Fix #1186: improve recycled buffer release logic (#1187)

Author: cowtowncoder

release-notes/VERSION-2.x

@@ -26,6 +26,8 @@ a pure JSON library.
 #1179: Allow configuring `DefaultPrettyPrinter` separators for empty
   Arrays and Objects
  (contributed by Guillaume L)
+#1186: `BufferRecycler` should avoid setting replacement if one already returned, bigger
+ (suggested by @kkkkkhhhh)
 
 2.16.2 (not yet released)
 

src/main/java/com/fasterxml/jackson/core/util/BufferRecycler.java

@@ -145,7 +145,12 @@ public byte[] allocByteBuffer(int ix, int minSize) {
     }
 
     public void releaseByteBuffer(int ix, byte[] buffer) {
-        _byteBuffers.set(ix, buffer);
+        // 13-Jan-2024, tatu: [core#1186] Replace only if beneficial:
+        byte[] oldBuffer = _byteBuffers.get(ix);
+        if ((oldBuffer == null) || buffer.length > oldBuffer.length) {
+            // Could use CAS, but should not really matter
+            _byteBuffers.set(ix, buffer);
+        }
     }
 
     /*
@@ -171,7 +176,12 @@ public char[] allocCharBuffer(int ix, int minSize) {
     }
 
     public void releaseCharBuffer(int ix, char[] buffer) {
-        _charBuffers.set(ix, buffer);
+        // 13-Jan-2024, tatu: [core#1186] Replace only if beneficial:
+        char[] oldBuffer = _charBuffers.get(ix);
+        if ((oldBuffer == null) || buffer.length > oldBuffer.length) {
+            // Could use CAS, but should not really matter
+            _charBuffers.set(ix, buffer);
+        }
     }
 
     /*