Refactor alot

- add django-redis-cache
- remove CurrentTrack db model

oliver_screen/api.py

@@ -1,55 +1,14 @@
-from django.utils import timezone
 from rest_framework.response import Response
 from rest_framework.views import APIView
-from django.contrib.humanize.templatetags.humanize import naturaltime
-from dateutil import parser
 
-from oliver_screen import lastfm, utils
+from oliver_screen.lastfm import get_track_data, get_last_track_data
 
 
 class LastTrackView(APIView):
-    def _get_playback_date(self, playback_date_string):
-        playback_date = parser.parse(playback_date_string)
-        return timezone.make_aware(playback_date, timezone.UTC())  # Last.fm API is in UTC
-
-    def _time_since(self, playback_date_string):
-        playback_date = self._get_playback_date(playback_date_string)
-        formatted = naturaltime(playback_date)
-        formatted = formatted.replace(u'\xa0', u' ')  # remove non-breaking space (in latin1)
-        return formatted
-
     def get(self, request, format=None):
-        user = lastfm.get_user()
-        playedtracks = user.get_recent_tracks(limit=2)
-
-        track_data = {
-            'artist': playedtracks[0].track.get_artist().get_name(),
-            'title': playedtracks[0].track.get_title(),
-            'playback_date': self._get_playback_date(playedtracks[0].playback_date),
-            'time_since': self._time_since(playedtracks[0].playback_date)
-        }
-        return Response({'track': track_data})
+        return Response({'track': get_last_track_data()})
 
 
 class CurrentTrackView(APIView):
     def get(self, request, format=None):
-        user = lastfm.get_user()
-        track = user.get_now_playing()
-
-        if track is None:
-            # No response from LastFM?
-            return Response({'track': utils.get_current_from_cache()})
-
-        artist = track.get_artist()
-        video = utils.get_youtubevideo(artist.get_name(), track.get_title())
-        image = artist.get_cover_image(size=4)
-
-        now_playing = {
-            'artist': artist.get_name(),
-            'title': track.get_title(),
-            'image': image,
-            'video': video
-        }
-        utils.cache_current(now_playing)
-
-        return Response({'track': now_playing})
+        return Response({'track': get_track_data()})

oliver_screen/consumers.py

@@ -1,9 +1,7 @@
 from channels import Group
 from channels.sessions import channel_session
 from django.conf import settings
-import json
 
-from oliver_screen.models import ScreenConsumer
 from oliver_screen.tasks import update_screens_task
 
 
@@ -17,21 +15,11 @@ def ws_connect(message):
     g = Group(settings.OLIVER_WS_GROUP, channel_layer=message.channel_layer)
     g.add(message.reply_channel)
 
-    active_consumers = ScreenConsumer.objects.filter(is_active=True)
-    # At last one
-    if active_consumers.exists():
-        screen_consumer = active_consumers.first()
-    else:
-        screen_consumer = ScreenConsumer.objects.create()
-        update_screens_task()  # async
-
-    g.send({'text': json.dumps({'screen_consumer': {'uuid': str(screen_consumer.uuid)}})})
+    update_screens_task()  # async
 
 
 @channel_session
 def ws_disconnect(message):
     Group(settings.OLIVER_WS_GROUP, channel_layer=message.channel_layer).discard(message.reply_channel)
 
-    # FIXME: only set specific uuid inactive and only revoke is no more active screens
-    ScreenConsumer.objects.filter(is_active=True).update(is_active=False)
-    update_screens_task.revoke()
+    # update_screens_task.revoke()

oliver_screen/lastfm.py

@@ -1,13 +1,65 @@
 import pylast
 from django.conf import settings
+from django.utils import timezone
+from django.contrib.humanize.templatetags.humanize import naturaltime
+from dateutil import parser
+
+from oliver_screen import utils
 from oliver_screen.models import LastFMUser
 
 
 def get_user():
     network = pylast.LastFMNetwork(api_key=settings.LASTFM_API_KEY, api_secret=settings.LASTFM_API_SECRET)
-    lastfmusers = LastFMUser.objects.filter(active=True)
-    if len(lastfmusers) != 1:
-        # default
-        return network.get_user(settings.LASTFM_DEFAULT_USERNAME)
 
