Mark ChannelHandler.exceptionCaught(...) as deprecated in preparation to move to ChannelInboundHandler. Related to [#1808]

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

@@ -194,7 +194,12 @@ public interface ChannelHandler {
 
     /**
      * Gets called if a {@link Throwable} was thrown.
+     *
+     * @deprecated  Will be removed in the future and only {@link ChannelInboundHandler} will receive
+     *              exceptionCaught events. For {@link ChannelOutboundHandler} the {@link ChannelPromise}
+     *              must be failed.
      */
+    @Deprecated
     void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception;
 
     /**

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

@@ -54,6 +54,7 @@ public abstract class ChannelHandlerAdapter implements ChannelHandler {
      *
      * Sub-classes may override this method to change behavior.
      */
+    @Deprecated
     @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
             throws Exception {

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

@@ -68,4 +68,10 @@ public interface ChannelInboundHandler extends ChannelHandler {
      * {@link Channel#isWritable()}.
      */
     void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception;
+
+    /**
+     * Gets called if a {@link Throwable} was thrown.
+     */
+    @Override
+    void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception;
 }

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

@@ -118,4 +118,16 @@ public class ChannelInboundHandlerAdapter extends ChannelHandlerAdapter implemen
     public void channelWritabilityChanged(ChannelHandlerContext ctx) throws Exception {
         ctx.fireChannelWritabilityChanged();
     }
+
+    /**
+     * Calls {@link ChannelHandlerContext#fireExceptionCaught(Throwable)} to forward
+     * to the next {@link ChannelHandler} in the {@link ChannelPipeline}.
+     *
+     * Sub-classes may override this method to change behavior.
+     */
+    @Override
+    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
+            throws Exception {
+        ctx.fireExceptionCaught(cause);
+    }
 }