subscriber: rename Layer::new_span to on_new_span (tokio-rs#1674)

While we're breaking things, we may as well do this as well.

Closes tokio-rs#630
Closes tokio-rs#662

tracing-opentelemetry/benches/trace.rs

@@ -60,7 +60,7 @@ impl<S> tracing_subscriber::Layer<S> for RegistryAccessLayer
 where
     S: tracing_core::Subscriber + for<'span> tracing_subscriber::registry::LookupSpan<'span>,
 {
-    fn new_span(
+    fn on_new_span(
         &self,
         _attrs: &tracing_core::span::Attributes<'_>,
         id: &tracing::span::Id,
@@ -87,7 +87,7 @@ impl<S> tracing_subscriber::Layer<S> for OtelDataLayer
 where
     S: tracing_core::Subscriber + for<'span> tracing_subscriber::registry::LookupSpan<'span>,
 {
-    fn new_span(
+    fn on_new_span(
         &self,
         attrs: &tracing_core::span::Attributes<'_>,
         id: &tracing::span::Id,

tracing-opentelemetry/src/layer.rs

@@ -410,7 +410,7 @@ where
     ///
     /// [OpenTelemetry `Span`]: opentelemetry::trace::Span
     /// [tracing `Span`]: tracing::Span
-    fn new_span(&self, attrs: &Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
+    fn on_new_span(&self, attrs: &Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
         let span = ctx.span(id).expect("Span not found, this is a bug");
         let mut extensions = span.extensions_mut();
 

tracing-subscriber/src/filter/layer_filters.rs

@@ -320,9 +320,9 @@ where
         }
     }
 
-    fn new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, cx: Context<'_, S>) {
+    fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, cx: Context<'_, S>) {
         self.did_enable(|| {
-            self.layer.new_span(attrs, id, cx.with_filter(self.id()));
+            self.layer.on_new_span(attrs, id, cx.with_filter(self.id()));
         })
     }
 

tracing-subscriber/src/fmt/fmt_layer.rs

@@ -557,7 +557,7 @@ where
     E: FormatEvent<S, N> + 'static,
     W: for<'writer> MakeWriter<'writer> + 'static,
 {
-    fn new_span(&self, attrs: &Attributes<'_>, id: &Id, ctx: Context<'_, S>) {
+    fn on_new_span(&self, attrs: &Attributes<'_>, id: &Id, ctx: Context<'_, S>) {
         let span = ctx.span(id).expect("Span not found, this is a bug");
         let mut extensions = span.extensions_mut();
 

tracing-subscriber/src/layer/layered.rs

@@ -97,7 +97,7 @@ where
 
     fn new_span(&self, span: &span::Attributes<'_>) -> span::Id {
         let id = self.inner.new_span(span);
-        self.layer.new_span(span, &id, self.ctx());
+        self.layer.on_new_span(span, &id, self.ctx());
         id
     }
 
@@ -233,9 +233,9 @@ where
     }
 
     #[inline]
-    fn new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
-        self.inner.new_span(attrs, id, ctx.clone());
-        self.layer.new_span(attrs, id, ctx);
+    fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
+        self.inner.on_new_span(attrs, id, ctx.clone());
+        self.layer.on_new_span(attrs, id, ctx);
     }
 
     #[inline]

tracing-subscriber/src/layer/mod.rs

@@ -650,7 +650,7 @@ where
 
     /// Notifies this layer that a new span was constructed with the given
     /// `Attributes` and `Id`.
-    fn new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
+    fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
         let _ = (attrs, id, ctx);
     }
 
@@ -1089,9 +1089,9 @@ where
     }
 
     #[inline]
-    fn new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
+    fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
         if let Some(ref inner) = self {
-            inner.new_span(attrs, id, ctx)
+            inner.on_new_span(attrs, id, ctx)
         }
     }
 
@@ -1190,8 +1190,8 @@ feature! {
             }
 
             #[inline]
-            fn new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
-                self.deref().new_span(attrs, id, ctx)
+            fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) {
+                self.deref().on_new_span(attrs, id, ctx)
             }
 
             #[inline]

tracing-subscriber/tests/support.rs

@@ -271,7 +271,7 @@ where
         // TODO: it should be possible to expect spans to follow from other spans
     }
 
-    fn new_span(&self, span: &Attributes<'_>, id: &Id, cx: Context<'_, S>) {
+    fn on_new_span(&self, span: &Attributes<'_>, id: &Id, cx: Context<'_, S>) {
         let meta = span.metadata();
         println!(
             "[{}] new_span: name={:?}; target={:?}; id={:?};",