jdk.nio.channels.AsynchronousSocketChannel — clojure-interop/java.nio 1.0.5

An asynchronous channel for stream-oriented connecting sockets.

Asynchronous socket channels are created in one of two ways. A newly-created AsynchronousSocketChannel is created by invoking one of the open methods defined by this class. A newly-created channel is open but not yet connected. A connected AsynchronousSocketChannel is created when a connection is made to the socket of an AsynchronousServerSocketChannel. It is not possible to create an asynchronous socket channel for an arbitrary, pre-existing socket.

A newly-created channel is connected by invoking its connect method; once connected, a channel remains connected until it is closed. Whether or not a socket channel is connected may be determined by invoking its getRemoteAddress method. An attempt to invoke an I/O operation upon an unconnected channel will cause a NotYetConnectedException to be thrown.

Channels of this type are safe for use by multiple concurrent threads. They support concurrent reading and writing, though at most one read operation and one write operation can be outstanding at any time. If a thread initiates a read operation before a previous read operation has completed then a ReadPendingException will be thrown. Similarly, an attempt to initiate a write operation before a previous write has completed will throw a WritePendingException.

Socket options are configured using the setOption method. Asynchronous socket channels support the following options:

Option Name
Description


 SO_SNDBUF
 The size of the socket send buffer


 SO_RCVBUF
 The size of the socket receive buffer


 SO_KEEPALIVE
 Keep connection alive


 SO_REUSEADDR
 Re-use address


 TCP_NODELAY
 Disable the Nagle algorithm

Additional (implementation specific) options may also be supported.

Timeouts

The read and write methods defined by this class allow a timeout to be specified when initiating a read or write operation. If the timeout elapses before an operation completes then the operation completes with the exception InterruptedByTimeoutException. A timeout may leave the channel, or the underlying connection, in an inconsistent state. Where the implementation cannot guarantee that bytes have not been read from the channel then it puts the channel into an implementation specific error state. A subsequent attempt to initiate a read operation causes an unspecified runtime exception to be thrown. Similarly if a write operation times out and the implementation cannot guarantee bytes have not been written to the channel then further attempts to write to the channel cause an unspecified runtime exception to be thrown. When a timeout elapses then the state of the ByteBuffer, or the sequence of buffers, for the I/O operation is not defined. Buffers should be discarded or at least care must be taken to ensure that the buffers are not accessed while the channel remains open. All methods that accept timeout parameters treat values less than or equal to zero to mean that the I/O operation does not timeout.

*open clj

(*open)

(*open group)

Opens an asynchronous socket channel.

The new channel is created by invoking the openAsynchronousSocketChannel method on the AsynchronousChannelProvider that created the group. If the group parameter is null then the resulting channel is created by the system-wide default provider, and bound to the default group.

group - The group to which the newly constructed channel should be bound, or null for the default group - java.nio.channels.AsynchronousChannelGroup

returns: A new asynchronous socket channel - java.nio.channels.AsynchronousSocketChannel

throws: java.nio.channels.ShutdownChannelGroupException - If the channel group is shutdown

bind clj

(bind this local)

Description copied from interface: NetworkChannel

local - The address to bind the socket, or null to bind the socket to an automatically assigned socket address - java.net.SocketAddress

returns: This channel - java.nio.channels.AsynchronousSocketChannel

throws: java.nio.channels.ConnectionPendingException - If a connection operation is already in progress on this channel

connect clj

(connect this remote)

(connect this remote attachment handler)

Connects this channel.

This method initiates an operation to connect this channel. The handler parameter is a completion handler that is invoked when the connection is successfully established or connection cannot be established. If the connection cannot be established then the channel is closed.

This method performs exactly the same security checks as the Socket class. That is, if a security manager has been installed then this method verifies that its checkConnect method permits connecting to the address and port number of the given remote endpoint.

remote - The remote address to which this channel is to be connected - java.net.SocketAddress attachment - The object to attach to the I/O operation; can be null - A handler - The handler for consuming the result - java.nio.channels.CompletionHandler

returns: <A> void

throws: java.nio.channels.UnresolvedAddressException - If the given remote address is not fully resolved

get-local-address clj

(get-local-address this)

Returns the socket address that this channel's socket is bound to.

Where the channel is bound to an Internet Protocol socket address then the return value from this method is of type InetSocketAddress.

If there is a security manager set, its checkConnect method is called with the local address and -1 as its arguments to see if the operation is allowed. If the operation is not allowed, a SocketAddress representing the loopback address and the local port of the channel's socket is returned.

returns: The SocketAddress that the socket is bound to, or the SocketAddress representing the loopback address if denied by the security manager, or null if the channel's socket is not bound - java.net.SocketAddress

throws: java.nio.channels.ClosedChannelException - If the channel is closed

get-remote-address clj

(get-remote-address this)

Returns the remote address to which this channel's socket is connected.

Where the channel is bound and connected to an Internet Protocol socket address then the return value from this method is of type InetSocketAddress.

returns: The remote address; null if the channel's socket is not connected - java.net.SocketAddress

throws: java.nio.channels.ClosedChannelException - If the channel is closed

provider clj

(provider this)

Returns the provider that created this channel.

returns: The provider that created this channel - java.nio.channels.spi.AsynchronousChannelProvider

read clj

(read this dst)

(read this dst attachment handler)

(read this dst timeout unit attachment handler)

(read this dsts offset length timeout unit attachment handler)

Reads a sequence of bytes from this channel into a subsequence of the given buffers. This operation, sometimes called a scattering read, is often useful when implementing network protocols that group data into segments consisting of one or more fixed-length headers followed by a variable-length body. The handler parameter is a completion handler that is invoked when the read operation completes (or fails). The result passed to the completion handler is the number of bytes read or -1 if no bytes could be read because the channel has reached end-of-stream.

