mirror of
https://github.com/borgbackup/borg.git
synced 2026-02-03 20:40:16 -05:00
b2dedee3c8
refactorings: - introduced concept of default answer: if the answer string is in the defaultish sequence, the return value of yes() will be the default. e.g. if just pressing <enter> when asked on the console or if an empty string or "default" is in the environment variable for overriding. if an environment var has an invalid value and no retries are enabled: return default if retries are enabled, next retry won't use the env var again, but either ask via input(). - simplify: only one default - this should be a SAFE default as it is used in some special conditions like EOF or invalid input with retries disallowed. no isatty() magic, the "yes" shell command exists, so we could receive input even if it is not from a tty. - clean: separate retry flag from retry_msg
416 lines
18 KiB
Python
416 lines
18 KiB
Python
import configparser
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from .remote import cache_if_remote
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from collections import namedtuple
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import os
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import stat
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from binascii import hexlify, unhexlify
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import shutil
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from .key import PlaintextKey
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from .logger import create_logger
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logger = create_logger()
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from .helpers import Error, get_cache_dir, decode_dict, int_to_bigint, \
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bigint_to_int, format_file_size, yes
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from .locking import UpgradableLock
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from .hashindex import ChunkIndex
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import msgpack
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class Cache:
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"""Client Side cache
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"""
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class RepositoryReplay(Error):
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"""Cache is newer than repository, refusing to continue"""
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class CacheInitAbortedError(Error):
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"""Cache initialization aborted"""
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class RepositoryAccessAborted(Error):
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"""Repository access aborted"""
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class EncryptionMethodMismatch(Error):
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"""Repository encryption method changed since last access, refusing to continue"""
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@staticmethod
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def break_lock(repository, path=None):
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path = path or os.path.join(get_cache_dir(), hexlify(repository.id).decode('ascii'))
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UpgradableLock(os.path.join(path, 'lock'), exclusive=True).break_lock()
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def __init__(self, repository, key, manifest, path=None, sync=True, do_files=False, warn_if_unencrypted=True,
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lock_wait=None):
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self.lock = None
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self.timestamp = None
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self.lock = None
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self.txn_active = False
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self.repository = repository
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self.key = key
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self.manifest = manifest
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self.path = path or os.path.join(get_cache_dir(), hexlify(repository.id).decode('ascii'))
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self.do_files = do_files
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# Warn user before sending data to a never seen before unencrypted repository
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if not os.path.exists(self.path):
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if warn_if_unencrypted and isinstance(key, PlaintextKey):
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msg = ("Warning: Attempting to access a previously unknown unencrypted repository!" +
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"\n" +
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"Do you want to continue? [yN] ")
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if not yes(msg, false_msg="Aborting.", env_var_override='BORG_UNKNOWN_UNENCRYPTED_REPO_ACCESS_IS_OK'):
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raise self.CacheInitAbortedError()
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self.create()
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self.open(lock_wait=lock_wait)
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# Warn user before sending data to a relocated repository
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if self.previous_location and self.previous_location != repository._location.canonical_path():
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msg = ("Warning: The repository at location {} was previously located at {}".format(repository._location.canonical_path(), self.previous_location) +
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"\n" +
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"Do you want to continue? [yN] ")
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if not yes(msg, false_msg="Aborting.", env_var_override='BORG_RELOCATED_REPO_ACCESS_IS_OK'):
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raise self.RepositoryAccessAborted()
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if sync and self.manifest.id != self.manifest_id:
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# If repository is older than the cache something fishy is going on
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if self.timestamp and self.timestamp > manifest.timestamp:
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raise self.RepositoryReplay()
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# Make sure an encrypted repository has not been swapped for an unencrypted repository
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if self.key_type is not None and self.key_type != str(key.TYPE):
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raise self.EncryptionMethodMismatch()
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self.sync()
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self.commit()
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def __enter__(self):
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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self.close()
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def __str__(self):
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fmt = """\
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All archives: {0.total_size:>20s} {0.total_csize:>20s} {0.unique_csize:>20s}
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Unique chunks Total chunks
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Chunk index: {0.total_unique_chunks:20d} {0.total_chunks:20d}"""
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return fmt.format(self.format_tuple())
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def format_tuple(self):
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# XXX: this should really be moved down to `hashindex.pyx`
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Summary = namedtuple('Summary', ['total_size', 'total_csize', 'unique_size', 'unique_csize', 'total_unique_chunks', 'total_chunks'])
