Reduce string allocations where possible (#506)

examples/async/src/main.rs

@@ -46,7 +46,7 @@ async fn write(stream: &mut TcpStream) -> io::Result<usize> {
 
 async fn run(addr: &SocketAddr) -> io::Result<usize> {
     let tracer = global::tracer("runner");
-    let span = tracer.start(&format!("running: {}", addr));
+    let span = tracer.start(format!("running: {}", addr));
     let cx = Context::current_with_span(span);
 
     let mut stream = connect(addr).with_context(cx.clone()).await?;

opentelemetry-datadog/src/exporter/model/mod.rs

@@ -80,7 +80,6 @@ pub(crate) mod tests {
         trace::{SpanContext, SpanId, SpanKind, StatusCode, TraceId, TraceState},
         Key,
     };
-    use std::sync::Arc;
     use std::time::{Duration, SystemTime};
 
     fn get_traces() -> Vec<Vec<trace::SpanData>> {
@@ -110,15 +109,15 @@ pub(crate) mod tests {
             span_context,
             parent_span_id: SpanId::from_u64(parent_span_id),
             span_kind: SpanKind::Client,
-            name: "resource".to_string(),
+            name: "resource".into(),
             start_time,
             end_time,
             attributes,
             message_events,
             links,
             status_code: StatusCode::Ok,
-            status_message: String::new(),
-            resource: Arc::new(sdk::Resource::default()),
+            status_message: "".into(),
+            resource: None,
             instrumentation_lib: InstrumentationLibrary::new("component", None),
         }
     }

opentelemetry-jaeger/src/exporter/mod.rs

@@ -499,7 +499,7 @@ fn convert_otel_span_into_jaeger_span(
         trace_id_high,
         span_id: span.span_context.span_id().to_u64() as i64,
         parent_span_id: span.parent_span_id.to_u64() as i64,
-        operation_name: span.name,
+        operation_name: span.name.into_owned(),
         references: links_to_references(span.links),
         flags: span.span_context.trace_flags() as i32,
         start_time: span
@@ -520,7 +520,7 @@ fn convert_otel_span_into_jaeger_span(
                 None
             },
             span.status_code,
-            span.status_message,
+            span.status_message.into_owned(),
             span.span_kind,
         )),
         logs: events_to_logs(span.message_events),
@@ -530,16 +530,15 @@ fn convert_otel_span_into_jaeger_span(
 fn build_process_tags(
     span_data: &trace::SpanData,
 ) -> Option<impl Iterator<Item = jaeger::Tag> + '_> {
-    if span_data.resource.is_empty() {
-        None
-    } else {
-        Some(
-            span_data
-                .resource
+    span_data
+        .resource
+        .as_ref()
+        .filter(|resource| !resource.is_empty())
+        .map(|resource| {
+            resource
                 .iter()
-                .map(|(k, v)| KeyValue::new(k.clone(), v.clone()).into()),
-        )
-    }
+                .map(|(k, v)| KeyValue::new(k.clone(), v.clone()).into())
+        })
 }
 
 fn build_span_tags(

opentelemetry-otlp/src/transform/traces.rs

@@ -60,7 +60,10 @@ mod tonic {
             let span_kind: span::SpanKind = source_span.span_kind.into();
             ResourceSpans {
                 resource: Some(Resource {
-                    attributes: resource_attributes(&source_span.resource).0,
+                    attributes: resource_attributes(
+                        source_span.resource.as_ref().map(AsRef::as_ref),
+                    )
+                    .0,
                     dropped_attributes_count: 0,
                 }),
                 instrumentation_library_spans: vec![InstrumentationLibrarySpans {
@@ -86,7 +89,7 @@ mod tonic {
                                 vec![]
                             }
                         },
-                        name: source_span.name,
+                        name: source_span.name.into_owned(),
                         kind: span_kind as i32,
                         start_time_unix_nano: to_nanos(source_span.start_time),
                         end_time_unix_nano: to_nanos(source_span.end_time),
@@ -107,7 +110,7 @@ mod tonic {
                         links: source_span.links.into_iter().map(Into::into).collect(),
                         status: Some(Status {
                             code: status::StatusCode::from(source_span.status_code).into(),
-                            message: source_span.status_message,
+                            message: source_span.status_message.into_owned(),
                             ..Default::default()
                         }),
                     }],
@@ -116,11 +119,14 @@ mod tonic {
         }
     }
 
