sun.nio.ch.Util Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of qbicc-rt-java.base Show documentation
Show all versions of qbicc-rt-java.base Show documentation
The Qbicc builder for the java.base JDK module
/*
* Copyright (c) 2000, 2021, 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.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.nio.ByteBuffer;
import java.nio.MappedByteBuffer;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collection;
import java.util.Iterator;
import java.util.Set;
import jdk.internal.access.foreign.MemorySegmentProxy;
import jdk.internal.misc.TerminatingThreadLocal;
import jdk.internal.misc.Unsafe;
import sun.security.action.GetPropertyAction;
public class Util {
// -- Caches --
// The number of temp buffers in our pool
private static final int TEMP_BUF_POOL_SIZE = IOUtil.IOV_MAX;
// The max size allowed for a cached temp buffer, in bytes
private static final long MAX_CACHED_BUFFER_SIZE = getMaxCachedBufferSize();
// Per-thread cache of temporary direct buffers
private static ThreadLocal bufferCache = new TerminatingThreadLocal<>() {
@Override
protected BufferCache initialValue() {
return new BufferCache();
}
@Override
protected void threadTerminated(BufferCache cache) { // will never be null
while (!cache.isEmpty()) {
ByteBuffer bb = cache.removeFirst();
free(bb);
}
}
};
/**
* Returns the max size allowed for a cached temp buffers, in
* bytes. It defaults to Long.MAX_VALUE. It can be set with the
* jdk.nio.maxCachedBufferSize property. Even though
* ByteBuffer.capacity() returns an int, we're using a long here
* for potential future-proofing.
*/
private static long getMaxCachedBufferSize() {
String s = GetPropertyAction
.privilegedGetProperty("jdk.nio.maxCachedBufferSize");
if (s != null) {
try {
long m = Long.parseLong(s);
if (m >= 0) {
return m;
} else {
// if it's negative, ignore the system property
}
} catch (NumberFormatException e) {
// if the string is not well formed, ignore the system property
}
}
return Long.MAX_VALUE;
}
/**
* Returns true if a buffer of this size is too large to be
* added to the buffer cache, false otherwise.
*/
private static boolean isBufferTooLarge(int size) {
return size > MAX_CACHED_BUFFER_SIZE;
}
/**
* Returns true if the buffer is too large to be added to the
* buffer cache, false otherwise.
*/
private static boolean isBufferTooLarge(ByteBuffer buf) {
return isBufferTooLarge(buf.capacity());
}
/**
* A simple cache of direct buffers.
*/
private static class BufferCache {
// the array of buffers
private ByteBuffer[] buffers;
// the number of buffers in the cache
private int count;
// the index of the first valid buffer (undefined if count == 0)
private int start;
private int next(int i) {
return (i + 1) % TEMP_BUF_POOL_SIZE;
}
BufferCache() {
buffers = new ByteBuffer[TEMP_BUF_POOL_SIZE];
}
/**
* Removes and returns a buffer from the cache of at least the given
* size (or null if no suitable buffer is found).
*/
ByteBuffer get(int size) {
// Don't call this if the buffer would be too large.
assert !isBufferTooLarge(size);
if (count == 0)
return null; // cache is empty
ByteBuffer[] buffers = this.buffers;
// search for suitable buffer (often the first buffer will do)
ByteBuffer buf = buffers[start];
if (buf.capacity() < size) {
buf = null;
int i = start;
while ((i = next(i)) != start) {
ByteBuffer bb = buffers[i];
if (bb == null)
break;
if (bb.capacity() >= size) {
buf = bb;
break;
}
}
if (buf == null)
return null;
// move first element to here to avoid re-packing
buffers[i] = buffers[start];
}
// remove first element
buffers[start] = null;
start = next(start);
count--;
// prepare the buffer and return it
buf.rewind();
buf.limit(size);
return buf;
}
boolean offerFirst(ByteBuffer buf) {
// Don't call this if the buffer is too large.
assert !isBufferTooLarge(buf);
if (count >= TEMP_BUF_POOL_SIZE) {
return false;
} else {
start = (start + TEMP_BUF_POOL_SIZE - 1) % TEMP_BUF_POOL_SIZE;
buffers[start] = buf;
count++;
return true;
}
}
boolean offerLast(ByteBuffer buf) {
// Don't call this if the buffer is too large.
