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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License, version 2.0 (the
* "License"); you may not use this file except in compliance with the License. You may obtain a
* copy of the License at:
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software distributed under the License
* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
* or implied. See the License for the specific language governing permissions and limitations under
* the License.
*/
package io.netty.util.collection;
import static io.netty.util.internal.MathUtil.safeFindNextPositivePowerOfTwo;
import java.util.AbstractCollection;
import java.util.AbstractSet;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* A hash map implementation of {@link IntObjectMap} that uses open addressing for keys.
* To minimize the memory footprint, this class uses open addressing rather than chaining.
* Collisions are resolved using linear probing. Deletions implement compaction, so cost of
* remove can approach O(N) for full maps, which makes a small loadFactor recommended.
*
* @param The value type stored in the map.
*/
public class IntObjectHashMap implements IntObjectMap {
/** Default initial capacity. Used if not specified in the constructor */
public static final int DEFAULT_CAPACITY = 8;
/** Default load factor. Used if not specified in the constructor */
public static final float DEFAULT_LOAD_FACTOR = 0.5f;
/**
* Placeholder for null values, so we can use the actual null to mean available.
* (Better than using a placeholder for available: less references for GC processing.)
*/
private static final Object NULL_VALUE = new Object();
/** The maximum number of elements allowed without allocating more space. */
private int maxSize;
/** The load factor for the map. Used to calculate {@link #maxSize}. */
private final float loadFactor;
private int[] keys;
private V[] values;
private int size;
private int mask;
private final Set keySet = new KeySet();
private final Set> entrySet = new EntrySet();
private final Iterable> entries = new Iterable>() {
@Override
public Iterator> iterator() {
return new PrimitiveIterator();
}
};
public IntObjectHashMap() {
this(DEFAULT_CAPACITY, DEFAULT_LOAD_FACTOR);
}
public IntObjectHashMap(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
public IntObjectHashMap(int initialCapacity, float loadFactor) {
if (loadFactor <= 0.0f || loadFactor > 1.0f) {
// Cannot exceed 1 because we can never store more than capacity elements;
// using a bigger loadFactor would trigger rehashing before the desired load is reached.
throw new IllegalArgumentException("loadFactor must be > 0 and <= 1");
}
this.loadFactor = loadFactor;
// Adjust the initial capacity if necessary.
int capacity = safeFindNextPositivePowerOfTwo(initialCapacity);
mask = capacity - 1;
// Allocate the arrays.
keys = new int[capacity];
@SuppressWarnings({ "unchecked", "SuspiciousArrayCast" })
V[] temp = (V[]) new Object[capacity];
values = temp;
// Initialize the maximum size value.
maxSize = calcMaxSize(capacity);
}
private static T toExternal(T value) {
assert value != null : "null is not a legitimate internal value. Concurrent Modification?";
return value == NULL_VALUE ? null : value;
}
@SuppressWarnings("unchecked")
private static T toInternal(T value) {
return value == null ? (T) NULL_VALUE : value;
}
@Override
public V get(int key) {
int index = indexOf(key);
return index == -1 ? null : toExternal(values[index]);
}
@Override
public V put(int key, V value) {
int startIndex = hashIndex(key);
int index = startIndex;
for (;;) {
if (values[index] == null) {
// Found empty slot, use it.
keys[index] = key;
values[index] = toInternal(value);
growSize();
return null;
}
if (keys[index] == key) {
// Found existing entry with this key, just replace the value.
V previousValue = values[index];
values[index] = toInternal(value);
return toExternal(previousValue);
}
// Conflict, keep probing ...
if ((index = probeNext(index)) == startIndex) {
// Can only happen if the map was full at MAX_ARRAY_SIZE and couldn't grow.
throw new IllegalStateException("Unable to insert");
}
}
}
@Override
public void putAll(Map sourceMap) {
if (sourceMap instanceof IntObjectHashMap) {
// Optimization - iterate through the arrays.
