framework/backends/compression.py

   1 # coding=utf-8
   2 # Copyright (c) 2015-2016, 2019 Intel Corporation
   3
   4 # Permission is hereby granted, free of charge, to any person obtaining a copy
   5 # of this software and associated documentation files (the "Software"), to deal
   6 # in the Software without restriction, including without limitation the rights
   7 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   8 # copies of the Software, and to permit persons to whom the Software is
   9 # furnished to do so, subject to the following conditions:
  10
  11 # The above copyright notice and this permission notice shall be included in
  12 # all copies or substantial portions of the Software.
  13
  14 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  15 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  16 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  17 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  19 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  20 # SOFTWARE.
  21
  22 """Compression support for backends.
  23
  24 This includes both compression and decompression support.
  25
  26 This provides a low level interface of dictionaries, COMPRESSORS and
  27 DECOMPRESSORS, which use compression modes ('bz2', 'gz', 'xz', 'none') to
  28 provide open-like functions with correct mode settings for writing or reading,
  29 respectively.
  30
  31 They should always take unicode (str in python 3.x) objects. It is up to the
  32 caller to ensure that they're passing unicode and not bytes.
  33
  34 A helper, get_mode(), is provided to return the user selected mode (it will try
  35 the PIGLIT_COMPRESSION environment variable, then the piglit.conf
  36 [core]:compression key, and finally the value of compression.DEFAULT). This is
  37 the best way to get a compressor.
  38
  39 """
  40
  41 import bz2
  42 import contextlib
  43 import errno
  44 import functools
  45 import gzip
  46 import io
  47 import lzma
  48 import os
  49 import subprocess
  50
  51 from framework import core
  52 from framework import exceptions
  53
  54 __all__ = [
  55     'UnsupportedCompressor',
  56     'COMPRESSORS',
  57     'DECOMPRESSORS',
  58     'get_mode',
  59 ]
  60
  61
  62 class UnsupportedCompressor(exceptions.PiglitInternalError):
  63     def __init__(self, method, *args, **kwargs):
  64         super(UnsupportedCompressor, self).__init__(*args, **kwargs)
  65         self.__method = method
  66
  67     def __str__(self):
  68         return 'unsupported compression method {}'.format(self.__method)
  69
  70
  71
  72 DEFAULT = 'bz2'
  73
  74 COMPRESSION_SUFFIXES = ['.gz', '.bz2', '.xz']
  75
  76 COMPRESSORS = {
  77     'bz2': functools.partial(bz2.open, mode='wt'),
  78     'gz': functools.partial(gzip.open, mode='wt'),
  79     'none': functools.partial(open, mode='w'),
  80     'xz': functools.partial(lzma.open, mode='wt'),
  81 }
  82
  83 DECOMPRESSORS = {
  84     'bz2': functools.partial(bz2.open, mode='rt'),
  85     'gz': functools.partial(gzip.open, mode='rt'),
  86     'none': functools.partial(open, mode='r'),
  87     'xz': functools.partial(lzma.open, mode='rt'),
  88 }
  89
  90
  91 def get_mode():
  92     """Return the key value of the correct compressor to use.
  93
  94     Try the environment variable PIGLIT_COMPRESSION; then check the
  95     PIGLIT_CONFIG section 'core', option 'compression'; finally fall back to
  96     DEFAULT.
  97
  98     This will raise an UnsupportedCompressionError if there isn't a compressor
  99     for that mode. It is the job of the caller to handle this exceptions
 100
 101     """
 102     # This is provided as a function rather than a constant because as a
 103     # function it can honor changes to the PIGLIT_CONFIG instance, or the
 104     # PIGLIT_COMPRESSION environment variable.
 105
 106     method = core.get_option('PIGLIT_COMPRESSION',
 107                              ('core', 'compression'),
 108                              default=DEFAULT)
 109
 110     if method not in COMPRESSORS:
 111         raise UnsupportedCompressor(method)
 112
 113     return method