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368 lines
16 KiB
368 lines
16 KiB
/*
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* Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved.
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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package java.net;
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/**
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* Defines the <em>standard</em> socket options.
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*
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* <p> The {@link SocketOption#name name} of each socket option defined by this
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* class is its field name.
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*
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* <p> In this release, the socket options defined here are used by {@link
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* java.nio.channels.NetworkChannel network} channels in the {@link
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* java.nio.channels channels} package.
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*
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* @since 1.7
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*/
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public final class StandardSocketOptions {
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private StandardSocketOptions() { }
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// -- SOL_SOCKET --
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/**
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* Allow transmission of broadcast datagrams.
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*
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* <p> The value of this socket option is a {@code Boolean} that represents
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* whether the option is enabled or disabled. The option is specific to
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* datagram-oriented sockets sending to {@link java.net.Inet4Address IPv4}
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* broadcast addresses. When the socket option is enabled then the socket
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* can be used to send <em>broadcast datagrams</em>.
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*
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* <p> The initial value of this socket option is {@code FALSE}. The socket
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* option may be enabled or disabled at any time. Some operating systems may
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* require that the Java virtual machine be started with implementation
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* specific privileges to enable this option or send broadcast datagrams.
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*
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* @see <a href="http://www.ietf.org/rfc/rfc919.txt">RFC 929:
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* Broadcasting Internet Datagrams</a>
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* @see DatagramSocket#setBroadcast
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*/
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public static final SocketOption<Boolean> SO_BROADCAST =
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new StdSocketOption<Boolean>("SO_BROADCAST", Boolean.class);
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/**
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* Keep connection alive.
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*
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* <p> The value of this socket option is a {@code Boolean} that represents
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* whether the option is enabled or disabled. When the {@code SO_KEEPALIVE}
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* option is enabled the operating system may use a <em>keep-alive</em>
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* mechanism to periodically probe the other end of a connection when the
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* connection is otherwise idle. The exact semantics of the keep alive
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* mechanism is system dependent and therefore unspecified.
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*
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* <p> The initial value of this socket option is {@code FALSE}. The socket
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* option may be enabled or disabled at any time.
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*
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* @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122
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* Requirements for Internet Hosts -- Communication Layers</a>
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* @see Socket#setKeepAlive
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*/
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public static final SocketOption<Boolean> SO_KEEPALIVE =
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new StdSocketOption<Boolean>("SO_KEEPALIVE", Boolean.class);
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/**
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* The size of the socket send buffer.
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*
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* <p> The value of this socket option is an {@code Integer} that is the
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* size of the socket send buffer in bytes. The socket send buffer is an
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* output buffer used by the networking implementation. It may need to be
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* increased for high-volume connections. The value of the socket option is
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* a <em>hint</em> to the implementation to size the buffer and the actual
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* size may differ. The socket option can be queried to retrieve the actual
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* size.
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*
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* <p> For datagram-oriented sockets, the size of the send buffer may limit
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* the size of the datagrams that may be sent by the socket. Whether
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* datagrams larger than the buffer size are sent or discarded is system
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* dependent.
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*
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* <p> The initial/default size of the socket send buffer and the range of
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* allowable values is system dependent although a negative size is not
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* allowed. An attempt to set the socket send buffer to larger than its
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* maximum size causes it to be set to its maximum size.
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*
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* <p> An implementation allows this socket option to be set before the
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* socket is bound or connected. Whether an implementation allows the
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* socket send buffer to be changed after the socket is bound is system
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* dependent.
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*
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* @see Socket#setSendBufferSize
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*/
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public static final SocketOption<Integer> SO_SNDBUF =
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new StdSocketOption<Integer>("SO_SNDBUF", Integer.class);
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/**
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* The size of the socket receive buffer.
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*
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* <p> The value of this socket option is an {@code Integer} that is the
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* size of the socket receive buffer in bytes. The socket receive buffer is
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* an input buffer used by the networking implementation. It may need to be
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* increased for high-volume connections or decreased to limit the possible
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* backlog of incoming data. The value of the socket option is a
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* <em>hint</em> to the implementation to size the buffer and the actual
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* size may differ.
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*
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* <p> For datagram-oriented sockets, the size of the receive buffer may
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* limit the size of the datagrams that can be received. Whether datagrams
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* larger than the buffer size can be received is system dependent.
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* Increasing the socket receive buffer may be important for cases where
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* datagrams arrive in bursts faster than they can be processed.
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*
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* <p> In the case of stream-oriented sockets and the TCP/IP protocol, the
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* size of the socket receive buffer may be used when advertising the size
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* of the TCP receive window to the remote peer.
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*
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* <p> The initial/default size of the socket receive buffer and the range
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* of allowable values is system dependent although a negative size is not
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* allowed. An attempt to set the socket receive buffer to larger than its
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* maximum size causes it to be set to its maximum size.
