Stabilize existing Context benchmark by adding black_box

Author: bantonsson

opentelemetry-sdk/benches/context.rs

@@ -1,4 +1,4 @@
-use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion, Throughput};
+use criterion::{black_box, criterion_group, criterion_main, BenchmarkId, Criterion, Throughput};
 use futures_util::future::BoxFuture;
 use opentelemetry::{
     global::BoxedTracer,
@@ -31,22 +31,30 @@ fn criterion_benchmark(c: &mut Criterion) {
             group.bench_function(
                 BenchmarkId::new("has_active_span", param.clone()),
                 |b| match api {
-                    Api::Alt => b.iter(|| Context::map_current(TraceContextExt::has_active_span)),
-                    Api::Spec => b.iter(|| Context::current().has_active_span()),
+                    Api::Alt => {
+                        b.iter(|| black_box(Context::map_current(TraceContextExt::has_active_span)))
+                    }
+                    Api::Spec => b.iter(|| black_box(Context::current().has_active_span())),
                 },
             );
             group.bench_function(
                 BenchmarkId::new("is_sampled", param.clone()),
                 |b| match api {
-                    Api::Alt => {
-                        b.iter(|| Context::map_current(|cx| cx.span().span_context().is_sampled()))
+                    Api::Alt => b.iter(|| {
+                        black_box(Context::map_current(|cx| {
+                            cx.span().span_context().is_sampled()
+                        }))
+                    }),
+                    Api::Spec => {
+                        b.iter(|| black_box(Context::current().span().span_context().is_sampled()))
                     }
-                    Api::Spec => b.iter(|| Context::current().span().span_context().is_sampled()),
                 },
             );
             group.bench_function(BenchmarkId::new("is_recording", param), |b| match api {
-                Api::Alt => b.iter(|| Context::map_current(|cx| cx.span().is_recording())),
-                Api::Spec => b.iter(|| Context::current().span().is_recording()),
+                Api::Alt => {
+                    b.iter(|| black_box(Context::map_current(|cx| cx.span().is_recording())))
+                }
+                Api::Spec => b.iter(|| black_box(Context::current().span().is_recording())),
             });
         }
     }