NOTE: This is the 2.x stable branch of nio4r. For the 1.x legacy branch (used by Rails 5), please see:
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::IO: Actor-based concurrency framework, uses nio4r for async I/O
- 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
- Ruby 2.2.2+
- Ruby 2.3
- Ruby 2.4
- JRuby 9000
- 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
We're also on IRC at ##socketry on irc.freenode.net.
Please see the nio4r wiki for more detailed documentation and usage notes:
- Getting Started: Introduction to nio4r's components
- Selectors: monitor multiple
IOobjects for readiness events
- Monitors: control interests and inspect readiness for specific
- Byte Buffers: fixed-size native buffers for high-performance I/O
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.
Copyright (c) 2011-2017 Tony Arcieri. Distributed under the MIT License. See LICENSE.txt for further details.
Includes libev 4.23. Copyright (c) 2007-2016 Marc Alexander Lehmann. Distributed under the BSD license. See ext/libev/LICENSE for details.