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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF 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
*
* http://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 hivemall.utils.collections.maps;
import hivemall.utils.math.Primes;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Arrays;
import javax.annotation.Nonnull;
/**
* An open-addressing hash table using double hashing.
*
*
* Primary hash function: h1(k) = k mod m
* Secondary hash function: h2(k) = 1 + (k mod(m-2))
*
*
* @see http://en.wikipedia.org/wiki/Double_hashing
*/
public final class Long2DoubleOpenHashTable implements Externalizable {
protected static final byte FREE = 0;
protected static final byte FULL = 1;
protected static final byte REMOVED = 2;
private static final float DEFAULT_LOAD_FACTOR = 0.75f;
private static final float DEFAULT_GROW_FACTOR = 2.0f;
private static final float SHRINK_FACTOR = 0.1f; // at least 10% of table must be FREE
private static final float GROW_FACTOR_AT_SHRINK = 1.7f;
protected/* final */float _loadFactor;
protected/* final */float _growFactor;
protected int _used;
protected int _freeEntries;
/** Used entry threshold to grow table */
protected int _growThreshold;
/**
* Free entry threshold to shrink table. Shrink threshold will be set in the first expansion to
* avoid shrink at very early remove().
*/
protected int _shrinkThreshold;
protected double _defaultReturnValue = 0.d;
protected long[] _keys;
protected double[] _values;
protected byte[] _states;
protected Long2DoubleOpenHashTable(int size, float loadFactor, float growFactor,
boolean forcePrime) {
if (size < 1) {
throw new IllegalArgumentException();
}
this._loadFactor = loadFactor;
this._growFactor = growFactor;
int actualSize = forcePrime ? Primes.findLeastPrimeNumber(size) : size;
this._keys = new long[actualSize];
this._values = new double[actualSize];
this._states = new byte[actualSize];
this._used = 0;
this._freeEntries = actualSize;
this._growThreshold = Math.round(actualSize * _loadFactor);
this._shrinkThreshold = Math.round(actualSize * SHRINK_FACTOR);
}
public Long2DoubleOpenHashTable(int size, int loadFactor, int growFactor) {
this(size, loadFactor, growFactor, true);
}
public Long2DoubleOpenHashTable(int size) {
this(size, DEFAULT_LOAD_FACTOR, DEFAULT_GROW_FACTOR, true);
}
/**
* Only for {@link Externalizable}
*/
public Long2DoubleOpenHashTable() {// required for serialization
this._loadFactor = DEFAULT_LOAD_FACTOR;
this._growFactor = DEFAULT_GROW_FACTOR;
}
public void defaultReturnValue(double v) {
this._defaultReturnValue = v;
}
public boolean containsKey(final long key) {
return _findKey(key) >= 0;
}
/**
* @return defaultReturnValue if not found
*/
public double get(final long key) {
return get(key, _defaultReturnValue);
}
public double get(final long key, final double defaultValue) {
final int i = _findKey(key);
if (i == -1) {
return defaultValue;
}
return _values[i];
}
public double _get(final int index) {
if (index < 0) {
return _defaultReturnValue;
}
return _values[index];
}
public double _set(final int index, final double value) {
double old = _values[index];
_values[index] = value;
return old;
}
public double _remove(final int index) {
_states[index] = REMOVED;
--_used;
return _values[index];
}
public double put(final long key, final double value) {
return put(key, value, _defaultReturnValue);
}
public double put(final long key, final double value, final double defaultValue) {
