Back to index...

	/*
	* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* 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
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.nio.ch;

	import java.io.FileDescriptor;
	import java.io.IOException;
	import java.nio.ByteBuffer;


	/**
	* File-descriptor based I/O utilities that are shared by NIO classes.
	*/

	public class IOUtil {

	/**
	* Max number of iovec structures that readv/writev supports
	*/
	static final int IOV_MAX;

	private IOUtil() { } // No instantiation

	static int write(FileDescriptor fd, ByteBuffer src, long position,
	NativeDispatcher nd)
	throws IOException
	{
	if (src instanceof DirectBuffer)
	return writeFromNativeBuffer(fd, src, position, nd);

	// Substitute a native buffer
	int pos = src.position();
	int lim = src.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);
	ByteBuffer bb = Util.getTemporaryDirectBuffer(rem);
	try {
	bb.put(src);
	bb.flip();
	// Do not update src until we see how many bytes were written
	src.position(pos);

	int n = writeFromNativeBuffer(fd, bb, position, nd);
	if (n > 0) {
	// now update src
	src.position(pos + n);
	}
	return n;
	} finally {
	Util.offerFirstTemporaryDirectBuffer(bb);
	}
	}

	private static int writeFromNativeBuffer(FileDescriptor fd, ByteBuffer bb,
	long position, NativeDispatcher nd)
	throws IOException
	{
	int pos = bb.position();
	int lim = bb.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);

	int written = 0;
	if (rem == 0)
	return 0;
	if (position != -1) {
	written = nd.pwrite(fd,
	((DirectBuffer)bb).address() + pos,
	rem, position);
	} else {
	written = nd.write(fd, ((DirectBuffer)bb).address() + pos, rem);
	}
	if (written > 0)
	bb.position(pos + written);
	return written;
	}

	static long write(FileDescriptor fd, ByteBuffer[] bufs, NativeDispatcher nd)
	throws IOException
	{
	return write(fd, bufs, 0, bufs.length, nd);
	}

	static long write(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
	NativeDispatcher nd)
	throws IOException
	{
	IOVecWrapper vec = IOVecWrapper.get(length);

	boolean completed = false;
	int iov_len = 0;
	try {

	// Iterate over buffers to populate native iovec array.
	int count = offset + length;
	int i = offset;
	while (i < count && iov_len < IOV_MAX) {
	ByteBuffer buf = bufs[i];
	int pos = buf.position();
	int lim = buf.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);
	if (rem > 0) {
	vec.setBuffer(iov_len, buf, pos, rem);

	// allocate shadow buffer to ensure I/O is done with direct buffer
	if (!(buf instanceof DirectBuffer)) {
	ByteBuffer shadow = Util.getTemporaryDirectBuffer(rem);
	shadow.put(buf);
	shadow.flip();
	vec.setShadow(iov_len, shadow);
	buf.position(pos); // temporarily restore position in user buffer
	buf = shadow;
	pos = shadow.position();
	}

	vec.putBase(iov_len, ((DirectBuffer)buf).address() + pos);
	vec.putLen(iov_len, rem);
	iov_len++;
	}
	i++;
	}
	if (iov_len == 0)
	return 0L;

	long bytesWritten = nd.writev(fd, vec.address, iov_len);

	// Notify the buffers how many bytes were taken
	long left = bytesWritten;
	for (int j=0; j<iov_len; j++) {
	if (left > 0) {
	ByteBuffer buf = vec.getBuffer(j);
	int pos = vec.getPosition(j);
	int rem = vec.getRemaining(j);
	int n = (left > rem) ? rem : (int)left;
	buf.position(pos + n);
	left -= n;
	}
	// return shadow buffers to buffer pool
	ByteBuffer shadow = vec.getShadow(j);
	if (shadow != null)
	Util.offerLastTemporaryDirectBuffer(shadow);
	vec.clearRefs(j);
	}

	completed = true;
	return bytesWritten;

	} finally {
	// if an error occurred then clear refs to buffers and return any shadow
	// buffers to cache
	if (!completed) {
	for (int j=0; j<iov_len; j++) {
	ByteBuffer shadow = vec.getShadow(j);
	if (shadow != null)
	Util.offerLastTemporaryDirectBuffer(shadow);
	vec.clearRefs(j);
	}
	}
	}
	}

	static int read(FileDescriptor fd, ByteBuffer dst, long position,
	NativeDispatcher nd)
	throws IOException
	{
	if (dst.isReadOnly())
	throw new IllegalArgumentException("Read-only buffer");
	if (dst instanceof DirectBuffer)
	return readIntoNativeBuffer(fd, dst, position, nd);

