Java example source code file (IOUtil.java)
The IOUtil.java Java example source code
/*
* 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();
}
}
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