@SuppressWarnings("unchecked")
IntObjectHashMap source = (IntObjectHashMap) sourceMap;
for (int i = 0; i < source.values.length; ++i) {
V sourceValue = source.values[i];
if (sourceValue != null) {
put(source.keys[i], sourceValue);
}
}
return;
}
// Otherwise, just add each entry.
for (Entry entry : sourceMap.entrySet()) {
put(entry.getKey(), entry.getValue());
}
}
@Override
public V remove(int key) {
int index = indexOf(key);
if (index == -1) {
return null;
}
V prev = values[index];
removeAt(index);
return toExternal(prev);
}
@Override
public int size() {
return size;
}
@Override
public boolean isEmpty() {
return size == 0;
}
@Override
public void clear() {
Arrays.fill(keys, (int) 0);
Arrays.fill(values, null);
size = 0;
}
@Override
public boolean containsKey(int key) {
return indexOf(key) >= 0;
}
@Override
public boolean containsValue(Object value) {
@SuppressWarnings("unchecked")
V v1 = toInternal((V) value);
for (V v2 : values) {
// The map supports null values; this will be matched as NULL_VALUE.equals(NULL_VALUE).
if (v2 != null && v2.equals(v1)) {
return true;
}
}
return false;
}
@Override
public Iterable> entries() {
return entries;
}
@Override
public Collection values() {
return new AbstractCollection() {
@Override
public Iterator iterator() {
return new Iterator() {
final PrimitiveIterator iter = new PrimitiveIterator();
@Override
public boolean hasNext() {
return iter.hasNext();
}
@Override
public V next() {
return iter.next().value();
}
@Override
public void remove() {
iter.remove();
}
};
}
@Override
public int size() {
return size;
}
};
}
@Override
public int hashCode() {
// Hashcode is based on all non-zero, valid keys. We have to scan the whole keys
// array, which may have different lengths for two maps of same size(), so the
// capacity cannot be used as input for hashing but the size can.
int hash = size;
for (int key : keys) {
// 0 can be a valid key or unused slot, but won't impact the hashcode in either case.
// This way we can use a cheap loop without conditionals, or hard-to-unroll operations,
// or the devastatingly bad memory locality of visiting value objects.
// Also, it's important to use a hash function that does not depend on the ordering
// of terms, only their values; since the map is an unordered collection and
// entries can end up in different positions in different maps that have the same
// elements, but with different history of puts/removes, due to conflicts.
hash ^= hashCode(key);
}
return hash;
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof IntObjectMap)) {
return false;
}
@SuppressWarnings("rawtypes")
IntObjectMap other = (IntObjectMap) obj;
if (size != other.size()) {
return false;
}
for (int i = 0; i < values.length; ++i) {
V value = values[i];
if (value != null) {
int key = keys[i];
Object otherValue = other.get(key);
if (value == NULL_VALUE) {
if (otherValue != null) {
return false;
}
} else if (!value.equals(otherValue)) {
return false;
}
}
}
return true;
}
@Override
public boolean containsKey(Object key) {
return containsKey(objectToKey(key));
}
@Override
public V get(Object key) {
return get(objectToKey(key));
}
@Override
public V put(Integer key, V value) {
return put(objectToKey(key), value);
}
@Override
public V remove(Object key) {
return remove(objectToKey(key));
}
@Override
public Set keySet() {
return keySet;
}
@Override
public Set> entrySet() {
return entrySet;
}
private int objectToKey(Object key) {
return (int) ((Integer) key).intValue();
}
/**
* Locates the index for the given key. This method probes using double hashing.
*
* @param key the key for an entry in the map.
* @return the index where the key was found, or {@code -1} if no entry is found for that key.
*/
private int indexOf(int key) {
int startIndex = hashIndex(key);
int index = startIndex;
for (;;) {
if (values[index] == null) {
// It's available, so no chance that this value exists anywhere in the map.
return -1;
}
if (key == keys[index]) {
return index;
}
// Conflict, keep probing ...
if ((index = probeNext(index)) == startIndex) {
return -1;
}
}
}
/**
* Returns the hashed index for the given key.
