Add bench for gauge instrument

opentelemetry-sdk/Cargo.toml

@@ -65,7 +65,10 @@ harness = false
 [[bench]]
 name = "metric_counter"
 harness = false
-required-features = ["metrics"]
+
+[[bench]]
+name = "metric_gauge"
+harness = false
 
 [[bench]]
 name = "attribute_set"

opentelemetry-sdk/benches/metric_gauge.rs

@@ -0,0 +1,82 @@
+/*
+    The benchmark results:
+    criterion = "0.5.1"
+    OS: Ubuntu 22.04.3 LTS (5.15.146.1-microsoft-standard-WSL2)
+    Hardware: AMD EPYC 7763 64-Core Processor - 2.44 GHz, 16vCPUs,
+    RAM: 64.0 GB
+    | Test                           | Average time|
+    |--------------------------------|-------------|
+    | Gauge_Add_4                    | 586 ns      |
+*/
+
+use criterion::{criterion_group, criterion_main, Criterion};
+use opentelemetry::{
+    metrics::{Gauge, MeterProvider as _},
+    KeyValue,
+};
+use opentelemetry_sdk::metrics::{ManualReader, SdkMeterProvider};
+use rand::{
+    rngs::{self},
+    Rng, SeedableRng,
+};
+use std::cell::RefCell;
+
+thread_local! {
+    /// Store random number generator for each thread
+    static CURRENT_RNG: RefCell<rngs::SmallRng> = RefCell::new(rngs::SmallRng::from_entropy());
+}
+
+// Run this benchmark with:
+// cargo bench --bench metric_gauge
+fn create_gauge() -> Gauge<u64> {
+    let meter_provider: SdkMeterProvider = SdkMeterProvider::builder()
+        .with_reader(ManualReader::builder().build())
+        .build();
+    let meter = meter_provider.meter("benchmarks");
+
+    meter.u64_gauge("gauge_bench").init()
+}
+
+fn criterion_benchmark(c: &mut Criterion) {
+    gauge_record(c);
+}
+
+fn gauge_record(c: &mut Criterion) {
+    let attribute_values = [
+        "value1", "value2", "value3", "value4", "value5", "value6", "value7", "value8", "value9",
+        "value10",
+    ];
+
+    let gauge = create_gauge();
+    c.bench_function("Gauge_Add_4", |b| {
+        b.iter(|| {
+            // 4*4*10*10 = 1600 time series.
+            let rands = CURRENT_RNG.with(|rng| {
+                let mut rng = rng.borrow_mut();
+                [
+                    rng.gen_range(0..4),
+                    rng.gen_range(0..4),
+                    rng.gen_range(0..10),
+                    rng.gen_range(0..10),
+                ]
+            });
+            let index_first_attribute = rands[0];
+            let index_second_attribute = rands[1];
+            let index_third_attribute = rands[2];
+            let index_forth_attribute = rands[3];
+            gauge.record(
+                1,
+                &[
+                    KeyValue::new("attribute1", attribute_values[index_first_attribute]),
+                    KeyValue::new("attribute2", attribute_values[index_second_attribute]),
+                    KeyValue::new("attribute3", attribute_values[index_third_attribute]),
+                    KeyValue::new("attribute4", attribute_values[index_forth_attribute]),
+                ],
+            );
+        });
+    });
+}
+
+criterion_group!(benches, criterion_benchmark);
+
+criterion_main!(benches);