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from io import open
import struct
import json
import os
import logging
import library.python.par_apply as lpp
import library.python.codecs as lpc
logger = logging.getLogger('compress')
def list_all_codecs():
return sorted(frozenset(lpc.list_all_codecs()))
def find_codec(ext):
def ext_compress(x):
return lpc.dumps(ext, x)
def ext_decompress(x):
return lpc.loads(ext, x)
ext_decompress(ext_compress(b''))
return {'c': ext_compress, 'd': ext_decompress, 'n': ext}
def codec_for(path):
for ext in reversed(path.split('.')):
try:
return find_codec(ext)
except Exception as e:
logger.debug('in codec_for(): %s', e)
raise Exception('unsupported file %s' % path)
def compress(fr, to, codec=None, fopen=open, threads=1):
if codec:
codec = find_codec(codec)
else:
codec = codec_for(to)
func = codec['c']
def iter_blocks():
with fopen(fr, 'rb') as f:
while True:
chunk = f.read(16 * 1024 * 1024)
if chunk:
yield chunk
else:
yield b''
return
def iter_results():
info = {
'codec': codec['n'],
}
if fr:
info['size'] = os.path.getsize(fr)
yield json.dumps(info, sort_keys=True) + '\n'
for c in lpp.par_apply(iter_blocks(), func, threads):
yield c
with fopen(to, 'wb') as f:
for c in iter_results():
logger.debug('complete %s', len(c))
f.write(struct.pack('<I', len(c)))
try:
f.write(c)
except TypeError:
f.write(c.encode('utf-8'))
def decompress(fr, to, codec=None, fopen=open, threads=1):
def iter_chunks():
with fopen(fr, 'rb') as f:
cnt = 0
while True:
ll = f.read(4)
if ll:
ll = struct.unpack('<I', ll)[0]
if ll:
if ll > 100000000:
raise Exception('broken stream')
yield f.read(ll)
cnt += ll
else:
if not cnt:
raise Exception('empty stream')
return
it = iter_chunks()
extra = []
for chunk in it:
hdr = {}
try:
hdr = json.loads(chunk)
except Exception as e:
logger.info('can not parse header, suspect old format: %s', e)
extra.append(chunk)
break
def resolve_codec():
if 'codec' in hdr:
return find_codec(hdr['codec'])
if codec:
return find_codec(codec)
return codec_for(fr)
dc = resolve_codec()['d']
def iter_all_chunks():
for x in extra:
yield x
for x in it:
yield x
with fopen(to, 'wb') as f:
for c in lpp.par_apply(iter_all_chunks(), dc, threads):
if c:
logger.debug('complete %s', len(c))
f.write(c)
else:
break
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