gnu.java.nio

Class VMChannel

java.lang.Object

gnu.java.nio.VMChannel

public final class VMChannel
extends Object

Native interface to support configuring of channel to run in a non-blocking manner and support scatter/gather io operations.

JikesRVM-specific implementation by Robin Garner and Filip Pizlo.

Note: JavaDoc from GNU Classpath has been deleted on methods where it would cause JavaDoc warnings.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static class	VMChannel.Kind An enumeration of possible kinds of channel.
private static class	VMChannel.LocalByteArray A thread-local store of non-moving buffers.
class	VMChannel.State A wrapper for a native file descriptor integer.

Field Summary

Fields

Modifier and Type	Field and Description
private VMChannel.Kind	kind
private static VMChannel.LocalByteArray	localByteArray Thread-local buffer for VM-side buffering of write calls
private static int	MAX_STANDARD_FD Don't do fast I/O for the standard file descriptors - these are used for throwing exceptions, so may not be able to allocate.
private VMChannel.State	nfd Our reference implementation uses an integer to store the native file descriptor.

Constructor Summary

Constructors

Constructor and Description
VMChannel()
VMChannel(int native_fd)

Method Summary

Modifier and Type	Method and Description
VMChannel	accept() Accept an incoming connection, returning a new VMChannel, or null if the channel is nonblocking and no connection is pending.
private static int	accept(int native_fd)
int	available()
private static int	available(int native_fd)
void	close() Close this socket.
(package private) static void	close(int native_fd)
boolean	connect(InetSocketAddress saddr, int timeout) Connect the underlying socket file descriptor to the remote host.
private static boolean	connect(int fd, byte[] addr, int port, int timeout)
private static boolean	connect6(int fd, byte[] addr, int port, int timeout)
void	disconnect() Disconnect this channel, if it is a datagram socket.
private static void	disconnect(int fd)
boolean	flush(boolean metadata)
private static boolean	flush(int fd, boolean metadata)
InetSocketAddress	getLocalAddress()
InetSocketAddress	getPeerAddress()
private static int	getpeername(int fd, ByteBuffer name)
private static int	getsockname(int fd, ByteBuffer name)
VMChannel.State	getState()
static VMChannel	getStderr()
static VMChannel	getStdin()
static VMChannel	getStdout()
private static void	initIDs()
void	initSocket(boolean stream) Create a new socket.
(package private) static boolean	isThreadInterrupted() Provides a simple mean for the JNI code to find out whether the current thread was interrupted by a call to Thread.interrupt().
private static boolean	lock(int fd, long pos, long len, boolean shared, boolean wait)
boolean	lock(long pos, long len, boolean shared, boolean wait)
MappedByteBuffer	map(char mode, long position, int size)
private static MappedByteBuffer	map(int fd, char mode, long position, int size)
private static int	max(int[] values)
private static int	open(String path, int mode)
void	openFile(String path, int mode)
long	position()
private static long	position(int fd)
int	read()
private int	read(byte[] dst, int pos, int len) Reads a byte array directly.
int	read(ByteBuffer dst) Reads a byte buffer directly using the supplied file descriptor.
private int	read(ByteBuffer dst, int pos, int len)
private static int	read(int fd)
private static int	read(int fd, byte[] dst, int position, int len) Use JikesRVM's internal read function - the fast way.
private static int	read(int fd, ByteBuffer dst) Classpath's native read method.
long	readScattering(ByteBuffer[] dsts, int offset, int length) Reads into byte buffers directly using the supplied file descriptor.
private static long	readScattering(int fd, ByteBuffer[] dsts, int offset, int length)
SocketAddress	receive(ByteBuffer dst)
private static int	receive(int fd, ByteBuffer dst, ByteBuffer address)
private static void	seek(int fd, long pos)
void	seek(long pos)
int	send(ByteBuffer src, InetSocketAddress dst)
private static int	send(int fd, ByteBuffer src, byte[] addr, int port)
private static int	send6(int fd, ByteBuffer src, byte[] addr, int port)
void	setBlocking(boolean blocking)
private static void	setBlocking(int fd, boolean blocking)
long	size()
private static long	size(int fd)
private static int	socket(boolean stream) Create a new socket, returning the native file descriptor.
private static int	stderr_fd()
private static int	stdin_fd()
private static int	stdout_fd()
private static void	truncate(int fd, long len)
void	truncate(long length)
private static void	unlock(int fd, long pos, long len)
void	unlock(long pos, long len)
int	write(byte[] src, int pos, int len) Writes from a byte array using the supplied file descriptor.
int	write(ByteBuffer src)
int	write(ByteBuffer src, int pos, int len)
void	write(int b)
private static int	write(int fd, byte[] src, int pos, int len) Use JikesRVM's internal read function - the fast way.
private static int	write(int fd, ByteBuffer src) Classpath's native write method.
private static void	write(int fd, int b)
long	writeGathering(ByteBuffer[] srcs, int offset, int length)
private long	writeGathering(int fd, ByteBuffer[] srcs, int offset, int length)