-    fn resource_attributes(resource: &sdk::Resource) -> Attributes {
+    fn resource_attributes(resource: Option<&sdk::Resource>) -> Attributes {
         resource
-            .iter()
-            .map(|(k, v)| opentelemetry::KeyValue::new(k.clone(), v.clone()))
-            .collect::<Vec<_>>()
+            .map(|res| {
+                res.iter()
+                    .map(|(k, v)| opentelemetry::KeyValue::new(k.clone(), v.clone()))
+                    .collect::<Vec<_>>()
+            })
+            .unwrap_or_default()
             .into()
     }
 }
@@ -186,7 +192,10 @@ mod grpcio {
         fn from(source_span: SpanData) -> Self {
             ResourceSpans {
                 resource: SingularPtrField::from(Some(Resource {
-                    attributes: resource_attributes(&source_span.resource).0,
+                    attributes: resource_attributes(
+                        source_span.resource.as_ref().map(AsRef::as_ref),
+                    )
+                    .0,
                     dropped_attributes_count: 0,
                     ..Default::default()
                 })),
@@ -214,7 +223,7 @@ mod grpcio {
                                     vec![]
                                 }
                             },
-                            name: source_span.name,
+                            name: source_span.name.into_owned(),
                             kind: source_span.span_kind.into(),
                             start_time_unix_nano: to_nanos(source_span.start_time),
                             end_time_unix_nano: to_nanos(source_span.end_time),
@@ -240,7 +249,7 @@ mod grpcio {
                             ),
                             status: SingularPtrField::some(Status {
                                 code: Status_StatusCode::from(source_span.status_code),
-                                message: source_span.status_message,
+                                message: source_span.status_message.into_owned(),
                                 ..Default::default()
                             }),
                             ..Default::default()
@@ -253,11 +262,15 @@ mod grpcio {
         }
     }
 
-    fn resource_attributes(resource: &sdk::Resource) -> Attributes {
+    fn resource_attributes(resource: Option<&sdk::Resource>) -> Attributes {
         resource
-            .iter()
-            .map(|(k, v)| opentelemetry::KeyValue::new(k.clone(), v.clone()))
-            .collect::<Vec<_>>()
+            .map(|resource| {
+                resource
+                    .iter()
+                    .map(|(k, v)| opentelemetry::KeyValue::new(k.clone(), v.clone()))
+                    .collect::<Vec<_>>()
+            })
+            .unwrap_or_default()
             .into()
     }
 }

opentelemetry-stackdriver/src/lib.rs

@@ -171,7 +171,7 @@ impl StackDriverExporter {
                 hex::encode(span.span_context.trace_id().to_u128().to_be_bytes()),
                 hex::encode(span.span_context.span_id().to_u64().to_be_bytes())
               ),
-              display_name: Some(to_truncate(span.name.clone())),
+              display_name: Some(to_truncate(span.name.into_owned())),
               span_id: hex::encode(span.span_context.span_id().to_u64().to_be_bytes()),
               parent_span_id: hex::encode(span.parent_span_id.to_u64().to_be_bytes()),
               start_time: Some(span.start_time.into()),