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*
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* <p> An implementation allows this socket option to be set before the
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* socket is bound or connected. Whether an implementation allows the
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* socket receive buffer to be changed after the socket is bound is system
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* dependent.
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*
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* @see <a href="http://www.ietf.org/rfc/rfc1323.txt">RFC 1323: TCP
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* Extensions for High Performance</a>
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* @see Socket#setReceiveBufferSize
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* @see ServerSocket#setReceiveBufferSize
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*/
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public static final SocketOption<Integer> SO_RCVBUF =
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new StdSocketOption<Integer>("SO_RCVBUF", Integer.class);
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/**
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* Re-use address.
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*
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* <p> The value of this socket option is a {@code Boolean} that represents
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* whether the option is enabled or disabled. The exact semantics of this
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* socket option are socket type and system dependent.
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*
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* <p> In the case of stream-oriented sockets, this socket option will
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* usually determine whether the socket can be bound to a socket address
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* when a previous connection involving that socket address is in the
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* <em>TIME_WAIT</em> state. On implementations where the semantics differ,
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* and the socket option is not required to be enabled in order to bind the
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* socket when a previous connection is in this state, then the
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* implementation may choose to ignore this option.
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*
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* <p> For datagram-oriented sockets the socket option is used to allow
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* multiple programs bind to the same address. This option should be enabled
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* when the socket is to be used for Internet Protocol (IP) multicasting.
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*
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* <p> An implementation allows this socket option to be set before the
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* socket is bound or connected. Changing the value of this socket option
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* after the socket is bound has no effect. The default value of this
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* socket option is system dependent.
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*
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* @see <a href="http://www.ietf.org/rfc/rfc793.txt">RFC 793: Transmission
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* Control Protocol</a>
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* @see ServerSocket#setReuseAddress
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*/
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public static final SocketOption<Boolean> SO_REUSEADDR =
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new StdSocketOption<Boolean>("SO_REUSEADDR", Boolean.class);
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/**
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* Linger on close if data is present.
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*
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* <p> The value of this socket option is an {@code Integer} that controls
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* the action taken when unsent data is queued on the socket and a method
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* to close the socket is invoked. If the value of the socket option is zero
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* or greater, then it represents a timeout value, in seconds, known as the
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* <em>linger interval</em>. The linger interval is the timeout for the
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* {@code close} method to block while the operating system attempts to
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* transmit the unsent data or it decides that it is unable to transmit the
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* data. If the value of the socket option is less than zero then the option
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* is disabled. In that case the {@code close} method does not wait until
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* unsent data is transmitted; if possible the operating system will transmit
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* any unsent data before the connection is closed.
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*
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* <p> This socket option is intended for use with sockets that are configured
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* in {@link java.nio.channels.SelectableChannel#isBlocking() blocking} mode
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* only. The behavior of the {@code close} method when this option is
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* enabled on a non-blocking socket is not defined.
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*
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* <p> The initial value of this socket option is a negative value, meaning
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* that the option is disabled. The option may be enabled, or the linger
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* interval changed, at any time. The maximum value of the linger interval
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* is system dependent. Setting the linger interval to a value that is
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* greater than its maximum value causes the linger interval to be set to
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* its maximum value.
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*
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* @see Socket#setSoLinger
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*/
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public static final SocketOption<Integer> SO_LINGER =
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new StdSocketOption<Integer>("SO_LINGER", Integer.class);
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// -- IPPROTO_IP --
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/**
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* The Type of Service (ToS) octet in the Internet Protocol (IP) header.
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*
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* <p> The value of this socket option is an {@code Integer} representing
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* the value of the ToS octet in IP packets sent by sockets to an {@link
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* StandardProtocolFamily#INET IPv4} socket. The interpretation of the ToS
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* octet is network specific and is not defined by this class. Further
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* information on the ToS octet can be found in <a
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* href="http://www.ietf.org/rfc/rfc1349.txt">RFC 1349</a> and <a
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* href="http://www.ietf.org/rfc/rfc2474.txt">RFC 2474</a>. The value
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* of the socket option is a <em>hint</em>. An implementation may ignore the
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* value, or ignore specific values.
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*
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* <p> The initial/default value of the TOS field in the ToS octet is
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* implementation specific but will typically be {@code 0}. For
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* datagram-oriented sockets the option may be configured at any time after
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* the socket has been bound. The new value of the octet is used when sending
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* subsequent datagrams. It is system dependent whether this option can be
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* queried or changed prior to binding the socket.
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*
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* <p> The behavior of this socket option on a stream-oriented socket, or an
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* {@link StandardProtocolFamily#INET6 IPv6} socket, is not defined in this
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* release.
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*
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* @see DatagramSocket#setTrafficClass
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*/
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public static final SocketOption<Integer> IP_TOS =
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new StdSocketOption<Integer>("IP_TOS", Integer.class);
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/**
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* The network interface for Internet Protocol (IP) multicast datagrams.