-    return network.get_user(lastfmusers[0].name)
+    lastfmusers = LastFMUser.objects.filter(active=True)
+    lastfm_username = lastfmusers[0].name if len(lastfmusers) == 1 else settings.LASTFM_DEFAULT_USERNAME
+
+    return network.get_user(lastfm_username)
+
+
+def _get_playback_date(playback_date_string):
+    playback_date = parser.parse(playback_date_string)
+
+    return timezone.make_aware(playback_date, timezone.UTC())  # Last.fm API is in UTC
+
+
+def _time_since(playback_date_string):
+    playback_date = _get_playback_date(playback_date_string)
+    formatted = naturaltime(playback_date)
+    formatted = formatted.replace(u'\xa0', u' ')  # remove non-breaking space (in latin1)
+
+    return formatted
+
+
+def get_last_track_data():
+    user = get_user()
+    playedtracks = user.get_recent_tracks(limit=2)
+
+    track_data = {
+        'artist': playedtracks[0].track.get_artist().get_name(),
+        'title': playedtracks[0].track.get_title(),
+        'playback_date': _get_playback_date(playedtracks[0].playback_date),
+        'time_since': _time_since(playedtracks[0].playback_date)
+    }
+    return track_data
+
+
+def get_track_data():
+    user = get_user()
+    track = user.get_now_playing()
+
+    if track is None:
+        return utils.get_current_from_cache()
+
+    artist = track.get_artist()
+    image = artist.get_cover_image(size=4)
+
+    track_data = {
+        'artist': artist.get_name(),
+        'title': track.get_title(),
+        'image': image,
+    }
+
+    utils.cache_current(track_data)
+
+    return track_data

oliver_screen/migrations/0004_delete_currenttrack.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('oliver_screen', '0003_auto_20160403_1343'),
+    ]
+
+    operations = [
+        migrations.DeleteModel(
+            name='CurrentTrack',
+        ),
+    ]

oliver_screen/models.py

@@ -12,16 +12,6 @@ class ScreenConsumer(models.Model):
         return str(self.uuid)
 
 
-class CurrentTrack(models.Model):
-    title = models.CharField(max_length=200)
-    artist = models.CharField(max_length=200)
-    image = models.CharField(max_length=200)
-    retries = models.IntegerField()
-
-    def __str__(self):
-        return self.title + " - " + self.artist
-
-
 class LastFMUser(models.Model):
     name = models.CharField(max_length=200)
     active = models.BooleanField(default=True)

oliver_screen/tasks.py

@@ -2,45 +2,44 @@ import json
 import logging
 
 from django.conf import settings
+from django.core.cache import cache
 from huey.contrib.djhuey import db_task
 from channels import Group
 
-from oliver_screen import utils, lastfm
-from oliver_screen.models import ScreenConsumer
+from oliver_screen import lastfm
 
 logger = logging.getLogger(__name__)
 
+LOCK_EXPIRE = 60 * 5  # Lock expires in 5 minutes
+
+
+def acquire_lock(lock_id):
+    # cache.add fails if the key already exists
+    return cache.add(lock_id, 'true', LOCK_EXPIRE)
+
+
+def release_lock(lock_id):
+    # memcache delete is very slow, but we have to use it to take advantage of using add() for atomic locking
+    return cache.delete(lock_id)
+
 
 @db_task()
 def update_screens_task():
     screen_channel_group = Group(settings.OLIVER_WS_GROUP)
+    lock_id = '{0}-lock'.format(settings.OLIVER_WS_GROUP)
+
     logger.debug('Updating screens')
+    if acquire_lock(lock_id):
+        try:
+            track_data = lastfm.get_track_data()
+        finally:
+            release_lock(lock_id)
 
-    user = lastfm.get_user()
-    track = user.get_now_playing()
-    if track is None:
-        track_data = utils.get_current_from_cache()
-        logger.debug("sending ", track_data, "to", screen_channel_group.name)
-        screen_channel_group.send({'track': json.dumps({'track': track_data})})
-        return
+        screen_channel_group.send({'text': json.dumps({'track': track_data})})
 