opentelemetry-zipkin/src/exporter/model/mod.rs

@@ -71,7 +71,10 @@ pub(crate) fn into_zipkin_span(local_endpoint: Endpoint, span_data: trace::SpanD
     );
     if let Some(status_code) = from_statuscode_to_str(span_data.status_code) {
         if status_code == "ERROR" {
-            tags.insert(OTEL_ERROR_DESCRIPTION.into(), span_data.status_message);
+            tags.insert(
+                OTEL_ERROR_DESCRIPTION.into(),
+                span_data.status_message.into_owned(),
+            );
         }
         tags.insert(OTEL_STATUS_CODE.into(), status_code.into());
     }
@@ -80,7 +83,7 @@ pub(crate) fn into_zipkin_span(local_endpoint: Endpoint, span_data: trace::SpanD
         .trace_id(span_data.span_context.trace_id().to_hex())
         .parent_id(span_data.parent_span_id.to_hex())
         .id(span_data.span_context.span_id().to_hex())
-        .name(span_data.name)
+        .name(span_data.name.into_owned())
         .kind(if user_defined_span_kind {
             None
         } else {

opentelemetry-zipkin/src/exporter/model/span.rs

@@ -64,7 +64,6 @@ mod tests {
     use opentelemetry::trace::{SpanContext, SpanId, SpanKind, StatusCode, TraceId};
     use std::collections::HashMap;
     use std::net::Ipv4Addr;
-    use std::sync::Arc;
     use std::time::SystemTime;
 
     #[test]
@@ -170,15 +169,15 @@ mod tests {
                 ),
                 parent_span_id: SpanId::from_u64(1),
                 span_kind: SpanKind::Client,
-                name: "".to_string(),
+                name: "".into(),
                 start_time: SystemTime::now(),
                 end_time: SystemTime::now(),
                 attributes: EvictedHashMap::new(20, 20),
                 message_events: EvictedQueue::new(20),
                 links: EvictedQueue::new(20),
                 status_code,
-                status_message: status_msg,
-                resource: Arc::new(Default::default()),
+                status_message: status_msg.into(),
+                resource: None,
                 instrumentation_lib: Default::default(),
             };
             let local_endpoint = Endpoint::new("test".into(), None);

opentelemetry/src/global/trace.rs

@@ -1,5 +1,6 @@
 use crate::trace::NoopTracerProvider;
 use crate::{trace, trace::TracerProvider, Context, KeyValue};
+use std::borrow::Cow;
 use std::fmt;
 use std::mem;
 use std::sync::{Arc, RwLock};
@@ -92,15 +93,21 @@ impl trace::Tracer for BoxedTracer {
     /// trace. A span is said to be a _root span_ if it does not have a parent. Each
     /// trace includes a single root span, which is the shared ancestor of all other
     /// spans in the trace.
-    fn start_with_context(&self, name: &str, cx: Context) -> Self::Span {
-        BoxedSpan(self.0.start_with_context_boxed(name, cx))
+    fn start_with_context<T>(&self, name: T, cx: Context) -> Self::Span
+    where
+        T: Into<Cow<'static, str>>,
+    {
+        BoxedSpan(self.0.start_with_context_boxed(name.into(), cx))
     }
 
     /// Creates a span builder
     ///
     /// An ergonomic way for attributes to be configured before the `Span` is started.
-    fn span_builder(&self, name: &str) -> trace::SpanBuilder {
-        trace::SpanBuilder::from_name(name.to_string())
+    fn span_builder<T>(&self, name: T) -> trace::SpanBuilder
+    where
+        T: Into<Cow<'static, str>>,
+    {
+        trace::SpanBuilder::from_name(name)
     }
 
     /// Create a span from a `SpanBuilder`
@@ -119,7 +126,7 @@ pub trait GenericTracer: fmt::Debug + 'static {
 
     /// Returns a trait object so the underlying implementation can be swapped
     /// out at runtime.
-    fn start_with_context_boxed(&self, name: &str, cx: Context) -> Box<DynSpan>;
+    fn start_with_context_boxed(&self, name: Cow<'static, str>, cx: Context) -> Box<DynSpan>;
 
     /// Returns a trait object so the underlying implementation can be swapped
     /// out at runtime.
@@ -138,7 +145,7 @@ where
 
