Macro efflux::update_counter

macro_rules! update_counter {
    ($group:expr, $label:expr, $amount:expr) => { ... };
}

Updates a counter for the current job.

A counter belongs to a group by a label; as such both must be given to this macro in order to compile correctly. Note that neither the group nor label can contain a ",", as Hadoop uses this to split the IO stream.

This is simply a sane wrapper around log! to ensure that counter updates are always logged in the correct formatting.