org.apache.hadoop.net.unix

Class DomainSocket

java.lang.Object

org.apache.hadoop.net.unix.DomainSocket

All Implemented Interfaces:

Closeable, AutoCloseable

@InterfaceAudience.LimitedPrivate(value="HDFS")
public class DomainSocket
extends Object
implements Closeable

The implementation of UNIX domain sockets in Java. See DomainSocket for more information about UNIX domain sockets.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
class	DomainSocket.DomainChannel
class	DomainSocket.DomainInputStream Input stream for UNIX domain sockets.
class	DomainSocket.DomainOutputStream Output stream for UNIX domain sockets.

Field Summary

Fields

Modifier and Type	Field and Description
static int	RECEIVE_BUFFER_SIZE
static int	RECEIVE_TIMEOUT
static int	SEND_BUFFER_SIZE
static int	SEND_TIMEOUT

Method Summary

Methods

Modifier and Type	Method and Description
DomainSocket	accept() Accept a new UNIX domain connection.
static DomainSocket	bindAndListen(String path) Create a new DomainSocket listening on the given path.
void	close() Close the Socket.
static DomainSocket	connect(String path) Create a new DomainSocket connected to the given path.
static void	disableBindPathValidation() Disable validation of the server bind paths.
int	getAttribute(int type)
DomainSocket.DomainChannel	getChannel()
static String	getEffectivePath(String path, int port) Given a path and a port, compute the effective path by replacing occurrences of _PORT with the port.
DomainSocket.DomainInputStream	getInputStream()
static String	getLoadingFailureReason() Return true only if UNIX domain sockets are available.
DomainSocket.DomainOutputStream	getOutputStream()
String	getPath()
boolean	isOpen() Return true if the file descriptor is currently open.
int	receiveFileDescriptors(FileDescriptor[] descriptors, byte[] jbuf, int offset, int length) Receive some FileDescriptor objects from the process on the other side of this socket.
int	recvFileInputStreams(FileInputStream[] streams, byte[] buf, int offset, int length) Receive some FileDescriptor objects from the process on the other side of this socket, and wrap them in FileInputStream objects.
void	sendFileDescriptors(FileDescriptor[] descriptors, byte[] jbuf, int offset, int length) Send some FileDescriptor objects to the process on the other side of this socket.
void	setAttribute(int type, int size)
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

SEND_BUFFER_SIZE

public static final int SEND_BUFFER_SIZE

See Also:

Constant Field Values

RECEIVE_BUFFER_SIZE

public static final int RECEIVE_BUFFER_SIZE

See Also:

Constant Field Values

SEND_TIMEOUT

public static final int SEND_TIMEOUT

See Also:

Constant Field Values

RECEIVE_TIMEOUT

public static final int RECEIVE_TIMEOUT

See Also:

Constant Field Values

Method Detail

getLoadingFailureReason

public static String getLoadingFailureReason()

Return true only if UNIX domain sockets are available.

disableBindPathValidation

public static void disableBindPathValidation()

Disable validation of the server bind paths.

getEffectivePath

public static String getEffectivePath(String path,
                      int port)

Given a path and a port, compute the effective path by replacing occurrences of _PORT with the port. This is mainly to make it possible to run multiple DataNodes locally for testing purposes.

Parameters:

path - The source path

port - Port number to use

Returns:

The effective path

bindAndListen

public static DomainSocket bindAndListen(String path)
                                  throws IOException

Create a new DomainSocket listening on the given path.

Parameters:

path - The path to bind and listen on.

Returns:

The new DomainSocket.

Throws:

IOException

accept

public DomainSocket accept()
                    throws IOException

Accept a new UNIX domain connection. This method can only be used on sockets that were bound with bind().

Returns:

The new connection.

Throws:

IOException - If there was an I/O error performing the accept-- such as the socket being closed from under us.

SocketTimeoutException - If the accept timed out.

connect

public static DomainSocket connect(String path)
                            throws IOException

Create a new DomainSocket connected to the given path.

Parameters:

path - The path to connect to.

Returns:

The new DomainSocket.

Throws:

IOException

isOpen

public boolean isOpen()

Return true if the file descriptor is currently open.

Returns:

True if the file descriptor is currently open.

getPath

public String getPath()

Returns:

The socket path.

getInputStream

public DomainSocket.DomainInputStream getInputStream()

Returns:

The socket InputStream

getOutputStream

public DomainSocket.DomainOutputStream getOutputStream()

Returns:

The socket OutputStream

getChannel

public DomainSocket.DomainChannel getChannel()

Returns:

The socket Channel

setAttribute

public void setAttribute(int type,
                int size)
                  throws IOException

Throws:

IOException

getAttribute

public int getAttribute(int type)
                 throws IOException

Throws:

IOException

close

public void close()
           throws IOException

Close the Socket.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

sendFileDescriptors

public void sendFileDescriptors(FileDescriptor[] descriptors,
                       byte[] jbuf,
                       int offset,
                       int length)
                         throws IOException

Send some FileDescriptor objects to the process on the other side of this socket.

Parameters:

descriptors - The file descriptors to send.

jbuf - Some bytes to send. You must send at least one byte.

offset - The offset in the jbuf array to start at.

length - Length of the jbuf array to use.

Throws:

IOException

receiveFileDescriptors

public int receiveFileDescriptors(FileDescriptor[] descriptors,
                         byte[] jbuf,
                         int offset,
                         int length)
                           throws IOException

Receive some FileDescriptor objects from the process on the other side of this socket.

Parameters:

descriptors - (output parameter) Array of FileDescriptors. We will fill as many slots as possible with file descriptors passed from the remote process. The other slots will contain NULL.

jbuf - (output parameter) Buffer to read into. The UNIX domain sockets API requires you to read at least one byte from the remote process, even if all you care about is the file descriptors you will receive.

offset - Offset into the byte buffer to load data

length - Length of the byte buffer to use for data

Returns:

The number of bytes read. This will be -1 if we reached EOF (similar to SocketInputStream); otherwise, it will be positive.

Throws:

IOException - if there was an I/O error.

recvFileInputStreams

public int recvFileInputStreams(FileInputStream[] streams,
                       byte[] buf,
                       int offset,
                       int length)
                         throws IOException

Receive some FileDescriptor objects from the process on the other side of this socket, and wrap them in FileInputStream objects. See DomainSocket#recvFileInputStreams(ByteBuffer)

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object