assert !isBufferTooLarge(buf);
if (count >= TEMP_BUF_POOL_SIZE) {
return false;
} else {
int next = (start + count) % TEMP_BUF_POOL_SIZE;
buffers[next] = buf;
count++;
return true;
}
}
boolean isEmpty() {
return count == 0;
}
ByteBuffer removeFirst() {
assert count > 0;
ByteBuffer buf = buffers[start];
buffers[start] = null;
start = next(start);
count--;
return buf;
}
}
/**
* Returns a temporary buffer of at least the given size
*/
public static ByteBuffer getTemporaryDirectBuffer(int size) {
// If a buffer of this size is too large for the cache, there
// should not be a buffer in the cache that is at least as
// large. So we'll just create a new one. Also, we don't have
// to remove the buffer from the cache (as this method does
// below) given that we won't put the new buffer in the cache.
if (isBufferTooLarge(size)) {
return ByteBuffer.allocateDirect(size);
}
BufferCache cache = bufferCache.get();
ByteBuffer buf = cache.get(size);
if (buf != null) {
return buf;
} else {
// No suitable buffer in the cache so we need to allocate a new
// one. To avoid the cache growing then we remove the first
// buffer from the cache and free it.
if (!cache.isEmpty()) {
buf = cache.removeFirst();
free(buf);
}
return ByteBuffer.allocateDirect(size);
}
}
/**
* Returns a temporary buffer of at least the given size and
* aligned to the alignment
*/
public static ByteBuffer getTemporaryAlignedDirectBuffer(int size,
int alignment) {
if (isBufferTooLarge(size)) {
return ByteBuffer.allocateDirect(size + alignment - 1)
.alignedSlice(alignment);
}
BufferCache cache = bufferCache.get();
ByteBuffer buf = cache.get(size);
if (buf != null) {
if (buf.alignmentOffset(0, alignment) == 0) {
return buf;
}
} else {
if (!cache.isEmpty()) {
buf = cache.removeFirst();
free(buf);
}
}
return ByteBuffer.allocateDirect(size + alignment - 1)
.alignedSlice(alignment);
}
/**
* Releases a temporary buffer by returning to the cache or freeing it.
*/
public static void releaseTemporaryDirectBuffer(ByteBuffer buf) {
offerFirstTemporaryDirectBuffer(buf);
}
/**
* Releases a temporary buffer by returning to the cache or freeing it. If
* returning to the cache then insert it at the start so that it is
* likely to be returned by a subsequent call to getTemporaryDirectBuffer.
*/
static void offerFirstTemporaryDirectBuffer(ByteBuffer buf) {
// If the buffer is too large for the cache we don't have to
// check the cache. We'll just free it.
if (isBufferTooLarge(buf)) {
free(buf);
return;
}
assert buf != null;
BufferCache cache = bufferCache.get();
if (!cache.offerFirst(buf)) {
// cache is full
free(buf);
}
}
/**
* Releases a temporary buffer by returning to the cache or freeing it. If
* returning to the cache then insert it at the end. This makes it
* suitable for scatter/gather operations where the buffers are returned to
* cache in same order that they were obtained.
*/
static void offerLastTemporaryDirectBuffer(ByteBuffer buf) {
// If the buffer is too large for the cache we don't have to
// check the cache. We'll just free it.
