Add gauge class

[bernd]

This adds gauges to record arbitrary values.

Please let me know what you think. Thanks!

[eric]

The way Coda Hale's metrics library works is it has you register a callback to be used when a gauge is reported.

I think I would prefer that style. Does that make sense?

[bernd]

Yes I saw that in Coda's library and my first version of this diff actually used a callback to collect the gauge. Then I thought about all the things that can go wrong when using the callback based approach (blocking calls, thread-safety issues - the callback is executed in the reporter thread etc.) and decided to do a "safe" version first. ;)

I liked the callback approach as well so I'll go ahead and update the diff with the code I dropped.

[eric]

Maybe it makes sense to support both...

On Thu, Feb 28, 2013 at 3:51 PM, Bernd Ahlers notifications@github.com wrote:

Yes I saw that in Coda's library and my first version of this diff actually used a callback to collect the gauge. Then I thought about all the things that can go wrong when using the callback based approach (blocking calls, thread-safety issues - the callback is executed in the reporter thread etc.) and decided to do a "safe" version first. ;)

I liked the callback approach as well so I'll go ahead and update the diff with the code I dropped.

Reply to this email directly or view it on GitHub: https://github.com/eric/metriks/pull/33#issuecomment-14265379

[bernd]

I added a callback method in a235d2e.

[bernd]

I thought some more about the API and I don't really like my first attempt with the #callback method. The following I like better.

# With block
gauge = Metriks.gauge('queue_size') { queue.size }

# With callable object
callable = proc { queue.size }
gauge = Metriks.gauge('queue_size', callable)

Any opinions?

[eric]

I think that's a lot better. It matches how it works in coda hale's metrics and generally just looks nice and easy to use.

[bernd]

I changed the interface in 6f1802a.

[eric]

I just had some minor comments, but I like this interface much better.

[bernd]

I changed the default value from 0 to nil.

[eric]

Looks great! Thanks for working though this.

[bernd]

Thank you!