Fix race condition with an AtomicReference

Netflix · Jan 19, 2024 · 1f16928 · 1f16928
1 parent 90be839
commit 1f16928
Showing 1 changed file with 7 additions and 9 deletions.
diff --git a/archaius-core/src/main/java/com/netflix/config/ConcurrentCompositeConfiguration.java b/archaius-core/src/main/java/com/netflix/config/ConcurrentCompositeConfiguration.java
@@ -30,6 +30,7 @@
 import java.util.HashSet;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.commons.configuration.AbstractConfiguration;
 import org.apache.commons.configuration.Configuration;
@@ -109,21 +110,18 @@ public class ConcurrentCompositeConfiguration extends ConcurrentMapConfiguration
     private final boolean enableStackTrace = Boolean.parseBoolean(System.getProperty(ENABLE_STACK_TRACE));
     private final boolean enableInstrumentation = Boolean.parseBoolean(System.getProperty(ENABLE_INSTRUMENTATION));
 
-    private Map<String, AbstractConfiguration> namedConfigurations = new ConcurrentHashMap<String, AbstractConfiguration>();
+    private Map<String, AbstractConfiguration> namedConfigurations = new ConcurrentHashMap<>();
 
     private final Map<String, Integer> stackTraces = new ConcurrentHashMap<>();
-    private final Set<String> usedProperties = ConcurrentHashMap.newKeySet();
+    private final AtomicReference<Set<String>> usedPropertiesRef = new AtomicReference<>(ConcurrentHashMap.newKeySet());
 
     public Set<String> getUsedProperties() {
-        return Collections.unmodifiableSet(new HashSet<>(usedProperties));
+        return Collections.unmodifiableSet(new HashSet<>(usedPropertiesRef.get()));
     }
 
     public Set<String> getAndClearUsedProperties() {
-        synchronized (usedProperties) {
-            Set<String> ret = getUsedProperties();
-            usedProperties.clear();
-            return ret;
-        }
+        Set<String> ret = usedPropertiesRef.getAndSet(ConcurrentHashMap.newKeySet());
+        return Collections.unmodifiableSet(new HashSet<>(ret));
     }
 
     private List<AbstractConfiguration> configList = new CopyOnWriteArrayList<AbstractConfiguration>();
@@ -590,7 +588,7 @@ private Object getProperty(String key, boolean instrument)
      */
     public void recordUsage(String key) {
         if (enableInstrumentation) {
-            usedProperties.add(key);
+            usedPropertiesRef.get().add(key);
             if (enableStackTrace) {
                 String trace = Arrays.toString(Thread.currentThread().getStackTrace());
                 stackTraces.merge(trace, 1, (v1, v2) -> v1 + 1);