Reduce even more garbage by exposing ByteBuf.internalNioBuffer()

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

@@ -950,6 +950,11 @@ public abstract class AbstractByteBuf implements ByteBuf {
         return nioBuffers(readerIndex, readableBytes());
     }
 
+    @Override
+    public ByteBuffer nioBuffer(int index, int length) {
+        return internalNioBuffer(index, length).slice();
+    }
+
     @Override
     public String toString(Charset charset) {
         return toString(readerIndex, readableBytes(), charset);

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

@@ -1784,6 +1784,11 @@ public interface ByteBuf extends ReferenceCounted, Comparable<ByteBuf> {
      */
     ByteBuffer nioBuffer(int index, int length);
 
+    /**
+     * Internal use only: Exposes the internal NIO buffer.
+     */
+    ByteBuffer internalNioBuffer(int index, int length);
+
     /**
      * Exposes this buffer's readable bytes as an NIO {@link ByteBuffer}'s.  The returned buffer
      * shares the content with this buffer, while changing the position and limit of the returned

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

@@ -991,9 +991,9 @@ public class DefaultCompositeByteBuf extends AbstractReferenceCountedByteBuf imp
     }
 
     @Override
-    public ByteBuffer nioBuffer(int index, int length) {
+    public ByteBuffer internalNioBuffer(int index, int length) {
         if (components.size() == 1) {
-            return components.get(0).buf.nioBuffer(index, length);
+            return components.get(0).buf.internalNioBuffer(index, length);
         }
         throw new UnsupportedOperationException();
     }

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

@@ -282,14 +282,14 @@ public class DuplicatedByteBuf extends AbstractDerivedByteBuf {
         return buffer.nioBufferCount();
     }
 
-    @Override
-    public ByteBuffer nioBuffer(int index, int length) {
-        return buffer.nioBuffer(index, length);
-    }
-
     @Override
     public ByteBuffer[] nioBuffers(int index, int length) {
         return buffer.nioBuffers(index, length);
     }
+
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        return buffer.internalNioBuffer(index, length);
+    }
 }
 

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

@@ -760,6 +760,11 @@ public final class EmptyByteBuf implements ByteBuf {
         return nioBuffers();
     }
 
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        return EMPTY_BYTE_BUFFER;
+    }
+
     @Override
     public boolean hasArray() {
         return true;

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

@@ -257,15 +257,15 @@ final class PooledDirectByteBuf extends PooledByteBuf<ByteBuffer> {
     }
 
     @Override
-    public ByteBuffer nioBuffer(int index, int length) {
+    public ByteBuffer[] nioBuffers(int index, int length) {
-        checkIndex(index, length);
+        return new ByteBuffer[] { nioBuffer(index, length) };
-        index = idx(index);
-        return ((ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length)).slice();
     }
 
     @Override
-    public ByteBuffer[] nioBuffers(int index, int length) {
+    public ByteBuffer internalNioBuffer(int index, int length) {
-        return new ByteBuffer[] { nioBuffer(index, length) };
+        checkIndex(index, length);
+        index = idx(index);
+        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
     }
 
     @Override

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

@@ -232,15 +232,15 @@ final class PooledHeapByteBuf extends PooledByteBuf<byte[]> {
     }
 
     @Override
-    public ByteBuffer nioBuffer(int index, int length) {
+    public ByteBuffer[] nioBuffers(int index, int length) {
-        checkIndex(index, length);
+        return new ByteBuffer[] { nioBuffer(index, length) };
-        index = idx(index);
-        return ((ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length)).slice();
     }
 
     @Override
-    public ByteBuffer[] nioBuffers(int index, int length) {
+    public ByteBuffer internalNioBuffer(int index, int length) {
-        return new ByteBuffer[] { nioBuffer(index, length) };
+        checkIndex(index, length);
+        index = idx(index);
+        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
     }
 
     @Override

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

@@ -294,15 +294,15 @@ final class PooledUnsafeDirectByteBuf extends PooledByteBuf<ByteBuffer> {
     }
 
     @Override
-    public ByteBuffer nioBuffer(int index, int length) {
+    public ByteBuffer[] nioBuffers(int index, int length) {
-        checkIndex(index, length);
+        return new ByteBuffer[] { nioBuffer(index, length) };
-        index = idx(index);
-        return ((ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length)).slice();
     }
 
     @Override
-    public ByteBuffer[] nioBuffers(int index, int length) {
+    public ByteBuffer internalNioBuffer(int index, int length) {
-        return new ByteBuffer[] { nioBuffer(index, length) };
+        checkIndex(index, length);
+        index = idx(index);
+        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
     }
 
     @Override

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

@@ -290,6 +290,11 @@ public class ReadOnlyByteBuf extends AbstractDerivedByteBuf {
         return buffer.nioBuffers(index, length);
     }
 
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        return buffer.internalNioBuffer(index, length);
+    }
+
     @Override
     public int capacity() {
         return buffer.capacity();

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

@@ -278,18 +278,14 @@ class ReadOnlyByteBufferBuf extends AbstractReferenceCountedByteBuf {
     }
 
     @Override
-    public ByteBuffer nioBuffer(int index, int length) {
+    public ByteBuffer[] nioBuffers(int index, int length) {
-        ensureAccessible();
+        return new ByteBuffer[] { nioBuffer(index, length) };
-        if (index == 0 && length == capacity()) {
-            return buffer.duplicate();
-        } else {
-            return ((ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length)).slice();
-        }
     }
 
     @Override
-    public ByteBuffer[] nioBuffers(int index, int length) {
+    public ByteBuffer internalNioBuffer(int index, int length) {
-        return new ByteBuffer[] { nioBuffer(index, length) };
+        ensureAccessible();
+        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
     }
 
