Ensure that prometheus-client is actually being used

autometrics/Cargo.toml

@@ -23,7 +23,7 @@ prometheus-exporter = [
   "once_cell",
   "opentelemetry-prometheus",
   "opentelemetry_sdk",
-  "prometheus"
+  "dep:prometheus"
 ]
 custom-objective-percentile = []
 custom-objective-latency = []

autometrics/src/tracker/mod.rs

@@ -9,18 +9,33 @@ mod prometheus;
 #[cfg(feature = "prometheus-client")]
 pub(crate) mod prometheus_client;
 
+// Priority if multiple features are enabled:
+// 1. prometheus
+// 2. prometheus-client
+// 3. metrics
+// 4. opentelemetry (default)
+
 // By default, use the opentelemetry crate
 #[cfg(all(
     feature = "opentelemetry",
-    not(any(feature = "metrics", feature = "prometheus"))
+    not(any(
+        feature = "metrics",
+        feature = "prometheus",
+        feature = "prometheus-client"
+    ))
 ))]
 pub use self::opentelemetry::OpenTelemetryTracker as AutometricsTracker;
 
-// But use one of the other crates if either of those features are enabled
-#[cfg(all(feature = "metrics", not(feature = "prometheus")))]
+// But use one of the other crates if any of those features are enabled
+#[cfg(all(
+    feature = "metrics",
+    not(any(feature = "prometheus", feature = "prometheus-client"))
+))]
 pub use self::metrics::MetricsTracker as AutometricsTracker;
 #[cfg(feature = "prometheus")]
 pub use self::prometheus::PrometheusTracker as AutometricsTracker;
+#[cfg(all(feature = "prometheus-client", not(feature = "prometheus")))]
+pub use self::prometheus_client::PrometheusClientTracker as AutometricsTracker;
 
 pub trait TrackMetrics {
     fn set_build_info(build_info_labels: &BuildInfoLabels);

autometrics/src/tracker/prometheus_client.rs

@@ -45,7 +45,7 @@ struct Metrics {
     build_info: Family<BuildInfoLabels, Gauge>,
 }
 
-struct PrometheusClientTracker {
+pub struct PrometheusClientTracker {
     gauge_labels: Option<GaugeLabels>,
     start_time: Instant,
 }