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subscriber: clear per-subscriber interest when short circuiting (#1569)
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Currently, when evaluating `register_callsite` for a stack containing
per-subscriber filters, the intermediate `Interest` from combining the
per-subscriber filters' `Interest`s is stored in the thread-local
`FilterState`. When all per-subscriber filters have been evaluated, we
reach the `Registry`, which clears the `FilterState` and bubbles the
`Interest` back up. However, when a _global_ filter in the stack returns
`Interest::never`, we short-circuit, and don't reach the `Registry`.
This means the `Interest` state is not cleared.

This branch adds code in `Layered` to ensure the per-subscriber filter
state is cleared when a global filter short circuits `Interest`
evaluation.

This fixes #1563.

Signed-off-by: Eliza Weisman <[email protected]>
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@hawkw
hawkw committed Mar 24, 2022
1 parent 36e6fb9 commit b26119c
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Showing 2 changed files with 21 additions and 49 deletions.
64 changes: 15 additions & 49 deletions tracing-subscriber/src/subscribe/context.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -86,7 +86,7 @@ where
}
}

/// Returns the wrapped subscriber's view of the current span.
/// Returns the wrapped collector's view of the current span.
#[inline]
pub fn current_span(&self) -> span::Current {
self.subscriber
Expand All @@ -96,7 +96,7 @@ where
.unwrap_or_else(span::Current::none)
}

/// Returns whether the wrapped subscriber would enable the current span.
/// Returns whether the wrapped collector would enable the current span.
#[inline]
pub fn enabled(&self, metadata: &Metadata<'_>) -> bool {
self.subscriber
Expand All @@ -108,20 +108,20 @@ where
.unwrap_or(true)
}

/// Records the provided `event` with the wrapped subscriber.
/// Records the provided `event` with the wrapped collector.
///
/// # Notes
///
/// - The subscriber is free to expect that the event's callsite has been
/// - The collector is free to expect that the event's callsite has been
/// [registered][register], and may panic or fail to observe the event if this is
/// not the case. The `tracing` crate's macros ensure that all events are
/// registered, but if the event is constructed through other means, the
/// user is responsible for ensuring that [`register_callsite`][register]
/// has been called prior to calling this method.
/// - This does _not_ call [`enabled`] on the inner subscriber. If the
/// caller wishes to apply the wrapped subscriber's filter before choosing
/// - This does _not_ call [`enabled`] on the inner collector. If the
/// caller wishes to apply the wrapped collector's filter before choosing
/// whether to record the event, it may first call [`Context::enabled`] to
/// check whether the event would be enabled. This allows `Layer`s to
/// check whether the event would be enabled. This allows subscriberss to
/// elide constructing the event if it would not be recorded.
///
/// [register]: https://docs.rs/tracing-core/latest/tracing_core/subscriber/trait.Subscriber.html#method.register_callsite
Expand Down Expand Up @@ -185,7 +185,7 @@ where
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <strong>Note</strong>: This requires the wrapped collector to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
Expand Down Expand Up @@ -225,7 +225,7 @@ where
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <strong>Note</strong>: This requires the wrapped collector to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
Expand All @@ -250,7 +250,7 @@ where
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <strong>Note</strong>: This requires the wrapped collector to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
Expand All @@ -263,14 +263,14 @@ where
self.subscriber.as_ref().and_then(|s| s.span(id)).is_some()
}

/// Returns [stored data] for the span that the wrapped subscriber considers
/// Returns [stored data] for the span that the wrapped collector considers
/// to be the current.
///
/// If this returns `None`, then we are not currently within a span.
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <strong>Note</strong>: This requires the wrapped collector to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
Expand Down Expand Up @@ -303,7 +303,7 @@ where
//
// Currently, `LookupSpan` doesn't have a nice way of exposing access to
// the whole span stack. However, if we can downcast the innermost
// subscriber to a a `Registry`, we can iterate over its current span
// collector to a a `Registry`, we can iterate over its current span
// stack.
//
// TODO(eliza): when https://github.com/tokio-rs/tracing/issues/1459 is
Expand Down Expand Up @@ -337,40 +337,6 @@ where
.find_map(|id| subscriber.span(id)?.try_with_filter(self.filter))
}

/// Returns an iterator over the [stored data] for all the spans in the
/// current context, starting the root of the trace tree and ending with
/// the current span.
///
/// If this iterator is empty, then there are no spans in the current context.
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
/// </pre></div>
///
/// [stored data]: ../registry/struct.SpanRef.html
#[deprecated(
note = "equivalent to `self.current_span().id().and_then(|id| self.span_scope(id).from_root())` but consider passing an explicit ID instead of relying on the contextual span",
since = "0.2.19"
)]
#[allow(deprecated)]
pub fn scope(&self) -> Scope<'_, C>
where
C: for<'lookup> LookupSpan<'lookup>,
{
Scope(
self.lookup_current()
.as_ref()
.map(registry::SpanRef::scope)
.map(registry::Scope::from_root)
.into_iter()
.flatten(),
)
}

/// Returns an iterator over the [stored data] for all the spans in the
/// current context, starting with the specified span and ending with the
/// root of the trace tree and ending with the current span.
Expand All @@ -391,7 +357,7 @@ where
/// </div>
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <strong>Note</strong>: This requires the wrapped collector to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
Expand Down Expand Up @@ -419,7 +385,7 @@ where
///
/// <div class="example-wrap" style="display:inline-block">
/// <pre class="ignore" style="white-space:normal;font:inherit;">
/// <strong>Note</strong>: This requires the wrapped subscriber to implement the
/// <strong>Note</strong>: This requires the wrapped collector to implement the
/// <a href="../registry/trait.LookupSpan.html"><code>LookupSpan</code></a> trait.
/// See the documentation on <a href="./struct.Context.html"><code>Context</code>'s
/// declaration</a> for details.
Expand Down
6 changes: 6 additions & 0 deletions tracing-subscriber/src/subscribe/layered.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -380,6 +380,12 @@ where
// If the outer subscriber has disabled the callsite, return now so that
// the inner subscriber/subscriber doesn't get its hopes up.
if outer.is_never() {
// If per-layer filters are in use, and we are short-circuiting
// (rather than calling into the inner type), clear the current
// per-layer filter interest state.
#[cfg(feature = "registry")]
drop(filter::FilterState::take_interest());

return outer;
}

Expand Down

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