subscriber: explain why we always call inner.register_callsite() be…

…fore if statement (#1433) * subscriber: explain why we always call `inner.register_callsite()` before if statement * Apply suggestions from code review Co-authored-by: Eliza Weisman <[email protected]>
tokio-rs · Jun 23, 2021 · 60f816b · 60f816b
1 parent 4af08fa
commit 60f816b
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/tracing-subscriber/src/subscribe.rs b/tracing-subscriber/src/subscribe.rs
@@ -589,6 +589,9 @@ where
             return outer;
         }
 
+        // The intention behind calling `inner.register_callsite()` before the if statement
+        // is to ensure that the inner subscriber is informed that the callsite exists
+        // regardless of the outer subscriber's filtering decision.
         let inner = self.inner.register_callsite(metadata);
         if outer.is_sometimes() {
             // if this interest is "sometimes", return "sometimes" to ensure that
@@ -715,6 +718,9 @@ where
             return outer;
         }
 
+        // The intention behind calling `inner.register_callsite()` before the if statement
+        // is to ensure that the inner subscriber is informed that the callsite exists
+        // regardless of the outer subscriber's filtering decision.
         let inner = self.inner.register_callsite(metadata);
         if outer.is_sometimes() {
             // if this interest is "sometimes", return "sometimes" to ensure that