def encode_decode(self, k):
print "\nTesting encoding and then decoding with k = %s" % k
md5 = hashlib.md5()
with FileChunker(k, SYMBOLSIZE, DEFAULT_FILE) as chunker:
chunk = chunker.chunk()
while chunk:
padding = chunk.padding
symbols = [(i, chunk[i]) for i in xrange(k)]
encoder = Encoder(k, symbols)
symbols = []
# Start at k/2 and produce 1.25k more symbols to get a mix
# of parity and source symbols
for i in xrange(k * 2):
symbols.append(encoder.next())
encoder = None
decoder = Decoder(k)
for tup in symbols:
decoder.append(tup)
decoder.decode()
decoded = bytearray()
for i in xrange(k):
esi, s = decoder.next()
decoded += s.tostring()
decoder = None
if padding:
padding = 0 - padding
print "Removing padding", padding, "bytes"
decoded = decoded[:padding]
md5.update(decoded)
# Continue on to the next chunk
chunk = chunker.chunk()
print "Original digest:", self.original_digest
print "Decoded digest:", md5.hexdigest()
return self.original_digest == md5.hexdigest()
def encode_decode(self, k):
print "\nTesting encoding and then decoding with k = %s" % k
md5 = hashlib.md5()
with FileChunker(k, SYMBOLSIZE, DEFAULT_FILE) as chunker:
chunk = chunker.chunk()
while chunk:
padding = chunk.padding
symbols = [(i, chunk[i]) for i in xrange(k)]
encoder = Encoder(k, symbols)
symbols = []
# Start at k/2 and produce 1.25k more symbols to get a mix
# of parity and source symbols
for i in xrange(k * 2):
symbols.append(encoder.next())
encoder = None
decoder = Decoder(k)
for tup in symbols:
decoder.append(tup)
decoder.decode()
decoded = bytearray()
for i in xrange(k):
esi, s = decoder.next()
decoded += s.tostring()
decoder = None
if padding:
padding = 0 - padding
print "Removing padding", padding, "bytes"
decoded = decoded[:padding]
md5.update(decoded)
# Continue on to the next chunk
chunk = chunker.chunk()
print "Original digest:", self.original_digest
print "Decoded digest:", md5.hexdigest()
return self.original_digest == md5.hexdigest()
def decode(self):
"""
Orchestrates the reading of file shares into encoded symbols
and decoding of the encoded symbols
"""
self.stats['start_time'] = time.time()
self.verify_input_dir()
self.verify_output_file()
# Outer loop will iterate over blocks in a directory.
# Block directories contain shares per block.
# Blocks start at 0 and increment by 1. If block n doesn't exist
# Then assume that is the end of the file
block = 0
blockdir = os.path.join(self.input_dir, str(block))
while os.path.exists(blockdir):
# Attempt to read metadata for this block
self.start_timer()
k, padding = self.read_block_meta_data(blockdir)
self.add_time(self.stop_timer(), 'io_time')
# For each file in the block directory(excluding meta) read each
# share. Each will be an encoding symbol
decoder = Decoder(k)
read_symbols = 0
for _file in os.listdir(blockdir):
# Skip non files
if not os.path.isfile(os.path.join(blockdir, _file)):
continue
try:
# A share should be a named integer indicating which symbol it
# is. int(_file) will raise an error if not and we ignore
# that file
id = int(_file)
# Open the share file in binary mode
self.start_timer()
symbol = numpy.fromfile(os.path.join(blockdir, _file),
dtype='uint64')
self.add_time(self.stop_timer(), 'io_time')
# Add the symbol to the decoder.
# A symbol is a (integer, numpy array) tuple
can_decode = decoder.append((int(_file), symbol))
read_symbols += 1
if can_decode:
break
except Exception, e:
continue
pass
# Ideally we want more than k encoded symbols.
# We will fail with less than k
if read_symbols < k:
self.exit(
"There were not sufficient symbols to recover block %s" %
block)
if not can_decode:
self.exit(
"A decoding schedule was not possible with the symbols provided."
