Use Process class to spawn rackup

[viking]

Ruby 1.9 and later comes with better support for spawning child processes (like rackup). I've switched Guard::RackRunner to use the Process class instead of direct system calls. This allows guard-rack to not have to bother with PID files.

This is not backward compatible with Ruby 1.8. If this is a deal breaker, I can work on adding back the PID file support.

[dblock]

I don't think we want to drop 1.8 compat. I have used posix-spawn in the past with great success, it has a nice process API, shouldn't be too much of a stretch?

Is UI.debug something coming from Rack?

[dblock]

You're saying this is not backward compatible with Ruby 1.8, but https://travis-ci.org/dblock/guard-rack/jobs/4155002 disagrees :) This probably means that specs don't actually test the functionality and we're stubbing too much.

[viking]

UI.debug prints things out when you use the -d flag with guard start. The spec passes in 1.8 because I'm using expectations on the Process class. Ruby 1.8 has a Process class, but not a Process.spawn function.

[dblock]

Alright, please try with posix-spawn. If it's too much work I'll sleep on whether I think Ruby 1.8 support should be cut (I think not right now).

[viking]

Tried just dropping in posix-spawn, but it doesn't behave the same way. Process.wait times out after trying to kill the process. I'll see if I can figure out what's happening.

[viking]

OK, got it worked out. If the command string has a space, it executes the command with sh -c, which returns the wrong PID value. Changed build_rack_command to return an array of arguments instead of a joined string.

[dblock]

Last thing, please update https://github.com/dblock/guard-rack/blob/master/CHANGELOG.md - add a "Next Release". Thanks.

[dblock]

I have merged the changes, and noticed that JRuby implementation broke. After some research I found spoon which uses libffi and works on everything. I also wrote an integration spec so that we can see whether a process is actually spawned (testing is awesome, but working is better).

Can you please check the gem and my last two commits after me (just need another pair of eyes) in case I missed anything, before I cut a release?

f769dd8
201d879

[viking]

Looks good to me :)