final int hash = keyHash(key);
int keyLength = _keys.length;
int keyIdx = hash % keyLength;
boolean expanded = preAddEntry(keyIdx);
if (expanded) {
keyLength = _keys.length;
keyIdx = hash % keyLength;
}
final long[] keys = _keys;
final double[] values = _values;
final byte[] states = _states;
byte state = states[keyIdx];
if (state == FULL) {// double hashing
if (keys[keyIdx] == key) {
double old = values[keyIdx];
values[keyIdx] = value;
return old;
}
// try second hash
final int loopIndex = keyIdx;
final int decr = 1 + (hash % (keyLength - 2));
for (;;) {
keyIdx -= decr;
if (keyIdx < 0) {
keyIdx += keyLength;
}
if (keyIdx == loopIndex) {
throw new IllegalStateException(
"Detected infinite loop where key=" + key + ", keyIdx=" + keyIdx);
}
state = states[keyIdx];
if (state == FREE) {
break;
}
if (keys[keyIdx] == key) {
if (state == FULL) {
double old = values[keyIdx];
values[keyIdx] = value;
return old;
} else {
assert (state == REMOVED);
break;
}
}
}
}
keys[keyIdx] = key;
values[keyIdx] = value;
states[keyIdx] = FULL;
++_used;
if (state == FREE) {
_freeEntries--;
if (_freeEntries < _shrinkThreshold) {
int newCapacity = Math.max(keys.length, Math.round(_used * GROW_FACTOR_AT_SHRINK));
ensureCapacity(newCapacity);
}
}
return defaultValue;
}
/** @return expanded or not */
protected boolean preAddEntry(final int index) {
if ((_used + 1) >= _growThreshold) {// too filled
int newCapacity = Math.round(_keys.length * _growFactor);
ensureCapacity(newCapacity);
return true;
}
return false;
}
/**
* @return -1 if not found
*/
public int _findKey(final long key) {
final long[] keys = _keys;
final byte[] states = _states;
final int keyLength = keys.length;
// double hashing
final int hash = keyHash(key);
final int decr = 1 + (hash % (keyLength - 2));
final int startIndex = hash % keyLength;
for (int keyIdx = startIndex;;) {
final byte state = states[keyIdx];
if (state == FREE) {
return -1;
}
if (keys[keyIdx] == key) {
if (state == FULL) {
return keyIdx;
} else {
assert (state == REMOVED);
return -1;
}
}
keyIdx -= decr;
if (keyIdx < 0) {
keyIdx += keyLength;
}
if (keyIdx == startIndex) {
throw new IllegalStateException(
"Detected infinite loop where key=" + key + ", keyIdx=" + keyIdx);
}
}
}
public double remove(final long key) {
final int keyIdx = _findKey(key);
if (keyIdx == -1) {
return _defaultReturnValue;
}
double old = _values[keyIdx];
_states[keyIdx] = REMOVED;
--_used;
return old;
}
public int size() {
return _used;
}
public void clear() {
Arrays.fill(_states, FREE);
this._used = 0;
this._freeEntries = _states.length;
}
public IMapIterator entries() {
return new MapIterator();
}
@Override
public String toString() {
int len = size() * 10 + 2;
StringBuilder buf = new StringBuilder(len);
buf.append('{');
IMapIterator i = entries();
while (i.next() != -1) {
buf.append(i.getKey());
buf.append('=');
buf.append(i.getValue());
if (i.hasNext()) {
buf.append(',');
}
}
buf.append('}');
return buf.toString();
}
protected void ensureCapacity(final int newCapacity) {
int prime = Primes.findLeastPrimeNumber(newCapacity);
rehash(prime);
}
private void rehash(final int newCapacity) {
final long[] oldKeys = _keys;
final double[] oldValues = _values;
final byte[] oldStates = _states;
final int oldCapacity = _keys.length;
final long[] newkeys = new long[newCapacity];
final double[] newValues = new double[newCapacity];
final byte[] newStates = new byte[newCapacity];
int used = 0;
for (int i = 0; i < oldCapacity; i++) {
if (oldStates[i] != FULL) {
continue;
}
