What is shlock ?
===============
shlock is a library that provides synchronization primitives that use shared memory.

Currently, mutexes (Shlock::Putex) and rwlocks (Shlock::Prwlock) are implemented.

Why ?
=====
If want to synchronize two ruby processes without using those painful file locks, you can use this.

TODO
====
- It is probably not safe to use these pthread exposed APIs in this way. I should probably reimplement
  the low-level locking primitives in C using atomic.h and futexes.

- Add documentation about Shlock::Prwlock

Sample Usage of Shlock::Putex
=============================

process1.rb:
require 'shlock'
f = Shlock::Putex.new("/test-mutex")
f.lock
puts("locked the mutex once, grabbing lock again to spin-wait; go run process2.rb once locked up...\n")
f.lock
puts("got the lock, exiting\n")


process2.rb:
require 'shlock'
f = Shlock::Putex.new("/text-mutex")
puts "alive, unlocking"
f.unlock
puts "done, exiting"
f.destroy


in your terminal:
% ruby process1.rb

when it tells you to run process2.rb, in another terminal enter:
% ruby process2.rb

you should see process2 unlock process1 and allow it to exit.

What's next ?
=============

Maybe some more process-to-process synchronization primitives?