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   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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  package java.net;
  
  /**
   * Defines the <em>standard</em> socket options.
   *
   * <p> The {@link SocketOption#name name} of each socket option defined by this
   * class is its field name.
   *
   * <p> In this release, the socket options defined here are used by {@link
   * java.nio.channels.NetworkChannel network} channels in the {@link
   * java.nio.channels channels} package.
   *
   * @since 1.7
   */
  
  public final class StandardSocketOptions {
      private StandardSocketOptions() { }
  
      // -- SOL_SOCKET --
  
      /**
       * Allow transmission of broadcast datagrams.
       *
       * <p> The value of this socket option is a {@code Boolean} that represents
       * whether the option is enabled or disabled. The option is specific to
       * datagram-oriented sockets sending to {@link Inet4Address IPv4}
       * broadcast addresses. When the socket option is enabled then the socket
       * can be used to send <em>broadcast datagrams</em>.
       *
       * <p> The initial value of this socket option is {@code FALSE}. The socket
       * option may be enabled or disabled at any time. Some operating systems may
       * require that the Java virtual machine be started with implementation
       * specific privileges to enable this option or send broadcast datagrams.
       *
       * @see <a href="http://www.ietf.org/rfc/rfc919.txt">RFC&nbsp;929:
       * Broadcasting Internet Datagrams</a>
       * @see DatagramSocket#setBroadcast
       */
      public static final SocketOption<Boolean> SO_BROADCAST =
          new StdSocketOption<Boolean>("SO_BROADCAST", Boolean.class);
  
      /**
       * Keep connection alive.
       *
       * <p> The value of this socket option is a {@code Boolean} that represents
       * whether the option is enabled or disabled. When the {@code SO_KEEPALIVE}
       * option is enabled the operating system may use a <em>keep-alive</em>
       * mechanism to periodically probe the other end of a connection when the
       * connection is otherwise idle. The exact semantics of the keep alive
       * mechanism is system dependent and therefore unspecified.
       *
       * <p> The initial value of this socket option is {@code FALSE}. The socket
       * option may be enabled or disabled at any time.
       *
       * @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC&nbsp;1122
       * Requirements for Internet Hosts -- Communication Layers</a>
       * @see Socket#setKeepAlive
       */
      public static final SocketOption<Boolean> SO_KEEPALIVE =
          new StdSocketOption<Boolean>("SO_KEEPALIVE", Boolean.class);
  
      /**
       * The size of the socket send buffer.
       *
       * <p> The value of this socket option is an {@code Integer} that is the
       * size of the socket send buffer in bytes. The socket send buffer is an
       * output buffer used by the networking implementation. It may need to be
       * increased for high-volume connections. The value of the socket option is
       * a <em>hint</em> to the implementation to size the buffer and the actual
       * size may differ. The socket option can be queried to retrieve the actual
       * size.
       *
       * <p> For datagram-oriented sockets, the size of the send buffer may limit
       * the size of the datagrams that may be sent by the socket. Whether
       * datagrams larger than the buffer size are sent or discarded is system
       * dependent.
       *
       * <p> The initial/default size of the socket send buffer and the range of
       * allowable values is system dependent although a negative size is not
       * allowed. An attempt to set the socket send buffer to larger than its
       * maximum size causes it to be set to its maximum size.
       *
       * <p> An implementation allows this socket option to be set before the
       * socket is bound or connected. Whether an implementation allows the
       * socket send buffer to be changed after the socket is bound is system
       * dependent.
       *
       * @see Socket#setSendBufferSize
       */
      public static final SocketOption<Integer> SO_SNDBUF =
          new StdSocketOption<Integer>("SO_SNDBUF", Integer.class);
  
  
      /**
       * The size of the socket receive buffer.
       *
       * <p> The value of this socket option is an {@code Integer} that is the
       * size of the socket receive buffer in bytes. The socket receive buffer is
       * an input buffer used by the networking implementation. It may need to be
       * increased for high-volume connections or decreased to limit the possible
       * backlog of incoming data. The value of the socket option is a
       * <em>hint</em> to the implementation to size the buffer and the actual
       * size may differ.
       *
       * <p> For datagram-oriented sockets, the size of the receive buffer may
       * limit the size of the datagrams that can be received. Whether datagrams
       * larger than the buffer size can be received is system dependent.
       * Increasing the socket receive buffer may be important for cases where
       * datagrams arrive in bursts faster than they can be processed.
       *
       * <p> In the case of stream-oriented sockets and the TCP/IP protocol, the
       * size of the socket receive buffer may be used when advertising the size
       * of the TCP receive window to the remote peer.
       *
       * <p> The initial/default size of the socket receive buffer and the range
       * of allowable values is system dependent although a negative size is not
       * allowed. An attempt to set the socket receive buffer to larger than its
       * maximum size causes it to be set to its maximum size.
       *
       * <p> An implementation allows this socket option to be set before the
       * socket is bound or connected. Whether an implementation allows the
       * socket receive buffer to be changed after the socket is bound is system
       * dependent.
       *
       * @see <a href="http://www.ietf.org/rfc/rfc1323.txt">RFC&nbsp;1323: TCP
       * Extensions for High Performance</a>
       * @see Socket#setReceiveBufferSize
       * @see ServerSocket#setReceiveBufferSize
       */
      public static final SocketOption<Integer> SO_RCVBUF =
          new StdSocketOption<Integer>("SO_RCVBUF", Integer.class);
  