This method initiates a read of up to r bytes from this channel, where r is the total number of bytes remaining in the specified subsequence of the given buffer array, that is,

dsts[offset].remaining() dsts[offset+1].remaining() ... dsts[offset+length-1].remaining()

at the moment that the read is attempted.

Suppose that a byte sequence of length n is read, where 0 < n <= r. Up to the first dsts[offset].remaining() bytes of this sequence are transferred into buffer dsts[offset], up to the next dsts[offset+1].remaining() bytes are transferred into buffer dsts[offset+1], and so forth, until the entire byte sequence is transferred into the given buffers. As many bytes as possible are transferred into each buffer, hence the final position of each updated buffer, except the last updated buffer, is guaranteed to be equal to that buffer's limit. The underlying operating system may impose a limit on the number of buffers that may be used in an I/O operation. Where the number of buffers (with bytes remaining), exceeds this limit, then the I/O operation is performed with the maximum number of buffers allowed by the operating system.

If a timeout is specified and the timeout elapses before the operation completes then it completes with the exception InterruptedByTimeoutException. Where a timeout occurs, and the implementation cannot guarantee that bytes have not been read, or will not be read from the channel into the given buffers, then further attempts to read from the channel will cause an unspecific runtime exception to be thrown.

dsts - The buffers into which bytes are to be transferred - java.nio.ByteBuffer[] offset - The offset within the buffer array of the first buffer into which bytes are to be transferred; must be non-negative and no larger than dsts.length - int length - The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset - int timeout - The maximum time for the I/O operation to complete - long unit - The time unit of the timeout argument - java.util.concurrent.TimeUnit attachment - The object to attach to the I/O operation; can be null - A handler - The handler for consuming the result - java.nio.channels.CompletionHandler

returns: <A> void

throws: java.lang.IndexOutOfBoundsException - If the pre-conditions for the offset and length parameter aren't met

set-option clj

(set-option this name value)

Description copied from interface: NetworkChannel

name - The socket option - java.net.SocketOption value - The value of the socket option. A value of null may be a valid value for some socket options. - T

returns: This channel - <T> java.nio.channels.AsynchronousSocketChannel

throws: java.lang.IllegalArgumentException - If the value is not a valid value for this socket option

shutdown-input clj

(shutdown-input this)

Shutdown the connection for reading without closing the channel.

Once shutdown for reading then further reads on the channel will return -1, the end-of-stream indication. If the input side of the connection is already shutdown then invoking this method has no effect. The effect on an outstanding read operation is system dependent and therefore not specified. The effect, if any, when there is data in the socket receive buffer that has not been read, or data arrives subsequently, is also system dependent.

returns: The channel - java.nio.channels.AsynchronousSocketChannel

throws: java.nio.channels.NotYetConnectedException - If this channel is not yet connected

shutdown-output clj

(shutdown-output this)

Shutdown the connection for writing without closing the channel.

Once shutdown for writing then further attempts to write to the channel will throw ClosedChannelException. If the output side of the connection is already shutdown then invoking this method has no effect. The effect on an outstanding write operation is system dependent and therefore not specified.

returns: The channel - java.nio.channels.AsynchronousSocketChannel

throws: java.nio.channels.NotYetConnectedException - If this channel is not yet connected

write clj

(write this src)

(write this src attachment handler)

(write this src timeout unit attachment handler)

(write this srcs offset length timeout unit attachment handler)

Writes a sequence of bytes to this channel from a subsequence of the given buffers. This operation, sometimes called a gathering write, is often useful when implementing network protocols that group data into segments consisting of one or more fixed-length headers followed by a variable-length body. The handler parameter is a completion handler that is invoked when the write operation completes (or fails). The result passed to the completion handler is the number of bytes written.

This method initiates a write of up to r bytes to this channel, where r is the total number of bytes remaining in the specified subsequence of the given buffer array, that is,

srcs[offset].remaining() srcs[offset+1].remaining() ... srcs[offset+length-1].remaining()

at the moment that the write is attempted.

Suppose that a byte sequence of length n is written, where 0 < n <= r. Up to the first srcs[offset].remaining() bytes of this sequence are written from buffer srcs[offset], up to the next srcs[offset+1].remaining() bytes are written from buffer srcs[offset+1], and so forth, until the entire byte sequence is written. As many bytes as possible are written from each buffer, hence the final position of each updated buffer, except the last updated buffer, is guaranteed to be equal to that buffer's limit. The underlying operating system may impose a limit on the number of buffers that may be used in an I/O operation. Where the number of buffers (with bytes remaining), exceeds this limit, then the I/O operation is performed with the maximum number of buffers allowed by the operating system.

If a timeout is specified and the timeout elapses before the operation completes then it completes with the exception InterruptedByTimeoutException. Where a timeout occurs, and the implementation cannot guarantee that bytes have not been written, or will not be written to the channel from the given buffers, then further attempts to write to the channel will cause an unspecific runtime exception to be thrown.

srcs - The buffers from which bytes are to be retrieved - java.nio.ByteBuffer[] offset - The offset within the buffer array of the first buffer from which bytes are to be retrieved; must be non-negative and no larger than srcs.length - int length - The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset - int timeout - The maximum time for the I/O operation to complete - long unit - The time unit of the timeout argument - java.util.concurrent.TimeUnit attachment - The object to attach to the I/O operation; can be null - A handler - The handler for consuming the result - java.nio.channels.CompletionHandler

returns: <A> void

throws: java.lang.IndexOutOfBoundsException - If the pre-conditions for the offset and length parameter aren't met