def init_lz4():
from lz4 import VERSION, block
import struct
block_compress = block.compress
block_decompress = block.decompress
LZ4_HEADER = struct.Struct(b'<L')
try:
from lz4 import library_version_string
version = library_version_string()
except ImportError:
from lz4.version import version
def lz4_compress(packet, level):
flag = min(15, level) | LZ4_FLAG
if level>=9:
return flag, block_compress(packet, mode="high_compression", compression=level)
if level<=3:
return flag, block_compress(packet, mode="fast", acceleration=8-level*2)
return flag, block_compress(packet)
def lz4_decompress(data):
size = LZ4_HEADER.unpack_from(data[:4])[0]
#it would be better to use the max_size we have in protocol,
#but this hardcoded value will do for now
if size>MAX_DECOMPRESSED_SIZE:
sizemb = size//1024//1024
maxmb = MAX_DECOMPRESSED_SIZE//1024//1024
raise Exception("uncompressed data is too large: %iMB, limit is %iMB" % (sizemb, maxmb))
return block_decompress(data)
return Compression("lz4", version, VERSION.encode("latin1"), lz4_compress, lz4_decompress)
python_lz4_version = None
lz4_version = None
has_lz4 = False
def no_lz4(packet, level):
raise Exception("lz4 is not supported!")
lz4_compress = no_lz4
try:
from lz4 import VERSION as python_lz4_version #@UnresolvedImport
from lz4.version import version as lz4_version
from lz4.block import compress, decompress as LZ4_uncompress
python_lz4_version = python_lz4_version.encode("latin1")
has_lz4 = True
def lz4_block_compress(packet, level):
flag = min(15, level) | LZ4_FLAG
if level >= 7:
return flag, compress(packet,
mode="high_compression",
compression=level)
if level <= 3:
return flag, compress(packet,
mode="fast",
acceleration=8 - level * 2)
return flag, compress(packet)
lz4_compress = lz4_block_compress