package org.zoodb.internal.util;
import java.lang.ref.WeakReference;
import java.util.AbstractCollection;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
/*
* @(#)HashMap.java 1.73 07/03/13
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
/**
* This is a modified version of the java.util.HashMap class with three important special features.
* Like PrimLongMapLI: <p>
* a) only 'long' are admitted as keys.
* b) As a) implies, this map does not inherit java.util.Map. This is also done to avoid performance
* penalty from polymorphism.
*
* In addition to PrimLongMapLI: <p>
* c) This map uses internally SoftReferences for all values. This should makes it suitable as
* cache.
* Strategy:
* 1) Do not remove gc()'d elements discovered in get(). The get() method is only called for
* checking whether an element is in the cache. If it is not, i.e. if it has been gc()'d, then
* the element will be added. Since replacing is cheaper than removing and adding, the get()
* method does not remove empty elements.
* 2) remove() doesn't need special treatment either
* 3) put() also does not need special treatment
* 4) values() does get special treatment, because this is where we will remove collected elements.
* The values() method is ideal, because it is often called, and because we have to check every
* element anyway, so we get the checking almost for free.
* How do we remove elements? There are two ways:
* a) Remove while iterating: Probably fastest, because we already look at the elements. But
* we need a special remove() method that cannot trigger resizing, which would invalidate
* the iterator. Also, we need to continuously update the modifyCount in order to allow
* out values() iterator to work while invalidating any other iterators().
* b) We could create a list of invalid elements. If the values() iterator finishes, it can
* remove all elements according to the temporary list.
*
* @param <V> the type of mapped values
*
* @author Doug Lea
* @author Josh Bloch
* @author Arthur van Hoff
* @author Neal Gafter
* @see java.util.HashMap
*/
public class PrimLongMapLIWeak<V> implements PrimLongMap<V> {
/**
* The default initial capacity - MUST be a power of two.
*/
static final int DEFAULT_INITIAL_CAPACITY = 16;
/**
* The maximum capacity, used if a higher value is implicitly specified
* by either of the constructors with arguments.
* MUST be a power of two <= 1<<30.
*/
static final int MAXIMUM_CAPACITY = 1 << 30;
/**
* The load factor used when none specified in constructor.
*/
static final float DEFAULT_LOAD_FACTOR = 0.75f;
/**
* The table, resized as necessary. Length MUST Always be a power of two.
*/
private transient Entry<V>[] table;
/**
* The number of key-value mappings contained in this map.
*/
private transient int size;
/**
* The next size value at which to resize (capacity * load factor).
* @serial
*/
private int threshold;
/**
* The load factor for the hash table.
*
* @serial
*/
private final float loadFactor;
/**
* The number of times this HashMap has been structurally modified
* Structural modifications are those that change the number of mappings in
* the HashMap or otherwise modify its internal structure (e.g.,
* rehash). This field is used to make iterators on Collection-views of
* the HashMap fail-fast. (See ConcurrentModificationException).
*/
private transient int modCount;
/**
* Constructs an empty <tt>HashMap</tt> with the specified initial
* capacity and load factor.
*
* @param initialCapacity the initial capacity
* @param loadFactor the load factor
* @throws IllegalArgumentException if the initial capacity is negative
* or the load factor is nonpositive
*/
@SuppressWarnings("unchecked")
public PrimLongMapLIWeak(int initialCapacity, final float loadFactor) {
if (initialCapacity < 0) {
throw new IllegalArgumentException("Illegal initial capacity: " + initialCapacity);
}
if (initialCapacity > MAXIMUM_CAPACITY) {
initialCapacity = MAXIMUM_CAPACITY;
}
if (loadFactor <= 0 || Float.isNaN(loadFactor)) {
throw new IllegalArgumentException("Illegal load factor: " + loadFactor);
}
// Find a power of 2 >= initialCapacity
int capacity = 1;
while (capacity < initialCapacity) {
capacity <<= 1;
}
this.loadFactor = loadFactor;
threshold = (int) (capacity * loadFactor);
table = new Entry[capacity];
}
/**
* Constructs an empty <tt>HashMap</tt> with the specified initial
* capacity and the default load factor (0.75).
*
* @param initialCapacity the initial capacity.
