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/*
* Copyright (c) 2008, 2020 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package org.glassfish.grizzly.attributes;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.function.Supplier;
/**
* {@link AttributeHolder}, which supports indexed access to stored {@link Attribute}s. Access to such indexed
* {@link Attribute}s could be as fast as access to array.
*
* This implementation is thread-safe.
*
* @see AttributeHolder
* @see NamedAttributeHolder
*
* @author Alexey Stashok
*/
public final class IndexedAttributeHolder implements AttributeHolder {
private final Object sync = new Object();
// dummy volatile
private volatile int count;
private Snapshot state;
protected final DefaultAttributeBuilder attributeBuilder;
protected final IndexedAttributeAccessor indexedAttributeAccessor;
/**
* @param attributeBuilder
* @deprecated use {@link AttributeBuilder#createSafeAttributeHolder()}
*/
@Deprecated
public IndexedAttributeHolder(final AttributeBuilder attributeBuilder) {
this.attributeBuilder = (DefaultAttributeBuilder) attributeBuilder;
state = new Snapshot(new Object[4], new int[] { -1, -1, -1, -1 }, 0);
indexedAttributeAccessor = new IndexedAttributeAccessorImpl();
}
/**
* {@inheritDoc}
*/
@Override
public Object getAttribute(final String name) {
return getAttribute(name, null);
}
/**
* {@inheritDoc}
*/
@Override
public Object getAttribute(final String name, final Supplier initializer) {
final Attribute attribute = attributeBuilder.getAttributeByName(name);
if (attribute != null) {
return indexedAttributeAccessor.getAttribute(attribute.index(), initializer);
}
return initializer != null ? initializer : null;
}
/**
* {@inheritDoc}
*/
@Override
public void setAttribute(final String name, final Object value) {
Attribute attribute = attributeBuilder.getAttributeByName(name);
if (attribute == null) {
attribute = attributeBuilder.createAttribute(name);
}
indexedAttributeAccessor.setAttribute(attribute.index(), value);
}
/**
* {@inheritDoc}
*/
@Override
public Object removeAttribute(final String name) {
final Attribute attribute = attributeBuilder.getAttributeByName(name);
if (attribute != null) {
return indexedAttributeAccessor.removeAttribute(attribute.index());
}
return null;
}
/**
* {@inheritDoc}
*/
@Override
public Set getAttributeNames() {
if (count != 0) {
final Set result = new HashSet<>();
final Snapshot stateNow = state;
final int localSize = stateNow.size;
final Object[] localAttributeValues = stateNow.values;
for (int i = 0; i < localSize; i++) {
final Object value = localAttributeValues[i];
if (value != null) {
Attribute attribute = attributeBuilder.getAttributeByIndex(i);
result.add(attribute.name());
}
}
return result;
} else {
return Collections.emptySet();
}
}
@Override
public void copyFrom(final AttributeHolder srcAttributes) {
if (srcAttributes instanceof IndexedAttributeHolder) {
final IndexedAttributeHolder iah = (IndexedAttributeHolder) srcAttributes;
final Snapshot stateNow = state;
final Snapshot srcState = iah.state;
int[] newI2v = stateNow.i2v;
if (newI2v.length < srcState.i2v.length) {
newI2v = Arrays.copyOf(srcState.i2v, srcState.i2v.length);
} else {
System.arraycopy(srcState.i2v, 0, newI2v, 0, srcState.i2v.length);
for (int i = srcState.i2v.length; i < newI2v.length; i++) {
newI2v[i] = -1;
}
}
Object[] newValues = stateNow.values;
if (newValues.length < srcState.size) {
newValues = Arrays.copyOf(srcState.values, srcState.size);
} else {
System.arraycopy(srcState.values, 0, newValues, 0, srcState.size);
for (int i = srcState.size; i < stateNow.size; i++) {
newValues[i] = null;
}
}
final Snapshot newState = new Snapshot(newValues, newI2v, srcState.size);
state = newState;
count++;
} else {
clear();
final Set names = srcAttributes.getAttributeNames();
if (names.isEmpty()) {
return;
}
for (String name : names) {
setAttribute(name, srcAttributes.getAttribute(name));
}
}
}
@Override
public void copyTo(final AttributeHolder dstAttributes) {
if (count != 0) {
if (dstAttributes instanceof IndexedAttributeHolder) {
final IndexedAttributeHolder iah = (IndexedAttributeHolder) dstAttributes;
final Snapshot stateNow = state;
final Snapshot dstState = iah.state;
int[] newI2v = dstState.i2v;
if (newI2v.length < stateNow.i2v.length) {
newI2v = Arrays.copyOf(stateNow.i2v, stateNow.i2v.length);
} else {
System.arraycopy(stateNow.i2v, 0, newI2v, 0, stateNow.i2v.length);
for (int i = stateNow.i2v.length; i < newI2v.length; i++) {
newI2v[i] = -1;
}
}
Object[] newValues = dstState.values;
if (newValues.length < stateNow.size) {
newValues = Arrays.copyOf(stateNow.values, stateNow.size);
} else {
System.arraycopy(stateNow.values, 0, newValues, 0, stateNow.size);
for (int i = stateNow.size; i < dstState.size; i++) {
newValues[i] = null;
}
}
final Snapshot newState = new Snapshot(newValues, newI2v, stateNow.size);
iah.state = newState;
iah.count++;
} else {
dstAttributes.clear();
final Snapshot stateNow = state;
final int localSize = stateNow.size;
final Object[] localAttributeValues = stateNow.values;
for (int i = 0; i < localSize; i++) {
final Object value = localAttributeValues[i];
if (value != null) {
final Attribute attribute = attributeBuilder.getAttributeByIndex(i);
dstAttributes.setAttribute(attribute.name(), value);
}
}
}
} else {
dstAttributes.clear();
}
}
/**
* {@inheritDoc}
*/
@Override
public void recycle() {
if (count != 0) {
final Snapshot stateNow = state;
// Recycle is not synchronized
for (int i = 0; i < stateNow.size; i++) {
stateNow.values[i] = null;
}
} else {
count = 0;
}
}
/**
* {@inheritDoc}
*/
@Override
public void clear() {
if (count != 0) {
count = 0;
for (int i = 0; i < state.size; i++) {
state.values[i] = null;
}
}
}
/**
* {@inheritDoc}
*/
@Override
public AttributeBuilder getAttributeBuilder() {
return attributeBuilder;
}
/**
* Returns {@link IndexedAttributeAccessor} for accessing {@link Attribute}s by index.
