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borg/darc/cache.py
2010-12-06 21:46:29 +01:00

119 lines
4 KiB
Python

import msgpack
import os
from . import NS_ARCHIVE_CHUNKS, NS_CHUNK, PACKET_ARCHIVE_CHUNKS, PACKET_CHUNK
class Cache(object):
"""Client Side cache
"""
def __init__(self, store, keychain):
self.tid = -1
self.store = store
self.keychain = keychain
self.path = os.path.join(Cache.cache_dir_path(),
'%s.cache' % self.store.id.encode('hex'))
self.open()
if self.tid != store.tid:
self.init()
@staticmethod
def cache_dir_path():
"""Return path to directory used for storing users cache files"""
return os.path.join(os.path.expanduser('~'), '.darc', 'cache')
def open(self):
if not os.path.exists(self.path):
return
with open(self.path, 'rb') as fd:
#data, hash = self.keychain.decrypt(fd.read())
cache = msgpack.unpackb(fd.read())
assert cache['version'] == 1
self.chunk_counts = cache['chunk_counts']
self.file_chunks = cache['file_chunks']
self.tid = cache['tid']
def init(self):
"""Initializes cache by fetching and reading all archive indicies
"""
print 'Initializing cache...'
self.chunk_counts = {}
self.file_chunks = {}
for id in self.store.list(NS_ARCHIVE_CHUNKS):
if len(id) != 32:
import ipdb
ipdb.set_trace()
magic, data, hash = self.keychain.decrypt(self.store.get(NS_ARCHIVE_CHUNKS, id))
assert magic == PACKET_ARCHIVE_CHUNKS
chunks = msgpack.unpackb(data)
for id, size in chunks:
try:
count, size = self.chunk_counts[id]
self.chunk_counts[id] = count + 1, size
except KeyError:
self.chunk_counts[id] = 1, size
self.save()
def filter_file_chunks(self):
for key, value in self.file_chunks.iteritems():
if value[0] < 8:
yield key, (value[0] + 1,) + value[1:]
def save(self):
for id, (count, size) in self.chunk_counts.iteritems():
if count > 1000000:
self.chunk_counts[id] = count - 1000000, size
cache = {'version': 1,
'tid': self.store.tid,
'chunk_counts': self.chunk_counts,
'file_chunks': dict(self.filter_file_chunks()),
}
# data, hash = self.keychain.encrypt_create(msgpack.packb(cache))
cachedir = os.path.dirname(self.path)
if not os.path.exists(cachedir):
os.makedirs(cachedir)
with open(self.path, 'wb') as fd:
fd.write(msgpack.packb(cache))
def add_chunk(self, id, data):
if self.seen_chunk(id):
return self.chunk_incref(id)
data, hash = self.keychain.encrypt(PACKET_CHUNK, data)
csize = len(data)
self.store.put(NS_CHUNK, id, data)
self.chunk_counts[id] = (1000001, csize)
return id
def seen_chunk(self, id):
return self.chunk_counts.get(id, (0, 0))[0]
def chunk_incref(self, id):
count, size = self.chunk_counts[id]
if count < 1000000:
self.chunk_counts[id] = (count + 1000001, size)
return id
def chunk_decref(self, id):
count, size = self.chunk_counts[id]
if count == 1:
del self.chunk_counts[id]
self.store.delete(NS_CHUNK, id)
else:
self.chunk_counts[id] = (count - 1, size)
def file_known_and_unchanged(self, path_hash, st):
entry = self.file_chunks.get(path_hash)
if (entry and entry[3] == st.st_mtime
and entry[2] == st.st_size and entry[1] == st.st_ino):
# reset entry age
self.file_chunks[path_hash] = (0,) + entry[1:]
return entry[4], entry[2]
else:
return None, 0
def memorize_file_chunks(self, path_hash, st, ids):
# Entry: Age, inode, size, mtime, chunk ids
self.file_chunks[path_hash] = 0, st.st_ino, st.st_size, st.st_mtime, ids