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stats = Summary(*self.chunks.summarize())._asdict()
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for field in ['total_size', 'total_csize', 'unique_csize']:
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stats[field] = format_file_size(stats[field])
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return Summary(**stats)
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def create(self):
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"""Create a new empty cache at `self.path`
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"""
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os.makedirs(self.path)
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with open(os.path.join(self.path, 'README'), 'w') as fd:
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fd.write('This is a Borg cache')
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config = configparser.ConfigParser(interpolation=None)
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config.add_section('cache')
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config.set('cache', 'version', '1')
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config.set('cache', 'repository', hexlify(self.repository.id).decode('ascii'))
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config.set('cache', 'manifest', '')
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with open(os.path.join(self.path, 'config'), 'w') as fd:
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config.write(fd)
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ChunkIndex().write(os.path.join(self.path, 'chunks').encode('utf-8'))
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os.makedirs(os.path.join(self.path, 'chunks.archive.d'))
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with open(os.path.join(self.path, 'files'), 'wb') as fd:
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pass # empty file
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def destroy(self):
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"""destroy the cache at `self.path`
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"""
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self.close()
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os.remove(os.path.join(self.path, 'config')) # kill config first
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shutil.rmtree(self.path)
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def _do_open(self):
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self.config = configparser.ConfigParser(interpolation=None)
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config_path = os.path.join(self.path, 'config')
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self.config.read(config_path)
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try:
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cache_version = self.config.getint('cache', 'version')
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wanted_version = 1
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if cache_version != wanted_version:
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raise Exception('%s has unexpected cache version %d (wanted: %d).' % (
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config_path, cache_version, wanted_version))
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except configparser.NoSectionError as e:
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raise Exception('%s does not look like a Borg cache.' % config_path) from None
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self.id = self.config.get('cache', 'repository')
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self.manifest_id = unhexlify(self.config.get('cache', 'manifest'))
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self.timestamp = self.config.get('cache', 'timestamp', fallback=None)
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self.key_type = self.config.get('cache', 'key_type', fallback=None)
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self.previous_location = self.config.get('cache', 'previous_location', fallback=None)
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self.chunks = ChunkIndex.read(os.path.join(self.path, 'chunks').encode('utf-8'))
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self.files = None
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def open(self, lock_wait=None):
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if not os.path.isdir(self.path):
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raise Exception('%s Does not look like a Borg cache' % self.path)
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self.lock = UpgradableLock(os.path.join(self.path, 'lock'), exclusive=True, timeout=lock_wait).acquire()
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self.rollback()
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def close(self):
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if self.lock is not None:
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self.lock.release()
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self.lock = None
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def _read_files(self):
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self.files = {}
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self._newest_mtime = 0
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logger.info('reading files cache')
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with open(os.path.join(self.path, 'files'), 'rb') as fd:
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u = msgpack.Unpacker(use_list=True)
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while True:
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data = fd.read(64 * 1024)
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if not data:
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break
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u.feed(data)
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for path_hash, item in u:
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item[0] += 1
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# in the end, this takes about 240 Bytes per file
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self.files[path_hash] = msgpack.packb(item)
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def begin_txn(self):
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# Initialize transaction snapshot
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txn_dir = os.path.join(self.path, 'txn.tmp')
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os.mkdir(txn_dir)
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shutil.copy(os.path.join(self.path, 'config'), txn_dir)
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shutil.copy(os.path.join(self.path, 'chunks'), txn_dir)
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shutil.copy(os.path.join(self.path, 'files'), txn_dir)
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os.rename(os.path.join(self.path, 'txn.tmp'),
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os.path.join(self.path, 'txn.active'))
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self.txn_active = True
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def commit(self):
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"""Commit transaction
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"""
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if not self.txn_active:
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return
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if self.files is not None:
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with open(os.path.join(self.path, 'files'), 'wb') as fd:
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for path_hash, item in self.files.items():
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# Discard cached files with the newest mtime to avoid
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# issues with filesystem snapshots and mtime precision
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item = msgpack.unpackb(item)
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if item[0] < 10 and bigint_to_int(item[3]) < self._newest_mtime:
