File: README — Documentation for ffi-rzmq (2.0.7)

ffi-rzmq

by Chuck Remes
http://www.zeromq.org/bindings:ruby-ffi

FUTURE SUPPORT

Most people writing Zeromq applications in Ruby should be using the rbczmq project. It wraps the CZMQ binding which is a much higher-level library for writing Zeromq code. Find the Ruby gem here:

http://github.com/methodmissing/rbczmq

Few projects need to write the low-level zeromq code that this gem allows. With the release of ffi-rzmq 2.0.3, this library is going into permanent maintenance mode. As new versions of libzmq are released, interested parties should send pull requests to this project or its related project ffi-rzmq-core to support new features.

The original README text follows…

DESCRIPTION:

This gem wraps the ZeroMQ networking library using the ruby FFI (foreign function interface). It’s a pure ruby wrapper so this gem can be loaded and run by any ruby runtime that supports FFI. That’s all of them: MRI 1.9.x, Rubinius and JRuby.

The Ruby API provided by this gem is NOT very Ruby-like. It very closely tracks the libzmq C API. However, the contributors to this project have done all of the hard work to wrap up all of libzmq and make it accessible from Ruby. If you want it to be more Ruby-like (e.g. raise Exceptions instead of returning integer codes) then *wrap this library* with your own and release it as a gem. We will all be grateful!

This single gem supports 0mq 3.2.x and 4.x APIs. The 0mq project started making backward-incompatible changes to the API with the 3.1.x release. The gem auto-configures itself to expose the API conforming to the loaded C library. 0mq 2.x is no longer supported. 0mq API 3.0 is not supported; the 0mq community voted to abandon it.

The impetus behind this library was to provide support for ZeroMQ in JRuby which has native threads. Unlike MRI, which has a GIL, JRuby and Rubinius allow for threaded access to Ruby code from outside extensions. ZeroMQ is heavily threaded, so until the MRI runtime removes its GIL, JRuby and Rubinius will likely be the best environments to run this library.

Please read the History.txt file for a description of all changes, including API changes, since the last release!

PERFORMANCE:

Check out the latest performance results:

http://www.zeromq.org/bindings:ruby-ffi

The short version is that the FFI bindings are a few microseconds slower than using a C extension.

FEATURES/PROBLEMS:

This gem needs more tests. This gem has been battle tested by myself and others for years, so I am fairly confident that it is solid. However, it is inevitable that there will be bugs, so please open issues for them here or fork this project, fix them, and send me a pull request.

The ‘ffi’ gem has dropped support for MRI 1.8.x. Since this project relies on that gem to load and run this code, then this project also no longer supports MRI 1.8.x. I recommend JRuby for the best performance and stability.

The ‘Socket` and `Context` classes have finalizers which will be called by the garbage collector when there are no more references. However, these finalizers should not be relied upon to orderly close your sockets and then the context. Finalizers run in a non-determinant order, so the `Context` finalizer may run first which will hang the program. To avoid this, make sure to close all sockets before the program exits.

All features are implemented.

BUILD STATUS:

SYNOPSIS:

0mq API v3.2-4 client code:

require 'rubygems'
require 'ffi-rzmq'

if ARGV.length < 3
  puts "usage: ruby local_lat.rb <connect-to> <message-size> <roundtrip-count>"
  exit
end

bind_to = ARGV[0]
message_size = ARGV[1].to_i
roundtrip_count = ARGV[2].to_i

ctx = ZMQ::Context.new
s   = ctx.socket ZMQ::REP
rc  = s.setsockopt(ZMQ::SNDHWM, 100)
rc  = s.setsockopt(ZMQ::RCVHWM, 100)
rc  = s.bind(bind_to)

roundtrip_count.times do
  msg = ""
  rc  = s.recv_string msg
  raise "Message size doesn't match, expected [#{message_size}] but received [#{msg.size}]" if message_size != msg.size
  rc  = s.send_string msg, 0
end

0mq API v3.2-4 server code:

require 'rubygems'
require 'ffi-rzmq'

if ARGV.length < 3
  puts "usage: ruby remote_lat.rb <connect-to> <message-size> <roundtrip-count>"
  exit
end

def assert(rc)
  raise "Last API call failed at #{caller(1)}" unless rc >= 0
end

connect_to = ARGV[0]
message_size = ARGV[1].to_i
roundtrip_count = ARGV[2].to_i

ctx = ZMQ::Context.new
s   = ctx.socket ZMQ::REQ
rc  = s.connect(connect_to)

msg = "#{ '3' * message_size }"

time_start = Time.now

roundtrip_count.times do
  assert(s.send_string(msg, 0))

  msg = ''
  assert(s.recv_string(msg, 0))

  raise "Message size doesn't match, expected [#{message_size}] but received [#{msg.size}]" if message_size != msg.size
end

time_end = Time.now
puts "Time #{( time_end - time_start )}"

Better Examples

I highly recommend visiting the Learn Ruby 0mq project for a bunch of good code examples.

http://github.com/andrewvc/learn-ruby-zeromq

REQUIREMENTS:

* 0mq 3.2.x, 4.x or later; 2.x, 3.0.x and 3.1.x are no longer supported

The ZeroMQ library must be installed on your system in a well-known location like /usr/local/lib. This is the default for new ZeroMQ installs.

If you have installed ZeroMQ using brew, you need to ‘brew link zeromq` before installing this gem.

* ffi (>= 1.0.0)

* ffi-rzmq-core

This is a requirement for MRI and Rubinius. JRuby has FFI support built in as a standard component. Do not run this gem under MRI with an old ‘ffi’ gem. It will crash randomly and you will be sad.

INSTALL:

Make sure the ZeroMQ library is already installed on your system. We recommend ‘brew’ or ‘macports’ to get it.

% gem install ffi-rzmq # should grab the latest release

To build from git master:

% git clone git://github.com/chuckremes/ffi-rzmq
% cd ffi-rzmq
% gem build ffi-rzmq.gemspec
% gem install ffi-rzmq-*.gem

NOTE for Windows users! In order for this gem to find the libzmq.dll, it must be on the Windows PATH. Google for “modify windows path” for instructions on how to do that if you are unfamiliar with that activity. That DLL also requires that you copy libstdc++-6.dll and libgcc_s_sjlj-1.dll from DevKit MinGW into the same folder that you copied libzmq.dll.

LICENSE:

(The MIT License)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the ‘Software’), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ‘AS IS’, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.