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