| 1 | """ |
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| 2 | CRS encoding and decoding. |
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| 3 | |
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| 4 | Ported to Python 3. |
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| 5 | """ |
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| 6 | |
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| 7 | from zope.interface import implementer |
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| 8 | from allmydata.util import mathutil |
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| 9 | from allmydata.util.assertutil import precondition |
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| 10 | from allmydata.util.cputhreadpool import defer_to_thread |
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| 11 | from allmydata.util.deferredutil import async_to_deferred |
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| 12 | from allmydata.interfaces import ICodecEncoder, ICodecDecoder |
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| 13 | import zfec |
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| 14 | |
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| 15 | @implementer(ICodecEncoder) |
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| 16 | class CRSEncoder: |
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| 17 | ENCODER_TYPE = b"crs" |
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| 18 | |
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| 19 | def set_params(self, data_size, required_shares, max_shares): |
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| 20 | assert required_shares <= max_shares |
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| 21 | self.data_size = data_size |
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| 22 | self.required_shares = required_shares |
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| 23 | self.max_shares = max_shares |
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| 24 | self.share_size = mathutil.div_ceil(data_size, required_shares) |
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| 25 | self.last_share_padding = mathutil.pad_size(self.share_size, required_shares) |
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| 26 | self.encoder = zfec.Encoder(required_shares, max_shares) |
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| 27 | |
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| 28 | def get_encoder_type(self): |
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| 29 | return self.ENCODER_TYPE |
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| 30 | |
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| 31 | def get_params(self): |
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| 32 | return (self.data_size, self.required_shares, self.max_shares) |
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| 33 | |
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| 34 | def get_serialized_params(self): |
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| 35 | return b"%d-%d-%d" % (self.data_size, self.required_shares, |
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| 36 | self.max_shares) |
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| 37 | |
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| 38 | def get_block_size(self): |
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| 39 | return self.share_size |
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| 40 | |
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| 41 | @async_to_deferred |
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| 42 | async def encode(self, inshares, desired_share_ids=None): |
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| 43 | precondition(desired_share_ids is None or len(desired_share_ids) <= self.max_shares, desired_share_ids, self.max_shares) |
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| 44 | |
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| 45 | if desired_share_ids is None: |
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| 46 | desired_share_ids = list(range(self.max_shares)) |
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| 47 | |
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| 48 | for inshare in inshares: |
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| 49 | assert len(inshare) == self.share_size, (len(inshare), self.share_size, self.data_size, self.required_shares) |
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| 50 | shares = await defer_to_thread(self.encoder.encode, inshares, desired_share_ids) |
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| 51 | return (shares, desired_share_ids) |
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| 52 | |
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| 53 | def encode_proposal(self, data, desired_share_ids=None): |
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| 54 | raise NotImplementedError() |
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| 55 | |
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| 56 | |
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| 57 | @implementer(ICodecDecoder) |
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| 58 | class CRSDecoder: |
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| 59 | |
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| 60 | def set_params(self, data_size, required_shares, max_shares): |
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| 61 | self.data_size = data_size |
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| 62 | self.required_shares = required_shares |
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| 63 | self.max_shares = max_shares |
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| 64 | |
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| 65 | self.chunk_size = self.required_shares |
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| 66 | self.num_chunks = mathutil.div_ceil(self.data_size, self.chunk_size) |
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| 67 | self.share_size = self.num_chunks |
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| 68 | self.decoder = zfec.Decoder(self.required_shares, self.max_shares) |
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| 69 | |
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| 70 | def get_needed_shares(self): |
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| 71 | return self.required_shares |
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| 72 | |
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| 73 | @async_to_deferred |
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| 74 | async def decode(self, some_shares, their_shareids): |
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| 75 | precondition(len(some_shares) == len(their_shareids), |
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| 76 | len(some_shares), len(their_shareids)) |
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| 77 | precondition(len(some_shares) == self.required_shares, |
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| 78 | len(some_shares), self.required_shares) |
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| 79 | return await defer_to_thread( |
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| 80 | self.decoder.decode, |
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| 81 | some_shares, |
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| 82 | [int(s) for s in their_shareids] |
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| 83 | ) |
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| 84 | |
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| 85 | def parse_params(serializedparams): |
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| 86 | pieces = serializedparams.split(b"-") |
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| 87 | return int(pieces[0]), int(pieces[1]), int(pieces[2]) |
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