1 # -*- test-case-name: allmydata.test.test_encode_share -*-
3 from zope.interface import implements
4 from twisted.internet import defer
5 from allmydata.util import mathutil
6 from allmydata.util.assertutil import precondition
7 from allmydata.interfaces import ICodecEncoder, ICodecDecoder
10 class CRSEncoder(object):
11 implements(ICodecEncoder)
14 def set_params(self, data_size, required_shares, max_shares):
15 assert required_shares <= max_shares
16 self.data_size = data_size
17 self.required_shares = required_shares
18 self.max_shares = max_shares
19 self.share_size = mathutil.div_ceil(data_size, required_shares)
20 self.last_share_padding = mathutil.pad_size(self.share_size, required_shares)
21 self.encoder = zfec.Encoder(required_shares, max_shares)
23 def get_encoder_type(self):
24 return self.ENCODER_TYPE
27 return (self.data_size, self.required_shares, self.max_shares)
29 def get_serialized_params(self):
30 return "%d-%d-%d" % (self.data_size, self.required_shares,
33 def get_block_size(self):
34 return self.share_size
36 def encode(self, inshares, desired_share_ids=None):
37 precondition(desired_share_ids is None or len(desired_share_ids) <= self.max_shares, desired_share_ids, self.max_shares)
39 if desired_share_ids is None:
40 desired_share_ids = range(self.max_shares)
42 for inshare in inshares:
43 assert len(inshare) == self.share_size, (len(inshare), self.share_size, self.data_size, self.required_shares)
44 shares = self.encoder.encode(inshares, desired_share_ids)
46 return defer.succeed((shares, desired_share_ids))
48 class CRSDecoder(object):
49 implements(ICodecDecoder)
51 def set_params(self, data_size, required_shares, max_shares):
52 self.data_size = data_size
53 self.required_shares = required_shares
54 self.max_shares = max_shares
56 self.chunk_size = self.required_shares
57 self.num_chunks = mathutil.div_ceil(self.data_size, self.chunk_size)
58 self.share_size = self.num_chunks
59 self.decoder = zfec.Decoder(self.required_shares, self.max_shares)
61 def get_needed_shares(self):
62 return self.required_shares
64 def decode(self, some_shares, their_shareids):
65 precondition(len(some_shares) == len(their_shareids),
66 len(some_shares), len(their_shareids))
67 precondition(len(some_shares) == self.required_shares,
68 len(some_shares), self.required_shares)
69 data = self.decoder.decode(some_shares,
70 [int(s) for s in their_shareids])
71 return defer.succeed(data)
73 def parse_params(serializedparams):
74 pieces = serializedparams.split("-")
75 return int(pieces[0]), int(pieces[1]), int(pieces[2])