fix apache#11986

looly · Apr 2, 2023 · 725fe23 · 725fe23
1 parent f32da50
commit 725fe23
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Showing 2 changed files with 24 additions and 1 deletion.
diff --git a/dubbo-common/src/main/java/org/apache/dubbo/common/utils/ConcurrentHashMapUtils.java b/dubbo-common/src/main/java/org/apache/dubbo/common/utils/ConcurrentHashMapUtils.java
@@ -35,7 +35,18 @@ public static <K, V> V computeIfAbsent(ConcurrentMap<K, V> map, K key, Function<
         if (JRE.JAVA_8.isCurrentVersion()) {
             V v = map.get(key);
             if (null == v) {
-                v = map.computeIfAbsent(key, func);
+                // issue#11986 lock bug
+                // v = map.computeIfAbsent(key, func);
+
+                // this bug fix methods maybe cause `func.apply` multiple calls.
+                value = func.apply(key);
+                final V res = map.putIfAbsent(key, value);
+                if(null != res){
+                    // if pre value present, means other thread put value already, and putIfAbsent not effect
+                    // return exist value
+				    return res;
+			    }
+                // if pre value is null, means putIfAbsent effected, return current value
             }
             return v;
         } else {

diff --git a/dubbo-common/src/test/java/org/apache/dubbo/common/utils/ConcurrentHashMapUtilsTest.java b/dubbo-common/src/test/java/org/apache/dubbo/common/utils/ConcurrentHashMapUtilsTest.java
@@ -37,4 +37,16 @@ public void testComputeIfAbsent() {
         ifAbsent = ConcurrentHashMapUtils.computeIfAbsent(map, "mxsm", k -> "mxsm1");
         assertEquals("mxsm1", ifAbsent);
     }
+
+    @Test
+	public void issue11986Test(){
+        // https://github.com/apache/dubbo/issues/11986
+		final ConcurrentHashMap<String,Integer> map=new ConcurrentHashMap<>();
+        // // map.computeIfAbsent("AaAa", key->map.computeIfAbsent("BBBB",key2->42));
+        ConcurrentHashMapUtils.computeIfAbsent(map, "AaAa", key->map.computeIfAbsent("BBBB",key2->42));
+
+		assertEquals(2, map.size());
+		assertEquals(Integer.valueOf(42), map.get("AaAa"));
+		assertEquals(Integer.valueOf(42), map.get("BBBB"));
+	}
 }