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76 lines
2.8 KiB
Python
76 lines
2.8 KiB
Python
# -*- test-case-name: allmydata.test.test_encode_share -*-
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from zope.interface import implementer
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from twisted.internet import defer
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from allmydata.util import mathutil
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from allmydata.util.assertutil import precondition
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from allmydata.interfaces import ICodecEncoder, ICodecDecoder
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import zfec
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@implementer(ICodecEncoder)
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class CRSEncoder(object):
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ENCODER_TYPE = "crs"
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def set_params(self, data_size, required_shares, max_shares):
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assert required_shares <= max_shares
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self.data_size = data_size
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self.required_shares = required_shares
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self.max_shares = max_shares
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self.share_size = mathutil.div_ceil(data_size, required_shares)
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self.last_share_padding = mathutil.pad_size(self.share_size, required_shares)
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self.encoder = zfec.Encoder(required_shares, max_shares)
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def get_encoder_type(self):
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return self.ENCODER_TYPE
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def get_params(self):
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return (self.data_size, self.required_shares, self.max_shares)
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def get_serialized_params(self):
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return "%d-%d-%d" % (self.data_size, self.required_shares,
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self.max_shares)
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def get_block_size(self):
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return self.share_size
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def encode(self, inshares, desired_share_ids=None):
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precondition(desired_share_ids is None or len(desired_share_ids) <= self.max_shares, desired_share_ids, self.max_shares)
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if desired_share_ids is None:
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desired_share_ids = range(self.max_shares)
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for inshare in inshares:
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assert len(inshare) == self.share_size, (len(inshare), self.share_size, self.data_size, self.required_shares)
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shares = self.encoder.encode(inshares, desired_share_ids)
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return defer.succeed((shares, desired_share_ids))
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@implementer(ICodecDecoder)
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class CRSDecoder(object):
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def set_params(self, data_size, required_shares, max_shares):
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self.data_size = data_size
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self.required_shares = required_shares
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self.max_shares = max_shares
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self.chunk_size = self.required_shares
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self.num_chunks = mathutil.div_ceil(self.data_size, self.chunk_size)
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self.share_size = self.num_chunks
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self.decoder = zfec.Decoder(self.required_shares, self.max_shares)
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def get_needed_shares(self):
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return self.required_shares
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def decode(self, some_shares, their_shareids):
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precondition(len(some_shares) == len(their_shareids),
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len(some_shares), len(their_shareids))
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precondition(len(some_shares) == self.required_shares,
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len(some_shares), self.required_shares)
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data = self.decoder.decode(some_shares,
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[int(s) for s in their_shareids])
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return defer.succeed(data)
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def parse_params(serializedparams):
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pieces = serializedparams.split("-")
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return int(pieces[0]), int(pieces[1]), int(pieces[2])
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