1 files changed, 189 insertions, 0 deletions
diff --git a/vendor/tracing/benches/subscriber.rs b/vendor/tracing/benches/subscriber.rs
new file mode 100644
index 000000000..c6418010f
--- /dev/null
+++ b/vendor/tracing/benches/subscriber.rs
@@ -0,0 +1,189 @@
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use tracing::Level;
+
+use std::{
+    fmt,
+    sync::{Mutex, MutexGuard},
+};
+use tracing::{field, span, Event, Id, Metadata};
+
+/// A subscriber that is enabled but otherwise does nothing.
+struct EnabledSubscriber;
+
+impl tracing::Subscriber for EnabledSubscriber {
+    fn new_span(&self, span: &span::Attributes<'_>) -> Id {
+        let _ = span;
+        Id::from_u64(0xDEAD_FACE)
+    }
+
+    fn event(&self, event: &Event<'_>) {
+        let _ = event;
+    }
+
+    fn record(&self, span: &Id, values: &span::Record<'_>) {
+        let _ = (span, values);
+    }
+
+    fn record_follows_from(&self, span: &Id, follows: &Id) {
+        let _ = (span, follows);
+    }
+
+    fn enabled(&self, metadata: &Metadata<'_>) -> bool {
+        let _ = metadata;
+        true
+    }
+
+    fn enter(&self, span: &Id) {
+        let _ = span;
+    }
+
+    fn exit(&self, span: &Id) {
+        let _ = span;
+    }
+}
+
+/// Simulates a subscriber that records span data.
+struct VisitingSubscriber(Mutex<String>);
+
+struct Visitor<'a>(MutexGuard<'a, String>);
+
+impl<'a> field::Visit for Visitor<'a> {
+    fn record_debug(&mut self, _field: &field::Field, value: &dyn fmt::Debug) {
+        use std::fmt::Write;
+        let _ = write!(&mut *self.0, "{:?}", value);
+    }
+}
+
+impl tracing::Subscriber for VisitingSubscriber {
+    fn new_span(&self, span: &span::Attributes<'_>) -> Id {
+        let mut visitor = Visitor(self.0.lock().unwrap());
+        span.record(&mut visitor);
+        Id::from_u64(0xDEAD_FACE)
+    }
+
+    fn record(&self, _span: &Id, values: &span::Record<'_>) {
+        let mut visitor = Visitor(self.0.lock().unwrap());
+        values.record(&mut visitor);
+    }
+
+    fn event(&self, event: &Event<'_>) {
+        let mut visitor = Visitor(self.0.lock().unwrap());
+        event.record(&mut visitor);
+    }
+
+    fn record_follows_from(&self, span: &Id, follows: &Id) {
+        let _ = (span, follows);
+    }
+
+    fn enabled(&self, metadata: &Metadata<'_>) -> bool {
+        let _ = metadata;
+        true
+    }
+
+    fn enter(&self, span: &Id) {
+        let _ = span;
+    }
+
+    fn exit(&self, span: &Id) {
+        let _ = span;
+    }
+}
+
+const N_SPANS: usize = 100;
+
+fn criterion_benchmark(c: &mut Criterion) {
+    c.bench_function("span_no_fields", |b| {
+        tracing::subscriber::with_default(EnabledSubscriber, || {
+            b.iter(|| span!(Level::TRACE, "span"))
+        });
+    });
+
+    c.bench_function("enter_span", |b| {
+        tracing::subscriber::with_default(EnabledSubscriber, || {
+            let span = span!(Level::TRACE, "span");
+            #[allow(clippy::unit_arg)]
+            b.iter(|| black_box(span.in_scope(|| {})))
+        });
+    });
+
+    c.bench_function("span_repeatedly", |b| {
+        #[inline]
+        fn mk_span(i: u64) -> tracing::Span {
+            span!(Level::TRACE, "span", i = i)
+        }
+
+        let n = black_box(N_SPANS);
+        tracing::subscriber::with_default(EnabledSubscriber, || {
+            b.iter(|| (0..n).fold(mk_span(0), |_, i| mk_span(i as u64)))
+        });
+    });
+
+    c.bench_function("span_with_fields", |b| {
+        tracing::subscriber::with_default(EnabledSubscriber, || {
+            b.iter(|| {
+                span!(
+                    Level::TRACE,
+                    "span",
+                    foo = "foo",
+                    bar = "bar",
+                    baz = 3,
+                    quuux = tracing::field::debug(0.99)
+                )
+            })
+        });
+    });
+
+    c.bench_function("span_with_fields_record", |b| {
+        let subscriber = VisitingSubscriber(Mutex::new(String::from("")));
+        tracing::subscriber::with_default(subscriber, || {
+            b.iter(|| {
+                span!(
+                    Level::TRACE,
+                    "span",
+                    foo = "foo",
+                    bar = "bar",
+                    baz = 3,
+                    quuux = tracing::field::debug(0.99)
+                )
+            })
+        });
+    });
+}
+
+fn bench_dispatch(c: &mut Criterion) {
+    let mut group = c.benchmark_group("dispatch");
+    group.bench_function("no_dispatch_get_ref", |b| {
+        b.iter(|| {
+            tracing::dispatcher::get_default(|current| {
+                black_box(&current);
+            })
+        })
+    });
+    group.bench_function("no_dispatch_get_clone", |b| {
+        b.iter(|| {
+            let current = tracing::dispatcher::get_default(|current| current.clone());
+            black_box(current);
+        })
+    });
+    group.bench_function("get_ref", |b| {
+        tracing::subscriber::with_default(EnabledSubscriber, || {
+            b.iter(|| {
+                tracing::dispatcher::get_default(|current| {
+                    black_box(&current);
+                })
+            })
+        })
+    });
+    group.bench_function("get_clone", |b| {
+        tracing::subscriber::with_default(EnabledSubscriber, || {
+            b.iter(|| {
+                let current = tracing::dispatcher::get_default(|current| current.clone());
+                black_box(current);
+            })
+        })
+    });
+    group.finish();
+}
+
+criterion_group!(benches, criterion_benchmark, bench_dispatch);
+criterion_main!(benches);