Make purgehook aware of files in data/ and issue xkey purges

For any changes to files in data/, issues an xkey purge of
data_<filename_without_extension>. This allows us to automatically purge
out data based on changes to data files in the git repository.

Author: mhagander

tools/purgehook/purgehook.py

@@ -47,5 +47,10 @@
             curs.execute("SELECT varnish_purge('^/' || %(u)s || '$')", {
                 'u': l.strip(),
             })
+        elif l.startswith('data/'):
+            # Data files map to xkeys with the same name as the file prefixed by data_
+            curs.execute("SELECT varnish_purge_xkey(%(key)s)", {
+                'key': 'data_{}'.format(os.path.splitext(os.path.basename(l))[0]),
+            })
     conn.commit()
     conn.close()