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# Copyright (C) 2008, One Laptop Per Child
#
# This program 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.
#
# This program 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 St, Fifth Floor, Boston, MA 02110-1301 USA
import os
import logging
MAX_QUERY_LIMIT = 40960
CURRENT_LAYOUT_VERSION = 4
class LayoutManager(object):
"""Provide the logic about how entries are stored inside the datastore
directory
"""
def __init__(self):
profile = os.environ.get('SUGAR_PROFILE', 'default')
base_dir = os.path.join(os.path.expanduser('~'), '.sugar', profile)
self._root_path = os.path.join(base_dir, 'datastore')
if not os.path.exists(self._root_path):
os.makedirs(self._root_path)
self._create_if_needed(self.get_checksums_dir())
self._create_if_needed(self.get_queue_path())
index_updated_path = os.path.join(self._root_path, 'index_updated')
if os.path.exists(index_updated_path):
self._index_updated = True
elif self._is_empty():
open(index_updated_path, 'w').close()
self.set_version(CURRENT_LAYOUT_VERSION)
self._index_updated = True
else:
self._index_updated = False
def _create_if_needed(self, path):
if not os.path.exists(path):
os.makedirs(path)
def get_version(self):
version_path = os.path.join(self._root_path, 'version')
version = 0
if os.path.exists(version_path):
try:
version = int(open(version_path, 'r').read())
except ValueError:
logging.exception('Can not read layout version')
version = 0
return version
def set_version(self, version):
version_path = os.path.join(self._root_path, 'version')
open(version_path, 'w').write(str(version))
def get_entry_path(self, uid):
# os.path.join() is just too slow
return '%s/%s/%s' % (self._root_path, uid[:2], uid)
def get_data_path(self, uid):
return '%s/%s/%s/data' % (self._root_path, uid[:2], uid)
def get_metadata_path(self, uid):
return '%s/%s/%s/metadata' % (self._root_path, uid[:2], uid)
def get_root_path(self):
return self._root_path
def get_index_path(self):
return os.path.join(self._root_path, 'index')
def get_checksums_dir(self):
return os.path.join(self._root_path, 'checksums')
def get_queue_path(self):
return os.path.join(self.get_checksums_dir(), 'queue')
def _is_index_updated(self):
return self._index_updated
def _set_index_updated(self, index_updated):
if index_updated != self._index_updated:
self._index_updated = index_updated
index_updated_path = os.path.join(self._root_path, 'index_updated')
if os.path.exists(index_updated_path):
os.remove(index_updated_path)
else:
open(index_updated_path, 'w').close()
index_updated = property(_is_index_updated, _set_index_updated)
def find_all(self):
uids = []
for f in os.listdir(self._root_path):
if os.path.isdir(os.path.join(self._root_path, f)) and len(f) == 2:
for g in os.listdir(os.path.join(self._root_path, f)):
if len(g) == 36:
uids.append(g)
return uids
def _is_empty(self):
for f in os.listdir(self._root_path):
if os.path.isdir(os.path.join(self._root_path, f)) and len(f) == 2:
for g in os.listdir(os.path.join(self._root_path, f)):
if len(g) == 36:
return False
return True
_instance = None
def get_instance():
global _instance
if _instance is None:
_instance = LayoutManager()
return _instance
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