Extract a method to allow easier injecting of custom shutdown behavior (

#1809)

zuul-core/src/main/java/com/netflix/zuul/netty/server/ClientConnectionsShutdown.java

@@ -52,6 +52,11 @@ public class ClientConnectionsShutdown {
     private static final DynamicIntProperty GRACEFUL_CLOSE_TIMEOUT =
             new DynamicIntProperty("server.outofservice.close.timeout", 30);
 
+    public enum ShutdownType {
+        OUT_OF_SERVICE,
+        SHUTDOWN
+    }
+
     private final ChannelGroup channels;
     private final EventExecutor executor;
     private final EurekaClient discoveryClient;
@@ -81,7 +86,7 @@ private void initDiscoveryListener() {
                     // Schedule to gracefully close all the client connections.
                     if (ENABLED.get()) {
                         executor.schedule(
-                                () -> gracefullyShutdownClientChannels(false),
+                                () -> gracefullyShutdownClientChannels(ShutdownType.OUT_OF_SERVICE),
                                 DELAY_AFTER_OUT_OF_SERVICE_MS.get(),
                                 TimeUnit.MILLISECONDS);
                     }
@@ -91,25 +96,23 @@ private void initDiscoveryListener() {
     }
 
     public Promise<Void> gracefullyShutdownClientChannels() {
-        return gracefullyShutdownClientChannels(true);
+        return gracefullyShutdownClientChannels(ShutdownType.SHUTDOWN);
     }
 
-    Promise<Void> gracefullyShutdownClientChannels(boolean forceCloseAfterTimeout) {
+    Promise<Void> gracefullyShutdownClientChannels(ShutdownType shutdownType) {
         // Mark all active connections to be closed after next response sent.
         LOG.warn("Flagging CLOSE_AFTER_RESPONSE on {} client channels.", channels.size());
 
         // racy situation if new connections are still coming in, but any channels created after newCloseFuture will
         // be closed during the force close stage
         ChannelGroupFuture closeFuture = channels.newCloseFuture();
         for (Channel channel : channels) {
-            ConnectionCloseType.setForChannel(channel, ConnectionCloseType.DELAYED_GRACEFUL);
-            ChannelPromise closePromise = channel.pipeline().newPromise();
-            channel.attr(ConnectionCloseChannelAttributes.CLOSE_AFTER_RESPONSE).set(closePromise);
+            flagChannelForClose(channel, shutdownType);
         }
 
         Promise<Void> promise = executor.newPromise();
         Runnable cancelTimeoutTask;
-        if (forceCloseAfterTimeout) {
+        if (shutdownType == ShutdownType.SHUTDOWN) {
             ScheduledFuture<?> timeoutTask = executor.schedule(
                     () -> {
                         LOG.warn("Force closing remaining {} active client channels.", channels.size());
@@ -141,4 +144,10 @@ Promise<Void> gracefullyShutdownClientChannels(boolean forceCloseAfterTimeout) {
 
         return promise;
     }
+
+    protected void flagChannelForClose(Channel channel, ShutdownType shutdownType) {
+        ConnectionCloseType.setForChannel(channel, ConnectionCloseType.DELAYED_GRACEFUL);
+        ChannelPromise closePromise = channel.pipeline().newPromise();
+        channel.attr(ConnectionCloseChannelAttributes.CLOSE_AFTER_RESPONSE).set(closePromise);
+    }
 }

zuul-core/src/test/java/com/netflix/zuul/netty/server/ClientConnectionsShutdownTest.java

@@ -18,9 +18,11 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyLong;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.ArgumentMatchers.isA;
+import static org.mockito.Mockito.doNothing;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.never;
 import static org.mockito.Mockito.spy;
@@ -31,6 +33,7 @@
 import com.netflix.discovery.EurekaClient;
 import com.netflix.discovery.EurekaEventListener;
 import com.netflix.discovery.StatusChangeEvent;
+import com.netflix.zuul.netty.server.ClientConnectionsShutdown.ShutdownType;
 import io.netty.bootstrap.Bootstrap;
 import io.netty.bootstrap.ServerBootstrap;
 import io.netty.channel.Channel;
@@ -225,7 +228,7 @@ void connectionsNotForceClosed() throws Exception {
         try {
             configuration.setProperty(configName, "0");
             createChannels(10);
-            Promise<Void> promise = shutdown.gracefullyShutdownClientChannels(false);
+            Promise<Void> promise = shutdown.gracefullyShutdownClientChannels(ShutdownType.OUT_OF_SERVICE);
             verify(eventLoop, never()).schedule(isA(Runnable.class), anyLong(), isA(TimeUnit.class));
             channels.forEach(Channel::close);
 
@@ -236,8 +239,22 @@ void connectionsNotForceClosed() throws Exception {
         }
     }
 
+    @Test
+    public void shutdownTypeForwardedToFlag() throws InterruptedException {
+        shutdown = spy(shutdown);
+        doNothing().when(shutdown).flagChannelForClose(any(), any());
+        createChannels(1);
+        Channel channel = channels.iterator().next();
+        for (ShutdownType type : ShutdownType.values()) {
+            shutdown.gracefullyShutdownClientChannels(type);
+            verify(shutdown).flagChannelForClose(channel, type);
+        }
+
+        channels.close().await(5, TimeUnit.SECONDS);
+    }
+
     private void createChannels(int numChannels) throws InterruptedException {
-        ChannelInitializer<LocalChannel> initializer = new ChannelInitializer<LocalChannel>() {
+        ChannelInitializer<LocalChannel> initializer = new ChannelInitializer<>() {
             @Override
             protected void initChannel(LocalChannel ch) {}
         };