trash derived buffers (#117744)

Author: mhl-b

modules/transport-netty4/src/main/java/org/elasticsearch/transport/netty4/NettyAllocator.java

@@ -362,49 +362,6 @@ public ByteBufAllocator getDelegate() {
         }
     }
 
-    static class TrashingByteBuf extends WrappedByteBuf {
-
-        private boolean trashed = false;
-
-        protected TrashingByteBuf(ByteBuf buf) {
-            super(buf);
-        }
-
-        @Override
-        public boolean release() {
-            if (refCnt() == 1) {
-                // see [NOTE on racy trashContent() calls]
-                trashContent();
-            }
-            return super.release();
-        }
-
-        @Override
-        public boolean release(int decrement) {
-            if (refCnt() == decrement && refCnt() > 0) {
-                // see [NOTE on racy trashContent() calls]
-                trashContent();
-            }
-            return super.release(decrement);
-        }
-
-        // [NOTE on racy trashContent() calls]: We trash the buffer content _before_ reducing the ref
-        // count to zero, which looks racy because in principle a concurrent caller could come along
-        // and successfully retain() this buffer to keep it alive after it's been trashed. Such a
-        // caller would sometimes get an IllegalReferenceCountException ofc but that's something it
-        // could handle - see for instance org.elasticsearch.transport.netty4.Netty4Utils.ByteBufRefCounted.tryIncRef.
-        // Yet in practice this should never happen, we only ever retain() these buffers while we
-        // know them to be alive (i.e. via RefCounted#mustIncRef or its moral equivalents) so it'd
-        // be a bug for a caller to retain() a buffer whose ref count is heading to zero and whose
-        // contents we've already decided to trash.
-        private void trashContent() {
-            if (trashed == false) {
-                trashed = true;
-                TrashingByteBufAllocator.trashBuffer(buf);
-            }
-        }
-    }
-
     static class TrashingCompositeByteBuf extends CompositeByteBuf {
 
         TrashingCompositeByteBuf(ByteBufAllocator alloc, boolean direct, int maxNumComponents) {