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encode_new.py: add comments, make variable names more illuminating

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This commit is contained in:
Brian Warner 2007-03-28 11:06:19 -07:00
parent a3a3f3f96f
commit a159ab3be8
1 changed files with 21 additions and 7 deletions
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28
src/allmydata/encode_new.py
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@ -125,14 +125,29 @@ class Encoder(object):
def do_segment(self, segnum):
chunks = []
subsharesize = self.encoder.get_share_size()
# the ICodecEncoder API wants to receive a total of self.segment_size
# bytes on each encode() call, broken up into a number of
# identically-sized pieces. Due to the way the codec algorithm works,
# these pieces need to be the same size as the share which the codec
# will generate. Therefore we must feed it with input_piece_size that
# equals the output share size.
input_piece_size = self.encoder.get_share_size()
# as a result, the number of input pieces per encode() call will be
# equal to the number of required shares with which the codec was
# constructed. You can think of the codec as chopping up a
# 'segment_size' of data into 'required_shares' shares (not doing any
# fancy math at all, just doing a split), then creating some number
# of additional shares which can be substituted if the primary ones
# are unavailable
for i in range(self.required_shares):
d = self.infile.read(subsharesize)
if len(d) < subsharesize:
input_piece = self.infile.read(input_piece_size)
if len(input_piece) < input_piece_size:
# padding
d += ('\x00' * (subsharesize - len(d)))
d = self.cryptor.encrypt(d)
chunks.append(d)
input_piece += ('\x00' * (input_piece_size - len(input_piece)))
encrypted_piece = self.cryptor.encrypt(input_piece)
chunks.append(encrypted_piece)
d = self.encoder.encode(chunks)
d.addCallback(self._encoded_segment)
return d
@ -142,7 +157,6 @@ class Encoder(object):
for i in range(len(shares)):
subshare = shares[i]
shareid = shareids[i]
#for shareid,subshare in zip(shareids, shares):
d = self.send_subshare(shareid, self.segment_num, subshare)
dl.append(d)
self.subshare_hashes[shareid].append(hash(subshare))