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# sysvmq [![Build Status](https://travis-ci.org/Sirupsen/sysvmq.png?branch=v0.1.0)](https://travis-ci.org/Sirupsen/sysvmq)

`sysvmq` is a C extension that wraps System V IPC Message Queues. It's similar
to the [POSIX MQ Ruby wrapper](https://github.com/Sirupsen/posix-mqueue).
Message queues are handy for interprocess communication where you want to be
able to take down either endpoint easily. For example, a pipe or socket requires
you to implement handover logic in both applications. The main disadvantage of
SysV message queues over POSIX MQs (on Linux) is that SysV doesn't expose a file
descriptor to do e.g. `select(2)` on. The advantage of SysV is that it's
implemented on OS X, which POSIX MQs are not.

Note that `sysvmq` doesn't rely on any third-party message broker. The message
queue is handled by the kernel. It's extremely stable and performant.

## Installation

Add `sysvm` to your Gemfile.

`gem 'sysvmq'`

Currently known to work on Linux and OS X for MRI >= 2.0.

## Usage

```ruby
# Create a message queue with a 1024 byte buffer.
require 'sysvmq'
mq = SysVMQ.new(0xDEADC0DE, 1024, SysVMQ::IPC_CREAT | 0666)

mq.send "Hellø Wårld!"
assert_equal 1, mq.stats[:count]

assert_equal "Hellø Wårld!", mq.receive.force_encoding("UTF-8")

# Raise an exception instead of blocking until a message is available
mq.receive(0, SysVMQ::IPC_NOWAIT)

ensure
# Delete queue
mq.destroy
```

## Todo

* Explain messages types
* Add named params for flags (e.g. `mq.receive(:front, blocking: false)`)
  instead of ORing flags directly.
* Add `IPC_INFO` on Linux
* Add all of `IPC_STAT`

Version data entries

1 entries across 1 versions & 1 rubygems

Version	Path
sysvmq-0.2.0	README.md