      /**
       * Re-use address.
       *
       * <p> The value of this socket option is a {@code Boolean} that represents
       * whether the option is enabled or disabled. The exact semantics of this
       * socket option are socket type and system dependent.
       *
       * <p> In the case of stream-oriented sockets, this socket option will
       * usually determine whether the socket can be bound to a socket address
       * when a previous connection involving that socket address is in the
       * <em>TIME_WAIT</em> state. On implementations where the semantics differ,
       * and the socket option is not required to be enabled in order to bind the
       * socket when a previous connection is in this state, then the
       * implementation may choose to ignore this option.
       *
       * <p> For datagram-oriented sockets the socket option is used to allow
       * multiple programs bind to the same address. This option should be enabled
       * when the socket is to be used for Internet Protocol (IP) multicasting.
       *
       * <p> An implementation allows this socket option to be set before the
       * socket is bound or connected. Changing the value of this socket option
       * after the socket is bound has no effect. The default value of this
       * socket option is system dependent.
       *
       * @see <a href="http://www.ietf.org/rfc/rfc793.txt">RFC&nbsp;793: Transmission
       * Control Protocol</a>
       * @see ServerSocket#setReuseAddress
       */
      public static final SocketOption<Boolean> SO_REUSEADDR =
          new StdSocketOption<Boolean>("SO_REUSEADDR", Boolean.class);
  
      /**
       * Linger on close if data is present.
       *
       * <p> The value of this socket option is an {@code Integer} that controls
       * the action taken when unsent data is queued on the socket and a method
       * to close the socket is invoked. If the value of the socket option is zero
       * or greater, then it represents a timeout value, in seconds, known as the
       * <em>linger interval</em>. The linger interval is the timeout for the
       * {@code close} method to block while the operating system attempts to
       * transmit the unsent data or it decides that it is unable to transmit the
       * data. If the value of the socket option is less than zero then the option
       * is disabled. In that case the {@code close} method does not wait until
       * unsent data is transmitted; if possible the operating system will transmit
       * any unsent data before the connection is closed.
       *
       * <p> This socket option is intended for use with sockets that are configured
       * in {@link java.nio.channels.SelectableChannel#isBlocking() blocking} mode
       * only. The behavior of the {@code close} method when this option is
       * enabled on a non-blocking socket is not defined.
       *
       * <p> The initial value of this socket option is a negative value, meaning
       * that the option is disabled. The option may be enabled, or the linger
       * interval changed, at any time. The maximum value of the linger interval
       * is system dependent. Setting the linger interval to a value that is
       * greater than its maximum value causes the linger interval to be set to
       * its maximum value.
       *
       * @see Socket#setSoLinger
       */
      public static final SocketOption<Integer> SO_LINGER =
          new StdSocketOption<Integer>("SO_LINGER", Integer.class);
  
  
      // -- IPPROTO_IP --
  
      /**
       * The Type of Service (ToS) octet in the Internet Protocol (IP) header.
       *
       * <p> The value of this socket option is an {@code Integer} representing
       * the value of the ToS octet in IP packets sent by sockets to an {@link
       * StandardProtocolFamily#INET IPv4} socket. The interpretation of the ToS
       * octet is network specific and is not defined by this class. Further
       * information on the ToS octet can be found in <a
       * href="http://www.ietf.org/rfc/rfc1349.txt">RFC&nbsp;1349</a> and <a
       * href="http://www.ietf.org/rfc/rfc2474.txt">RFC&nbsp;2474</a>. The value
       * of the socket option is a <em>hint</em>. An implementation may ignore the
       * value, or ignore specific values.
       *
       * <p> The initial/default value of the TOS field in the ToS octet is
       * implementation specific but will typically be {@code 0}. For
       * datagram-oriented sockets the option may be configured at any time after
       * the socket has been bound. The new value of the octet is used when sending
       * subsequent datagrams. It is system dependent whether this option can be
       * queried or changed prior to binding the socket.
       *
       * <p> The behavior of this socket option on a stream-oriented socket, or an
       * {@link StandardProtocolFamily#INET6 IPv6} socket, is not defined in this
       * release.
       *
       * @see DatagramSocket#setTrafficClass
       */
      public static final SocketOption<Integer> IP_TOS =
          new StdSocketOption<Integer>("IP_TOS", Integer.class);
  
