New I/O for Ruby (nio4r): cross-platform asynchronous I/O primitives for scalable network clients and servers. Modeled after the Java NIO API, but simplified for ease-of-use.
nio4r provides an abstract, cross-platform stateful I/O selector API for Ruby. I/O selectors are the heart of "reactor"-based event loops, and monitor multiple I/O objects for various types of readiness, e.g. ready for reading or writing.
Projects using nio4r
- ActionCable: Rails 5 WebSocket protocol, uses nio4r for a WebSocket server
- Celluloid: Actor-based concurrency framework, uses nio4r for async I/O
- Async: Asynchronous I/O framework for Ruby
- Puma: Ruby/Rack web server built for concurrency
Goals
- Expose high-level interfaces for stateful IO selectors
- Keep the API small to maximize both portability and performance across many different OSes and Ruby VMs
- Provide inherently thread-safe facilities for working with IO objects
Supported platforms
- Ruby 2.4
- Ruby 2.5
- Ruby 2.6
- Ruby 2.7
- Ruby 3.0
- JRuby
- TruffleRuby
Supported backends
- libev: MRI C extension targeting multiple native IO selector APIs (e.g epoll, kqueue)
- Java NIO: JRuby extension which wraps the Java NIO subsystem
- Pure Ruby:
Kernel.select
-based backend that should work on any Ruby interpreter
Documentation
Please see the nio4r wiki for more detailed documentation and usage notes:
- Getting Started: Introduction to nio4r's components
- Selectors: monitor multiple
IO
objects for readiness events - Monitors: control interests and inspect readiness for specific
IO
objects - Byte Buffers: fixed-size native buffers for high-performance I/O
See also:
Non-goals
nio4r is not a full-featured event framework like EventMachine or Cool.io. Instead, nio4r is the sort of thing you might write a library like that on top of. nio4r provides a minimal API such that individual Ruby implementers may choose to produce optimized versions for their platform, without having to maintain a large codebase.
Releases
CRuby
rake clean
rake release
JRuby
You might need to delete Gemfile.lock
before trying to bundle install
.
rake clean
rake compile
rake release