Make PooledByteBuf recyclable regardless its maxCapacity

- Make AbstractByteBuf.maxCapacity internally mutable so that PooledByteBuf is completely recyclable

buffer/src/main/java/io/netty/buffer/AbstractByteBuf.java

@@ -39,7 +39,7 @@ public abstract class AbstractByteBuf implements ByteBuf {
     private int markedReaderIndex;
     private int markedWriterIndex;
 
-    private final int maxCapacity;
+    private int maxCapacity;
 
     private SwappedByteBuf swappedBuf;
 
@@ -55,6 +55,10 @@ public abstract class AbstractByteBuf implements ByteBuf {
         return maxCapacity;
     }
 
+    protected final void maxCapacity(int maxCapacity) {
+        this.maxCapacity = maxCapacity;
+    }
+
     @Override
     public int readerIndex() {
         return readerIndex;
@@ -216,7 +220,7 @@ public abstract class AbstractByteBuf implements ByteBuf {
         return this;
     }
 
-    protected void adjustMarkers(int decrement) {
+    protected final void adjustMarkers(int decrement) {
         int markedReaderIndex = this.markedReaderIndex;
         if (markedReaderIndex <= decrement) {
             this.markedReaderIndex = 0;

buffer/src/main/java/io/netty/buffer/PooledDirectByteBuf.java

@@ -31,16 +31,14 @@ final class PooledDirectByteBuf extends PooledByteBuf<ByteBuffer> {
     private static final Recycler<PooledDirectByteBuf> RECYCLER = new Recycler<PooledDirectByteBuf>() {
         @Override
         protected PooledDirectByteBuf newObject(Handle handle) {
-            return new PooledDirectByteBuf(handle, Integer.MAX_VALUE);
+            return new PooledDirectByteBuf(handle, 0);
         }
     };
 
     static PooledDirectByteBuf newInstance(int maxCapacity) {
-        if (maxCapacity == Integer.MAX_VALUE) {
-            return RECYCLER.get();
-        } else {
-            return new PooledDirectByteBuf(null, maxCapacity);
-        }
+        PooledDirectByteBuf buf = RECYCLER.get();
+        buf.maxCapacity(maxCapacity);
+        return buf;
     }
 
     private PooledDirectByteBuf(Recycler.Handle recyclerHandle, int maxCapacity) {

buffer/src/main/java/io/netty/buffer/PooledHeapByteBuf.java

@@ -30,16 +30,14 @@ final class PooledHeapByteBuf extends PooledByteBuf<byte[]> {
     private static final Recycler<PooledHeapByteBuf> RECYCLER = new Recycler<PooledHeapByteBuf>() {
         @Override
         protected PooledHeapByteBuf newObject(Handle handle) {
-            return new PooledHeapByteBuf(handle, Integer.MAX_VALUE);
+            return new PooledHeapByteBuf(handle, 0);
         }
     };
 
     static PooledHeapByteBuf newInstance(int maxCapacity) {
-        if (maxCapacity == Integer.MAX_VALUE) {
-            return RECYCLER.get();
-        } else {
-            return new PooledHeapByteBuf(null, maxCapacity);
-        }
+        PooledHeapByteBuf buf = RECYCLER.get();
+        buf.maxCapacity(maxCapacity);
+        return buf;
     }
 
     private PooledHeapByteBuf(Recycler.Handle recyclerHandle, int maxCapacity) {

buffer/src/main/java/io/netty/buffer/PooledUnsafeDirectByteBuf.java

@@ -35,16 +35,14 @@ final class PooledUnsafeDirectByteBuf extends PooledByteBuf<ByteBuffer> {
     private static final Recycler<PooledUnsafeDirectByteBuf> RECYCLER = new Recycler<PooledUnsafeDirectByteBuf>() {
         @Override
         protected PooledUnsafeDirectByteBuf newObject(Handle handle) {
-            return new PooledUnsafeDirectByteBuf(handle, Integer.MAX_VALUE);
+            return new PooledUnsafeDirectByteBuf(handle, 0);
         }
     };
 
     static PooledUnsafeDirectByteBuf newInstance(int maxCapacity) {
-        if (maxCapacity == Integer.MAX_VALUE) {
-            return RECYCLER.get();
-        } else {
-            return new PooledUnsafeDirectByteBuf(null, maxCapacity);
-        }
+        PooledUnsafeDirectByteBuf buf = RECYCLER.get();
+        buf.maxCapacity(maxCapacity);
+        return buf;
     }
 
     private long memoryAddress;