      /**
       * The network interface for Internet Protocol (IP) multicast datagrams.
       *
       * <p> The value of this socket option is a {@link NetworkInterface} that
       * represents the outgoing interface for multicast datagrams sent by the
       * datagram-oriented socket. For {@link StandardProtocolFamily#INET6 IPv6}
       * sockets then it is system dependent whether setting this option also
       * sets the outgoing interface for multicast datagrams sent to IPv4
       * addresses.
       *
       * <p> The initial/default value of this socket option may be {@code null}
       * to indicate that outgoing interface will be selected by the operating
       * system, typically based on the network routing tables. An implementation
       * allows this socket option to be set after the socket is bound. Whether
       * the socket option can be queried or changed prior to binding the socket
       * is system dependent.
       *
       * @see java.nio.channels.MulticastChannel
       * @see MulticastSocket#setInterface
       */
      public static final SocketOption<NetworkInterface> IP_MULTICAST_IF =
          new StdSocketOption<NetworkInterface>("IP_MULTICAST_IF", NetworkInterface.class);
  
      /**
       * The <em>time-to-live</em> for Internet Protocol (IP) multicast datagrams.
       *
       * <p> The value of this socket option is an {@code Integer} in the range
       * {@code 0 <= value <= 255}. It is used to control the scope of multicast
       * datagrams sent by the datagram-oriented socket.
       * In the case of an {@link StandardProtocolFamily#INET IPv4} socket
       * the option is the time-to-live (TTL) on multicast datagrams sent by the
       * socket. Datagrams with a TTL of zero are not transmitted on the network
       * but may be delivered locally. In the case of an {@link
       * StandardProtocolFamily#INET6 IPv6} socket the option is the
       * <em>hop limit</em> which is number of <em>hops</em> that the datagram can
       * pass through before expiring on the network. For IPv6 sockets it is
       * system dependent whether the option also sets the <em>time-to-live</em>
       * on multicast datagrams sent to IPv4 addresses.
       *
       * <p> The initial/default value of the time-to-live setting is typically
       * {@code 1}. An implementation allows this socket option to be set after
       * the socket is bound. Whether the socket option can be queried or changed
       * prior to binding the socket is system dependent.
       *
       * @see java.nio.channels.MulticastChannel
       * @see MulticastSocket#setTimeToLive
       */
      public static final SocketOption<Integer> IP_MULTICAST_TTL =
          new StdSocketOption<Integer>("IP_MULTICAST_TTL", Integer.class);
  
      /**
       * Loopback for Internet Protocol (IP) multicast datagrams.
       *
       * <p> The value of this socket option is a {@code Boolean} that controls
       * the <em>loopback</em> of multicast datagrams. The value of the socket
       * option represents if the option is enabled or disabled.
       *
       * <p> The exact semantics of this socket options are system dependent.
       * In particular, it is system dependent whether the loopback applies to
       * multicast datagrams sent from the socket or received by the socket.
       * For {@link StandardProtocolFamily#INET6 IPv6} sockets then it is
       * system dependent whether the option also applies to multicast datagrams
       * sent to IPv4 addresses.
       *
       * <p> The initial/default value of this socket option is {@code TRUE}. An
       * implementation allows this socket option to be set after the socket is
       * bound. Whether the socket option can be queried or changed prior to
       * binding the socket is system dependent.
       *
       * @see java.nio.channels.MulticastChannel
       *  @see MulticastSocket#setLoopbackMode
       */
      public static final SocketOption<Boolean> IP_MULTICAST_LOOP =
          new StdSocketOption<Boolean>("IP_MULTICAST_LOOP", Boolean.class);
  
  
      // -- IPPROTO_TCP --
  
      /**
       * Disable the Nagle algorithm.
       *
       * <p> The value of this socket option is a {@code Boolean} that represents
       * whether the option is enabled or disabled. The socket option is specific to
       * stream-oriented sockets using the TCP/IP protocol. TCP/IP uses an algorithm
       * known as <em>The Nagle Algorithm</em> to coalesce short segments and
       * improve network efficiency.
       *
       * <p> The default value of this socket option is {@code FALSE}. The
       * socket option should only be enabled in cases where it is known that the
       * coalescing impacts performance. The socket option may be enabled at any
       * time. In other words, the Nagle Algorithm can be disabled. Once the option
       * is enabled, it is system dependent whether it can be subsequently
       * disabled. If it cannot, then invoking the {@code setOption} method to
       * disable the option has no effect.
       *
       * @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC&nbsp;1122:
       * Requirements for Internet Hosts -- Communication Layers</a>
       * @see Socket#setTcpNoDelay
       */
      public static final SocketOption<Boolean> TCP_NODELAY =
          new StdSocketOption<Boolean>("TCP_NODELAY", Boolean.class);
  
  
      private static class StdSocketOption<T> implements SocketOption<T> {
          private final String name;
          private final Class<T> type;
          StdSocketOption(String name, Class<T> type) {
              this.name = name;
              this.type = type;
          }
          @Override public String name() { return name; }
          @Override public Class<T> type() { return type; }
          @Override public String toString() { return name; }
      }
  }
  