Methods inherited from class java.lang.Object

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

Field Detail

nfd

private final VMChannel.State nfd

Our reference implementation uses an integer to store the native file descriptor.

kind

private VMChannel.Kind kind

MAX_STANDARD_FD

private static int MAX_STANDARD_FD

Don't do fast I/O for the standard file descriptors - these are used for throwing exceptions, so may not be able to allocate. Cache the max of the IDs to avoid gratuitous native calls.

localByteArray

private static final VMChannel.LocalByteArray localByteArray

Thread-local buffer for VM-side buffering of write calls

Constructor Detail

VMChannel

public VMChannel()

VMChannel

VMChannel(int native_fd)
   throws IOException

Throws:

IOException

Method Detail

getState

public VMChannel.State getState()

max

private static int max(int[] values)

getStdin

public static VMChannel getStdin()
                          throws IOException

Throws:

IOException

getStdout

public static VMChannel getStdout()
                           throws IOException

Throws:

IOException

getStderr

public static VMChannel getStderr()
                           throws IOException

Throws:

IOException

stdin_fd

private static int stdin_fd()

stdout_fd

private static int stdout_fd()

stderr_fd

private static int stderr_fd()

setBlocking

public void setBlocking(boolean blocking)
                 throws IOException

Throws:

IOException

setBlocking

private static void setBlocking(int fd,
                                boolean blocking)
                         throws IOException

Throws:

IOException

available

public int available()
              throws IOException

Throws:

IOException

available

private static int available(int native_fd)
                      throws IOException

Throws:

IOException

read

public int read(ByteBuffer dst)
         throws IOException

Reads a byte buffer directly using the supplied file descriptor.

Parameters:

dst - Direct Byte Buffer to read to.

Returns:

Number of bytes read.

Throws:

IOException - If an error occurs or dst is not a direct buffers.

read

private int read(ByteBuffer dst,
                 int pos,
                 int len)
          throws IOException

Throws:

IOException

read

private int read(byte[] dst,
                 int pos,
                 int len)
          throws IOException

Reads a byte array directly. Performs optimal buffering. If the target buffer is pinned, use it directly. Otherwise allocate one of the thread-local buffers, perform the IO to that, and copy the result to the target array.

Parameters:

dst - Byte array to read to

pos - Starting offset in the buffer

len - Number of bytes to read

Returns:

Number of bytes read.

Throws:

IOException - If an error occurs or dst is not a direct buffers.

read

private static int read(int fd,
                        byte[] dst,
                        int position,
                        int len)
                 throws IOException

Use JikesRVM's internal read function - the fast way.

Parameters:

fd - File descriptor

dst - Destination buffer

position - Starting offset in the buffer

len - Number of bytes to read

Returns:

Number of bytes read, or -1 for end of file.

Throws:

IOException - when an error occurs during reading

read

private static int read(int fd,
                        ByteBuffer dst)
                 throws IOException

Classpath's native read method. Slow, due to the amount of JNI processing.

