From 9ff04fd2f046bbb5dd35a7c8c1646b3dcf1157a3 Mon Sep 17 00:00:00 2001
From: Eliza Weisman <eliza@buoyant.io>
Date: Fri, 17 Sep 2021 10:12:43 -0700
Subject: [PATCH] subscriber: clear `enabled` filter map when short circuiting

This is essentially the same change as #1569, but for `enabled` states
rather than `register_callsite`. When a global filter returns `false`
from `enabled`, ensure that the per-layer filter `FilterMap` and debug
counters are cleared, so that they are empty on the next `enabled` call.

See #1563
---
 tracing-subscriber/src/filter/layer_filters.rs | 14 ++++++++++++++
 tracing-subscriber/src/layer/layered.rs        |  7 +++++++
 2 files changed, 21 insertions(+)

diff --git a/tracing-subscriber/src/filter/layer_filters.rs b/tracing-subscriber/src/filter/layer_filters.rs
index bc59125a9e..e1cee05089 100644
--- a/tracing-subscriber/src/filter/layer_filters.rs
+++ b/tracing-subscriber/src/filter/layer_filters.rs
@@ -45,6 +45,7 @@ use tracing_core::{
     subscriber::{Interest, Subscriber},
     Event, Metadata,
 };
+use tracing_futures::Instrument;
 
 /// A [`Layer`] that wraps an inner [`Layer`] and adds a [`Filter`] which
 /// controls what spans and events are enabled for that layer.
@@ -700,6 +701,19 @@ impl FilterState {
         }
     }
 
+    /// Clears the current in-progress filter state.
+    ///
+    /// This resets the [`FilterMap`] and current [`Interest`] as well as
+    /// clearing the debug counters.
+    pub(crate) fn clear_enabled() {
+        FILTERING.try_with(|filtering| {
+            filtering.enabled.set(FilterMap::default());
+
+            #[cfg(debug_assertions)]
+            filtering.counters.in_filter_pass.set(0);
+        });
+    }
+
     pub(crate) fn take_interest() -> Option<Interest> {
         FILTERING
             .try_with(|filtering| {
diff --git a/tracing-subscriber/src/layer/layered.rs b/tracing-subscriber/src/layer/layered.rs
index dae885269d..def6c0ce16 100644
--- a/tracing-subscriber/src/layer/layered.rs
+++ b/tracing-subscriber/src/layer/layered.rs
@@ -80,6 +80,13 @@ where
             self.inner.enabled(metadata)
         } else {
             // otherwise, the callsite is disabled by the layer
+
+            // 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 `enabled` state.
+            #[cfg(feature = "registry")]
+            filter::FilterState::clear_enabled();
+
             false
         }
     }