[#2665] Continue writing on IOException when using DatagramChannel

Motivation:

As a DatagramChannel supports to write to multiple remote peers we must not close the Channel once a IOException accours as this error may be only valid for one remote peer.

Modification:

Continue writing on IOException.

Result:

DatagramChannel can be used even after an IOException accours during writing.

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

@@ -256,6 +256,7 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
                 break;
             }
 
+            try {
                 boolean done = false;
                 for (int i = config().getWriteSpinCount() - 1; i >= 0; i--) {
                     if (doWriteMessage(msg)) {
@@ -271,6 +272,12 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
                     setEpollOut();
                     break;
                 }
+            } catch (IOException e) {
+                // Continue on write error as a DatagramChannel can write to multiple remote peers
+                //
+                // See https://github.com/netty/netty/issues/2665
+                in.remove(e);
+            }
         }
     }
 

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

@@ -138,9 +138,9 @@ public abstract class AbstractNioMessageChannel extends AbstractNioChannel {
                 }
                 break;
             }
-
+            try {
                 boolean done = false;
-            for (int i = config().getWriteSpinCount() - 1; i >= 0; i --) {
+                for (int i = config().getWriteSpinCount() - 1; i >= 0; i--) {
                     if (doWriteMessage(msg, in)) {
                         done = true;
                         break;
@@ -156,8 +156,22 @@ public abstract class AbstractNioMessageChannel extends AbstractNioChannel {
                     }
                     break;
                 }
+            } catch (IOException e) {
+                if (continueOnWriteError()) {
+                    in.remove(e);
+                } else {
+                    throw e;
                 }
             }
+        }
+    }
+
+    /**
+     * Returns {@code true} if we should continue the write loop on a write error.
+     */
+    protected boolean continueOnWriteError() {
+        return false;
+    }
 
     /**
      * Read messages into the given array and return the amount which was read.

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

@@ -291,10 +291,17 @@ public final class NioDatagramChannel
         } else {
             writtenBytes = javaChannel().write(nioData);
         }
-
         return writtenBytes > 0;
     }
 
+    @Override
+    protected boolean continueOnWriteError() {
+        // Continue on write error as a DatagramChannel can write to multiple remote peers
+        //
+        // See https://github.com/netty/netty/issues/2665
+        return true;
+    }
+
     @Override
     public InetSocketAddress localAddress() {
         return (InetSocketAddress) super.localAddress();

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

@@ -276,8 +276,15 @@ public class OioDatagramChannel extends AbstractOioMessageChannel
                 data.getBytes(data.readerIndex(), tmp);
                 tmpPacket.setData(tmp);
             }
+            try {
                 socket.send(tmpPacket);
                 in.remove();
+            } catch (IOException e) {
+                // Continue on write error as a DatagramChannel can write to multiple remote peers
+                //
+                // See https://github.com/netty/netty/issues/2665
+                in.remove(e);
+            }
         }
     }