* @throws IllegalArgumentException if the initial capacity is negative.
*/
public PrimLongMapLIWeak(final int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
/**
* Constructs an empty <tt>HashMap</tt> with the default initial capacity
* (16) and the default load factor (0.75).
*/
@SuppressWarnings("unchecked")
public PrimLongMapLIWeak() {
this.loadFactor = DEFAULT_LOAD_FACTOR;
threshold = (int) (DEFAULT_INITIAL_CAPACITY * DEFAULT_LOAD_FACTOR);
table = new Entry[DEFAULT_INITIAL_CAPACITY];
}
/**
* Constructs a new <tt>HashMap</tt> with the same mappings as the
* specified <tt>Map</tt>. The <tt>HashMap</tt> is created with
* default load factor (0.75) and an initial capacity sufficient to
* hold the mappings in the specified <tt>Map</tt>.
*
* @param m the map whose mappings are to be placed in this map
* @throws NullPointerException if the specified map is null
*/
public PrimLongMapLIWeak(PrimLongMap<? extends V> m) {
this(Math.max((int) (m.size() / DEFAULT_LOAD_FACTOR) + 1,
DEFAULT_INITIAL_CAPACITY), DEFAULT_LOAD_FACTOR);
putAllForCreate(m);
}
// internal utilities
/**
* Returns index for hash code h.
*/
private static int indexFor(long h, int length) {
return (int)h & (length - 1);
}
/**
* Returns the number of key-value mappings in this map.
*
* @return the number of key-value mappings in this map
*/
@Override
public int size() {
return size;
}
/**
* Returns <tt>true</tt> if this map contains no key-value mappings.
*
* @return <tt>true</tt> if this map contains no key-value mappings
*/
public boolean isEmpty() {
return size == 0;
}
/**
* Returns the value to which the specified key is mapped,
* or {@code null} if this map contains no mapping for the key.
*
* <p>More formally, if this map contains a mapping from a key
* {@code k} to a value {@code v} such that {@code (key==null ? k==null :
* key.equals(k))}, then this method returns {@code v}; otherwise
* it returns {@code null}. (There can be at most one such mapping.)
*
* <p>A return value of {@code null} does not <i>necessarily</i>
* indicate that the map contains no mapping for the key; it's also
* possible that the map explicitly maps the key to {@code null}.
* The {@link #containsKey containsKey} operation may be used to
* distinguish these two cases.
*
* @see #put(long, Object)
*/
@Override
public V get(long keyBits) {
for (Entry<V> e = table[indexFor(keyBits, table.length)];
e != null;
e = e.next) {
if (e.key == keyBits) {
return e.getValue();
}
}
return null;
}
/**
* Returns <tt>true</tt> if this map contains a mapping for the
* specified key.
*
* @param key The key whose presence in this map is to be tested
* @return <tt>true</tt> if this map contains a mapping for the specified
* key.
*/
@Override
public boolean containsKey(long key) {
return getEntry(key) != null;
}
/**
* Returns the entry associated with the specified key in the
* HashMap. Returns null if the HashMap contains no mapping
* for the key.
*/
private final Entry<V> getEntry(long keyBits) {
for (Entry<V> e = table[indexFor(keyBits, table.length)];
e != null;
e = e.next) {
if (e.key == keyBits) {
return e;
}
}
return null;
}
/**
* Associates the specified value with the specified key in this map.
* If the map previously contained a mapping for the key, the old
* value is replaced.
*
* @param keyBits key with which the specified value is to be associated
* @param value value to be associated with the specified key
* @return the previous value associated with <tt>key</tt>, or
* <tt>null</tt> if there was no mapping for <tt>key</tt>.
* (A <tt>null</tt> return can also indicate that the map
* previously associated <tt>null</tt> with <tt>key</tt>.)
*/
@Override
public V put(long keyBits, V value) {
int i = indexFor(keyBits, table.length);
//TZ: remove, in case it already exists
removeEntryForKey(keyBits);
// for (Entry<V> e = table[i]; e != null; e = e.next) {
// if (e.key == keyBits) {
// return e.setValue(value);
// }
// }
modCount++;
addEntry(keyBits, value, i);
return null;
}
/**
* This method is used instead of put by constructors and
* pseudoconstructors (clone, readObject). It does not resize the table,
* check for comodification, etc. It calls createEntry rather than
* addEntry.
