Replace once_cell with OnceLock (#152)

Co-authored-by: Cijo Thomas <cijo.thomas@gmail.com>

Author: gruebel

opentelemetry-aws/Cargo.toml

@@ -25,7 +25,6 @@ detector-aws-lambda = ["dep:opentelemetry-semantic-conventions"]
 internal-logs = ["tracing"]
 
 [dependencies]
-once_cell = "1.12"
 opentelemetry = { workspace = true }
 opentelemetry_sdk = { workspace = true, optional = true }
 opentelemetry-semantic-conventions = { workspace = true, optional = true }

opentelemetry-aws/src/trace/xray_propagator.rs

@@ -38,7 +38,6 @@
 //! }
 //! ```
 
-use once_cell::sync::Lazy;
 use opentelemetry::{
     otel_error,
     propagation::{text_map_propagator::FieldIter, Extractor, Injector, TextMapPropagator},
@@ -47,6 +46,7 @@ use opentelemetry::{
 };
 use std::borrow::Cow;
 use std::convert::TryFrom;
+use std::sync::OnceLock;
 
 const AWS_XRAY_TRACE_HEADER: &str = "x-amzn-trace-id";
 const AWS_XRAY_VERSION_KEY: &str = "1";
@@ -60,7 +60,12 @@ const REQUESTED_SAMPLE_DECISION: &str = "?";
 
 const TRACE_FLAG_DEFERRED: TraceFlags = TraceFlags::new(0x02);
 
-static AWS_XRAY_HEADER_FIELD: Lazy<[String; 1]> = Lazy::new(|| [AWS_XRAY_TRACE_HEADER.to_owned()]);
+// TODO Replace this with LazyLock when MSRV is 1.80+
+static TRACE_CONTEXT_HEADER_FIELDS: OnceLock<[String; 1]> = OnceLock::new();
+
+fn trace_context_header_fields() -> &'static [String; 1] {
+    TRACE_CONTEXT_HEADER_FIELDS.get_or_init(|| [AWS_XRAY_TRACE_HEADER.to_owned()])
+}
 
 /// Extracts and injects `SpanContext`s into `Extractor`s or `Injector`s using AWS X-Ray header format.
 ///
@@ -220,7 +225,7 @@ impl TextMapPropagator for XrayPropagator {
     }
 
     fn fields(&self) -> FieldIter<'_> {
-        FieldIter::new(AWS_XRAY_HEADER_FIELD.as_ref())
+        FieldIter::new(trace_context_header_fields())
     }
 }
 

opentelemetry-contrib/Cargo.toml

@@ -34,7 +34,6 @@ async-trait = { version = "0.1", optional = true }
 base64 = { version = "0.13", optional = true }
 futures-core = { version = "0.3", optional = true }
 futures-util = { version = "0.3", optional = true, default-features = false }
-once_cell = "1.17.1"
 opentelemetry = { workspace = true }
 opentelemetry_sdk = { workspace = true, optional = true }
 opentelemetry-semantic-conventions = { workspace = true, optional = true }

opentelemetry-contrib/src/trace/propagator/trace_context_response.rs

@@ -11,19 +11,24 @@
 //! See the [w3c trace-context docs] for more details.
 //!
 //! [w3c trace-context docs]: https://w3c.github.io/trace-context/#traceresponse-header
-use once_cell::sync::Lazy;
+
 use opentelemetry::{
     propagation::{text_map_propagator::FieldIter, Extractor, Injector, TextMapPropagator},
     trace::{SpanContext, SpanId, TraceContextExt, TraceFlags, TraceId, TraceState},
     Context,
 };
+use std::sync::OnceLock;
 
 const SUPPORTED_VERSION: u8 = 0;
 const MAX_VERSION: u8 = 254;
 const TRACERESPONSE_HEADER: &str = "traceresponse";
 
