Class: MultiCompress::Codec

Inherits:
Object
  • Object
show all
Defined in:
lib/multi_compress/codec.rb

Constant Summary collapse

MAGIC = 
"\x89MCDB".b
VERSION =

reserved 5-byte namespace; 0x89 is an invalid UTF-8 lead byte, so it won't collide with valid text. For BINARY data this prefix is reserved, not collision-free.

1
HEADER_SIZE =

magic + version byte + algo byte

MAGIC.bytesize + 2
B64_PREFIX = 
"mc1:"
MAX_NATIVE_OUTPUT = 
(2**(0.size * 8 - 1)) - 1
ALGO_ID = 
{ zstd: 1, lz4: 2, brotli: 3 }.freeze
ID_ALGO = 
ALGO_ID.invert.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(algo: :zstd, level: nil, encode: nil, serializer: nil, encoding: Encoding::UTF_8, max_output_size: nil, legacy: :reject, dictionary: nil) ⇒ Codec

Returns a new instance of Codec.

Raises:

  • (ArgumentError) 


21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
 
# File 'lib/multi_compress/codec.rb', line 21

def initialize(algo: :zstd, level: nil, encode: nil, serializer: nil,
               encoding: Encoding::UTF_8, max_output_size: nil,
               legacy: :reject, dictionary: nil)
  raise ArgumentError, "unknown algo #{algo.inspect}" unless ALGO_ID.key?(algo)
  raise ArgumentError, "encode must be nil or :base64" unless [nil, :base64].include?(encode)

  @algo            = algo
  @level           = level
  @encode          = encode
  @serializer      = serializer
  @encoding        = encoding
  limit            = Integer(max_output_size || MultiCompress.config.max_output_size)
  raise ArgumentError, "max_output_size must be greater than 0" unless limit.positive?
  if limit > MAX_NATIVE_OUTPUT
    raise ArgumentError,
          "max_output_size must be at most #{MAX_NATIVE_OUTPUT} bytes on this platform"
  end

  @max_output_size = limit
  @legacy          = normalize_legacy(legacy)
  @dictionary      = dictionary
end

Instance Attribute Details

#algo ⇒ Object (readonly)

Returns the value of attribute algo.



19
20
21
 
# File 'lib/multi_compress/codec.rb', line 19

def algo
  @algo
end

#level ⇒ Object (readonly)

Returns the value of attribute level.



19
20
21
 
# File 'lib/multi_compress/codec.rb', line 19

def level
  @level
end

#max_output_size ⇒ Object (readonly)

Returns the value of attribute max_output_size.



19
20
21
 
# File 'lib/multi_compress/codec.rb', line 19

def max_output_size
  @max_output_size
end

Instance Method Details

#dump(value) ⇒ Object 



44
45
46
47
48
49
50
51
52
 
# File 'lib/multi_compress/codec.rb', line 44

def dump(value)
  return nil if value.nil?

  payload = serialize_payload(value)
  body    = MultiCompress.compress(payload, algo: @algo, level: @level, dictionary: @dictionary)
  framed  = header + body

  @encode == :base64 ? B64_PREFIX + [framed].pack("m0") : framed
end

#load(stored) ⇒ Object 



54
55
56
57
58
59
60
61
 
# File 'lib/multi_compress/codec.rb', line 54

def load(stored)
  return nil if stored.nil?

  framed = decode_transport(stored)
  return decode_payload(unwrap(framed)) if framed

  read_legacy(stored)
end