FP in Java - Finding Total CPUs Number in the Grid

I just wrote a pretty interesting piece of code that actually demonstrates nicely the power of the Functional Java APIs introduced in GridGain 3.0. I needed to calculate the total number of CPUs in the topology (grid or cloud).

Here’s the full source code of this method as I wrote it just now:

private int getTotalCpus() {
    return F.fold(ctx.grid().neighborhood(), 0, new C2<GridProjection, Integer, Integer>() {
        @Override public Integer apply(GridProjection p, Integer cnt) {
            return cnt + F.first(p.nodes()).metrics().getAvailableProcessors();
        }
    });
}

In a few lines of Java code we use:

• F which is typedef for GridFunc – GridGain’s “global scope” for Functional APIs
• F.fold which is classic functional fold-left operation on the collection
• C2 which is a typedef for GridClosure2
• GridProjection class that gives you monad over arbitrary set of grid nodes
• Method neighborhood() that gives you collection of GridProject where each projection has nodes from the same physical computer (coming up in 3.0.5)
• Method F.first() from our functional framework that gives you simply the first element in the collection
• Node metrics() that gives you over 40 dynamically updated metrics for any GridGain node in the topology

Enjoy!