if (isBufferTooLarge(buf)) {
free(buf);
return;
}
assert buf != null;
BufferCache cache = bufferCache.get();
if (!cache.offerLast(buf)) {
// cache is full
free(buf);
}
}
/**
* Frees the memory for the given direct buffer
*/
private static void free(ByteBuffer buf) {
((DirectBuffer)buf).cleaner().clean();
}
// -- Random stuff --
static ByteBuffer[] subsequence(ByteBuffer[] bs, int offset, int length) {
if ((offset == 0) && (length == bs.length))
return bs;
int n = length;
ByteBuffer[] bs2 = new ByteBuffer[n];
for (int i = 0; i < n; i++)
bs2[i] = bs[offset + i];
return bs2;
}
static Set ungrowableSet(final Set s) {
return new Set() {
public int size() { return s.size(); }
public boolean isEmpty() { return s.isEmpty(); }
public boolean contains(Object o) { return s.contains(o); }
public Object[] toArray() { return s.toArray(); }
public T[] toArray(T[] a) { return s.toArray(a); }
public String toString() { return s.toString(); }
public Iterator iterator() { return s.iterator(); }
public boolean equals(Object o) { return s.equals(o); }
public int hashCode() { return s.hashCode(); }
public void clear() { s.clear(); }
public boolean remove(Object o) { return s.remove(o); }
public boolean containsAll(Collection coll) {
return s.containsAll(coll);
}
public boolean removeAll(Collection coll) {
return s.removeAll(coll);
}
public boolean retainAll(Collection coll) {
return s.retainAll(coll);
}
public boolean add(E o){
throw new UnsupportedOperationException();
}
public boolean addAll(Collection coll) {
throw new UnsupportedOperationException();
}
};
}
// -- Unsafe access --
private static Unsafe unsafe = Unsafe.getUnsafe();
private static byte _get(long a) {
return unsafe.getByte(a);
}
private static void _put(long a, byte b) {
unsafe.putByte(a, b);
}
static void erase(ByteBuffer bb) {
unsafe.setMemory(((DirectBuffer)bb).address(), bb.capacity(), (byte)0);
}
static Unsafe unsafe() {
return unsafe;
}
private static int pageSize = -1;
static int pageSize() {
if (pageSize == -1)
pageSize = unsafe().pageSize();
return pageSize;
}
private static volatile Constructor directByteBufferConstructor;
@SuppressWarnings("removal")
private static void initDBBConstructor() {
AccessController.doPrivileged(new PrivilegedAction() {
public Void run() {
try {
Class cl = Class.forName("java.nio.DirectByteBuffer");
Constructor ctor = cl.getDeclaredConstructor(
new Class[] { int.class,
long.class,
FileDescriptor.class,
Runnable.class,
boolean.class, MemorySegmentProxy.class});
ctor.setAccessible(true);
directByteBufferConstructor = ctor;
} catch (ClassNotFoundException |
NoSuchMethodException |
IllegalArgumentException |
ClassCastException x) {
throw new InternalError(x);
}
return null;
}});
}
static MappedByteBuffer newMappedByteBuffer(int size, long addr,
FileDescriptor fd,
Runnable unmapper,
boolean isSync)
{
MappedByteBuffer dbb;
if (directByteBufferConstructor == null)
initDBBConstructor();
try {
dbb = (MappedByteBuffer)directByteBufferConstructor.newInstance(
new Object[] { size,
addr,
fd,
unmapper,
isSync, null});
} catch (InstantiationException |
IllegalAccessException |
InvocationTargetException e) {
throw new InternalError(e);
}
return dbb;
}
private static volatile Constructor directByteBufferRConstructor;
@SuppressWarnings("removal")
private static void initDBBRConstructor() {
AccessController.doPrivileged(new PrivilegedAction() {
public Void run() {
try {
Class cl = Class.forName("java.nio.DirectByteBufferR");
Constructor ctor = cl.getDeclaredConstructor(
new Class[] { int.class,
long.class,
FileDescriptor.class,
Runnable.class,
boolean.class, MemorySegmentProxy.class });
ctor.setAccessible(true);
directByteBufferRConstructor = ctor;
} catch (ClassNotFoundException |
NoSuchMethodException |
IllegalArgumentException |
ClassCastException x) {
throw new InternalError(x);
}
return null;
}});
}
static MappedByteBuffer newMappedByteBufferR(int size, long addr,
FileDescriptor fd,
Runnable unmapper,
boolean isSync)
{
MappedByteBuffer dbb;
if (directByteBufferRConstructor == null)
initDBBRConstructor();
try {
dbb = (MappedByteBuffer)directByteBufferRConstructor.newInstance(
new Object[] { size,
addr,
fd,
unmapper,
isSync, null});
} catch (InstantiationException |
IllegalAccessException |
InvocationTargetException e) {
throw new InternalError(e);
}
return dbb;
}
static void checkBufferPositionAligned(ByteBuffer bb,
int pos, int alignment)
throws IOException
{
if (bb.alignmentOffset(pos, alignment) != 0) {
throw new IOException("Current location of the bytebuffer ("
+ pos + ") is not a multiple of the block size ("
+ alignment + ")");
}
}
static void checkRemainingBufferSizeAligned(int rem,
int alignment)
throws IOException
{
if (rem % alignment != 0) {
throw new IOException("Number of remaining bytes ("
+ rem + ") is not a multiple of the block size ("
+ alignment + ")");
}
}
static void checkChannelPositionAligned(long position,
int alignment)
throws IOException
{
if (position % alignment != 0) {
throw new IOException("Channel position (" + position
+ ") is not a multiple of the block size ("
+ alignment + ")");
}
}
}