use cached payload count in satellite view

db/base/tasks.py

@@ -2,9 +2,7 @@ import csv
 import logging
 from datetime import datetime, timedelta
 
-from django.db.models import Count, Max
 from django.conf import settings
-from django.core.cache import cache
 from django.core.mail import send_mail
 from django.contrib.sites.models import Site
 from django.template.loader import render_to_string
@@ -17,9 +15,9 @@ from sgp4.io import twoline2rv
 from satellite_tle import fetch_tle_from_celestrak, fetch_tles
 
 from db.base.models import Satellite, DemodData
-from db.base.utils import calculate_statistics
 from db.celery import app
 from db.base.utils import decode_data
+from db.base.utils import cache_statistics
 
 logger = logging.getLogger('db')
 
@@ -153,23 +151,9 @@ def export_frames(norad, email, uid, period=None):
 
 
 @app.task
-def cache_statistics():
+def background_cache_statistics():
-    statistics = calculate_statistics()
+    """Task to periodically cache statistics"""
-    cache.set('stats_transmitters', statistics, 60 * 60 * 2)
+    cache_statistics()
-
-    satellites = Satellite.objects \
-                          .values('name', 'norad_cat_id') \
-                          .annotate(count=Count('telemetry_data'),
-                                    latest_payload=Max('telemetry_data__timestamp')) \
-                          .order_by('-count')
-    cache.set('stats_satellites', satellites, 60 * 60 * 2)
-
-    observers = DemodData.objects \
-                         .values('observer') \
-                         .annotate(count=Count('observer'),
-                                   latest_payload=Max('timestamp')) \
-                         .order_by('-count')
-    cache.set('stats_observers', observers, 60 * 60 * 2)
 
 
 # resets all decoded data and changes the is_decoded flag back to False

db/base/utils.py

@@ -3,10 +3,12 @@ import binascii
 
 from datetime import datetime, timedelta
 from db.base.models import Satellite, Transmitter, Mode, DemodData, Telemetry
+from django.db.models import Count, Max
 from django.conf import settings
 from django.utils.timezone import make_aware
 from influxdb import InfluxDBClient
 from satnogsdecoders import decoder
+from django.core.cache import cache
 
 logger = logging.getLogger('db')
 
@@ -21,11 +23,14 @@ def calculate_statistics():
     total_transmitters = transmitters.count()
     total_data = DemodData.objects.all().count()
     alive_transmitters = transmitters.filter(alive=True).count()
-    try:
+    if alive_transmitters > 0 and total_transmitters > 0:
-        alive_transmitters_percentage = '{0}%'.format(round((float(alive_transmitters) /
+        try:
-                                                             float(total_transmitters)) * 100, 2))
+            alive_transmitters_percentage = '{0}%'.format(round((float(alive_transmitters)
-    except ZeroDivisionError as error:
+                                                          / float(total_transmitters)) * 100, 2))
-        logger.error(error, exc_info=True)
+        except ZeroDivisionError as error:
+            logger.error(error, exc_info=True)
+            alive_transmitters_percentage = '0%'
+    else:
         alive_transmitters_percentage = '0%'
 
     mode_label = []
@@ -35,6 +40,12 @@ def calculate_statistics():
         mode_label.append(mode.name)
         mode_data.append(tr)
 
+    # needed to pass testing in a fresh environment with no modes in db
+    if len(mode_label) == 0:
+        mode_label = ['FM']
+    if len(mode_data) == 0:
+        mode_data = ['FM']
+
     band_label = []
     band_data = []
 
@@ -242,3 +253,23 @@ def decode_data(norad, period=None):
                             break
                 except IOError:
                     continue
+
+
+# Caches stats about satellites and data
+def cache_statistics():
+    statistics = calculate_statistics()
+    cache.set('stats_transmitters', statistics, 60 * 60 * 2)
+
+    satellites = Satellite.objects \
+                          .values('name', 'norad_cat_id') \
+                          .annotate(count=Count('telemetry_data'),
+                                    latest_payload=Max('telemetry_data__timestamp')) \
+                          .order_by('-count')
+    cache.set('stats_satellites', satellites, 60 * 60 * 2)
+
+    observers = DemodData.objects \
+                         .values('observer') \
+                         .annotate(count=Count('observer'),
+                                   latest_payload=Max('timestamp')) \
+                         .order_by('-count')
+    cache.set('stats_observers', observers, 60 * 60 * 2)