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msgpack.pack((path_hash, item), fd)
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self.config.set('cache', 'manifest', hexlify(self.manifest.id).decode('ascii'))
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self.config.set('cache', 'timestamp', self.manifest.timestamp)
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self.config.set('cache', 'key_type', str(self.key.TYPE))
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self.config.set('cache', 'previous_location', self.repository._location.canonical_path())
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with open(os.path.join(self.path, 'config'), 'w') as fd:
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self.config.write(fd)
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self.chunks.write(os.path.join(self.path, 'chunks').encode('utf-8'))
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os.rename(os.path.join(self.path, 'txn.active'),
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os.path.join(self.path, 'txn.tmp'))
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shutil.rmtree(os.path.join(self.path, 'txn.tmp'))
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self.txn_active = False
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def rollback(self):
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"""Roll back partial and aborted transactions
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"""
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# Remove partial transaction
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if os.path.exists(os.path.join(self.path, 'txn.tmp')):
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shutil.rmtree(os.path.join(self.path, 'txn.tmp'))
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# Roll back active transaction
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txn_dir = os.path.join(self.path, 'txn.active')
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if os.path.exists(txn_dir):
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shutil.copy(os.path.join(txn_dir, 'config'), self.path)
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shutil.copy(os.path.join(txn_dir, 'chunks'), self.path)
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shutil.copy(os.path.join(txn_dir, 'files'), self.path)
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os.rename(txn_dir, os.path.join(self.path, 'txn.tmp'))
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if os.path.exists(os.path.join(self.path, 'txn.tmp')):
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shutil.rmtree(os.path.join(self.path, 'txn.tmp'))
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self.txn_active = False
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self._do_open()
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def sync(self):
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"""Re-synchronize chunks cache with repository.
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Maintains a directory with known backup archive indexes, so it only
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needs to fetch infos from repo and build a chunk index once per backup
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archive.
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If out of sync, missing archive indexes get added, outdated indexes
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get removed and a new master chunks index is built by merging all
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archive indexes.
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"""
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archive_path = os.path.join(self.path, 'chunks.archive.d')
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def mkpath(id, suffix=''):
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id_hex = hexlify(id).decode('ascii')
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path = os.path.join(archive_path, id_hex + suffix)
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return path.encode('utf-8')
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def cached_archives():
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if self.do_cache:
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fns = os.listdir(archive_path)
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# filenames with 64 hex digits == 256bit
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return set(unhexlify(fn) for fn in fns if len(fn) == 64)
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else:
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return set()
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def repo_archives():
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return set(info[b'id'] for info in self.manifest.archives.values())
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def cleanup_outdated(ids):
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for id in ids:
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os.unlink(mkpath(id))
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def fetch_and_build_idx(archive_id, repository, key):
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chunk_idx = ChunkIndex()
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cdata = repository.get(archive_id)
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data = key.decrypt(archive_id, cdata)
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chunk_idx.add(archive_id, 1, len(data), len(cdata))
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archive = msgpack.unpackb(data)
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if archive[b'version'] != 1:
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raise Exception('Unknown archive metadata version')
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decode_dict(archive, (b'name',))
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unpacker = msgpack.Unpacker()
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for item_id, chunk in zip(archive[b'items'], repository.get_many(archive[b'items'])):
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data = key.decrypt(item_id, chunk)
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chunk_idx.add(item_id, 1, len(data), len(chunk))
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unpacker.feed(data)
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for item in unpacker:
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if not isinstance(item, dict):
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logger.error('Error: Did not get expected metadata dict - archive corrupted!')
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continue
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if b'chunks' in item:
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for chunk_id, size, csize in item[b'chunks']:
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chunk_idx.add(chunk_id, 1, size, csize)
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if self.do_cache:
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fn = mkpath(archive_id)
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fn_tmp = mkpath(archive_id, suffix='.tmp')
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try:
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chunk_idx.write(fn_tmp)
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except Exception:
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os.unlink(fn_tmp)
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else:
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os.rename(fn_tmp, fn)
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return chunk_idx
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def lookup_name(archive_id):
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for name, info in self.manifest.archives.items():
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if info[b'id'] == archive_id:
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return name
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def create_master_idx(chunk_idx):
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logger.info('Synchronizing chunks cache...')
