Proposed API for JEP 259: Stack-Walking API (original) (raw)

Peter Levart peter.levart at gmail.com
Sat Oct 31 19:23:14 UTC 2015

On 10/31/2015 07:29 PM, Remi Forax wrote:

also instead of Optional.orElse, orElseGet is better because it avoids to evaluate Thread.currentThread().getClass() if not necessary.

So the example should be: walk(s -> s.map(StackFrame::getDeclaringClass) .findFirst()).orElseGet(() -> Thread.currentThread().getClass());

It might be hard to believe, but the evaluation of constant lambda expression is approx. equally expensive as the expression it encapsulates in this example, so it really is an overkill here:

Benchmark Mode Cnt Score Error Units LambdaVsCurrentThreadBench.getCurrentThreadClass avgt 10 2.202 ± 0.058 ns/op LambdaVsCurrentThreadBench.getCurrentThreadClassSupplier avgt 10 2.196 ± 0.159 ns/op

@BenchmarkMode(Mode.AverageTime) @Fork(1) @Warmup(iterations = 5) @Measurement(iterations = 10) @OutputTimeUnit(TimeUnit.NANOSECONDS) public class LambdaVsCurrentThreadBench { @Benchmark public Class<?> getCurrentThreadClass() { return Thread.currentThread().getClass(); }

 @Benchmark
 public Supplier<Class<?>> getCurrentThreadClassSupplier() {
     return () -> Thread.currentThread().getClass();
 }

}

Regards, Peter

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