     @Override

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

@@ -267,4 +267,10 @@ public class SlicedByteBuf extends AbstractDerivedByteBuf {
         checkIndex(index, length);
         return buffer.nioBuffers(index + adjustment, length);
     }
+
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        checkIndex(index, length);
+        return buffer.internalNioBuffer(index + adjustment, length);
+    }
 }

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

@@ -755,6 +755,12 @@ public final class SwappedByteBuf implements ByteBuf {
         return buf.nioBuffer(index, length).order(order);
     }
 
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        // Do not mess with the internal buffer's byte order.
+        return buf.nioBuffer(index, length).order(order);
+    }
+
     @Override
     public ByteBuffer[] nioBuffers() {
         ByteBuffer[] nioBuffers = buf.nioBuffers();

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

@@ -470,16 +470,6 @@ public class UnpooledDirectByteBuf extends AbstractReferenceCountedByteBuf {
         return 1;
     }
 
-    @Override
-    public ByteBuffer nioBuffer(int index, int length) {
-        ensureAccessible();
-        if (index == 0 && length == capacity()) {
-            return buffer.duplicate();
-        } else {
-            return ((ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length)).slice();
-        }
-    }
-
     @Override
     public ByteBuffer[] nioBuffers(int index, int length) {
         return new ByteBuffer[] { nioBuffer(index, length) };
@@ -503,6 +493,11 @@ public class UnpooledDirectByteBuf extends AbstractReferenceCountedByteBuf {
         return new UnpooledDirectByteBuf(alloc(), dst, maxCapacity());
     }
 
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
+    }
+
     private ByteBuffer internalNioBuffer() {
         ByteBuffer tmpNioBuf = this.tmpNioBuf;
         if (tmpNioBuf == null) {

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

@@ -256,6 +256,11 @@ public class UnpooledHeapByteBuf extends AbstractReferenceCountedByteBuf {
         return new ByteBuffer[] { nioBuffer(index, length) };
     }
 
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
+    }
+
     @Override
     public byte getByte(int index) {
         ensureAccessible();

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

@@ -409,16 +409,6 @@ public class UnpooledUnsafeDirectByteBuf extends AbstractReferenceCountedByteBuf
         return 1;
     }
 
-    @Override
-    public ByteBuffer nioBuffer(int index, int length) {
-        ensureAccessible();
-        if (index == 0 && length == capacity()) {
-            return buffer.duplicate();
-        } else {
-            return ((ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length)).slice();
-        }
-    }
-
     @Override
     public ByteBuffer[] nioBuffers(int index, int length) {
         return new ByteBuffer[] { nioBuffer(index, length) };
@@ -435,6 +425,11 @@ public class UnpooledUnsafeDirectByteBuf extends AbstractReferenceCountedByteBuf
         return copy;
     }
 
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
+    }
+
     private ByteBuffer internalNioBuffer() {
         ByteBuffer tmpNioBuf = this.tmpNioBuf;
         if (tmpNioBuf == null) {

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

@@ -771,6 +771,11 @@ final class UnreleasableByteBuf implements ByteBuf {
         return buf.nioBuffers(index, length);
     }
 
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        return buf.internalNioBuffer(index, length);
+    }
+
     @Override
     public boolean hasArray() {
         return buf.hasArray();

codec/src/main/java/io/netty/handler/codec/ReplayingDecoderBuffer.java

@@ -729,6 +729,12 @@ final class ReplayingDecoderBuffer implements ByteBuf {
         return buffer.nioBuffers(index, length);
     }
 
+    @Override
+    public ByteBuffer internalNioBuffer(int index, int length) {
+        checkIndex(index, length);
+        return buffer.internalNioBuffer(index, length);
+    }
+
     @Override
     public String toString(int index, int length, Charset charset) {
         checkIndex(index, length);

transport/src/main/java/io/netty/channel/socket/nio/NioSocketChannel.java

@@ -280,6 +280,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
         long expectedWrittenBytes = 0;
         for (int i = index; i < size; i++) {
             ByteBuf buf = bufs.get(i);
+            int readerIndex = buf.readerIndex();
             int readableBytes = buf.readableBytes();
             expectedWrittenBytes += readableBytes;
 
@@ -289,7 +290,7 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
                     if (nioBufferCnt == nioBuffers.length) {
                         nioBuffers = doubleNioBufferArray(nioBuffers, nioBufferCnt);
                     }
-                    nioBuffers[nioBufferCnt ++] = buf.nioBuffer();
+                    nioBuffers[nioBufferCnt ++] = buf.internalNioBuffer(readerIndex, readableBytes);
                 } else {
                     ByteBuffer[] nioBufs = buf.nioBuffers();
                     if (nioBufferCnt + nioBufs.length == nioBuffers.length + 1) {
@@ -304,13 +305,13 @@ public class NioSocketChannel extends AbstractNioByteChannel implements io.netty
                 }
             } else {
                 ByteBuf directBuf = alloc().directBuffer(readableBytes);
-                directBuf.writeBytes(buf, buf.readerIndex(), readableBytes);
+                directBuf.writeBytes(buf, readerIndex, readableBytes);
                 buf.release();
                 bufs.set(i, directBuf);
                 if (nioBufferCnt == nioBuffers.length) {
                     nioBuffers = doubleNioBufferArray(nioBuffers, nioBufferCnt);
                 }
-                nioBuffers[nioBufferCnt ++] = directBuf.nioBuffer();
+                nioBuffers[nioBufferCnt ++] = directBuf.internalNioBuffer(0, readableBytes);
             }
         }