Allow to obtain RecvByteBufAllocator.Handle to allow more flexible implementations

Motivation:

At the moment it's only possible for a user to set the RecvByteBufAllocator for a Channel but not access the Handle once it is assigned. This makes it hard to write more flexible implementations.

Modifications:

Add a new method to the Channel.Unsafe to allow access the the used Handle for the Channel. The RecvByteBufAllocator.Handle is created lazily.

Result:

It's possible to write more flexible implementatons that allow to adjust stuff on the fly for a Handle that is used by a Channel

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollDatagramChannel.java

@@ -386,7 +386,6 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
     }
 
     final class EpollDatagramChannelUnsafe extends AbstractEpollUnsafe {
-        private RecvByteBufAllocator.Handle allocHandle;
 
         @Override
         public void connect(SocketAddress remote, SocketAddress local, ChannelPromise channelPromise) {
@@ -419,10 +418,7 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
         @Override
         void epollInReady() {
             DatagramChannelConfig config = config();
-            RecvByteBufAllocator.Handle allocHandle = this.allocHandle;
+            RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
-            if (allocHandle == null) {
-                this.allocHandle = allocHandle = config.getRecvByteBufAllocator().newHandle();
-            }
 
             assert eventLoop().inEventLoop();
             final ChannelPipeline pipeline = pipeline();

transport-native-epoll/src/main/java/io/netty/channel/epoll/EpollSocketChannel.java

@@ -693,10 +693,7 @@ public final class EpollSocketChannel extends AbstractEpollChannel implements So
             final ChannelConfig config = config();
             final ChannelPipeline pipeline = pipeline();
             final ByteBufAllocator allocator = config.getAllocator();
-            RecvByteBufAllocator.Handle allocHandle = this.allocHandle;
+            RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
-            if (allocHandle == null) {
-                this.allocHandle = allocHandle = config.getRecvByteBufAllocator().newHandle();
-            }
 
             ByteBuf byteBuf = null;
             boolean close = false;

transport-sctp/src/main/java/io/netty/channel/sctp/nio/NioSctpChannel.java

@@ -68,8 +68,6 @@ public class NioSctpChannel extends AbstractNioMessageChannel implements io.nett
 
     private final NotificationHandler<?> notificationHandler;
 
-    private RecvByteBufAllocator.Handle allocHandle;
-
     private static SctpChannel newSctpChannel() {
         try {
             return SctpChannel.open();
@@ -265,10 +263,7 @@ public class NioSctpChannel extends AbstractNioMessageChannel implements io.nett
     protected int doReadMessages(List<Object> buf) throws Exception {
         SctpChannel ch = javaChannel();
 
-        RecvByteBufAllocator.Handle allocHandle = this.allocHandle;
+        RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
-        if (allocHandle == null) {
-            this.allocHandle = allocHandle = config().getRecvByteBufAllocator().newHandle();
-        }
         ByteBuf buffer = allocHandle.allocate(config().getAllocator());
         boolean free = true;
         try {

transport-sctp/src/main/java/io/netty/channel/sctp/oio/OioSctpChannel.java

@@ -76,8 +76,6 @@ public class OioSctpChannel extends AbstractOioMessageChannel
 
     private final NotificationHandler<?> notificationHandler;
 
-    private RecvByteBufAllocator.Handle allocHandle;
-
     private static SctpChannel openChannel() {
         try {
             return SctpChannel.open();
@@ -187,10 +185,7 @@ public class OioSctpChannel extends AbstractOioMessageChannel
         Set<SelectionKey> reableKeys = readSelector.selectedKeys();
         try {
             for (SelectionKey ignored : reableKeys) {
-                RecvByteBufAllocator.Handle allocHandle = this.allocHandle;
+                RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
-                if (allocHandle == null) {
-                    this.allocHandle = allocHandle = config().getRecvByteBufAllocator().newHandle();
-                }
                 ByteBuf buffer = allocHandle.allocate(config().getAllocator());
                 boolean free = true;
 

transport/src/main/java/io/netty/channel/AbstractChannel.java

@@ -419,8 +419,17 @@ public abstract class AbstractChannel extends DefaultAttributeMap implements Cha
     protected abstract class AbstractUnsafe implements Unsafe {
 
         private ChannelOutboundBuffer outboundBuffer = new ChannelOutboundBuffer(AbstractChannel.this);
+        private RecvByteBufAllocator.Handle recvHandle;
         private boolean inFlush0;
 
+        @Override
+        public RecvByteBufAllocator.Handle recvBufAllocHandle() {
+            if (recvHandle == null) {
+                recvHandle = config().getRecvByteBufAllocator().newHandle();
+            }
+            return recvHandle;
+        }
+
         @Override
         public final ChannelHandlerInvoker invoker() {
             // return the unwrapped invoker.