Parameters:

fd - the file descriptor of the file to read

dst - the buffer that the read bytes will be written to

Returns:

the number of bytes actually read

Throws:

IOException - when an error occurs during reading

read

public int read()
         throws IOException

Throws:

IOException

read

private static int read(int fd)
                 throws IOException

Throws:

IOException

readScattering

public long readScattering(ByteBuffer[] dsts,
                           int offset,
                           int length)
                    throws IOException

Reads into byte buffers directly using the supplied file descriptor. Assumes that the buffer list contains DirectBuffers. Will perform a scattering read.

Parameters:

dsts - An array direct byte buffers.

offset - Index of the first buffer to read to.

length - The number of buffers to read to.

Returns:

Number of bytes read.

Throws:

IOException - If an error occurs or the dsts are not direct buffers.

readScattering

private static long readScattering(int fd,
                                   ByteBuffer[] dsts,
                                   int offset,
                                   int length)
                            throws IOException

Throws:

IOException

receive

public SocketAddress receive(ByteBuffer dst)
                      throws IOException

Throws:

IOException

receive

private static int receive(int fd,
                           ByteBuffer dst,
                           ByteBuffer address)
                    throws IOException

Throws:

IOException

write

public int write(byte[] src,
                 int pos,
                 int len)
          throws IOException

Writes from a byte array using the supplied file descriptor.

Parameters:

src - The source buffer.

pos - Starting offset in the buffer

len - Number of bytes to write

Returns:

Number of bytes written.

Throws:

IOException - when an error occurs during writing

write

public int write(ByteBuffer src,
                 int pos,
                 int len)
          throws IOException

Throws:

IOException

write

public int write(ByteBuffer src)
          throws IOException

Throws:

IOException

write

private static int write(int fd,
                         byte[] src,
                         int pos,
                         int len)
                  throws IOException

Use JikesRVM's internal read function - the fast way.

Parameters:

fd - File descriptor

src - Source buffer

pos - Starting offset in the buffer

len - Number of bytes to write

Returns:

Number of bytes written.

Throws:

IOException - when an error occurs during writing

write

private static int write(int fd,
                         ByteBuffer src)
                  throws IOException

Classpath's native write method. Slow, due to the amount of JNI processing.

Parameters:

fd - the file's descriptor

src - the source buffer for the bytes that will be written

Returns:

Number of bytes written

Throws:

IOException - when an error occurs during writing

writeGathering

public long writeGathering(ByteBuffer[] srcs,
                           int offset,
                           int length)
                    throws IOException

Throws:

IOException

writeGathering

private long writeGathering(int fd,
                            ByteBuffer[] srcs,
                            int offset,
                            int length)
                     throws IOException

Throws:

IOException

send

public int send(ByteBuffer src,
                InetSocketAddress dst)
         throws IOException

Throws:

IOException

send

private static int send(int fd,
                        ByteBuffer src,
                        byte[] addr,
                        int port)
                 throws IOException

Throws:

IOException

send6

private static int send6(int fd,
                         ByteBuffer src,
                         byte[] addr,
                         int port)
                  throws IOException

Throws:

IOException

write

public void write(int b)
           throws IOException

Throws:

IOException

write

private static void write(int fd,
                          int b)
                   throws IOException

Throws:

IOException

initIDs

private static void initIDs()

initSocket

public void initSocket(boolean stream)
                throws IOException

Create a new socket. This method will initialize the native file descriptor state of this instance.

Parameters:

stream - Whether or not to create a streaming socket, or a datagram socket.

Throws:

IOException - If creating a new socket fails, or if this channel already has its native descriptor initialized.

socket

private static int socket(boolean stream)
                   throws IOException

Create a new socket, returning the native file descriptor.

Parameters:

stream - Set to true for streaming sockets; false for datagrams.

Returns:

The native file descriptor.

Throws:

IOException - If creating the socket fails.

connect

public boolean connect(InetSocketAddress saddr,
                       int timeout)
                throws SocketException

Connect the underlying socket file descriptor to the remote host.