*/
private void putForCreate(long key, V value) {
if (value == null) {
return;
}
int i = indexFor(key, table.length);
/**
* Look for preexisting entry for key. This will never happen for
* clone or deserialize. It will only happen for construction if the
* input Map is a sorted map whose ordering is inconsistent w/ equals.
*/
//TZ: remove, in case it already exists
removeEntryForKey(key);
// for (Entry<V> e = table[i]; e != null; e = e.next) {
// if (e.key == key) {
// e.value = valueRef;
// return;
// }
// }
createEntry(key, value, i);
}
@SuppressWarnings({ "rawtypes", "unchecked" })
private void putAllForCreate(final PrimLongMap<? extends V> m) {
for (final Iterator i = m.entrySet().iterator(); i.hasNext();) {
final PrimLongMapLIWeak.Entry<V> e = (Entry<V>) i.next();
putForCreate(e.getKey(), e.getValue());
}
}
/**
* Rehashes the contents of this map into a new array with a
* larger capacity. This method is called automatically when the
* number of keys in this map reaches its threshold.
*
* If current capacity is MAXIMUM_CAPACITY, this method does not
* resize the map, but sets threshold to Integer.MAX_VALUE.
* This has the effect of preventing future calls.
*
* @param newCapacity the new capacity, MUST be a power of two;
* must be greater than current capacity unless current
* capacity is MAXIMUM_CAPACITY (in which case value
* is irrelevant).
*/
private void resize(int newCapacity) {
Entry<V>[] oldTable = table;
int oldCapacity = oldTable.length;
if (oldCapacity == MAXIMUM_CAPACITY) {
threshold = Integer.MAX_VALUE;
return;
}
@SuppressWarnings("unchecked")
Entry<V>[] newTable = new Entry[newCapacity];
transfer(newTable);
table = newTable;
threshold = (int) (newCapacity * loadFactor);
}
/**
* Transfers all entries from current table to newTable.
*/
private void transfer(Entry<V>[] newTable) {
Entry<V>[] src = table;
int newCapacity = newTable.length;
for (Entry<V> e: src) {
if (e != null) {
//src[j] = null; //TZ: seems unnecessary
do {
//TODO skip gc()'d entries? --> Decrement entry counter.
Entry<V> next = e.next;
int i = indexFor(e.key, newCapacity);
e.next = newTable[i];
newTable[i] = e;
e = next;
} while (e != null);
}
}
}
/**
* Copies all of the mappings from the specified map to this map.
* These mappings will replace any mappings that this map had for
* any of the keys currently in the specified map.
*
* @param m mappings to be stored in this map
* @throws NullPointerException if the specified map is null
*/
@SuppressWarnings({ "rawtypes", "unchecked" })
@Override
public void putAll(PrimLongMap<? extends V> m) {
int numKeysToBeAdded = m.size();
if (numKeysToBeAdded == 0) {
return;
}
/*
* Expand the map if the map if the number of mappings to be added
* is greater than or equal to threshold. This is conservative; the
* obvious condition is (m.size() + size) >= threshold, but this
* condition could result in a map with twice the appropriate capacity,
* if the keys to be added overlap with the keys already in this map.
* By using the conservative calculation, we subject ourself
* to at most one extra resize.
*/
if (numKeysToBeAdded > threshold) {
int targetCapacity = (int) (numKeysToBeAdded / loadFactor + 1);
if (targetCapacity > MAXIMUM_CAPACITY) {
targetCapacity = MAXIMUM_CAPACITY;
}
int newCapacity = table.length;
while (newCapacity < targetCapacity) {
newCapacity <<= 1;
}
if (newCapacity > table.length) {
resize(newCapacity);
}
}
for (final Iterator i = m.entrySet().iterator(); i.hasNext();) {
PrimLongMapLIWeak.Entry<? extends V> e = (Entry<? extends V>) i.next();
put(e.getKey(), e.getValue());
}
}
/**
* Removes the mapping for the specified key from this map if present.