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cached_ids = cached_archives()
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archive_ids = repo_archives()
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logger.info('Archives: %d, w/ cached Idx: %d, w/ outdated Idx: %d, w/o cached Idx: %d.' % (
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len(archive_ids), len(cached_ids),
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len(cached_ids - archive_ids), len(archive_ids - cached_ids), ))
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# deallocates old hashindex, creates empty hashindex:
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chunk_idx.clear()
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cleanup_outdated(cached_ids - archive_ids)
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if archive_ids:
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chunk_idx = None
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for archive_id in archive_ids:
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archive_name = lookup_name(archive_id)
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if archive_id in cached_ids:
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archive_chunk_idx_path = mkpath(archive_id)
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logger.info("Reading cached archive chunk index for %s ..." % archive_name)
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archive_chunk_idx = ChunkIndex.read(archive_chunk_idx_path)
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else:
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logger.info('Fetching and building archive index for %s ...' % archive_name)
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archive_chunk_idx = fetch_and_build_idx(archive_id, repository, self.key)
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logger.info("Merging into master chunks index ...")
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if chunk_idx is None:
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# we just use the first archive's idx as starting point,
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# to avoid growing the hash table from 0 size and also
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# to save 1 merge call.
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chunk_idx = archive_chunk_idx
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else:
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chunk_idx.merge(archive_chunk_idx)
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logger.info('Done.')
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return chunk_idx
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def legacy_cleanup():
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"""bring old cache dirs into the desired state (cleanup and adapt)"""
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try:
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os.unlink(os.path.join(self.path, 'chunks.archive'))
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except:
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pass
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try:
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os.unlink(os.path.join(self.path, 'chunks.archive.tmp'))
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except:
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pass
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try:
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os.mkdir(archive_path)
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except:
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pass
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self.begin_txn()
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with cache_if_remote(self.repository) as repository:
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legacy_cleanup()
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# TEMPORARY HACK: to avoid archive index caching, create a FILE named ~/.cache/borg/REPOID/chunks.archive.d -
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# this is only recommended if you have a fast, low latency connection to your repo (e.g. if repo is local disk)
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self.do_cache = os.path.isdir(archive_path)
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self.chunks = create_master_idx(self.chunks)
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def add_chunk(self, id, data, stats):
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if not self.txn_active:
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self.begin_txn()
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size = len(data)
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if self.seen_chunk(id, size):
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return self.chunk_incref(id, stats)
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data = self.key.encrypt(data)
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csize = len(data)
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self.repository.put(id, data, wait=False)
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self.chunks[id] = (1, size, csize)
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stats.update(size, csize, True)
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return id, size, csize
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def seen_chunk(self, id, size=None):
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refcount, stored_size, _ = self.chunks.get(id, (0, None, None))
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if size is not None and stored_size is not None and size != stored_size:
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# we already have a chunk with that id, but different size.
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# this is either a hash collision (unlikely) or corruption or a bug.
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raise Exception("chunk has same id [%r], but different size (stored: %d new: %d)!" % (
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id, stored_size, size))
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return refcount
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def chunk_incref(self, id, stats):
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if not self.txn_active:
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self.begin_txn()
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count, size, csize = self.chunks[id]
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self.chunks[id] = (count + 1, size, csize)
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stats.update(size, csize, False)
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return id, size, csize
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def chunk_decref(self, id, stats):
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if not self.txn_active:
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self.begin_txn()
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count, size, csize = self.chunks[id]
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if count == 1:
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del self.chunks[id]
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self.repository.delete(id, wait=False)
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stats.update(-size, -csize, True)
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else:
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self.chunks[id] = (count - 1, size, csize)
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stats.update(-size, -csize, False)
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def file_known_and_unchanged(self, path_hash, st):
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if not (self.do_files and stat.S_ISREG(st.st_mode)):
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return None
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if self.files is None:
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self._read_files()
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entry = self.files.get(path_hash)
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if not entry:
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return None
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entry = msgpack.unpackb(entry)
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if entry[2] == st.st_size and bigint_to_int(entry[3]) == st.st_mtime_ns and entry[1] == st.st_ino:
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# reset entry age
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entry[0] = 0
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self.files[path_hash] = msgpack.packb(entry)
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return entry[4]
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else:
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return None
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def memorize_file(self, path_hash, st, ids):
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if not (self.do_files and stat.S_ISREG(st.st_mode)):
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return
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# Entry: Age, inode, size, mtime, chunk ids
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mtime_ns = st.st_mtime_ns
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self.files[path_hash] = msgpack.packb((0, st.st_ino, st.st_size, int_to_bigint(mtime_ns), ids))
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self._newest_mtime = max(self._newest_mtime, mtime_ns)
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