zstd-ruby

zstd-ruby

Ruby binding for zstd(Zstandard - Fast real-time compression algorithm)

See https://github.com/facebook/zstd

Fork from https://github.com/jarredholman/ruby-zstd.

Zstd version

v1.5.7

Versioning Policy

Starting from v2.0.0, this gem follows Semantic Versioning.

• Major version (X.0.0): Breaking changes to the API
• Minor version (X.Y.0): New features, including Zstd library version updates
• Patch version (X.Y.Z): Bug fixes and other backward-compatible changes

Zstd Library Updates

Updates to the underlying Zstd library version will be released as minor version updates, as they may introduce new features or performance improvements while maintaining backward compatibility.

Note: Versions prior to v2.0.0 followed the Zstd library versioning scheme with an additional patch number (e.g., 1.5.6.2). This approach has been replaced with semantic versioning to provide clearer expectations for API stability.

Installation

Add this line to your application's Gemfile:

gem 'zstd-ruby'

And then execute:

$ bundle

Or install it yourself as:

$ gem install zstd-ruby

Usage

require 'zstd-ruby'

Compression

Simple Compression

compressed_data = Zstd.compress(data)
compressed_data = Zstd.compress(data, level: complession_level) # default compression_level is 3

Compression with Dictionary

# dictionary is supposed to have been created using `zstd --train`
compressed_using_dict = Zstd.compress("", dict: File.read('dictionary_file'))

Compression with CDict

If you use the same dictionary repeatedly, you can speed up the setup by creating CDict in advance:

cdict = Zstd::CDict.new(File.read('dictionary_file'))
compressed_using_dict = Zstd.compress("", dict: cdict)

The compression_level can be specified on creating CDict.

cdict = Zstd::CDict.new(File.read('dictionary_file'), 5)
compressed_using_dict = Zstd.compress("", dict: cdict)

Streaming Compression

stream = Zstd::StreamingCompress.new
stream << "abc" << "def"
res = stream.flush
stream << "ghi"
res << stream.finish

or

stream = Zstd::StreamingCompress.new
res = stream.compress("abc")
res << stream.flush
res << stream.compress("def")
res << stream.finish

Streaming Compression with Dictionary

stream = Zstd::StreamingCompress.new(dict: File.read('dictionary_file'))
stream << "abc" << "def"
res = stream.flush
stream << "ghi"
res << stream.finish

Streaming Compression with level and Dictionary

stream = Zstd::StreamingCompress.new(level: 5, dict: File.read('dictionary_file'))
stream << "abc" << "def"
res = stream.flush
stream << "ghi"
res << stream.finish

Streaming Compression with CDict of level 5

cdict = Zstd::CDict.new(File.read('dictionary_file', 5)
stream = Zstd::StreamingCompress.new(dict: cdict)
stream << "abc" << "def"
res = stream.flush
stream << "ghi"
res << stream.finish

Decompression

Simple Decompression

data = Zstd.decompress(compressed_data)

Decompression with Dictionary

# dictionary is supposed to have been created using `zstd --train`
Zstd.decompress(compressed_using_dict, dict: File.read('dictionary_file'))

Decompression with DDict

If you use the same dictionary repeatedly, you can speed up the setup by creating DDict in advance:

ddict = Zstd::Ddict.new(File.read('dictionary_file'))
data = Zstd.compress(compressed_using_dict, ddict)

Streaming Decompression

cstr = "" # Compressed data
stream = Zstd::StreamingDecompress.new
result = ''
result << stream.decompress(cstr[0, 10])
result << stream.decompress(cstr[10..-1])

Streaming Decompression with dictionary

cstr = "" # Compressed data
stream = Zstd::StreamingDecompress.new(dict: File.read('dictionary_file'))
result = ''
result << stream.decompress(cstr[0, 10])
result << stream.decompress(cstr[10..-1])

DDict can also be specified to dict:.

Streaming Decompression with Position Tracking

If you need to know how much of the input data was consumed during decompression, you can use the decompress_with_pos method:

cstr = "" # Compressed data
stream = Zstd::StreamingDecompress.new
result, consumed_bytes = stream.decompress_with_pos(cstr[0, 10])
# result contains the decompressed data
# consumed_bytes contains the number of bytes from input that were processed

This is particularly useful when processing streaming data where you need to track the exact position in the input stream.

Skippable frame

compressed_data_with_skippable_frame = Zstd.write_skippable_frame(compressed_data, "sample data")

Zstd.read_skippable_frame(compressed_data_with_skippable_frame)
# => "sample data"

Stream Writer and Reader Wrapper

EXPERIMENTAL

• These features are experimental and may be subject to API changes in future releases.
• There may be performance and compatibility issues, so extensive testing is required before production use.
• If you have any questions, encounter bugs, or have suggestions, please report them via GitHub issues.

Zstd::StreamWriter

require 'stringio'
require 'zstd-ruby'

io = StringIO.new
stream = Zstd::StreamWriter.new(io)
stream.write("abc")
stream.finish

io.rewind
# Retrieve the compressed data
compressed_data = io.read

Zstd::StreamReader

require 'stringio'
require 'zstd-ruby' # Add the appropriate require statement if necessary

io = StringIO.new(compressed_data)
reader = Zstd::StreamReader.new(io)

# Read and output the decompressed data
puts reader.read(10)  # 'abc'
puts reader.read(10)  # 'def'
puts reader.read(10)  # '' (end of data)

JRuby

This gem does not support JRuby.

Please consider using https://github.com/luben/zstd-jni.

Sample code is below.

require 'java'
require_relative './zstd-jni-1.5.2-3.jar'

str = "testtest"
compressed = com.github.luben.zstd.Zstd.compress(str.to_java_bytes)
puts com.github.luben.zstd.Zstd.decompress(compressed, str.length)

% ls
test.rb              zstd-jni-1.5.2-3.jar
% ruby -v
jruby 9.3.2.0 (2.6.8) 2021-12-01 0b8223f905 OpenJDK 64-Bit Server VM 11.0.12+0 on 11.0.12+0 +jit [darwin-x86_64]
% ruby test.rb
testtest

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/SpringMT/zstd-ruby. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the BSD-3-Clause License.