Fetch HSL timetables with threads instead of cron

add_cronjob.sh

@@ -1,11 +0,0 @@
-#!/bin/bash
-
-echo "Adding cron entries..."
-# write out current crontab
-crontab -l > temp_crontab
-# echo new cron into cron file
-printf "*/5 * * * * source $PWD/../virtualenv.sikweb/bin/activate && python $PWD/manage.py hsl &>$PWD/logs/fetch_hsl.log\n\n" >> temp_crontab
-# install new cron file
-crontab temp_crontab
-rm temp_crontab
-echo "Done. View your crontab with 'crontab -l' and edit it with 'crontab -e'."

infoscreen/hsl_fetcher.py

@@ -2,10 +2,20 @@ from infoscreen.models import HSLDataModel
 from django.conf import settings
 import urllib.request
 import json
-
+import logging
+from datetime import datetime, timedelta
 
 class HSLFetcher:
     
+    last_fetched = datetime.fromtimestamp(0)  # epoch
+    INTERVAL = 1  # minutes
+
+    logging.info("Set up scheduled HSL API fetch every {} minutes".format(INTERVAL))
+
+    def fetch_if_needed(self):
+        if datetime.now() - HSLFetcher.last_fetched > timedelta(minutes=HSLFetcher.INTERVAL):
+            self.fetch()
+
     def fetch(self):
         location_coords = (2545565, 6675319)
         src = urllib.request.urlopen(
@@ -26,3 +36,8 @@ class HSLFetcher:
                         "dist": element['dist'], "departures": parsed['departures']})
 
         HSLDataModel.objects.create(data=json.dumps(arr))
+
+        now = datetime.now()
+        HSLFetcher.last_fetched = now
+
+        logging.info("Fetched HSL timetable data with size {} bytes.".format(len(src)))

infoscreen/views.py

@@ -9,8 +9,10 @@ from infoscreen.models import Rotation, InfoItem, InfoInstance
 from infoscreen.models import ABBInfoItem, ExternalImageInfoItem, ImageInfoItem, SossoInfoItem, HslInfoItem
 from infoscreen.models import ImageUploadForm
 from infoscreen.models import HSLDataModel
+from infoscreen.hsl_fetcher import HSLFetcher
 import json
 import logging
+import threading
 
 
 def index(request, idx, *args, **kwargs):
@@ -184,11 +186,17 @@ def delete_rotation(request, *args, **kwargs):
 
 @require_http_methods(["GET"])
 def CurrentHSLView(request, *args, **kwargs):
+
+    fetcher = HSLFetcher()
+    fetcherThread = threading.Thread(target=fetcher.fetch_if_needed, args=[])
+    fetcherThread.setDaemon(False)
+    fetcherThread.start()
+
     data = HSLDataModel.objects.all()
     if len(data) < 1:
         return HttpResponse('{"error" : "Could not find timetables from database."}', status=500)
 
-    return HttpResponse(data[len(data)-1].data, status=200)
+    return HttpResponse(data[len(data) - 1].data, status=200)
 
 createInstance = create_item_generator(InfoInstance)
 deleteInstance = delete_item_generator(InfoInstance)

readme.md

@@ -56,12 +56,6 @@ pip install --upgrade pip
 pip install -r requirements.txt
 ```
 
-### Register cron jobs
-
-```
-./add_cronjob.sh
-```
-
 ## Configure Django settings
 
 `cp sikweb/settings-sample.py sikweb/settings.py`