Skip log formatting entirely for DevNull output
What the developer wrote
Authored by Joost Jager
Skip log formatting entirely for DevNull output
Even though DevNull discards the bytes, the formatting work
(SubstringFormatter, fmt::write, from_utf8) was still being done
on every log call. Short-circuit in TestLogger::log via a TypeId
check, which monomorphization resolves at compile time.
AI tools were used in preparing this commit.
What changed, and why it matters
This commit is a performance optimization for a test-only fuzzing logger. It skips formatting log messages when the output is a special 'DevNull' sink that discards everything anyway. There is no security relevance: no bug is fixed, no memory safety issue is addressed, and no attacker-controlled behavior is changed.
No security action needed. Treat as a normal performance improvement in test infrastructure.
Security signals we found
No strong security signals were identified.
Evidence from the diff
The change adds a compile-time-resolved TypeId check in TestLogger::log to return early when the generic output type is DevNull. Previously, formatting work (SubstringFormatter, fmt::write, from_utf8) was performed even though the result was discarded. This is purely a reduction of wasted CPU work in fuzz/test code and does not alter observable behavior or fix any vulnerability.
Changed components
fuzz/src/utils/test_logger.rsInspect captured patch +4 / −0
diff --git a/fuzz/src/utils/test_logger.rs b/fuzz/src/utils/test_logger.rs
index 193ccc0..e629a7f 100644
--- a/fuzz/src/utils/test_logger.rs
+++ b/fuzz/src/utils/test_logger.rs
@@ -8,6 +8,7 @@
// licenses.
use lightning::util::logger::{Logger, Record};
+use std::any::TypeId;
use std::io::Write;
use std::sync::{Arc, Mutex};
@@ -66,6 +67,9 @@ impl<'a, Out: Output> Write for LockedWriteAdapter<'a, Out> {
impl<Out: Output> Logger for TestLogger<Out> {
fn log(&self, record: Record) {
+ if TypeId::of::<Out>() == TypeId::of::<DevNull>() {
+ return;
+ }
writeln!(LockedWriteAdapter(&self.out), "{:<6} {}", self.id, record).unwrap();
}
}
Why this scored 15/100
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