(viewer): make asset navigation instantaneous (#2539)

tests/test_viewer.py

@@ -79,18 +79,6 @@ class TestLoadBrowser(ViewerTestCase):
         self.m_cmd.assert_called_once_with('ScreenlyWebview')
 
 
-class TestSignalHandlers(ViewerTestCase):
-    @mock.patch('vlc.Instance', mock.MagicMock())
-    @mock.patch(
-        'viewer.media_player.get_device_type',
-        return_value='pi4'
-    )
-    def test_usr1(self, lookup_mock):
-        self.p_killall.start()
-        self.assertEqual(None, self.u.sigusr1(None, None))
-        self.p_killall.stop()
-
-
 class TestWatchdog(ViewerTestCase):
     def test_watchdog_should_create_file_if_not_exists(self):
         try:

viewer/__init__.py

@@ -7,7 +7,7 @@ import logging
 import sys
 from builtins import range
 from os import getenv, path
-from signal import SIGALRM, SIGUSR1, signal
+from signal import SIGALRM, signal
 from time import sleep
 
 import django
@@ -31,8 +31,8 @@ from viewer.media_player import MediaPlayerProxy
 from viewer.playback import navigate_to_asset, play_loop, skip_asset, stop_loop
 from viewer.utils import (
     command_not_found,
+    get_skip_event,
     sigalrm,
-    sigusr1,
     wait_for_server,
     watchdog,
 )
@@ -196,9 +196,13 @@ def view_video(uri, duration):
     view_image('null')
 
     try:
-        while media_player.is_playing():
-            watchdog()
-            sleep(1)
+        skip_event = get_skip_event()
+        skip_event.clear()
+        if skip_event.wait(timeout=int(duration)):
+            logging.info('Skip detected during video playback, stopping video')
+            media_player.stop()
+        else:
+            pass
     except sh.ErrorReturnCode_1:
         logging.info(
             'Resource URI is not correct, remote host is not responding or '
@@ -225,7 +229,15 @@ def asset_loop(scheduler):
         logging.info(
             'Playlist is empty. Sleeping for %s seconds', EMPTY_PL_DELAY)
         view_image(STANDBY_SCREEN)
-        sleep(EMPTY_PL_DELAY)
+        skip_event = get_skip_event()
+        skip_event.clear()
+        if skip_event.wait(timeout=EMPTY_PL_DELAY):
+            # Skip was triggered, continue immediately to next iteration
+            logging.info(
+                'Skip detected during empty playlist wait, continuing')
+        else:
+            # Duration elapsed normally, continue to next iteration
+            pass
 
     elif (
         path.isfile(asset['uri']) or
@@ -248,12 +260,27 @@ def asset_loop(scheduler):
         if 'image' in mime or 'web' in mime:
             duration = int(asset['duration'])
             logging.info('Sleeping for %s', duration)
-            sleep(duration)
+            skip_event = get_skip_event()
+            skip_event.clear()
+            if skip_event.wait(timeout=duration):
+                # Skip was triggered, continue immediately to next iteration
+                logging.info('Skip detected, moving to next asset immediately')
+            else:
+                # Duration elapsed normally, continue to next asset
+                pass
 
     else:
         logging.info('Asset %s at %s is not available, skipping.',
                      asset['name'], asset['uri'])
-        sleep(0.5)
+        skip_event = get_skip_event()
+        skip_event.clear()
+        if skip_event.wait(timeout=0.5):
+            # Skip was triggered, continue immediately to next iteration
+            logging.info(
+                'Skip detected during asset unavailability wait, continuing')
+        else:
+            # Duration elapsed normally, continue to next iteration
+            pass
 
 
 def setup():
@@ -266,7 +293,7 @@ def setup():
         # or we can create a new class that extends Exception.
         sys.exit(1)
 
-    signal(SIGUSR1, sigusr1)
+    # Skip event is now handled via threading instead of signals
     signal(SIGALRM, sigalrm)
 
     load_settings()

viewer/media_player.py

@@ -1,6 +1,8 @@
 from __future__ import unicode_literals
 
-import sh
+import logging
+import subprocess
+
 import vlc
 
 from lib.device_helper import get_device_type
@@ -29,31 +31,30 @@ class MediaPlayer():
 class FFMPEGMediaPlayer(MediaPlayer):
     def __init__(self):
         MediaPlayer.__init__(self)
-        self.run = None
-        self.player_args = list()
-        self.player_kwargs = dict()
+        self.process = None
 
     def set_asset(self, uri, duration):
-        self.player_args = ['ffplay', uri, '-autoexit']
-        self.player_kwargs = {
-            '_bg': True,
-            '_ok_code': [0, 124],
-        }
+        self.uri = uri
 
     def play(self):
-        self.run = sh.Command(self.player_args[0])(
-            *self.player_args[1:], **self.player_kwargs
+        self.process = subprocess.Popen(
+            ['ffplay', '-autoexit', self.uri],
+            stdout=subprocess.DEVNULL,
+            stderr=subprocess.DEVNULL
         )
 
     def stop(self):
         try:
-            if self.run:
-                self.run.kill()
-        except OSError:
-            pass
+            if self.process:
+                self.process.terminate()
+                self.process = None
+        except Exception as e:
+            logging.error(f'Exception in stop(): {e}')
 
     def is_playing(self):
-        return bool(self.run.process.alive)
+        if self.process:
+            return self.process.poll() is None
+        return False
 
 
 class VLCMediaPlayer(MediaPlayer):

viewer/playback.py

@@ -1,15 +1,18 @@
-from os import system
+import threading
+
+# Global event for instant asset switching
+skip_event = threading.Event()
 
 
 def skip_asset(scheduler, back=False):
     if back is True:
         scheduler.reverse = True
-    system('pkill -SIGUSR1 -f viewer')
+    skip_event.set()
 
 
 def navigate_to_asset(scheduler, asset_id):
     scheduler.extra_asset = asset_id
-    system('pkill -SIGUSR1 -f viewer')
+    skip_event.set()
 
 
 def stop_loop(scheduler):

viewer/utils.py

@@ -6,7 +6,6 @@ import requests
 
 from lib.errors import SigalrmError
 from settings import LISTEN, PORT
-from viewer.media_player import MediaPlayerProxy
 
 WATCHDOG_PATH = '/tmp/screenly.watchdog'
 
@@ -18,13 +17,12 @@ def sigalrm(signum, frame):
     raise SigalrmError("SigalrmError")
 
 
-def sigusr1(signum, frame):
+def get_skip_event():
     """
-    The signal interrupts sleep() calls, so the currently
-    playing web or image asset is skipped.
+    Get the global skip event for instant asset switching.
     """
-    logging.info('USR1 received, skipping.')
-    MediaPlayerProxy.get_instance().stop()
+    from viewer.playback import skip_event
+    return skip_event
 
 
 def command_not_found():