1 files changed, 136 insertions, 0 deletions
diff --git a/vendor/tracing/benches/global_subscriber.rs b/vendor/tracing/benches/global_subscriber.rs
new file mode 100644
index 000000000..83519610a
--- /dev/null
+++ b/vendor/tracing/benches/global_subscriber.rs
@@ -0,0 +1,136 @@
+use std::fmt::Write;
+
+use criterion::{black_box, criterion_group, criterion_main, Criterion};
+use tracing::Level;
+
+use tracing::{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;
+    }
+}
+
+const NOP_LOGGER: NopLogger = NopLogger;
+
+struct NopLogger;
+
+impl log::Log for NopLogger {
+    fn enabled(&self, _metadata: &log::Metadata) -> bool {
+        true
+    }
+
+    fn log(&self, record: &log::Record) {
+        if self.enabled(record.metadata()) {
+            let mut this = self;
+            let _ = write!(this, "{}", record.args());
+        }
+    }
+
+    fn flush(&self) {}
+}
+
+impl Write for &NopLogger {
+    fn write_str(&mut self, s: &str) -> std::fmt::Result {
+        black_box(s);
+        Ok(())
+    }
+}
+
+const N_SPANS: usize = 100;
+
+fn criterion_benchmark(c: &mut Criterion) {
+    let mut c = c.benchmark_group("global/subscriber");
+    let _ = tracing::subscriber::set_global_default(EnabledSubscriber);
+    let _ = log::set_logger(&NOP_LOGGER);
+    log::set_max_level(log::LevelFilter::Trace);
+    c.bench_function("span_no_fields", |b| b.iter(|| span!(Level::TRACE, "span")));
+
+    c.bench_function("event", |b| {
+        b.iter(|| {
+            tracing::event!(Level::TRACE, "hello");
+        })
+    });
+
+    c.bench_function("enter_span", |b| {
+        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);
+        b.iter(|| (0..n).fold(mk_span(0), |_, i| mk_span(i as u64)))
+    });
+
+    c.bench_function("span_with_fields", |b| {
+        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("global/dispatch");
+    let _ = tracing::subscriber::set_global_default(EnabledSubscriber);
+    let _ = log::set_logger(&NOP_LOGGER);
+    log::set_max_level(log::LevelFilter::Trace);
+    group.bench_function("get_ref", |b| {
+        b.iter(|| {
+            tracing::dispatcher::get_default(|current| {
+                black_box(&current);
+            })
+        })
+    });
+    group.bench_function("get_clone", |b| {
+        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);