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|
import zlib
from abc import abstractmethod
from typing import Union
import lz4
import lz4.frame
import zstandard
try:
import brotli
except ImportError:
brotli = None
available_compression = ['lz4', 'zstd']
if brotli:
available_compression.append('br')
available_compression.extend(['gzip', 'deflate'])
comp_map = {}
class Compressor:
def __init_subclass__(cls, tag: str, thread_safe: bool = True):
comp_map[tag] = cls() if thread_safe else cls
@abstractmethod
def compress_block(self, block) -> Union[bytes, bytearray]:
return block
def flush(self):
pass
class GzipCompressor(Compressor, tag='gzip', thread_safe=False):
def __init__(self, level: int = 6, wbits: int = 31):
self.zlib_obj = zlib.compressobj(level=level, wbits=wbits)
def compress_block(self, block):
return self.zlib_obj.compress(block)
def flush(self):
return self.zlib_obj.flush()
class Lz4Compressor(Compressor, tag='lz4', thread_safe=False):
def __init__(self):
self.comp = lz4.frame.LZ4FrameCompressor()
def compress_block(self, block):
output = self.comp.begin(len(block))
output += self.comp.compress(block)
return output + self.comp.flush()
class ZstdCompressor(Compressor, tag='zstd'):
def compress_block(self, block):
return zstandard.compress(block)
class BrotliCompressor(Compressor, tag='br'):
def compress_block(self, block):
return brotli.compress(block)
null_compressor = Compressor()
def get_compressor(compression: str) -> Compressor:
if not compression:
return null_compressor
comp = comp_map[compression]
try:
return comp()
except TypeError:
return comp
|
