From af67dfa72034ed4b4f4daa605380be5654e534e2 Mon Sep 17 00:00:00 2001
From: Brian Devins-Suresh <brian.devinssuresh@datadoghq.com>
Date: Mon, 24 Feb 2020 14:38:10 -0500
Subject: [PATCH] Need to cache the boolean. The list can be taken later as
 debug is expected to be slower

---
 .../trace/agent/tooling/Instrumenter.java        |  4 ++--
 .../agent/tooling/muzzle/ReferenceMatcher.java   | 16 +++++++---------
 2 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/Instrumenter.java b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/Instrumenter.java
index 294724a1e3..57a7d6a666 100644
--- a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/Instrumenter.java
+++ b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/Instrumenter.java
@@ -135,9 +135,9 @@ public interface Instrumenter {
         if (null != muzzle) {
           final boolean isMatch = muzzle.matches(classLoader);
           if (!isMatch) {
-            final List<Reference.Mismatch> mismatches =
-                muzzle.getMismatchedReferenceSources(classLoader);
             if (log.isDebugEnabled()) {
+              final List<Reference.Mismatch> mismatches =
+                  muzzle.getMismatchedReferenceSources(classLoader);
               log.debug(
                   "Instrumentation muzzled: {} -- {} on {}",
                   instrumentationNames,
diff --git a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/muzzle/ReferenceMatcher.java b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/muzzle/ReferenceMatcher.java
index 4997dc98d4..b86acfbc3e 100644
--- a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/muzzle/ReferenceMatcher.java
+++ b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/muzzle/ReferenceMatcher.java
@@ -22,9 +22,8 @@ import net.bytebuddy.pool.TypePool;
 
 /** Matches a set of references against a classloader. */
 @Slf4j
-public class ReferenceMatcher
-    implements WeakMap.ValueSupplier<ClassLoader, List<Reference.Mismatch>> {
-  private final WeakMap<ClassLoader, List<Reference.Mismatch>> mismatchCache = newWeakMap();
+public class ReferenceMatcher implements WeakMap.ValueSupplier<ClassLoader, Boolean> {
+  private final WeakMap<ClassLoader, Boolean> mismatchCache = newWeakMap();
   private final Reference[] references;
   private final Set<String> helperClassNames;
 
@@ -52,6 +51,11 @@ public class ReferenceMatcher
       loader = Utils.getBootstrapProxy();
     }
 
+    return mismatchCache.computeIfAbsent(loader, this);
+  }
+
+  @Override
+  public Boolean get(final ClassLoader loader) {
     final List<Mismatch> mismatches = new ArrayList<>(0);
 
     for (final Reference reference : references) {
@@ -65,7 +69,6 @@ public class ReferenceMatcher
       }
     }
 
-    mismatchCache.put(loader, mismatches);
     return mismatches.size() == 0;
   }
 
@@ -80,11 +83,6 @@ public class ReferenceMatcher
       loader = Utils.getBootstrapProxy();
     }
 
-    return mismatchCache.computeIfAbsent(loader, this);
-  }
-
-  @Override
-  public List<Mismatch> get(final ClassLoader loader) {
     final List<Mismatch> mismatches = new ArrayList<>(0);
 
     for (final Reference reference : references) {