chore(sampling): pr review feedback

Author: bantonsson

.codecov.yml

@@ -55,6 +55,10 @@ component_management:
       name: libdd-profiling-ffi  # this is a display name, and can be changed freely
       paths:
         - libdd-profiling-ffi
+    - component_id: sampling  # this is an identifier that should not be changed
+      name: libdd-sampling  # this is a display name, and can be changed freely
+      paths:
+        - libdd-sampling
     - component_id: sidecar  # this is an identifier that should not be changed
       name: datadog-sidecar  # this is a display name, and can be changed freely
       paths:

libdd-common/src/lib.rs

@@ -10,7 +10,7 @@ use anyhow::Context;
 use http::uri;
 use serde::de::Error;
 use serde::{Deserialize, Deserializer, Serialize, Serializer};
-use std::sync::{Mutex, MutexGuard};
+use std::sync::{Mutex, MutexGuard, RwLock, RwLockReadGuard, RwLockWriteGuard};
 use std::{borrow::Cow, ops::Deref, path::PathBuf, str::FromStr};
 
 pub mod azure_app_services;
@@ -90,6 +90,51 @@ impl<T> MutexExt<T> for Mutex<T> {
     }
 }
 
+/// Extension trait for `RwLock` to provide methods that acquire read/write locks, panicking if
+/// the lock is poisoned.
+///
+/// Mirrors [`MutexExt`] for `RwLock` so callers avoid `#[allow(clippy::unwrap_used)]` at each
+/// lock site.
+///
+/// # Examples
+///
+/// ```
+/// use libdd_common::RwLockExt;
+/// use std::sync::{Arc, RwLock};
+///
+/// let data = Arc::new(RwLock::new(5));
+/// let data_clone = Arc::clone(&data);
+///
+/// std::thread::spawn(move || {
+///     let mut num = data_clone.write_or_panic();
+///     *num += 1;
+/// })
+/// .join()
+/// .expect("Thread panicked");
+///
+/// assert_eq!(*data.read_or_panic(), 6);
+/// ```
+pub trait RwLockExt<T> {
+    fn read_or_panic(&self) -> RwLockReadGuard<'_, T>;
+    fn write_or_panic(&self) -> RwLockWriteGuard<'_, T>;
+}
+
+impl<T> RwLockExt<T> for RwLock<T> {
+    #[inline(always)]
+    #[track_caller]
+    fn read_or_panic(&self) -> RwLockReadGuard<'_, T> {
+        #[allow(clippy::unwrap_used)]
+        self.read().unwrap()
+    }
+
+    #[inline(always)]
+    #[track_caller]
+    fn write_or_panic(&self) -> RwLockWriteGuard<'_, T> {
+        #[allow(clippy::unwrap_used)]
+        self.write().unwrap()
+    }
+}
+
 pub mod header {
     #![allow(clippy::declare_interior_mutable_const)]
     use http::{header::HeaderName, HeaderValue};

libdd-sampling/Cargo.toml

@@ -26,6 +26,7 @@ required-features = ["v04_span"]
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 lru = "0.16.3"
+libdd-common = { path = "../libdd-common", version = "4.0.0" }
 libdd-trace-utils = { path = "../libdd-trace-utils", version = "3.0.1", optional = true }
 
 [features]
@@ -34,4 +35,3 @@ v04_span = ["dep:libdd-trace-utils"]
 [dev-dependencies]
 criterion = "0.5"
 libdd-common = { path = "../libdd-common", version = "4.0.0", features = ["bench-utils"] }
-libdd-trace-utils = { path = "../libdd-trace-utils", version = "3.0.1" }

libdd-sampling/src/agent_service_sampler.rs

@@ -6,6 +6,8 @@ use std::{
     sync::{Arc, RwLock},
 };
 
+use libdd_common::RwLockExt;
+
 use crate::rate_sampler::RateSampler;
 
 #[derive(Debug, serde::Deserialize)]
@@ -21,31 +23,31 @@ pub struct ServicesSampler {
 
 impl ServicesSampler {
     pub fn get(&self, service: &str) -> Option<RateSampler> {
-        self.inner.read().unwrap().get(service).cloned()
+        self.inner.read_or_panic().get(service).cloned()
     }
 
     pub fn update_rates<I: IntoIterator<Item = (String, f64)>>(&self, rates: I) {
         let new_rates: HashMap<_, _> = rates
             .into_iter()
             .map(|(s, r)| (s, RateSampler::new(r)))
             .collect();
-        *self.inner.write().unwrap() = new_rates;
+        *self.inner.write_or_panic() = new_rates;
     }
 
-    // used for testing purposes
+    // Test-only inspection helpers.
 
-    #[allow(dead_code)]
+    #[cfg(test)]
     pub(crate) fn is_empty(&self) -> bool {
-        self.inner.read().unwrap().is_empty()
+        self.inner.read_or_panic().is_empty()
     }
 
-    #[allow(dead_code)]
+    #[cfg(test)]
     pub(crate) fn len(&self) -> usize {
-        self.inner.read().unwrap().len()
+        self.inner.read_or_panic().len()
     }
 
-    #[allow(dead_code)]
+    #[cfg(test)]
     pub(crate) fn contains_key(&self, service: &str) -> bool {
-        self.inner.read().unwrap().contains_key(service)
+        self.inner.read_or_panic().contains_key(service)
     }
 }

libdd-sampling/src/constants.rs

@@ -1,7 +1,7 @@
 // Copyright 2025-Present Datadog, Inc. https://www.datadoghq.com/
 // SPDX-License-Identifier: Apache-2.0
 
-//! Shared constants for the datadog_opentelemetry::sampling crate
+//! Shared constants for the libdd-sampling crate
 
 /// Sampling rate limits
 pub mod rate {