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# Copyright 2015 Lars Wirzenius
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#
# =*= License: GPL-3+ =*=
import os
import random
import obnamlib
class BagStore(object):
def __init__(self):
self._fs = None
self._dirname = None
self._id_inventor = IdInventor()
self._id_inventor.set_filename_maker(self._make_bag_filename)
def _make_bag_filename(self, bag_id):
basename = '%016x' % bag_id
return os.path.join(
self._dirname,
basename[0:2],
basename[2:4],
basename[4:6],
'%s.bag' % basename)
def set_location(self, fs, dirname):
self._fs = fs
self._dirname = dirname
self._id_inventor.set_fs(fs)
def reserve_bag_id(self):
return self._id_inventor.reserve_id()
def put_bag(self, bag):
filename = self._make_bag_filename(bag.get_id())
serialised = serialise_bag(bag)
self._fs.overwrite_file(filename, serialised)
def get_bag(self, bag_id):
filename = self._make_bag_filename(bag_id)
serialised = self._fs.cat(filename)
return deserialise_bag(serialised)
def has_bag(self, bag_id):
filename = self._make_bag_filename(bag_id)
try:
st = self._fs.lstat(filename)
except (IOError, OSError): # pragma: no cover
return False
return st.st_size > 0
def get_bag_ids(self):
for pathname, _ in self._fs.scan_tree(self._dirname):
if self._is_bag_filename(pathname):
yield self._get_bag_id_from_filename(pathname)
def _is_bag_filename(self, pathname):
return pathname.endswith('.bag')
def _get_bag_id_from_filename(self, pathname):
basename = os.path.basename(pathname)
return int(basename[:-len('.bag')], 16)
def remove_bag(self, bag_id):
filename = self._make_bag_filename(bag_id)
self._fs.remove(filename)
class IdInventor(object):
def __init__(self):
self.set_fs(None)
self._filename_maker = None
def set_fs(self, fs):
self._fs = fs
self._prev_id = None
def set_filename_maker(self, maker):
self._filename_maker = maker
def reserve_id(self):
while True:
self._next_id()
if self._reserve_succeeds():
return self._prev_id
self._prev_id = None # pragma: no cover
def _next_id(self):
if self._prev_id is None:
self._prev_id = random.randint(0, obnamlib.MAX_ID)
else:
self._prev_id += 1 # pragma: no cover
def _reserve_succeeds(self):
filename = self._filename_maker(self._prev_id)
try:
self._fs.write_file(filename, '')
except OSError as e: # pragma: no cover
if e.errno == e.EEXIST:
return False
raise
return True
def serialise_bag(bag):
obj = {
'bag-id': bag.get_id(),
'blobs': [bag[i] for i in range(len(bag))],
}
return obnamlib.serialise_object(obj)
def deserialise_bag(serialised):
obj = obnamlib.deserialise_object(serialised)
bag = obnamlib.Bag()
bag.set_id(obj['bag-id'])
for blob in obj['blobs']:
bag.append(blob)
return bag
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