zstd-ruby
Ruby binding for zstd(Zstandard - Fast real-time compression algorithm)
See https://github.com/facebook/zstd
Zstd version
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:
ruby
gem 'zstd-ruby'
And then execute:
$ bundle
Or install it yourself as:
$ gem install zstd-ruby
Usage
ruby
require 'zstd-ruby'
Compression
Simple Compression
ruby
compressed_data = Zstd.compress(data)
compressed_data = Zstd.compress(data, level: complession_level) # default compression_level is 3
Compression with Dictionary
ruby
# 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:
ruby
cdict = Zstd::CDict.new(File.read('dictionary_file'))
compressed_using_dict = Zstd.compress("", dict: cdict)
The compression_level can be specified on creating CDict.
ruby
cdict = Zstd::CDict.new(File.read('dictionary_file'), 5)
compressed_using_dict = Zstd.compress("", dict: cdict)
Streaming Compression
ruby
stream = Zstd::StreamingCompress.new
stream << "abc" << "def"
res = stream.flush
stream << "ghi"
res << stream.finish
or
ruby
stream = Zstd::StreamingCompress.new
res = stream.compress("abc")
res << stream.flush
res << stream.compress("def")
res << stream.finish
Streaming Compression with Dictionary
ruby
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
ruby
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
ruby
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
ruby
data = Zstd.decompress(compressed_data)
Decompression with Dictionary
ruby
# 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:
ruby
ddict = Zstd::Ddict.new(File.read('dictionary_file'))
data = Zstd.compress(compressed_using_dict, ddict)
Streaming Decompression
ruby
cstr = "" # Compressed data
stream = Zstd::StreamingDecompress.new
result = ''
result << stream.decompress(cstr[0, 10])
result << stream.decompress(cstr[10..-1])
Streaming Decompression with dictionary
ruby
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:
ruby
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
```ruby 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
```ruby 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
```ruby 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.