Read the OSM database lag directly from the database

This allows us to know if the PostGIS database is up and gets us a lag
information that is not refreshed only every minute by a cronjob.

Signed-off-by: Maxime Petazzoni <maxime.petazzoni@bulix.org>

www/maposmatic/context_processors.py

@@ -38,17 +38,25 @@ def get_latest_blog_posts():
     return f.entries[:5]
 
 def get_osm_database_last_update():
+    """Returns the timestamp of the last PostGIS database update, which is
+    placed into the maposmatic_admin table in the PostGIS database by the
+    planet-update incremental update script."""
+
+    db = gisdb.get()
+    if db is None:
+        return None
+
+    cursor = db.cursor()
+
     try:
-        with open(www.settings.GIS_DATABASE_LAG_FILE) as f:
-            try:
-                return datetime.datetime.strptime(
-                    '%s' % f.read().strip(),
-                    '%Y-%m-%d %H:%M:%S')
-            except ValueError:
-                pass
-    except IOError:
+        cursor.execute("""select last_update from maposmatic_admin""")
+        last_update = cursor.fetchone()
+        if last_update is not None and len(last_update) == 1:
+            return datetime.datetime.strptime(last_update[0], '%Y-%m-%d %H:%M:%S')
+    except:
         pass
 
+    cursor.close()
     return None
 
 def all(request):

www/maposmatic/gisdb.py

@@ -40,7 +40,7 @@ def get():
         return _DB
 
     try:
-        _DB = psycopg2.connect("dbname='%s' user='%s' host='%s' password='%s' port='%s'" %
+        _DB = psycopg2.connect("dbname='%s' user='%s' host='%s' password='%s' port='%s' connection_timeout=1" %
                                 (www.settings.GIS_DATABASE_NAME,
                                  www.settings.GIS_DATABASE_USER,
                                  www.settings.GIS_DATABASE_HOST,

www/media/css/style.css

@@ -87,6 +87,11 @@ form#langsel {
   margin-right: 1em;
 }
 
+p.error {
+  color: red;
+  font-weight: bold;
+}
+
 /* Navigation menu */
 ul#nav {
   list-style: none;

www/templates/maposmatic/base.html

@@ -105,9 +105,9 @@
         <div id="bosmtimestamp">
           <h3>{% trans "OSM database status" %}</h3>
           {% if osm_date %}
-          <p>{% blocktrans with osm_date|timesince:utc_now as date %}Lag of MapOSMatic OSM database: {{ date }}.{% endblocktrans %}</p>
+          <p>{% blocktrans with osm_date|timesince:utc_now as date %}Database is online, <span title="{{ osm_date|date:"r" }}">last update {{ date }} ago</span>.{% endblocktrans %}</p>
           {% else %}
-          <p>{% blocktrans %}Lag of MapOSMatic OSM database: unknown.{% endblocktrans %}</p>
+          <p class="error">{% blocktrans %}Could not connect to OSM database!{% endblocktrans %}</p>
           {% endif %}
         </div>