-static TRACE_CONTEXT_HEADER_FIELDS: Lazy<[String; 1]> =
-    Lazy::new(|| [TRACERESPONSE_HEADER.to_owned()]);
+// TODO Replace this with LazyLock when MSRV is 1.80+
+static TRACE_CONTEXT_HEADER_FIELDS: OnceLock<[String; 1]> = OnceLock::new();
+
+fn trace_context_header_fields() -> &'static [String; 1] {
+    TRACE_CONTEXT_HEADER_FIELDS.get_or_init(|| [TRACERESPONSE_HEADER.to_owned()])
+}
 
 /// Propagates trace response using the [W3C TraceContext] format
 ///
@@ -124,7 +129,7 @@ impl TextMapPropagator for TraceContextResponsePropagator {
     }
 
     fn fields(&self) -> FieldIter<'_> {
-        FieldIter::new(TRACE_CONTEXT_HEADER_FIELDS.as_ref())
+        FieldIter::new(trace_context_header_fields())
     }
 }
 

opentelemetry-contrib/src/trace/tracer_source.rs

@@ -1,7 +1,7 @@
 //! Abstracts away details for acquiring a `Tracer` by instrumented libraries.
-use once_cell::sync::OnceCell;
 use opentelemetry::global::BoxedTracer;
 use std::fmt::Debug;
+use std::sync::OnceLock;
 
 /// Holds either a borrowed `BoxedTracer` or a factory that can produce one when
 /// and if needed.
@@ -11,7 +11,7 @@ use std::fmt::Debug;
 #[derive(Debug)]
 pub struct TracerSource<'a> {
     variant: Variant<'a>,
-    tracer: OnceCell<BoxedTracer>,
+    tracer: OnceLock<BoxedTracer>,
 }
 
 enum Variant<'a> {
@@ -24,7 +24,7 @@ impl<'a> TracerSource<'a> {
     pub fn borrowed(tracer: &'a BoxedTracer) -> Self {
         Self {
             variant: Variant::Borrowed(tracer),
-            tracer: OnceCell::new(),
+            tracer: OnceLock::new(),
         }
     }
 
@@ -33,7 +33,7 @@ impl<'a> TracerSource<'a> {
     pub fn lazy(factory: &'a dyn Fn() -> BoxedTracer) -> Self {
         Self {
             variant: Variant::Lazy(factory),
-            tracer: OnceCell::new(),
+            tracer: OnceLock::new(),
         }
     }
 

opentelemetry-datadog/Cargo.toml

@@ -26,7 +26,6 @@ intern-std = []
 
 [dependencies]
 indexmap = "2.0"
-once_cell = "1.12"
 opentelemetry = { workspace = true }
 opentelemetry_sdk = { workspace = true, features = ["trace"] }
 opentelemetry-http = { workspace = true }

opentelemetry-datadog/src/lib.rs

@@ -145,12 +145,12 @@ pub use exporter::{
 pub use propagator::{DatadogPropagator, DatadogTraceState, DatadogTraceStateBuilder};
 
 mod propagator {
-    use once_cell::sync::Lazy;
     use opentelemetry::{
         propagation::{text_map_propagator::FieldIter, Extractor, Injector, TextMapPropagator},
         trace::{SpanContext, SpanId, TraceContextExt, TraceFlags, TraceId, TraceState},
         Context,
     };
+    use std::sync::OnceLock;
 
     const DATADOG_TRACE_ID_HEADER: &str = "x-datadog-trace-id";
     const DATADOG_PARENT_ID_HEADER: &str = "x-datadog-parent-id";
@@ -163,13 +163,18 @@ mod propagator {
     const TRACE_STATE_TRUE_VALUE: &str = "1";
     const TRACE_STATE_FALSE_VALUE: &str = "0";
 