*/
private int hashIndex(int key) {
// The array lengths are always a power of two, so we can use a bitmask to stay inside the array bounds.
return hashCode(key) & mask;
}
/**
* Returns the hash code for the key.
*/
private static int hashCode(int key) {
return (int) key;
}
/**
* Get the next sequential index after {@code index} and wraps if necessary.
*/
private int probeNext(int index) {
// The array lengths are always a power of two, so we can use a bitmask to stay inside the array bounds.
return (index + 1) & mask;
}
/**
* Grows the map size after an insertion. If necessary, performs a rehash of the map.
*/
private void growSize() {
size++;
if (size > maxSize) {
if(keys.length == Integer.MAX_VALUE) {
throw new IllegalStateException("Max capacity reached at size=" + size);
}
// Double the capacity.
rehash(keys.length << 1);
}
}
/**
* Removes entry at the given index position. Also performs opportunistic, incremental rehashing
* if necessary to not break conflict chains.
*
* @param index the index position of the element to remove.
* @return {@code true} if the next item was moved back. {@code false} otherwise.
*/
private boolean removeAt(final int index) {
--size;
// Clearing the key is not strictly necessary (for GC like in a regular collection),
// but recommended for security. The memory location is still fresh in the cache anyway.
keys[index] = 0;
values[index] = null;
// In the interval from index to the next available entry, the arrays may have entries
// that are displaced from their base position due to prior conflicts. Iterate these
// entries and move them back if possible, optimizing future lookups.
// Knuth Section 6.4 Algorithm R, also used by the JDK's IdentityHashMap.
int nextFree = index;
int i = probeNext(index);
for (V value = values[i]; value != null; value = values[i = probeNext(i)]) {
int key = keys[i];
int bucket = hashIndex(key);
if (i < bucket && (bucket <= nextFree || nextFree <= i) ||
bucket <= nextFree && nextFree <= i) {
// Move the displaced entry "back" to the first available position.
keys[nextFree] = key;
values[nextFree] = value;
// Put the first entry after the displaced entry
keys[i] = 0;
values[i] = null;
nextFree = i;
}
}
return nextFree != index;
}
/**
* Calculates the maximum size allowed before rehashing.
*/
private int calcMaxSize(int capacity) {
// Clip the upper bound so that there will always be at least one available slot.
int upperBound = capacity - 1;
return Math.min(upperBound, (int) (capacity * loadFactor));
}
/**
* Rehashes the map for the given capacity.
*
* @param newCapacity the new capacity for the map.
*/
private void rehash(int newCapacity) {
int[] oldKeys = keys;
V[] oldVals = values;
keys = new int[newCapacity];
@SuppressWarnings({ "unchecked", "SuspiciousArrayCast" })
V[] temp = (V[]) new Object[newCapacity];
values = temp;
maxSize = calcMaxSize(newCapacity);
mask = newCapacity - 1;
// Insert to the new arrays.
for (int i = 0; i < oldVals.length; ++i) {
V oldVal = oldVals[i];
if (oldVal != null) {
// Inlined put(), but much simpler: we don't need to worry about
// duplicated keys, growing/rehashing, or failing to insert.
int oldKey = oldKeys[i];
int index = hashIndex(oldKey);
for (;;) {
if (values[index] == null) {
keys[index] = oldKey;
values[index] = oldVal;
break;
}
// Conflict, keep probing. Can wrap around, but never reaches startIndex again.
index = probeNext(index);
}
}
}
}
@Override
public String toString() {
if (isEmpty()) {
return "{}";
}
StringBuilder sb = new StringBuilder(4 * size);
sb.append('{');
boolean first = true;
for (int i = 0; i < values.length; ++i) {
V value = values[i];
if (value != null) {
if (!first) {
sb.append(", ");
}
sb.append(keyToString(keys[i])).append('=').append(value == this ? "(this Map)" :
toExternal(value));
first = false;
}
}
return sb.append('}').toString();
}
/**
* Helper method called by {@link #toString()} in order to convert a single map key into a string.
* This is protected to allow subclasses to override the appearance of a given key.