-    artist = track.get_artist()
-    image = artist.get_cover_image(size=4)
-
-    track_data = {
-        'artist': artist.get_name(),
-        'title': track.get_title(),
-        'image': image,
-    }
-    utils.cache_current(track_data)
-
-    logger.debug("sending ", track_data, "to", screen_channel_group.name)
-    screen_channel_group.send({'text': json.dumps({'track': track_data})})
-
-    # At least one active screen
-    if ScreenConsumer.objects.filter(is_active=True).exists():
         update_screens_task.schedule(delay=settings.OLIVER_LASTFM_POLL_INTERVAL)
-    else:
-        logger.debug('No active screens, bailing')
 
-    return track_data
+        return track_data
+
+    logger.debug('Last.FM is already being polled, doing nothing.')
+

oliver_screen/utils.py

@@ -1,4 +1,5 @@
-from oliver_screen.models import CurrentTrack, YouTubeVideo
+from django.core.cache import cache
+from oliver_screen.models import YouTubeVideo
 
 
 def get_youtubevideo(artist, title):
@@ -9,45 +10,12 @@ def get_youtubevideo(artist, title):
 
     return videos[0]
 
+CACHE_KEY = 'oliver-track'
 
-def cache_current(now_playing):
-    # Fetch the one CurrentTrack entry in the db and update it with the current track.
-    try:
-        current = CurrentTrack.objects.get(pk=1)
-    except CurrentTrack.DoesNotExist:
-        # update
-        current = CurrentTrack(artist="", title="", image="", retries=0)
 
-    current.artist = now_playing['artist']
-    current.title = now_playing['title']
-    current.image = now_playing['image']
-    current.retries = 0
-    current.save()
+def cache_current(track):
+    return cache.set(CACHE_KEY, track, 20)  # in seconds
 
 
 def get_current_from_cache():
-    try:
-        current = CurrentTrack.objects.get(pk=1)
-    except CurrentTrack.DoesNotExist:
-        current = CurrentTrack(artist="", title="", image="", retries=0)
-        current.save()
-
-    now_playing = {}
-
-    # try 3 times before clearing the cache
-    if current.artist != "" and current.retries < 3:
-        now_playing = {
-            'artist': current.artist,
-            'title': current.title,
-            'image': current.image
-        }
-
-        current.retries += 1
-        current.save()
-    else:
-        current.artist = ""
-        current.title = ""
-        current.image = ""
-        current.save()
-
-    return now_playing
+    return cache.get(CACHE_KEY)

oliversite/settings.py

@@ -1,14 +1,12 @@
-from __future__ import unicode_literals
 # Build paths inside the project like this: os.path.join(BASE_DIR, ...)
 import os
-
 from huey import RedisHuey
 
 BASE_DIR = os.path.dirname(os.path.dirname(__file__))
 
 
 # Quick-start development settings - unsuitable for production
-# See https://docs.djangoproject.com/en/1.7/howto/deployment/checklist/
+# See https://docs.djangoproject.com/en/1.8/howto/deployment/checklist/
 
 # SECURITY WARNING: keep the secret key used in production secret!
 SECRET_KEY = '#r65fsg)wsk&cs8m^i)@##7-wg=#z=*b_)a82#5z#4%&!j_9=6'
@@ -102,6 +100,13 @@ OLIVER_LASTFM_POLL_INTERVAL = 10  # seconds
 
 HUEY = RedisHuey('oliverscreen', result_store=True)
 
+CACHES = {
+    'default': {
+        'BACKEND': 'redis_cache.RedisCache',
+        'LOCATION': 'localhost:6379',
+    }
+}
+
 # Local settings
 try:
     from .local_settings import *

requirements.txt

@@ -3,6 +3,7 @@ channels==0.10.3
 Django>=1.8,<1.9
 django-extensions==1.6.1
 django-flat-theme==1.1.3
+django-redis-cache==1.6.5
 djangorestframework==3.3.3
 gevent==1.1.0
 gunicorn==19.4.5