Handle different behaviour of UDP sockets on Linux and Mac OS X in Ud…

…pTransportTest

It seems that Netty (or maybe the respective OS kernel) is handling datagrams larger than
the configured receive buffer differently on Linux and Mac OS X.

While on Mac OS X the data is completely discarded, the datagram is truncated on Linux.

graylog2-inputs/src/test/java/org/graylog2/inputs/transports/UdpTransportTest.java

@@ -19,6 +19,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.util.concurrent.Callables;
 import com.google.common.util.concurrent.Uninterruptibles;
+import org.apache.commons.lang3.SystemUtils;
 import org.graylog2.plugin.LocalMetricRegistry;
 import org.graylog2.plugin.configuration.Configuration;
 import org.graylog2.plugin.configuration.ConfigurationRequest;
@@ -50,6 +51,7 @@
 
 import static com.jayway.awaitility.Awaitility.await;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.Assume.assumeTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
@@ -113,7 +115,9 @@ public Boolean call() throws Exception {
     }
 
     @Test
-    public void transportDiscardsDataLargerRecvBufferSize() throws Exception {
+    public void transportDiscardsDataLargerRecvBufferSizeOnMacOsX() throws Exception {
+        assumeTrue(SystemUtils.IS_OS_MAC_OSX);
+
         final CountingChannelUpstreamHandler handler = new CountingChannelUpstreamHandler();
         final UdpTransport transport = launchTransportForBootStrapTest(handler);
 
@@ -125,6 +129,25 @@ public void transportDiscardsDataLargerRecvBufferSize() throws Exception {
         assertThat(handler.getBytesWritten()).isEmpty();
     }
 
+    @Test
+    public void transportTruncatesDataLargerRecvBufferSizeOnLinux() throws Exception {
+        assumeTrue(SystemUtils.IS_OS_LINUX);
+
+        final CountingChannelUpstreamHandler handler = new CountingChannelUpstreamHandler();
+        final UdpTransport transport = launchTransportForBootStrapTest(handler);
+
+        sendUdpDatagram(BIND_ADDRESS, PORT, 2 * RECV_BUFFER_SIZE);
+        await().atMost(5, TimeUnit.SECONDS).until(new Callable<Boolean>() {
+            @Override
+            public Boolean call() throws Exception {
+                return !handler.getBytesWritten().isEmpty();
+            }
+        });
+        transport.stop();
+
+        assertThat(handler.getBytesWritten()).containsExactly(RECV_BUFFER_SIZE);
+    }
+
     private UdpTransport launchTransportForBootStrapTest(final ChannelHandler channelHandler) throws MisfireException {
         final UdpTransport transport = new UdpTransport(CONFIGURATION, throughputCounter, new LocalMetricRegistry()) {
             @Override