mirror of https://github.com/borgbackup/borg.git
105 lines
3.3 KiB
Python
105 lines
3.3 KiB
Python
import cPickle
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import hashlib
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import os
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import sys
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import zlib
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NS_ARCHIVES = 'ARCHIVES'
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NS_CHUNKS = 'CHUNKS'
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class Cache(object):
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"""Client Side cache
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"""
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def __init__(self, store):
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self.store = store
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self.path = os.path.join(os.path.expanduser('~'), '.dedupestore', 'cache',
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'%s.cache' % self.store.uuid)
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self.tid = -1
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self.open()
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if self.tid != self.store.tid:
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self.init()
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def open(self):
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if not os.path.exists(self.path):
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return
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data = open(self.path, 'rb').read()
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id = data[:32]
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data = data[32:]
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if hashlib.sha256(data).digest() != id:
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raise Exception('Cache hash did not match')
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data = cPickle.loads(zlib.decompress(data))
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if data['uuid'] != self.store.uuid:
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raise Exception('Cache UUID mismatch')
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self.chunkmap = data['chunkmap']
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self.archives = data['archives']
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self.tid = data['tid']
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def init(self):
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"""Initializes cache by fetching and reading all archive indicies
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"""
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self.chunkmap = {}
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self.archives = {}
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self.tid = self.store.tid
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if self.store.tid == 0:
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return
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for id in list(self.store.list(NS_ARCHIVES)):
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data = self.store.get(NS_ARCHIVES, id)
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if hashlib.sha256(data).digest() != id:
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raise Exception('Archive hash did not match')
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archive = cPickle.loads(zlib.decompress(data))
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self.archives[archive['name']] = id
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for id, csize, osize in archive['chunks']:
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if self.seen_chunk(id):
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self.chunk_incref(id)
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else:
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self.init_chunk(id, csize, osize)
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def save(self):
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assert self.store.state == self.store.OPEN
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data = {'uuid': self.store.uuid,
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'chunkmap': self.chunkmap,
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'tid': self.store.tid, 'archives': self.archives}
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cachedir = os.path.dirname(self.path)
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if not os.path.exists(cachedir):
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os.makedirs(cachedir)
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with open(self.path, 'wb') as fd:
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data = zlib.compress(cPickle.dumps(data))
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id = hashlib.sha256(data).digest()
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fd.write(id + data)
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def add_chunk(self, data):
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id = hashlib.sha256(data).digest()
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if self.seen_chunk(id):
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return self.chunk_incref(id)
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osize = len(data)
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data = zlib.compress(data)
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data = hashlib.sha256(data).digest() + data
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csize = len(data)
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self.store.put(NS_CHUNKS, id, data)
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return self.init_chunk(id, csize, osize)
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def init_chunk(self, id, csize, osize):
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self.chunkmap[id] = (1, csize, osize)
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return id, csize, osize
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def seen_chunk(self, id):
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count, csize, osize = self.chunkmap.get(id, (0, 0, 0))
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return count
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def chunk_incref(self, id):
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count, csize, osize = self.chunkmap[id]
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self.chunkmap[id] = (count + 1, csize, osize)
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return id, csize, osize
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def chunk_decref(self, id):
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count, csize, osize = self.chunkmap[id]
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if count == 1:
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del self.chunkmap[id]
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self.store.delete(NS_CHUNKS, id)
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else:
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self.chunkmap[id] = (count - 1, csize, osize)
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