8253119: Remove the legacy PlainSocketImpl and PlainDatagramSocketImp…

…l implementation

Reviewed-by: alanb, dfuchs, chegar

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1995, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1995, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -52,14 +52,6 @@
 public final
 class DatagramPacket {
 
-    /**
-     * Perform class initialization
-     */
-    static {
-        jdk.internal.loader.BootLoader.loadLibrary("net");
-        init();
-    }
-
     /*
      * The fields of this class are package-private since DatagramSocketImpl
      * classes needs to access them.
@@ -424,9 +416,4 @@ public synchronized void setLength(int length) {
         this.length = length;
         this.bufLength = this.length;
     }
-
-    /**
-     * Perform class load-time initializations.
-     */
-    private static native void init();
 }

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

@@ -31,6 +31,7 @@
 import java.nio.channels.MulticastChannel;
 import java.security.AccessController;
 import java.security.PrivilegedAction;
+import java.util.Objects;
 import java.util.Set;
 import sun.net.NetProperties;
 import sun.nio.ch.DefaultSelectorProvider;
@@ -1338,14 +1339,6 @@ public void leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf)
 
     // Temporary solution until JDK-8237352 is addressed
     private static final SocketAddress NO_DELEGATE = new SocketAddress() {};
-    private static final boolean USE_PLAINDATAGRAMSOCKET = usePlainDatagramSocketImpl();
-
-    private static boolean usePlainDatagramSocketImpl() {
-        PrivilegedAction<String> pa = () -> NetProperties.get("jdk.net.usePlainDatagramSocketImpl");
-        @SuppressWarnings("removal")
-        String s = AccessController.doPrivileged(pa);
-        return (s != null) && (s.isEmpty() || s.equalsIgnoreCase("true"));
-    }
 
     /**
      * Best effort to convert an {@link IOException}
@@ -1398,14 +1391,11 @@ static <T extends DatagramSocket> T createDelegate(SocketAddress bindaddr, Class
         boolean initialized = false;
         try {
             DatagramSocketImplFactory factory = DatagramSocket.factory;
-            if (USE_PLAINDATAGRAMSOCKET || factory != null) {
+            if (factory != null) {
                 // create legacy DatagramSocket delegate
-                DatagramSocketImpl impl;
-                if (factory != null) {
-                    impl = factory.createDatagramSocketImpl();
-                } else {
-                    impl = DefaultDatagramSocketImplFactory.createDatagramSocketImpl(multicast);
-                }
+                DatagramSocketImpl impl = factory.createDatagramSocketImpl();
+                Objects.requireNonNull(impl,
+                        "Implementation returned by installed DatagramSocketImplFactory is null");
                 delegate = new NetMulticastSocket(impl);
                 ((NetMulticastSocket) delegate).getImpl(); // ensure impl.create() is called.
             } else {

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1996, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1996, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,24 +33,6 @@
 /**
  * Abstract datagram and multicast socket implementation base class.
  *
- * @implNote Sockets created with the {@code DatagramSocket} and {@code
- * MulticastSocket} public constructors historically delegated all socket
- * operations to a {@code DatagramSocketImpl} implementation named
- * "PlainDatagramSocketImpl". {@code DatagramSocket} and {@code MulticastSocket}
- * have since been changed to a new implementation based on {@code DatagramChannel}.
- * The JDK continues to ship with the older implementation to allow code to run
- * that depends on unspecified behavior that differs between the old and new
- * implementations. The old implementation will be used if the Java virtual
- * machine is started with the system property {@systemProperty
- * jdk.net.usePlainDatagramSocketImpl} set to use the old implementation. It may
- * also be set in the JDK's network configuration file, located in {@code
- * ${java.home}/conf/net.properties}. The value of the property is the string
- * representation of a boolean. If set without a value then it defaults to {@code
- * true}, hence running with {@code -Djdk.net.usePlainDatagramSocketImpl} or
- * {@code -Djdk.net.usePlainDatagramSocketImpl=true} will configure the Java
- * virtual machine to use the old implementation. The property and old
- * implementation will be removed in a future version.
- *
  * @author Pavani Diwanji
  * @since  1.1
  */

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

@@ -136,8 +136,7 @@ private synchronized void connectInternal(InetAddress address, int port) throws
             bind(new InetSocketAddress(0));
 
         // old impls do not support connect/disconnect
-        if (oldImpl || (impl instanceof AbstractPlainDatagramSocketImpl &&
-                ((AbstractPlainDatagramSocketImpl) impl).nativeConnectDisabled())) {
+        if (oldImpl) {
             connectState = ST_CONNECTED_NO_IMPL;
         } else {
             try {

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

@@ -29,12 +29,9 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
-import java.security.AccessController;
-import java.security.PrivilegedAction;
 import java.util.Objects;
 import java.util.Set;
 
-import sun.net.NetProperties;
 import sun.net.PlatformSocketImpl;
 import sun.nio.ch.NioSocketImpl;
 
@@ -43,45 +40,16 @@
  * of all classes that actually implement sockets. It is used to
  * create both client and server sockets.
  *
- * @implNote Client and server sockets created with the {@code Socket} and
- * {@code SocketServer} public constructors create a system-default
- * {@code SocketImpl}. The JDK historically used a {@code SocketImpl}
- * implementation type named "PlainSocketImpl" that has since been replaced by a
- * newer implementation. The JDK continues to ship with the older implementation
- * to allow code to run that depends on unspecified behavior that differs between
- * the old and new implementations. The old implementation will be used if the
- * Java virtual machine is started with the system property {@systemProperty
- * jdk.net.usePlainSocketImpl} set to use the old implementation. It may also be
- * set in the JDK's network configuration file, located in {@code
- * ${java.home}/conf/net.properties}. The value of the property is the string
- * representation of a boolean. If set without a value then it defaults to {@code
- * true}, hence running with {@code -Djdk.net.usePlainSocketImpl} or {@code
- * -Djdk.net.usePlainSocketImpl=true} will configure the Java virtual machine
- * to use the old implementation. The property and old implementation will be
- * removed in a future version.
- *
  * @since   1.0
  */
 public abstract class SocketImpl implements SocketOptions {
-    private static final boolean USE_PLAINSOCKETIMPL = usePlainSocketImpl();
-
-    private static boolean usePlainSocketImpl() {
-        PrivilegedAction<String> pa = () -> NetProperties.get("jdk.net.usePlainSocketImpl");
-        @SuppressWarnings("removal")
-        String s = AccessController.doPrivileged(pa);
-        return (s != null) && !s.equalsIgnoreCase("false");
-    }
 
     /**
      * Creates an instance of platform's SocketImpl
      */
     @SuppressWarnings("unchecked")
     static <S extends SocketImpl & PlatformSocketImpl> S createPlatformSocketImpl(boolean server) {
-        if (USE_PLAINSOCKETIMPL) {
-            return (S) new PlainSocketImpl(server);
-        } else {
-            return (S) new NioSocketImpl(server);
-        }
+        return (S) new NioSocketImpl(server);
     }
 
     /**