final long k = oldKeys[i];
final double v = oldValues[i];
final int hash = keyHash(k);
int keyIdx = hash % newCapacity;
if (newStates[keyIdx] == FULL) {// second hashing
final int decr = 1 + (hash % (newCapacity - 2));
final int loopIndex = keyIdx;
do {
keyIdx -= decr;
if (keyIdx < 0) {
keyIdx += newCapacity;
}
if (keyIdx == loopIndex) {
throw new IllegalStateException(
"Detected infinite loop where key=" + k + ", keyIdx=" + keyIdx);
}
} while (newStates[keyIdx] != FREE);
}
newkeys[keyIdx] = k;
newValues[keyIdx] = v;
newStates[keyIdx] = FULL;
used++;
}
this._keys = newkeys;
this._values = newValues;
this._states = newStates;
this._used = used;
this._freeEntries = newCapacity - used;
this._growThreshold = Math.round(newCapacity * _loadFactor);
this._shrinkThreshold = Math.round(newCapacity * SHRINK_FACTOR);
}
private static int keyHash(final long key) {
return (int) (key ^ (key >>> 32)) & 0x7FFFFFFF;
}
public interface IMapIterator {
public boolean hasNext();
/**
* @return -1 if not found
*/
public int next();
public long getKey();
public double getValue();
}
private final class MapIterator implements IMapIterator {
int nextEntry;
int lastEntry = -1;
MapIterator() {
this.nextEntry = nextEntry(0);
}
/** find the index of next full entry */
int nextEntry(int index) {
while (index < _keys.length && _states[index] != FULL) {
index++;
}
return index;
}
public boolean hasNext() {
return nextEntry < _keys.length;
}
public int next() {
if (!hasNext()) {
return -1;
}
int curEntry = nextEntry;
this.lastEntry = curEntry;
this.nextEntry = nextEntry(curEntry + 1);
return curEntry;
}
public long getKey() {
if (lastEntry == -1) {
throw new IllegalStateException();
}
return _keys[lastEntry];
}
public double getValue() {
if (lastEntry == -1) {
throw new IllegalStateException();
}
return _values[lastEntry];
}
}
@Override
public void writeExternal(@Nonnull ObjectOutput out) throws IOException {
out.writeFloat(_loadFactor);
out.writeFloat(_growFactor);
out.writeInt(_used);
out.writeDouble(_defaultReturnValue);
final IMapIterator i = entries();
while (i.next() != -1) {
out.writeLong(i.getKey());
out.writeDouble(i.getValue());
}
}
@Override
public void readExternal(@Nonnull ObjectInput in) throws IOException, ClassNotFoundException {
this._loadFactor = in.readFloat();
this._growFactor = in.readFloat();
final int used = in.readInt();
this._defaultReturnValue = in.readDouble();
final int newCapacity = Primes.findLeastPrimeNumber(Math.round(used * 1.7f));
final long[] keys = new long[newCapacity];
final double[] values = new double[newCapacity];
final byte[] states = new byte[newCapacity];
for (int i = 0; i < used; i++) {
final long k = in.readLong();
final double v = in.readDouble();
final int hash = keyHash(k);
int keyIdx = hash % newCapacity;
if (states[keyIdx] != FREE) {// second hashing
final int decr = 1 + (hash % (newCapacity - 2));
final int loopIndex = keyIdx;
do {
keyIdx -= decr;
if (keyIdx < 0) {
keyIdx += newCapacity;
}
if (keyIdx == loopIndex) {
throw new IllegalStateException(
"Detected infinite loop where key=" + k + ", keyIdx=" + keyIdx);
}
} while (states[keyIdx] != FREE);
}
keys[keyIdx] = k;
values[keyIdx] = v;
states[keyIdx] = FULL;
}
this._keys = keys;
this._values = values;
this._states = states;
this._used = used;
this._freeEntries = newCapacity - used;
this._growThreshold = Math.round(newCapacity * _loadFactor);
this._shrinkThreshold = Math.round(newCapacity * SHRINK_FACTOR);
}
}
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