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*
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* <p> The value of this socket option is a {@link NetworkInterface} that
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* represents the outgoing interface for multicast datagrams sent by the
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* datagram-oriented socket. For {@link StandardProtocolFamily#INET6 IPv6}
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* sockets then it is system dependent whether setting this option also
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* sets the outgoing interface for multicast datagrams sent to IPv4
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* addresses.
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*
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* <p> The initial/default value of this socket option may be {@code null}
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* to indicate that outgoing interface will be selected by the operating
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* system, typically based on the network routing tables. An implementation
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* allows this socket option to be set after the socket is bound. Whether
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* the socket option can be queried or changed prior to binding the socket
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* is system dependent.
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*
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* @see java.nio.channels.MulticastChannel
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* @see MulticastSocket#setInterface
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*/
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public static final SocketOption<NetworkInterface> IP_MULTICAST_IF =
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new StdSocketOption<NetworkInterface>("IP_MULTICAST_IF", NetworkInterface.class);
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/**
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* The <em>time-to-live</em> for Internet Protocol (IP) multicast datagrams.
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*
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* <p> The value of this socket option is an {@code Integer} in the range
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* {@code 0 <= value <= 255}. It is used to control the scope of multicast
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* datagrams sent by the datagram-oriented socket.
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* In the case of an {@link StandardProtocolFamily#INET IPv4} socket
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* the option is the time-to-live (TTL) on multicast datagrams sent by the
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* socket. Datagrams with a TTL of zero are not transmitted on the network
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* but may be delivered locally. In the case of an {@link
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* StandardProtocolFamily#INET6 IPv6} socket the option is the
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* <em>hop limit</em> which is number of <em>hops</em> that the datagram can
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* pass through before expiring on the network. For IPv6 sockets it is
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* system dependent whether the option also sets the <em>time-to-live</em>
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* on multicast datagrams sent to IPv4 addresses.
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*
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* <p> The initial/default value of the time-to-live setting is typically
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* {@code 1}. An implementation allows this socket option to be set after
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* the socket is bound. Whether the socket option can be queried or changed
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* prior to binding the socket is system dependent.
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*
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* @see java.nio.channels.MulticastChannel
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* @see MulticastSocket#setTimeToLive
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*/
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public static final SocketOption<Integer> IP_MULTICAST_TTL =
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new StdSocketOption<Integer>("IP_MULTICAST_TTL", Integer.class);
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/**
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* Loopback for Internet Protocol (IP) multicast datagrams.
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*
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* <p> The value of this socket option is a {@code Boolean} that controls
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* the <em>loopback</em> of multicast datagrams. The value of the socket
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* option represents if the option is enabled or disabled.
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*
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* <p> The exact semantics of this socket options are system dependent.
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* In particular, it is system dependent whether the loopback applies to
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* multicast datagrams sent from the socket or received by the socket.
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* For {@link StandardProtocolFamily#INET6 IPv6} sockets then it is
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* system dependent whether the option also applies to multicast datagrams
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* sent to IPv4 addresses.
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*
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* <p> The initial/default value of this socket option is {@code TRUE}. An
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* implementation allows this socket option to be set after the socket is
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* bound. Whether the socket option can be queried or changed prior to
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* binding the socket is system dependent.
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*
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* @see java.nio.channels.MulticastChannel
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* @see MulticastSocket#setLoopbackMode
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*/
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public static final SocketOption<Boolean> IP_MULTICAST_LOOP =
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new StdSocketOption<Boolean>("IP_MULTICAST_LOOP", Boolean.class);
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// -- IPPROTO_TCP --
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/**
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* Disable the Nagle algorithm.
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*
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* <p> The value of this socket option is a {@code Boolean} that represents
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* whether the option is enabled or disabled. The socket option is specific to
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* stream-oriented sockets using the TCP/IP protocol. TCP/IP uses an algorithm
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* known as <em>The Nagle Algorithm</em> to coalesce short segments and
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* improve network efficiency.
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*
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* <p> The default value of this socket option is {@code FALSE}. The
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* socket option should only be enabled in cases where it is known that the
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* coalescing impacts performance. The socket option may be enabled at any
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* time. In other words, the Nagle Algorithm can be disabled. Once the option
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* is enabled, it is system dependent whether it can be subsequently
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* disabled. If it cannot, then invoking the {@code setOption} method to
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* disable the option has no effect.
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*
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* @see <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122:
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* Requirements for Internet Hosts -- Communication Layers</a>
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* @see Socket#setTcpNoDelay
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*/
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public static final SocketOption<Boolean> TCP_NODELAY =
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new StdSocketOption<Boolean>("TCP_NODELAY", Boolean.class);
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private static class StdSocketOption<T> implements SocketOption<T> {
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private final String name;
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private final Class<T> type;
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StdSocketOption(String name, Class<T> type) {
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this.name = name;
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this.type = type;
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}
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@Override public String name() { return name; }
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@Override public Class<T> type() { return type; }
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@Override public String toString() { return name; }
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}
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}
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