Add toString implementations to all Drop implementations

This is helpful when debugging.

src/main/java/io/netty/buffer/api/CleanerPooledDrop.java

@@ -64,6 +64,11 @@ class CleanerPooledDrop implements Drop<Buffer> {
         cleanable = new GatedCleanable(gate, CLEANER.register(this, new CleanAction(pool, mem, ref, gate)));
     }
 
+    @Override
+    public String toString() {
+        return "CleanerPooledDrop(" + delegate + ')';
+    }
+
     private static final class CleanAction implements Runnable {
         private final SizeClassedMemoryPool pool;
         private final Object mem;

src/main/java/io/netty/buffer/api/CompositeBuffer.java

@@ -31,11 +31,19 @@ final class CompositeBuffer extends RcSupport<Buffer, CompositeBuffer> implement
      * non-composite copy of the buffer.
      */
     private static final int MAX_CAPACITY = Integer.MAX_VALUE - 8;
-    private static final Drop<CompositeBuffer> COMPOSITE_DROP = buf -> {
-        for (Buffer b : buf.bufs) {
-            b.close();
+    private static final Drop<CompositeBuffer> COMPOSITE_DROP = new Drop<CompositeBuffer>() {
+        @Override
+        public void drop(CompositeBuffer buf) {
+            for (Buffer b : buf.bufs) {
+                b.close();
+            }
+            buf.makeInaccessible();
+        }
+
+        @Override
+        public String toString() {
+            return "COMPOSITE_DROP";
         }
-        buf.makeInaccessible();
     };
 
     private final BufferAllocator allocator;

src/main/java/io/netty/buffer/api/SizeClassedMemoryPool.java

@@ -105,6 +105,11 @@ class SizeClassedMemoryPool implements BufferAllocator, AllocatorControl, Drop<B
         }
     }
 
+    @Override
+    public String toString() {
+        return "SizeClassedMemoryPool";
+    }
+
     @Override
     public Object allocateUntethered(Buffer originator, int size) {
         var sizeClassPool = getSizeClassPool(size);

src/main/java/io/netty/buffer/api/Statics.java

@@ -21,7 +21,15 @@ import java.lang.ref.Cleaner;
 
 interface Statics {
     Cleaner CLEANER = Cleaner.create();
-    Drop<Buffer> NO_OP_DROP = buf -> {
+    Drop<Buffer> NO_OP_DROP = new Drop<Buffer>() {
+        @Override
+        public void drop(Buffer obj) {
+        }
+
+        @Override
+        public String toString() {
+            return "NO_OP_DROP";
+        }
     };
 
     static VarHandle findVarHandle(Lookup lookup, Class<?> recv, String name, Class<?> type) {

src/main/java/io/netty/buffer/api/memseg/ArcDrop.java

@@ -94,6 +94,16 @@ final class ArcDrop implements Drop<MemSegBuffer> {
         return delegate;
     }
 
+    @Override
+    public String toString() {
+        StringBuilder builder = new StringBuilder().append("ArcDrop(").append(count).append(", ");
+        Drop<MemSegBuffer> drop = this;
+        while ((drop = ((ArcDrop) drop).unwrap()) instanceof ArcDrop) {
+            builder.append(((ArcDrop) drop).count).append(", ");
+        }
+        return builder.append(drop).append(')').toString();
+    }
+
     private static void checkValidState(int count) {
         if (count == 0) {
             throw new IllegalStateException("Underlying resources have already been freed.");

src/main/java/io/netty/buffer/api/memseg/MemSegBuffer.java

@@ -58,8 +58,16 @@ class MemSegBuffer extends RcSupport<Buffer, MemSegBuffer> implements Buffer, Re
     static {
         CLOSED_SEGMENT = MemorySegment.ofArray(new byte[0]);
         CLOSED_SEGMENT.close();
-        SEGMENT_CLOSE = buf -> {
-            buf.base.close();
+        SEGMENT_CLOSE = new Drop<MemSegBuffer>() {
+            @Override
+            public void drop(MemSegBuffer buf) {
+                buf.base.close();
+            }
+
+            @Override
+            public String toString() {
+                return "SEGMENT_CLOSE";
+            }
         };
     }
 
@@ -100,6 +108,11 @@ class MemSegBuffer extends RcSupport<Buffer, MemSegBuffer> implements Buffer, Re
         public void attach(MemSegBuffer buf) {
             delegate.attach(buf);
         }
+
+        @Override
+        public String toString() {
+            return "MemSegDrop(" + delegate + ')';
+        }
     }
 
     @Override