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# Copyright 2017 Free Software Foundation, Inc.
# This file is part of GNU Radio
#
# GNU Radio Companion is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
#
# GNU Radio Companion is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
from __future__ import absolute_import, print_function, unicode_literals
from io import open
import json
import logging
import os
import six
from .io import yaml
logger = logging.getLogger(__name__)
class Cache(object):
def __init__(self, filename):
self.cache_file = filename
self.cache = {}
self.need_cache_write = True
self._accessed_items = set()
try:
os.makedirs(os.path.dirname(filename))
except OSError:
pass
try:
self._converter_mtime = os.path.getmtime(filename)
except OSError:
self._converter_mtime = -1
def load(self):
try:
logger.debug("Loading block cache from: {}".format(self.cache_file))
with open(self.cache_file, encoding='utf-8') as cache_file:
self.cache = json.load(cache_file)
self.need_cache_write = False
except (IOError, ValueError):
self.need_cache_write = True
def get_or_load(self, filename):
self._accessed_items.add(filename)
if os.path.getmtime(filename) <= self._converter_mtime:
try:
return self.cache[filename]
except KeyError:
pass
with open(filename, encoding='utf-8') as fp:
data = yaml.safe_load(fp)
self.cache[filename] = data
self.need_cache_write = True
return data
def save(self):
if not self.need_cache_write:
return
logger.debug('Saving %d entries to json cache', len(self.cache))
# Dumping to binary file is only supported for Python3 >= 3.6
with open(self.cache_file, 'w', encoding='utf8') as cache_file:
cache_file.write(json.dumps(self.cache, ensure_ascii=False))
def prune(self):
for filename in (set(self.cache) - self._accessed_items):
del self.cache[filename]
def __enter__(self):
self.load()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.save()
def byteify(data):
if isinstance(data, dict):
return {byteify(key): byteify(value) for key, value in six.iteritems(data)}
elif isinstance(data, list):
return [byteify(element) for element in data]
elif isinstance(data, six.text_type) and six.PY2:
return data.encode('utf-8')
else:
return data
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