-    static DATADOG_HEADER_FIELDS: Lazy<[String; 3]> = Lazy::new(|| {
-        [
-            DATADOG_TRACE_ID_HEADER.to_string(),
-            DATADOG_PARENT_ID_HEADER.to_string(),
-            DATADOG_SAMPLING_PRIORITY_HEADER.to_string(),
-        ]
-    });
+    // TODO Replace this with LazyLock when MSRV is 1.80+
+    static TRACE_CONTEXT_HEADER_FIELDS: OnceLock<[String; 3]> = OnceLock::new();
+
+    fn trace_context_header_fields() -> &'static [String; 3] {
+        TRACE_CONTEXT_HEADER_FIELDS.get_or_init(|| {
+            [
+                DATADOG_TRACE_ID_HEADER.to_owned(),
+                DATADOG_PARENT_ID_HEADER.to_owned(),
+                DATADOG_SAMPLING_PRIORITY_HEADER.to_owned(),
+            ]
+        })
+    }
 
     #[derive(Default)]
     pub struct DatadogTraceStateBuilder {
@@ -449,7 +454,7 @@ mod propagator {
         }
 
         fn fields(&self) -> FieldIter<'_> {
-            FieldIter::new(DATADOG_HEADER_FIELDS.as_ref())
+            FieldIter::new(trace_context_header_fields())
         }
     }
 

opentelemetry-stackdriver/Cargo.toml

@@ -21,7 +21,6 @@ prost = "0.13"
 prost-types = "0.13"
 thiserror = "2.0"
 tonic = { version = "0.12", default-features = false, features = ["channel", "codegen", "gzip", "prost", "tls"] }
-once_cell = { version = "1.19", optional = true }
 tracing = { version = "0.1", optional = true }
 
 # Futures
@@ -34,7 +33,7 @@ default = ["gcp-authorizer", "tls-native-roots", "internal-logs"]
 gcp-authorizer = ["dep:gcp_auth"]
 tls-native-roots = ["tonic/tls-roots"]
 tls-webpki-roots = ["tonic/tls-webpki-roots"]
-propagator = ["once_cell"]
+propagator = []
 internal-logs = ["tracing"]
 
 [dev-dependencies]

opentelemetry-stackdriver/src/google_trace_context_propagator.rs

@@ -1,10 +1,9 @@
-use std::str::FromStr;
-
-use once_cell::sync::Lazy;
 use opentelemetry::propagation::text_map_propagator::FieldIter;
 use opentelemetry::propagation::{Extractor, Injector, TextMapPropagator};
 use opentelemetry::trace::{SpanContext, SpanId, TraceContextExt, TraceFlags, TraceId, TraceState};
 use opentelemetry::Context;
+use std::str::FromStr;
+use std::sync::OnceLock;
 
 /// Propagates span context in the Google Cloud Trace format,
 /// using the __X-Cloud-Trace-Context__ header.
@@ -27,8 +26,12 @@ pub struct GoogleTraceContextPropagator {
 
 const CLOUD_TRACE_CONTEXT_HEADER: &str = "X-Cloud-Trace-Context";
 
-static TRACE_CONTEXT_HEADER_FIELDS: Lazy<[String; 1]> =
-    Lazy::new(|| [CLOUD_TRACE_CONTEXT_HEADER.to_owned()]);
+// TODO Replace this with LazyLock when MSRV is 1.80+
+static TRACE_CONTEXT_HEADER_FIELDS: OnceLock<[String; 1]> = OnceLock::new();
+
+fn trace_context_header_fields() -> &'static [String; 1] {
+    TRACE_CONTEXT_HEADER_FIELDS.get_or_init(|| [CLOUD_TRACE_CONTEXT_HEADER.to_owned()])
+}
 
 impl GoogleTraceContextPropagator {
     fn extract_span_context(&self, extractor: &dyn Extractor) -> Result<SpanContext, ()> {
@@ -85,7 +88,7 @@ impl TextMapPropagator for GoogleTraceContextPropagator {
     }
 
     fn fields(&self) -> FieldIter<'_> {
-        FieldIter::new(TRACE_CONTEXT_HEADER_FIELDS.as_ref())
+        FieldIter::new(trace_context_header_fields())
     }
 }