*/
protected String keyToString(int key) {
return Integer.toString(key);
}
/**
* Set implementation for iterating over the entries of the map.
*/
private final class EntrySet extends AbstractSet> {
@Override
public Iterator> iterator() {
return new MapIterator();
}
@Override
public int size() {
return IntObjectHashMap.this.size();
}
}
/**
* Set implementation for iterating over the keys.
*/
private final class KeySet extends AbstractSet {
@Override
public int size() {
return IntObjectHashMap.this.size();
}
@Override
public boolean contains(Object o) {
return IntObjectHashMap.this.containsKey(o);
}
@Override
public boolean remove(Object o) {
return IntObjectHashMap.this.remove(o) != null;
}
@Override
public boolean retainAll(Collection retainedKeys) {
boolean changed = false;
for(Iterator> iter = entries().iterator(); iter.hasNext(); ) {
PrimitiveEntry entry = iter.next();
if (!retainedKeys.contains(entry.key())) {
changed = true;
iter.remove();
}
}
return changed;
}
@Override
public void clear() {
IntObjectHashMap.this.clear();
}
@Override
public Iterator iterator() {
return new Iterator() {
private final Iterator> iter = entrySet.iterator();
@Override
public boolean hasNext() {
return iter.hasNext();
}
@Override
public Integer next() {
return iter.next().getKey();
}
@Override
public void remove() {
iter.remove();
}
};
}
}
/**
* Iterator over primitive entries. Entry key/values are overwritten by each call to {@link #next()}.
*/
private final class PrimitiveIterator implements Iterator>, PrimitiveEntry {
private int prevIndex = -1;
private int nextIndex = -1;
private int entryIndex = -1;
private void scanNext() {
while (++nextIndex != values.length && values[nextIndex] == null) {
}
}
@Override
public boolean hasNext() {
if (nextIndex == -1) {
scanNext();
}
return nextIndex != values.length;
}
@Override
public PrimitiveEntry next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
prevIndex = nextIndex;
scanNext();
// Always return the same Entry object, just change its index each time.
entryIndex = prevIndex;
return this;
}
@Override
public void remove() {
if (prevIndex == -1) {
throw new IllegalStateException("next must be called before each remove.");
}
if (removeAt(prevIndex)) {
// removeAt may move elements "back" in the array if they have been displaced because their spot in the
// array was occupied when they were inserted. If this occurs then the nextIndex is now invalid and
// should instead point to the prevIndex which now holds an element which was "moved back".
nextIndex = prevIndex;
}
prevIndex = -1;
}
// Entry implementation. Since this implementation uses a single Entry, we coalesce that
// into the Iterator object (potentially making loop optimization much easier).
@Override
public int key() {
return keys[entryIndex];
}
@Override
public V value() {
return toExternal(values[entryIndex]);
}
@Override
public void setValue(V value) {
values[entryIndex] = toInternal(value);
}
}
/**
* Iterator used by the {@link Map} interface.
*/
private final class MapIterator implements Iterator> {
private final PrimitiveIterator iter = new PrimitiveIterator();
@Override
public boolean hasNext() {
return iter.hasNext();
}
@Override
public Entry next() {
if (!hasNext()) {
throw new NoSuchElementException();
}
iter.next();
return new MapEntry(iter.entryIndex);
}
@Override
public void remove() {
iter.remove();
}
}
/**
* A single entry in the map.
*/
final class MapEntry implements Entry {
private final int entryIndex;
MapEntry(int entryIndex) {
this.entryIndex = entryIndex;
}
@Override
public Integer getKey() {
verifyExists();
return keys[entryIndex];
}
@Override
public V getValue() {
verifyExists();
return toExternal(values[entryIndex]);
}
@Override
public V setValue(V value) {
verifyExists();
V prevValue = toExternal(values[entryIndex]);
values[entryIndex] = toInternal(value);
return prevValue;
}
private void verifyExists() {
if (values[entryIndex] == null) {
throw new IllegalStateException("The map entry has been removed");
}
}
}
}