transport/src/main/java/io/netty/channel/Channel.java

@@ -464,6 +464,12 @@ public interface Channel extends AttributeMap, Comparable<Channel> {
      */
     interface Unsafe {
 
+        /**
+         * Return the assigned {@link RecvByteBufAllocator.Handle} which will be used to allocate {@link ByteBuf}'s when
+         * receiving data.
+         */
+        RecvByteBufAllocator.Handle recvBufAllocHandle();
+
         /**
          * Returns the {@link ChannelHandlerInvoker} which is used by default unless specified by a user.
          */

transport/src/main/java/io/netty/channel/nio/AbstractNioByteChannel.java

@@ -58,7 +58,6 @@ public abstract class AbstractNioByteChannel extends AbstractNioChannel {
     }
 
     private final class NioByteUnsafe extends AbstractNioUnsafe {
-        private RecvByteBufAllocator.Handle allocHandle;
 
         private void closeOnRead(ChannelPipeline pipeline) {
             SelectionKey key = selectionKey();
@@ -102,10 +101,7 @@ public abstract class AbstractNioByteChannel extends AbstractNioChannel {
             final ChannelPipeline pipeline = pipeline();
             final ByteBufAllocator allocator = config.getAllocator();
             final int maxMessagesPerRead = config.getMaxMessagesPerRead();
-            RecvByteBufAllocator.Handle allocHandle = this.allocHandle;
+            RecvByteBufAllocator.Handle allocHandle = recvBufAllocHandle();
-            if (allocHandle == null) {
-                this.allocHandle = allocHandle = config.getRecvByteBufAllocator().newHandle();
-            }
 
             ByteBuf byteBuf = null;
             int messages = 0;

transport/src/main/java/io/netty/channel/oio/AbstractOioByteChannel.java

@@ -39,7 +39,6 @@ public abstract class AbstractOioByteChannel extends AbstractOioChannel {
             " (expected: " + StringUtil.simpleClassName(ByteBuf.class) + ", " +
             StringUtil.simpleClassName(FileRegion.class) + ')';
 
-    private RecvByteBufAllocator.Handle allocHandle;
     private volatile boolean inputShutdown;
 
     /**
@@ -82,10 +81,7 @@ public abstract class AbstractOioByteChannel extends AbstractOioChannel {
         final ChannelConfig config = config();
         final ChannelPipeline pipeline = pipeline();
 
-        RecvByteBufAllocator.Handle allocHandle = this.allocHandle;
+        RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
-        if (allocHandle == null) {
-            this.allocHandle = allocHandle = config.getRecvByteBufAllocator().newHandle();
-        }
 
         ByteBuf byteBuf = allocHandle.allocate(alloc());
 

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

@@ -72,7 +72,6 @@ public final class NioDatagramChannel
     private final DatagramChannelConfig config;
 
     private Map<InetAddress, List<MembershipKey>> memberships;
-    private RecvByteBufAllocator.Handle allocHandle;
 
     private static DatagramChannel newSocket(SelectorProvider provider) {
         try {
@@ -230,10 +229,8 @@ public final class NioDatagramChannel
     protected int doReadMessages(List<Object> buf) throws Exception {
         DatagramChannel ch = javaChannel();
         DatagramChannelConfig config = config();
-        RecvByteBufAllocator.Handle allocHandle = this.allocHandle;
+        RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
-        if (allocHandle == null) {
+
-            this.allocHandle = allocHandle = config.getRecvByteBufAllocator().newHandle();
-        }
         ByteBuf data = allocHandle.allocate(config.getAllocator());
         boolean free = true;
         try {

transport/src/main/java/io/netty/channel/socket/oio/OioDatagramChannel.java

@@ -71,8 +71,6 @@ public class OioDatagramChannel extends AbstractOioMessageChannel
     private final DatagramChannelConfig config;
     private final java.net.DatagramPacket tmpPacket = new java.net.DatagramPacket(EmptyArrays.EMPTY_BYTES, 0);
 
-    private RecvByteBufAllocator.Handle allocHandle;
-
     private static MulticastSocket newSocket() {
         try {
             return new MulticastSocket(null);
@@ -202,10 +200,7 @@ public class OioDatagramChannel extends AbstractOioMessageChannel
     @Override
     protected int doReadMessages(List<Object> buf) throws Exception {
         DatagramChannelConfig config = config();
-        RecvByteBufAllocator.Handle allocHandle = this.allocHandle;
+        RecvByteBufAllocator.Handle allocHandle = unsafe().recvBufAllocHandle();
-        if (allocHandle == null) {
-            this.allocHandle = allocHandle = config.getRecvByteBufAllocator().newHandle();
-        }
 
         ByteBuf data = config.getAllocator().heapBuffer(allocHandle.guess());
         boolean free = true;