)
# Instruct decoder to calculate intermediate symbols from
# known encoding symbols
self.start_timer()
decoder.decode()
self.add_time(self.stop_timer(), 'decoding_time')
# Steam source symbol output by encoding the first
# k encoded symbols.
# The first k source symbols == the first k encoding symbols
target = open(self.output_file, 'ab')
for i in xrange(k):
self.start_timer()
s = decoder.next()[1]
self.add_time(self.stop_timer(), 'decoding_time')
self.start_timer()
s.tofile(target)
self.add_time(self.stop_timer(), 'io_time')
target.close()
# Padding should only be on the last block but we check anyway
# @TODO - Ensure file size is accurate before truncating
if (padding):
self.start_timer()
size = os.path.getsize(self.output_file) - padding
target = io.open(self.output_file, 'a+b')
target.truncate(size)
target.close()
self.add_time(self.stop_timer(), 'io_time')
# Increment block number by 1
block += 1
blockdir = os.path.join(self.input_dir, str(block))
def decode(self):
"""
Orchestrates the reading of file shares into encoded symbols
and decoding of the encoded symbols
"""
self.stats['start_time'] = time.time()
self.verify_input_dir()
self.verify_output_file()
# Outer loop will iterate over blocks in a directory.
# Block directories contain shares per block.
# Blocks start at 0 and increment by 1. If block n doesn't exist
# Then assume that is the end of the file
block = 0
blockdir = os.path.join(self.input_dir, str(block))
while os.path.exists(blockdir):
# Attempt to read metadata for this block
self.start_timer()
k, padding = self.read_block_meta_data(blockdir)
self.add_time(self.stop_timer(), 'io_time')
# For each file in the block directory(excluding meta) read each
# share. Each will be an encoding symbol
decoder = Decoder(k)
read_symbols = 0
for _file in os.listdir(blockdir):
# Skip non files
if not os.path.isfile(os.path.join(blockdir, _file)):
continue
try:
# Open the share file in binary mode
self.start_timer()
symbol = numpy.fromfile(os.path.join(blockdir, _file),
dtype='uint64')
self.add_time(self.stop_timer(), 'io_time')
# Add the symbol to the decoder.
# A symbol is a (integer, numpy array) tuple
can_decode = decoder.append((int(_file), symbol))
read_symbols += 1
if can_decode:
break
except Exception:
continue
pass
# Ideally we want more than k encoded symbols.
# We will fail with less than k
if read_symbols < k:
self.exit("There were not sufficient symbols"
" to recover block %s" % block)
if not can_decode:
self.exit("A decoding schedule was not possible "
"with the symbols provided.")
# Instruct decoder to calculate intermediate symbols from
# known encoding symbols
self.start_timer()
decoder.decode()
self.add_time(self.stop_timer(), 'decoding_time')
# Steam source symbol output by encoding the first
# k encoded symbols.
# The first k source symbols == the first k encoding symbols
target = open(self.output_file, 'ab')
for i in xrange(k):
self.start_timer()
s = decoder.next()[1]
self.add_time(self.stop_timer(), 'decoding_time')
self.start_timer()
s.tofile(target)
self.add_time(self.stop_timer(), 'io_time')
target.close()
# Padding should only be on the last block but we check anyway
# @TODO - Ensure file size is accurate before truncating
if (padding):
self.start_timer()
size = os.path.getsize(self.output_file) - padding
target = io.open(self.output_file, 'a+b')
target.truncate(size)
target.close()
self.add_time(self.stop_timer(), 'io_time')
# Increment block number by 1
block += 1
blockdir = os.path.join(self.input_dir, str(block))
self.stats['blocks_decoded'] = block
self.stats['end_time'] = time.time()
self.stats['elapsed_time'] = \
self.stats['end_time'] - self.stats['start_time']
