From cd0ae687835cd9acef7ebeb7413e98f098d76ccd Mon Sep 17 00:00:00 2001
From: Harold Dost <github@hdost.com>
Date: Fri, 17 Jun 2022 09:11:57 +0200
Subject: [PATCH] WIP - Benchmarks

---
 opentelemetry-sdk/Cargo.toml       |  5 ++--
 opentelemetry-sdk/benches/trace.rs | 46 ++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/opentelemetry-sdk/Cargo.toml b/opentelemetry-sdk/Cargo.toml
index 7d810cbdfc..a783e88812 100644
--- a/opentelemetry-sdk/Cargo.toml
+++ b/opentelemetry-sdk/Cargo.toml
@@ -17,7 +17,7 @@ once_cell = "1.10"
 opentelemetry-api = { version = "0.1", path = "../opentelemetry-api/" }
 percent-encoding = { version = "2.0", optional = true }
 pin-project = { version = "1.0.2", optional = true }
-rand = { version = "0.8", default-features = false, features = ["std", "std_rng"], optional = true }
+rand = { version = "0.8", default-features = false, features = ["std", "std_rng","small_rng"], optional = true }
 serde = { version = "1.0", features = ["derive", "rc"], optional = true }
 thiserror = "1"
 tokio = { version = "1.0", default-features = false, features = ["rt", "time"], optional = true }
@@ -29,7 +29,7 @@ rustdoc-args = ["--cfg", "docsrs"]
 
 [dev-dependencies]
 bincode = "1.2"
-criterion = "0.3.1"
+criterion = { version = "0.3.1", features = ["html_reports"] }
 rand_distr = "0.4.0"
 
 [features]
@@ -44,6 +44,7 @@ rt-async-std = ["async-std"]
 [[bench]]
 name = "trace"
 harness = false
+required-features = ["testing"]
 
 [[bench]]
 name = "batch_span_processor"
diff --git a/opentelemetry-sdk/benches/trace.rs b/opentelemetry-sdk/benches/trace.rs
index 4d75e7493c..f50d25755e 100644
--- a/opentelemetry-sdk/benches/trace.rs
+++ b/opentelemetry-sdk/benches/trace.rs
@@ -1,11 +1,15 @@
 use criterion::{criterion_group, criterion_main, Criterion};
 use futures_util::future::BoxFuture;
+use opentelemetry_api::trace::{SpanId, TraceId};
+use rand::{SeedableRng, Rng,rngs::SmallRng};
+use std::cell::RefCell;
 use opentelemetry_api::{
     trace::{Span, Tracer, TracerProvider},
     Key, KeyValue,
 };
 use opentelemetry_sdk::{
     export::trace::{ExportResult, SpanData, SpanExporter},
+    trace::IdGenerator,
     trace as sdktrace,
 };
 
@@ -107,6 +111,30 @@ impl SpanExporter for VoidExporter {
     }
 }
 
+
+/// Test [`IdGenerator`] implementation.
+///
+/// Generates Trace and Span ids using a random number generator using SmallRng
+#[derive(Clone, Debug, Default)]
+pub struct SmallRandomIdGenerator {
+    _private: (),
+}
+
+impl IdGenerator for SmallRandomIdGenerator {
+    fn new_trace_id(&self) -> TraceId {
+        CURRENT_RNG.with(|rng| TraceId::from(rng.borrow_mut().gen::<[u8; 16]>()))
+    }
+
+    fn new_span_id(&self) -> SpanId {
+        CURRENT_RNG.with(|rng| SpanId::from(rng.borrow_mut().gen::<[u8; 8]>()))
+    }
+}
+
+thread_local! {
+    /// Store random number generator for each thread
+    static CURRENT_RNG: RefCell<SmallRng> = RefCell::new(SmallRng::from_entropy());
+}
+
 fn trace_benchmark_group<F: Fn(&sdktrace::Tracer)>(c: &mut Criterion, name: &str, f: F) {
     let mut group = c.benchmark_group(name);
 
@@ -129,6 +157,24 @@ fn trace_benchmark_group<F: Fn(&sdktrace::Tracer)>(c: &mut Criterion, name: &str
         b.iter(|| f(&never_sample));
     });
 
+    group.bench_function("always-sample-smallrng", |b| {
+        let provider = sdktrace::TracerProvider::builder()
+            .with_config(sdktrace::config().with_sampler(sdktrace::Sampler::AlwaysOn).with_id_generator(SmallRandomIdGenerator::default()))
+            .with_simple_exporter(VoidExporter)
+            .build();
+        let always_sample = provider.tracer("always-sample-smallrng");
+
+        b.iter(|| f(&always_sample));
+    });
+
+    group.bench_function("never-sample-smallrng", |b| {
+        let provider = sdktrace::TracerProvider::builder()
+            .with_config(sdktrace::config().with_sampler(sdktrace::Sampler::AlwaysOff).with_id_generator(SmallRandomIdGenerator::default()))
+            .with_simple_exporter(VoidExporter)
+            .build();
+        let never_sample = provider.tracer("never-sample-smallrng");
+        b.iter(|| f(&never_sample));
+    });
     group.finish();
 }