test(profiling): add profiles dictionary benchmarks

libdd-profiling/benches/main.rs

@@ -5,5 +5,10 @@ use criterion::criterion_main;
 
 mod add_samples;
 mod interning_strings;
+mod profiles_dictionary;
 
-criterion_main!(interning_strings::benches, add_samples::benches);
+criterion_main!(
+    interning_strings::benches,
+    add_samples::benches,
+    profiles_dictionary::benches
+);

libdd-profiling/benches/profiles_dictionary.rs

@@ -0,0 +1,102 @@
+// Copyright 2026-Present Datadog, Inc. https://www.datadoghq.com/
+// SPDX-License-Identifier: Apache-2.0
+
+use criterion::{black_box, criterion_group, BatchSize, BenchmarkId, Criterion, Throughput};
+use libdd_profiling::profiles::datatypes::ProfilesDictionary;
+use std::sync::Barrier;
+use std::thread;
+use std::time::Duration;
+
+const THREAD_COUNTS: [usize; 4] = [1, 2, 4, 16];
+const STRINGS_PER_THREAD: usize = 1024;
+// Bound one generated function-name component so the input has repeated
+// function-like fragments while each full string stays unique.
+const FUNCTION_NAME_VARIANTS: usize = 97;
+const STRING_SHAPE_VARIANTS: usize = 4;
+// Knuth/Fibonacci multiplicative hash constant, used only to vary synthetic input.
+const KNUTH_MULTIPLICATIVE_HASH: usize = 2_654_435_761;
+
+// The outer Vec partitions precomputed input by benchmark worker thread; each
+// inner Vec is the set of strings inserted by one worker.
+fn make_partitioned_strings(thread_count: usize) -> Vec<Vec<String>> {
+    (0..thread_count)
+        .map(|thread_id| {
+            (0..STRINGS_PER_THREAD)
+                .map(|string_id| {
+                    let function_id = string_id % FUNCTION_NAME_VARIANTS;
+                    let mixed_id = string_id.wrapping_mul(KNUTH_MULTIPLICATIVE_HASH);
+
+                    match string_id % STRING_SHAPE_VARIANTS {
+                        0 => format!("function_{function_id}::{mixed_id}"),
+                        1 => format!("/src/thread_{thread_id}/module_{function_id}/file_{string_id:04}.rs"),
+                        2 => {
+                            format!("datadog::profiling::module_{function_id}::function_{mixed_id}")
+                        }
+                        _ => format!(
+                            "/opt/datadog/profiler/thread-{thread_id}/module-{function_id}/src/file_{string_id:04}.rs::function_{function_id}::{mixed_id}",
+                        ),
+                    }
+                })
+                .collect()
+        })
+        .collect()
+}
+
+fn insert_profile_strings(dict: &ProfilesDictionary, strings: &[String]) {
+    for string in strings {
+        black_box(dict.try_insert_str2(string.as_str()).unwrap());
+    }
+}
+
+fn insert_dictionary_strings_concurrently(strings: &[Vec<String>]) -> ProfilesDictionary {
+    let dict = ProfilesDictionary::try_new().unwrap();
+
+    if let [strings] = strings {
+        insert_profile_strings(&dict, strings);
+        return dict;
+    }
+
+    let barrier = Barrier::new(strings.len());
+    thread::scope(|scope| {
+        for thread_strings in strings {
+            let dict = &dict;
+            let barrier = &barrier;
+            scope.spawn(move || {
+                barrier.wait();
+                insert_profile_strings(dict, thread_strings);
+            });
+        }
+    });
+
+    dict
+}
+
+pub fn bench_profiles_dictionary(c: &mut Criterion) {
+    let mut group = c.benchmark_group("profiles_dictionary/unique_string_inserts");
+    group.warm_up_time(Duration::from_secs(1));
+    group.measurement_time(Duration::from_secs(5));
+    group.sample_size(10);
+
+    for thread_count in THREAD_COUNTS {
+        // Precompute input outside the measured closure so the benchmark measures
+        // dictionary insertion rather than string formatting/allocation.
+        let strings = make_partitioned_strings(thread_count);
+        let total_strings = thread_count * STRINGS_PER_THREAD;
+        group.throughput(Throughput::Elements(total_strings as u64));
+        group.bench_with_input(
+            BenchmarkId::new("threads", thread_count),
+            &strings,
+            |b, strings| {
+                b.iter_batched(
+                    || strings,
+                    |strings| black_box(insert_dictionary_strings_concurrently(strings)),
+                    BatchSize::LargeInput,
+                );
+            },
+        );
+    }
+
+    group.finish();
+}
+
+criterion_group!(benches, bench_profiles_dictionary);