[Wisp] Socket.getChannel() should return null.

Summary:
Changing the return value of Socket.getChannel() will affect the
correctness of some libraries. For example, Apache geode tests whether
it is a nio adaptor channel through the return value of getChannel().

Test Plan: SocketGetChannelTest

Reviewed-by: yulei

Issue:
dragonwell-project#140

src/java.base/share/classes/java/net/ServerSocket.java

@@ -797,7 +797,7 @@ public void close() throws IOException {
      * @since 1.4
      */
     public ServerSocketChannel getChannel() {
-        return WispEngine.transparentWispSwitch() ? asyncImpl.getChannel() : null;
+        return null;
     }
 
     /**

src/java.base/share/classes/java/net/Socket.java

@@ -948,7 +948,7 @@ public SocketAddress getLocalSocketAddress() {
      * @since 1.4
      */
     public SocketChannel getChannel() {
-        return WispEngine.transparentWispSwitch() ? asyncImpl.getChannel() : null;
+        return null;
     }
 
     /**

src/java.base/share/classes/sun/nio/ch/WispServerSocketImpl.java

@@ -15,9 +15,9 @@
 
 public class WispServerSocketImpl
 {
-    private static WispEngineAccess WEA = SharedSecrets.getWispEngineAccess();
+    private static final WispEngineAccess WEA = SharedSecrets.getWispEngineAccess();
 
-    private WispSocketLockSupport wispSocketLockSupport = new WispSocketLockSupport();
+    private final WispSocketLockSupport wispSocketLockSupport = new WispSocketLockSupport();
     // The channel being adapted
     private ServerSocketChannelImpl ssc = null;
 
@@ -100,10 +100,6 @@ public void close() throws IOException {
         }
     }
 
-    public ServerSocketChannel getChannel() {
-        return ssc;
-    }
-
     public boolean isBound() {
         return ssc != null && ssc.isBound();
     }

src/java.base/share/classes/sun/nio/ch/WispSocketImpl.java

@@ -19,13 +19,13 @@
 
 public class WispSocketImpl
 {
-    private static WispEngineAccess WEA = SharedSecrets.getWispEngineAccess();
+    private static final WispEngineAccess WEA = SharedSecrets.getWispEngineAccess();
 
-    WispSocketLockSupport wispSocketLockSupport = new WispSocketLockSupport();
+    private final WispSocketLockSupport wispSocketLockSupport = new WispSocketLockSupport();
     // The channel being adapted
     private SocketChannelImpl sc = null;
     // 1 verse 1 related socket
-    private Socket so;
+    private final Socket so;
     // Timeout "option" value for reads
     protected int timeout = 0;
     private InputStream socketInputStream = null;
@@ -39,10 +39,6 @@ public WispSocketImpl(SocketChannel sc, Socket so) {
         this.sc = (SocketChannelImpl) sc;
     }
 
-    public SocketChannel getChannel() {
-        return sc;
-    }
-
     // Override this method just to protect against changes in the superclass
     //
     public void connect(SocketAddress remote) throws IOException {

test/jdk/com/alibaba/wisp/io/TestGlobalPoller.java

@@ -13,30 +13,28 @@
 import jdk.internal.access.SharedSecrets;
 import jdk.internal.access.WispEngineAccess;
 import sun.nio.ch.SelChImpl;
+import sun.nio.ch.WispSocketImpl;
 
 import java.lang.reflect.Field;
 import java.net.Socket;
 import java.nio.channels.SelectionKey;
 import java.nio.channels.SocketChannel;
+import java.security.PrivilegedAction;
 import java.util.Properties;
 
 import static jdk.test.lib.Asserts.assertTrue;
 import static jdk.test.lib.Asserts.assertNotNull;
 
 public class TestGlobalPoller {
-    private static WispEngineAccess access = SharedSecrets.getWispEngineAccess();
+    private static final WispEngineAccess access = SharedSecrets.getWispEngineAccess();
 
     static Properties p;
     static String socketAddr;
     static {
         p = java.security.AccessController.doPrivileged(
-                new java.security.PrivilegedAction<Properties>() {
-                    public Properties run() {
-                        return System.getProperties();
-                    }
-                }
+                (PrivilegedAction<Properties>) System::getProperties
         );
-        socketAddr = (String)p.get("test.wisp.socketAddress");
+        socketAddr = (String) p.get("test.wisp.socketAddress");
         if (socketAddr == null) {
             socketAddr = "www.example.com";
         }
@@ -50,7 +48,7 @@ public static void main(String[] args) throws Exception {
         // now server returns the data..
         // so is readable
         // current task is interested in read event.
-        SocketChannel ch = so.getChannel();
+        SocketChannel ch = getCh(so);
         access.registerEvent(ch, SelectionKey.OP_READ);
 
         Class<?> clazz = Class.forName("com.alibaba.wisp.engine.WispEventPump$Pool");
@@ -75,4 +73,13 @@ public static void main(String[] args) throws Exception {
 
         so.close();
     }
+
+    private static SocketChannel getCh(Socket so) throws Exception {
+        Field f = Socket.class.getDeclaredField("asyncImpl");
+        f.setAccessible(true);
+        WispSocketImpl wispSocket = (WispSocketImpl) f.get(so);
+        f = wispSocket.getClass().getDeclaredField("sc");
+        f.setAccessible(true);
+        return (SocketChannel) f.get(wispSocket);
+    }
 }

test/jdk/com/alibaba/wisp2/SocketGetChannelTest.java

@@ -0,0 +1,26 @@
+/*
+ * @test
+ * @library /test/lib
+ * @summary test Socket.getChannel returns null
+ * @requires os.family == "linux"
+ * @modules java.base/jdk.internal.access
+ * @modules java.base/com.alibaba.wisp.engine:+open
+ * @run main SocketGetChannelTest
+ * @run main/othervm -XX:+UseWisp2 SocketGetChannelTest
+ */
+
+import java.net.ServerSocket;
+import java.net.Socket;
+
+import static jdk.test.lib.Asserts.assertNull;
+
+public class SocketGetChannelTest {
+    public static void main(String[] args) throws Exception {
+        ServerSocket ss = new ServerSocket(0);
+        Socket s1 = new Socket("localhost", ss.getLocalPort());
+        Socket s2 = ss.accept();
+        assertNull(ss.getChannel());
+        assertNull(s1.getChannel());
+        assertNull(s2.getChannel());
+    }
+}