From dfb1315ff5f188ca1d896f1b084099487ceb178f Mon Sep 17 00:00:00 2001
From: Andreas Dangel <andreas.dangel@pmd-code.org>
Date: Sun, 16 Feb 2020 10:43:35 +0100
Subject: [PATCH] [core] Use concurrent hash map in ParameterizedMetricKey

---
 .../pmd/lang/metrics/ParameterizedMetricKey.java       | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/metrics/ParameterizedMetricKey.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/metrics/ParameterizedMetricKey.java
index 474852c8ec..fd863681d9 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/metrics/ParameterizedMetricKey.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/metrics/ParameterizedMetricKey.java
@@ -4,8 +4,8 @@
 
 package net.sourceforge.pmd.lang.metrics;
 
-import java.util.HashMap;
-import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.ast.Node;
@@ -24,7 +24,7 @@ import net.sourceforge.pmd.util.DataMap.DataKey;
 @Deprecated
 public final class ParameterizedMetricKey<N extends Node> implements DataKey<ParameterizedMetricKey<N>, Double> {
 
-    private static final Map<ParameterizedMetricKey<?>, ParameterizedMetricKey<?>> POOL = new HashMap<>();
+    private static final ConcurrentMap<ParameterizedMetricKey<?>, ParameterizedMetricKey<?>> POOL = new ConcurrentHashMap<>();
 
     /** The metric key. */
     public final MetricKey<N> key;
@@ -72,9 +72,7 @@ public final class ParameterizedMetricKey<N extends Node> implements DataKey<Par
     public static <N extends Node> ParameterizedMetricKey<N> getInstance(MetricKey<N> key, MetricOptions options) {
         // sharing instances allows using DataMap, which uses reference identity
         ParameterizedMetricKey<N> tmp = new ParameterizedMetricKey<>(key, options);
-        if (!POOL.containsKey(tmp)) {
-            POOL.put(tmp, tmp);
-        }
+        POOL.putIfAbsent(tmp, tmp);
 
         @SuppressWarnings("unchecked")
         ParameterizedMetricKey<N> result = (ParameterizedMetricKey<N>) POOL.get(tmp);