db/base/views.py

@@ -1,6 +1,6 @@
 import logging
 
-from django.db.models import Count, Max
+from django.db.models import Max
 from django.conf import settings
 from django.contrib.auth.decorators import login_required
 from django.contrib.auth.models import User
@@ -16,7 +16,8 @@ from django.views.decorators.http import require_POST
 from db.base.models import Mode, Transmitter, Satellite, Suggestion, DemodData, TRANSMITTER_TYPE
 from db.base.forms import SuggestionForm
 from db.base.helpers import get_apikey
-from db.base.tasks import export_frames, cache_statistics
+from db.base.tasks import export_frames
+from db.base.utils import cache_statistics
 from _mysql_exceptions import OperationalError
 
 
@@ -57,12 +58,21 @@ def robots(request):
 def satellite(request, norad):
     """View to render satellite page."""
     satellite_query = Satellite.objects \
-                               .annotate(latest_payload_time=Max('telemetry_data__timestamp'),
+                               .annotate(latest_payload_time=Max('telemetry_data__timestamp'))
-                                         payload_frames_count=Count('telemetry_data'))
     satellite = get_object_or_404(satellite_query, norad_cat_id=norad)
     suggestions = Suggestion.objects.filter(satellite=satellite)
     modes = Mode.objects.all()
     types = TRANSMITTER_TYPE
+    sats_cache = cache.get('stats_satellites')
+    if not sats_cache:
+        try:
+            cache_statistics()
+        except OperationalError:
+            pass
+    try:
+        sat_cache = sats_cache.filter(norad_cat_id=norad)
+    except AttributeError:
+        sat_cache = [{'count': 'err'}]
 
     try:
         latest_frame = DemodData.objects.get(satellite=satellite,
@@ -75,6 +85,7 @@ def satellite(request, norad):
                                                    'modes': modes,
                                                    'types': types,
                                                    'latest_frame': latest_frame,
+                                                   'sat_cache': sat_cache[0],
                                                    'mapbox_token': settings.MAPBOX_TOKEN})
 
 
@@ -154,7 +165,7 @@ def stats(request):
     observers = cache.get('stats_observers')
     if not satellites or not observers:
         try:
-            cache_statistics.delay()
+            cache_statistics()
         except OperationalError:
             pass
     return render(request, 'base/stats.html', {'satellites': satellites,
@@ -164,7 +175,7 @@ def stats(request):
 def statistics(request):
     statistics = cache.get('stats_transmitters')
     if not statistics:
-        cache_statistics.delay()
+        cache_statistics()
         statistics = []
     return JsonResponse(statistics, safe=False)
 

db/celery.py

@@ -20,13 +20,13 @@ app.autodiscover_tasks(lambda: settings.INSTALLED_APPS)
 
 @app.on_after_finalize.connect
 def setup_periodic_tasks(sender, **kwargs):
-    from db.base.tasks import update_all_tle, cache_statistics, decode_recent_data
+    from db.base.tasks import update_all_tle, background_cache_statistics, decode_recent_data
 
     sender.add_periodic_task(RUN_DAILY, update_all_tle.s(),
                              name='update-all-tle')
 
-    sender.add_periodic_task(RUN_HOURLY, cache_statistics.s(),
+    sender.add_periodic_task(RUN_HOURLY, background_cache_statistics.s(),
-                             name='cache-statistics')
+                             name='background-cache-statistics')
 
     sender.add_periodic_task(RUN_EVERY_15, decode_recent_data.s(),
                              name='decode-recent-data')

db/templates/base/satellite.html

@@ -462,7 +462,7 @@
             </div>
           {% endif %}
           <div class="panel-footer">
-            <span class="badge">Frames: {{ satellite.payload_frames_count }}</span>
+            <span class="badge">Frames: {{ sat_cache.count }}</span>
             Latest frame submitted on {{ latest_frame.timestamp|date:'Y-m-d H:i:s' }} by
             {{ latest_frame.observer }}
           </div>