Parameters:

saddr - The address to connect to.

timeout - The connect timeout to use for blocking connects.

Returns:

True if the connection succeeded; false if the file descriptor is in non-blocking mode and the connection did not immediately succeed.

Throws:

SocketException - If an error occurs while connecting.

connect

private static boolean connect(int fd,
                               byte[] addr,
                               int port,
                               int timeout)
                        throws SocketException

Throws:

SocketException

connect6

private static boolean connect6(int fd,
                                byte[] addr,
                                int port,
                                int timeout)
                         throws SocketException

Throws:

SocketException

disconnect

public void disconnect()
                throws IOException

Disconnect this channel, if it is a datagram socket. Disconnecting a datagram channel will disassociate it from any address, so the socket will remain open, but can send and receive datagrams from any address.

Throws:

IOException - If disconnecting this channel fails, or if this channel is not a datagram channel.

disconnect

private static void disconnect(int fd)
                        throws IOException

Throws:

IOException

getLocalAddress

public InetSocketAddress getLocalAddress()
                                  throws IOException

Throws:

IOException

getsockname

private static int getsockname(int fd,
                               ByteBuffer name)
                        throws IOException

Throws:

IOException

getPeerAddress

public InetSocketAddress getPeerAddress()
                                 throws IOException

Throws:

IOException

getpeername

private static int getpeername(int fd,
                               ByteBuffer name)
                        throws IOException

Throws:

IOException

accept

public VMChannel accept()
                 throws IOException

Accept an incoming connection, returning a new VMChannel, or null if the channel is nonblocking and no connection is pending.

Returns:

The accepted connection, or null.

Throws:

IOException - If an IO error occurs.

accept

private static int accept(int native_fd)
                   throws IOException

Throws:

IOException

openFile

public void openFile(String path,
                     int mode)
              throws IOException

Throws:

IOException

open

private static int open(String path,
                        int mode)
                 throws IOException

Throws:

IOException

position

public long position()
              throws IOException

Throws:

IOException

position

private static long position(int fd)
                      throws IOException

Throws:

IOException

seek

public void seek(long pos)
          throws IOException

Throws:

IOException

seek

private static void seek(int fd,
                         long pos)
                  throws IOException

Throws:

IOException

truncate

public void truncate(long length)
              throws IOException

Throws:

IOException

truncate

private static void truncate(int fd,
                             long len)
                      throws IOException

Throws:

IOException

lock

public boolean lock(long pos,
                    long len,
                    boolean shared,
                    boolean wait)
             throws IOException

Throws:

IOException

lock

private static boolean lock(int fd,
                            long pos,
                            long len,
                            boolean shared,
                            boolean wait)
                     throws IOException

Throws:

IOException

unlock

public void unlock(long pos,
                   long len)
            throws IOException

Throws:

IOException

unlock

private static void unlock(int fd,
                           long pos,
                           long len)
                    throws IOException

Throws:

IOException

size

public long size()
          throws IOException

Throws:

IOException

size

private static long size(int fd)
                  throws IOException

Throws:

IOException

map

public MappedByteBuffer map(char mode,
                            long position,
                            int size)
                     throws IOException

Throws:

IOException

map

private static MappedByteBuffer map(int fd,
                                    char mode,
                                    long position,
                                    int size)
                             throws IOException

Throws:

IOException

flush

public boolean flush(boolean metadata)
              throws IOException

Throws:

IOException

flush

private static boolean flush(int fd,
                             boolean metadata)
                      throws IOException

Throws:

IOException

close

public void close()
           throws IOException

Close this socket. The socket is also automatically closed when this object is finalized.

Throws:

IOException - If closing the socket fails, or if this object has no open socket.

close

static void close(int native_fd)
           throws IOException

Throws:

IOException

isThreadInterrupted

static boolean isThreadInterrupted()

Provides a simple mean for the JNI code to find out whether the current thread was interrupted by a call to Thread.interrupt().

Returns:

true if the current thread was interrupted, false otherwise