mirror of https://github.com/borgbackup/borg.git
219 lines
8.4 KiB
Python
219 lines
8.4 KiB
Python
from configparser import RawConfigParser
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from itertools import zip_longest
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import msgpack
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import os
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from binascii import hexlify
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import shutil
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from .helpers import Error, get_cache_dir, decode_dict, st_mtime_ns, unhexlify, UpgradableLock
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from .hashindex import ChunkIndex
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class Cache(object):
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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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def __init__(self, repository, key, manifest):
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self.timestamp = 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 = os.path.join(get_cache_dir(), hexlify(repository.id).decode('ascii'))
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if not os.path.exists(self.path):
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self.create()
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self.open()
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if 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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self.sync()
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self.commit()
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def __del__(self):
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self.close()
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def create(self):
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"""Create a new empty cache at `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 an Attic cache')
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config = RawConfigParser()
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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.create(os.path.join(self.path, 'chunks').encode('utf-8'))
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with open(os.path.join(self.path, 'files'), 'w') as fd:
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pass # empty file
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def open(self):
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if not os.path.isdir(self.path):
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raise Exception('%s Does not look like an Attic cache' % self.path)
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self.lock = UpgradableLock(os.path.join(self.path, 'config'), exclusive=True)
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self.rollback()
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self.config = RawConfigParser()
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self.config.read(os.path.join(self.path, 'config'))
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if self.config.getint('cache', 'version') != 1:
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raise Exception('%s Does not look like an Attic cache')
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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.chunks = ChunkIndex(os.path.join(self.path, 'chunks').encode('utf-8'))
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self.files = None
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def close(self):
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self.lock.release()
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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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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 hash, item in u:
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item[0] += 1
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self.files[hash] = 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 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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if item[1][0] < 10 and item[1][3] < self._newest_mtime:
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msgpack.pack(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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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.flush()
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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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# 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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# 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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self.txn_active = False
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def sync(self):
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"""Initializes cache by fetching and reading all archive indicies
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"""
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def add(id, size, csize):
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try:
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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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except KeyError:
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self.chunks[id] = 1, size, csize
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self.begin_txn()
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print('Initializing cache...')
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self.chunks.clear()
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unpacker = msgpack.Unpacker()
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for name, info in self.manifest.archives.items():
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id = info[b'id']
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cdata = self.repository.get(id)
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data = self.key.decrypt(id, cdata)
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add(id, 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', b'hostname', b'username', b'time')) # fixme: argv
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print('Analyzing archive:', archive[b'name'])
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for id_, chunk in zip_longest(archive[b'items'], self.repository.get_many(archive[b'items'])):
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data = self.key.decrypt(id_, chunk)
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add(id_, len(data), len(chunk))
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unpacker.feed(data)
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for item in unpacker:
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if b'chunks' in item:
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for id_, size, csize in item[b'chunks']:
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add(id_, size, csize)
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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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if self.seen_chunk(id):
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return self.chunk_incref(id, stats)
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size = len(data)
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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):
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return self.chunks.get(id, (0, 0, 0))[0]
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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):
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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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else:
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self.chunks[id] = (count - 1, size, csize)
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def file_known_and_unchanged(self, path_hash, st):
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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 (entry and entry[3] == st_mtime_ns(st)
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and entry[2] == st.st_size and entry[1] == st.st_ino):
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# reset entry age
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self.files[path_hash][0] = 0
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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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# Entry: Age, inode, size, mtime, chunk ids
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mtime_ns = st_mtime_ns(st)
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self.files[path_hash] = 0, st.st_ino, st.st_size, mtime_ns, ids
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self._newest_mtime = max(self._newest_mtime, mtime_ns)
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