     /// Returns a trait object so the underlying implementation can be swapped
     /// out at runtime.
-    fn start_with_context_boxed(&self, name: &str, cx: Context) -> Box<DynSpan> {
+    fn start_with_context_boxed(&self, name: Cow<'static, str>, cx: Context) -> Box<DynSpan> {
         Box::new(self.start_with_context(name, cx))
     }
 

opentelemetry/src/sdk/env.rs

@@ -62,7 +62,7 @@ mod tests {
     use crate::sdk::env::OTEL_RESOURCE_ATTRIBUTES;
     use crate::sdk::resource::{Resource, ResourceDetector};
     use crate::sdk::EnvResourceDetector;
-    use crate::{Key, KeyValue};
+    use crate::KeyValue;
     use std::{env, time};
 
     #[test]
@@ -75,10 +75,10 @@ mod tests {
         assert_eq!(
             resource,
             Resource::new(vec![
-                KeyValue::new(Key::new("key".to_string()), "value"),
-                KeyValue::new(Key::new("k".to_string()), "v"),
-                KeyValue::new(Key::new("a".to_string()), "x"),
-                KeyValue::new(Key::new("a".to_string()), "z"),
+                KeyValue::new("key", "value"),
+                KeyValue::new("k", "v"),
+                KeyValue::new("a", "x"),
+                KeyValue::new("a", "z"),
             ])
         );
 

opentelemetry/src/sdk/export/trace/mod.rs

@@ -1,16 +1,15 @@
 //! Trace exporters
-use std::fmt::Debug;
-use std::sync::Arc;
-use std::time::SystemTime;
-
-use async_trait::async_trait;
-#[cfg(feature = "serialize")]
-use serde::{Deserialize, Serialize};
-
 use crate::{
     sdk,
     trace::{Event, Link, SpanContext, SpanId, SpanKind, StatusCode, TraceError},
 };
+use async_trait::async_trait;
+#[cfg(feature = "serialize")]
+use serde::{Deserialize, Serialize};
+use std::borrow::Cow;
+use std::fmt::Debug;
+use std::sync::Arc;
+use std::time::SystemTime;
 
 pub mod stdout;
 
@@ -66,7 +65,7 @@ pub struct SpanData {
     /// Span kind
     pub span_kind: SpanKind,
     /// Span name
-    pub name: String,
+    pub name: Cow<'static, str>,
     /// Span start time
     pub start_time: SystemTime,
     /// Span end time
@@ -80,9 +79,9 @@ pub struct SpanData {
     /// Span status code
     pub status_code: StatusCode,
     /// Span status message
-    pub status_message: String,
+    pub status_message: Cow<'static, str>,
     /// Resource contains attributes representing an entity that produced this span.
-    pub resource: Arc<sdk::Resource>,
+    pub resource: Option<Arc<sdk::Resource>>,
     /// Instrumentation library that produced this span
     #[cfg_attr(feature = "serialize", serde(skip))]
     pub instrumentation_lib: sdk::InstrumentationLibrary,
@@ -111,7 +110,7 @@ mod tests {
 
         let parent_span_id = 1;
         let span_kind = SpanKind::Client;
-        let name = "foo/bar baz 人?!".to_string();
+        let name = "foo/bar baz 人?!".into();
         let start_time = crate::time::now();
         let end_time = crate::time::now();
 
@@ -121,8 +120,8 @@ mod tests {
         let links = sdk::trace::EvictedQueue::new(capacity);
 
         let status_code = StatusCode::Ok;
-        let status_message = String::new();
-        let resource = Arc::new(sdk::Resource::default());
+        let status_message = "".into();
+        let resource = None;
 
         let span_data = SpanData {
             span_context,

opentelemetry/src/sdk/resource.rs

@@ -260,10 +260,10 @@ mod tests {
         assert_eq!(
             resource,
             Resource::new(vec![
-                KeyValue::new(Key::new("key".to_string()), "value"),
-                KeyValue::new(Key::new("k".to_string()), "v"),
-                KeyValue::new(Key::new("a".to_string()), "x"),
-                KeyValue::new(Key::new("a".to_string()), "z")
+                KeyValue::new("key", "value"),
+                KeyValue::new("k", "v"),
+                KeyValue::new("a", "x"),
+                KeyValue::new("a", "z")
             ])
         )
     }