	// Substitute a native buffer
	ByteBuffer bb = Util.getTemporaryDirectBuffer(dst.remaining());
	try {
	int n = readIntoNativeBuffer(fd, bb, position, nd);
	bb.flip();
	if (n > 0)
	dst.put(bb);
	return n;
	} finally {
	Util.offerFirstTemporaryDirectBuffer(bb);
	}
	}

	private static int readIntoNativeBuffer(FileDescriptor fd, ByteBuffer bb,
	long position, NativeDispatcher nd)
	throws IOException
	{
	int pos = bb.position();
	int lim = bb.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);

	if (rem == 0)
	return 0;
	int n = 0;
	if (position != -1) {
	n = nd.pread(fd, ((DirectBuffer)bb).address() + pos,
	rem, position);
	} else {
	n = nd.read(fd, ((DirectBuffer)bb).address() + pos, rem);
	}
	if (n > 0)
	bb.position(pos + n);
	return n;
	}

	static long read(FileDescriptor fd, ByteBuffer[] bufs, NativeDispatcher nd)
	throws IOException
	{
	return read(fd, bufs, 0, bufs.length, nd);
	}

	static long read(FileDescriptor fd, ByteBuffer[] bufs, int offset, int length,
	NativeDispatcher nd)
	throws IOException
	{
	IOVecWrapper vec = IOVecWrapper.get(length);

	boolean completed = false;
	int iov_len = 0;
	try {

	// Iterate over buffers to populate native iovec array.
	int count = offset + length;
	int i = offset;
	while (i < count && iov_len < IOV_MAX) {
	ByteBuffer buf = bufs[i];
	if (buf.isReadOnly())
	throw new IllegalArgumentException("Read-only buffer");
	int pos = buf.position();
	int lim = buf.limit();
	assert (pos <= lim);
	int rem = (pos <= lim ? lim - pos : 0);

	if (rem > 0) {
	vec.setBuffer(iov_len, buf, pos, rem);

	// allocate shadow buffer to ensure I/O is done with direct buffer
	if (!(buf instanceof DirectBuffer)) {
	ByteBuffer shadow = Util.getTemporaryDirectBuffer(rem);
	vec.setShadow(iov_len, shadow);
	buf = shadow;
	pos = shadow.position();
	}

	vec.putBase(iov_len, ((DirectBuffer)buf).address() + pos);
	vec.putLen(iov_len, rem);
	iov_len++;
	}
	i++;
	}
	if (iov_len == 0)
	return 0L;

	long bytesRead = nd.readv(fd, vec.address, iov_len);

	// Notify the buffers how many bytes were read
	long left = bytesRead;
	for (int j=0; j<iov_len; j++) {
	ByteBuffer shadow = vec.getShadow(j);
	if (left > 0) {
	ByteBuffer buf = vec.getBuffer(j);
	int rem = vec.getRemaining(j);
	int n = (left > rem) ? rem : (int)left;
	if (shadow == null) {
	int pos = vec.getPosition(j);
	buf.position(pos + n);
	} else {
	shadow.limit(shadow.position() + n);
	buf.put(shadow);
	}
	left -= n;
	}
	if (shadow != null)
	Util.offerLastTemporaryDirectBuffer(shadow);
	vec.clearRefs(j);
	}

	completed = true;
	return bytesRead;

	} finally {
	// if an error occurred then clear refs to buffers and return any shadow
	// buffers to cache
	if (!completed) {
	for (int j=0; j<iov_len; j++) {
	ByteBuffer shadow = vec.getShadow(j);
	if (shadow != null)
	Util.offerLastTemporaryDirectBuffer(shadow);
	vec.clearRefs(j);
	}
	}
	}
	}

	public static FileDescriptor newFD(int i) {
	FileDescriptor fd = new FileDescriptor();
	setfdVal(fd, i);
	return fd;
	}

	static native boolean randomBytes(byte[] someBytes);

	/**
	* Returns two file descriptors for a pipe encoded in a long.
	* The read end of the pipe is returned in the high 32 bits,
	* while the write end is returned in the low 32 bits.
	*/
	static native long makePipe(boolean blocking);

	static native boolean drain(int fd) throws IOException;

	public static native void configureBlocking(FileDescriptor fd,
	boolean blocking)
	throws IOException;

	public static native int fdVal(FileDescriptor fd);

	static native void setfdVal(FileDescriptor fd, int value);

	static native int fdLimit();

	static native int iovMax();

	static native void initIDs();

	/**
	* Used to trigger loading of native libraries
	*/
	public static void load() { }

	static {
	java.security.AccessController.doPrivileged(
	new java.security.PrivilegedAction<Void>() {
	public Void run() {
	System.loadLibrary("net");
	System.loadLibrary("nio");
	return null;
	}
	});

	initIDs();

	IOV_MAX = iovMax();
	}

	}

Back to index...