def _loadjson(self, fname, dest):
"""Load JSON file located under self._directory, if needed
:param fname: short file name (without path and .json)
:type fname: str.
:param dest: destination
:type dest: dict
"""
try:
fname = "%s/%s.json" % (self._directory, fname)
mtime = os.stat(fname).st_mtime
if self._mtimes.get(fname, 0) == mtime:
# no need to reload the file: the mtime has not been changed
return
with open(fname) as f:
json_data = f.read()
except Exception as e:
raise BackendIOException("Unable to read json file %s: %s" % (fname, e))
try:
json_obj = json.loads(json_data)
dest.clear()
dest.update(json_obj)
self._mtimes[fname] = os.stat(fname).st_mtime
except Exception as e:
raise BackendIOException("Unable to parse JSON data from %s: %s" \
% (fname, e))
def _savejson(self, fname, obj):
"""Save obj in JSON format in a file in self._directory"""
fname = "%s/%s.json" % (self._directory, fname)
try:
s = json.dumps(obj)
with open("%s.tmp" % fname, 'wb') as f:
f.write(s)
f.flush()
shutil.move("%s.tmp" % fname, fname)
except Exception as e:
raise BackendIOException("Unable to save JSON file %s: %s" \
% (fname, e))