trace: Allow specifying a new span's parent (#923)

This branch allows users of `tokio-trace` to explicitly set a span's parent, or indicate that a span should be a new root of its own trace tree. A `parent: ` key has been added to the `span!` macros. When a span is provided, that span will be set as the parent, while `parent: None` will result in a new root span. No `parent:` key results in the current behaviour. A new type, `span::Attributes`, was added to `tokio-trace-core` to act as an arguments struct for the `Subscriber::new_span` method. This will allow future fields to be added without causing breaking API changes. The `Attributes` struct currently contains the new span's metadata, `ValueSet`, and parent. Finally, the `span::Span` type in `-core` was renamed to `span::Id`, for consistency with `tokio-trace` and to differentiate it from `span::Attributes`. This name was chosen primarily due to precedent in other tracing systems. Closes #920 Signed-off-by: Eliza Weisman <[email protected]>
2026-09-09 00:00:08 +02:00 · 2019-03-01 11:29:11 -08:00
parent 43d69d77e2
commit 5ff6e37c59
15 changed files with 671 additions and 103 deletions
@@ -476,3 +476,108 @@ fn new_span_with_target_and_log_level() {

    handle.assert_finished();
 }
+
+#[test]
+fn explicit_root_span_is_root() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("foo").with_explicit_parent(None))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        span!(parent: None, "foo");
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn explicit_root_span_is_root_regardless_of_ctx() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("foo"))
+        .enter(span::mock().named("foo"))
+        .new_span(span::mock().named("bar").with_explicit_parent(None))
+        .exit(span::mock().named("foo"))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        span!("foo").enter(|| {
+            span!(parent: None, "bar");
+        })
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn explicit_child() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("foo"))
+        .new_span(span::mock().named("bar").with_explicit_parent(Some("foo")))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        let foo = span!("foo");
+        span!(parent: foo.id(), "bar");
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn explicit_child_regardless_of_ctx() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("foo"))
+        .new_span(span::mock().named("bar"))
+        .enter(span::mock().named("bar"))
+        .new_span(span::mock().named("baz").with_explicit_parent(Some("foo")))
+        .exit(span::mock().named("bar"))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        let foo = span!("foo");
+        span!("bar").enter(|| span!(parent: foo.id(), "baz"))
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn contextual_root() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("foo").with_contextual_parent(None))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        span!("foo");
+    });
+
+    handle.assert_finished();
+}
+
+#[test]
+fn contextual_child() {
+    let (subscriber, handle) = subscriber::mock()
+        .new_span(span::mock().named("foo"))
+        .enter(span::mock().named("foo"))
+        .new_span(
+            span::mock()
+                .named("bar")
+                .with_contextual_parent(Some("foo")),
+        )
+        .exit(span::mock().named("foo"))
+        .done()
+        .run_with_handle();
+
+    with_default(subscriber, || {
+        span!("foo").enter(|| {
+            span!("bar");
+        })
+    });
+
+    handle.assert_finished();
+}