zstd

Crystal bindings to the Zstandard (zstd) compression library

Features

• [x] Performance optimized. 20M small decompression messages/sec.
• [x] All API calls allow reusable buffers to reduce GC overhead.
• [x] No heap allocations after #initialize.
• [x] Crystal IO compatible Streaming API.
• [x] Snappy like buffer API for handling small messages.
• [x] export ZSTD_CLEVEL=1 sets the default compression level just like the zstd command line utilities.
• [x] Only require what you need for faster compilation. (require "zstd/compress/context")

Experimental Features. API's subject to change.

• [x] Custom dictionaries.

Todo

• [ ] Auto install the most recent zstd if the system library is old or unavailable.
• [ ] Support more zstd params.
• [ ] More specs.

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     zstd:
       github: didactic-drunk/zstd.cr

2. Run shards install

Usage

require "zstd"

Buffer API

cctx = Zstd::Compress::Context.new(level: 1)
cbuf = cctx.compress buf

dctx = Zstd::Decompress::Context.new
dbuf = dctx.decompress cbuf

Streaming API

buf = Bytes.new 5
mio = IO::Memory.new
Zstd::Compress::IO.open(mio, level: 1) do |cio|
  cio.write buf
end

mio.rewind
str = Zstd::Decompress::IO.open(mio) do |dio|
  dio.gets_to_end
end

Dictionary API

dict_buffer = File.read("dictionary").to_slice
dict = Zstd::Dict.new dict_buffer, level: 3

cctx = Zstd::Compress::Context.new dict: dict
dctx = Zstd::Decompress::Context.new dict: dict

# Compress or decompress using the Buffer or Streaming API's

p dict.dict_id
p dict.memsize

Contributing

1. Fork it (https://github.com/your-github-user/zstd/fork)
2. Install a formatting check git hook (ln -sf ../../scripts/git/pre-commit .git/hooks)
3. Create your feature branch (git checkout -b my-new-feature)
4. Commit your changes (git commit -am 'Add some feature')
5. Push to the branch (git push origin my-new-feature)
6. Create a new Pull Request

Contributors

• Didactic Drunk - creator and maintainer