[GitHub] [pulsar] Demogorgon314 commented on a diff in pull request #15707: [fix][ML]Fix NPE when put value to `RangeCache`.

[GitBox <gi...@apache.org>]

Demogorgon314 commented on code in PR #15707:
URL: https://github.com/apache/pulsar/pull/15707#discussion_r878992514


##########
managed-ledger/src/main/java/org/apache/bookkeeper/mledger/util/RangeCache.java:
##########
@@ -73,12 +73,11 @@ public RangeCache(Weighter<Value> weighter, TimestampExtractor<Value> timestampE
      * @return whether the entry was inserted in the cache
      */
     public boolean put(Key key, Value value) {
-        if (entries.putIfAbsent(key, value) == null) {
+        Value v = entries.computeIfAbsent(key, (k) -> {
             size.addAndGet(weighter.getSize(value));
-            return true;
-        } else {
-            return false;
-        }
+            return value;
+        });
+        return v == value;

Review Comment:
   Nice catch! But look like it changed the original behavior. See the following test. Its success in the old code but failed in this change.
   ```java
       @Test
       public void test() {
           RangeCache<Integer, RefString> cache = new RangeCache<>();
           RefString s0 = new RefString("zero");
           assertEquals(s0.refCnt(), 1);
           assertTrue(cache.put(0, s0));
           assertFalse(cache.put(0, s0));
       }
   ```



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