*
* @return {@link IndexedAttributeAccessor} for accessing {@link Attribute}s by index.
*/
@Override
public IndexedAttributeAccessor getIndexedAttributeAccessor() {
return indexedAttributeAccessor;
}
/**
* {@link IndexedAttributeAccessor} implementation.
*/
protected final class IndexedAttributeAccessorImpl implements IndexedAttributeAccessor {
/**
* {@inheritDoc}
*/
@Override
public Object getAttribute(final int index) {
return getAttribute(index, null);
}
/**
* {@inheritDoc}
*/
@Override
public Object getAttribute(final int index, final Supplier initializer) {
Object value = weakGet(index);
if (value == null && initializer != null) {
synchronized (sync) {
// we want to make sure that parallel getAttribute(int, Suppler)
// won't create multiple value instances (everyone will call Supplier.get())
value = weakGet(index);
if (value == null) {
value = initializer.get();
setAttribute(index, value);
}
}
}
return value;
}
private Object weakGet(final int index) {
if (count != 0) {
final Snapshot stateNow = state;
if (index < stateNow.i2v.length) {
final int idx = stateNow.i2v[index];
if (idx != -1 && idx < stateNow.size) {
return stateNow.values[idx];
}
}
}
return null;
}
/**
* {@inheritDoc}
*/
@Override
public void setAttribute(final int index, final Object value) {
final Snapshot stateNow = state;
int mappedIdx;
if (index < stateNow.i2v.length && (mappedIdx = stateNow.i2v[index]) != -1) {
stateNow.values[mappedIdx] = value;
count++;
} else if (value != null) {
setSync(index, value);
}
}
@Override
public Object removeAttribute(final int index) {
final Snapshot stateNow = state;
Object oldValue = null;
int mappedIdx;
if (index < stateNow.i2v.length && (mappedIdx = stateNow.i2v[index]) != -1) {
oldValue = stateNow.values[mappedIdx];
stateNow.values[mappedIdx] = null;
count++;
}
return oldValue;
}
private void setSync(final int index, final Object value) {
synchronized (sync) {
final Snapshot stateNow = state;
int mappedIdx;
final int[] newI2v;
if (index < stateNow.i2v.length) {
if ((mappedIdx = stateNow.i2v[index]) != -1 && mappedIdx < stateNow.size) {
stateNow.values[mappedIdx] = value;
count++;
return;
}
newI2v = stateNow.i2v;
} else {
newI2v = ensureSize(stateNow.i2v, index + 1);
}
mappedIdx = stateNow.size;
final int newSize = mappedIdx + 1;
final Object[] newValues = mappedIdx < stateNow.values.length ? stateNow.values : ensureSize(stateNow.values, newSize);
newValues[mappedIdx] = value;
newI2v[index] = mappedIdx;
state = new Snapshot(newValues, newI2v, newSize);
count++;
}
}
}
private static Object[] ensureSize(final Object[] array, final int size) {
final int arrayLength = array.length;
final int delta = size - arrayLength;
final int newLength = Math.max(arrayLength + delta, arrayLength * 3 / 2 + 1);
return Arrays.copyOf(array, newLength);
}
private static int[] ensureSize(final int[] array, final int size) {
final int arrayLength = array.length;
final int delta = size - arrayLength;
final int newLength = Math.max(arrayLength + delta, arrayLength * 3 / 2 + 1);
final int[] newArray = Arrays.copyOf(array, newLength);
Arrays.fill(newArray, array.length, newLength, -1);
return newArray;
}
private static class Snapshot {
private final Object[] values;
private final int[] i2v;
private final int size;
public Snapshot(Object[] values, int[] i2v, int size) {
this.values = values;
this.i2v = i2v;
this.size = size;
}
}
}
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