[#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

@@ -256,20 +256,27 @@ public final class EpollDatagramChannel extends AbstractEpollChannel implements
                 break;
             }
 
-            boolean done = false;
-            for (int i = config().getWriteSpinCount() - 1; i >= 0; i--) {
-                if (doWriteMessage(msg)) {
-                    done = true;
+            try {
+                boolean done = false;
+                for (int i = config().getWriteSpinCount() - 1; i >= 0; i--) {
+                    if (doWriteMessage(msg)) {
+                        done = true;
+                        break;
+                    }
+                }
+
+                if (done) {
+                    in.remove();
+                } else {
+                    // Did not write all messages.
+                    setEpollOut();
                     break;
                 }
-            }
-
-            if (done) {
-                in.remove();
-            } else {
-                // Did not write all messages.
-                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

@@ -138,27 +138,41 @@ public abstract class AbstractNioMessageChannel extends AbstractNioChannel {
                 }
                 break;
             }
+            try {
+                boolean done = false;
+                for (int i = config().getWriteSpinCount() - 1; i >= 0; i--) {
+                    if (doWriteMessage(msg, in)) {
+                        done = true;
+                        break;
+                    }
+                }
 
-            boolean done = false;
-            for (int i = config().getWriteSpinCount() - 1; i >= 0; i --) {
-                if (doWriteMessage(msg, in)) {
-                    done = true;
+                if (done) {
+                    in.remove();
+                } else {
+                    // Did not write all messages.
+                    if ((interestOps & SelectionKey.OP_WRITE) == 0) {
+                        key.interestOps(interestOps | SelectionKey.OP_WRITE);
+                    }
                     break;
                 }
-            }
-
-            if (done) {
-                in.remove();
-            } else {
-                // Did not write all messages.
-                if ((interestOps & SelectionKey.OP_WRITE) == 0) {
-                    key.interestOps(interestOps | SelectionKey.OP_WRITE);
+            } catch (IOException e) {
+                if (continueOnWriteError()) {
+                    in.remove(e);
+                } else {
+                    throw e;
                 }
-                break;
             }
         }
     }
 
+    /**
+     * 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);
             }
-            socket.send(tmpPacket);
-            in.remove();
+            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);
+            }
         }
     }