*
* @param key key whose mapping is to be removed from the map
* @return the previous value associated with <tt>key</tt>, or
* <tt>null</tt> if there was no mapping for <tt>key</tt>.
* (A <tt>null</tt> return can also indicate that the map
* previously associated <tt>null</tt> with <tt>key</tt>.)
*/
@Override
public V remove(long key) {
Entry<V> e = removeEntryForKey(key);
return e == null ? null : e.getValue();
}
/**
* Removes and returns the entry associated with the specified key
* in the HashMap. Returns null if the HashMap contains no mapping
* for this key.
*/
private final Entry<V> removeEntryForKey(long keyBits) {
int i = indexFor(keyBits, table.length);
Entry<V> prev = table[i];
Entry<V> e = prev;
while (e != null) {
Entry<V> next = e.next;
if (e.key == keyBits) {
modCount++;
size--;
if (prev == e) {
table[i] = next;
} else {
prev.next = next;
}
return e;
}
prev = e;
e = next;
}
//TODO reduce size?
return e;
}
/**
* Special version of remove for EntrySet.
*/
private final Entry<V> removeMapping(Entry<V> entry) {
long keyBits = entry.key;
int i = indexFor(keyBits, table.length);
Entry<V> prev = table[i];
Entry<V> e = prev;
while (e != null) {
Entry<V> next = e.next;
if (e.key == keyBits) {
modCount++;
size--;
if (prev == e) {
table[i] = next;
} else {
prev.next = next;
}
return e;
}
prev = e;
e = next;
}
return e;
}
/**
* Removes all of the mappings from this map.
* The map will be empty after this call returns.
*/
@Override
public void clear() {
modCount++;
Entry<V>[] tab = table;
for (int i = 0; i < tab.length; i++) {
tab[i] = null;
}
size = 0;
}
/**
* Returns <tt>true</tt> if this map maps one or more keys to the
* specified value.
*
* @param value value whose presence in this map is to be tested
* @return <tt>true</tt> if this map maps one or more keys to the
* specified value
*/
@Override
public boolean containsValue(V value) {
if (value == null) {
return containsNullValue();
}
Entry<V>[] tab = table;
for (int i = 0; i < tab.length; i++) {
for (Entry<V> e = tab[i]; e != null; e = e.next) {
if (value.equals(e.getValue())) {
return true;
}
}
}
return false;
}
/**
* Special-case code for containsValue with null argument
*/
private boolean containsNullValue() {
Entry<V>[] tab = table;
for (int i = 0; i < tab.length; i++) {
for (Entry<V> e = tab[i]; e != null; e = e.next) {
if (e.getValue() == null) {
return true;
}
}
}
return false;
}
public static final class Entry<V> extends WeakReference<V> implements PrimLongEntry<V> {
private final long key;
private Entry<V> next;
/**
* Creates new entry.
*/
Entry(long k, V v, Entry<V> n) {
super(v);
next = n;
key = k;
}
@Override
public final long getKey() {
return key;
}
@Override
public final V getValue() {
return get();
}
@SuppressWarnings({ "unchecked", "rawtypes" })
@Override
public final boolean equals(Object o) {
if (!(o instanceof Entry)) {
return false;
}
if (this == o) {
return true;
}
Entry<V> e = (Entry) o;
long k1 = key;
long k2 = e.key;
if (k1 == k2) {
Object v1 = getValue();
Object v2 = e.getValue();
if (v1 == v2 || (v1 != null && v1.equals(v2))) {
return true;
}
}
return false;
}
@Override
public final int hashCode() {
V value = get();
return ((int) key) //hashCode()) -> see hash(...)
^ (value == null ? 0 : value.hashCode());
}
@Override
public final String toString() {
return getKey() + "=" + getValue();
}
}
/**
* Adds a new entry with the specified key, value and hash code to
* the specified bucket. It is the responsibility of this
* method to resize the table if appropriate.
*
* Subclass overrides this to alter the behavior of put method.
*/
private void addEntry(long key, V value, int bucketIndex) {
Entry<V> e = table[bucketIndex];
table[bucketIndex] = new Entry<V>(key, value, e);
if (size++ >= threshold) {
resize(2 * table.length);
}
}
/**
* Like addEntry except that this version is used when creating entries
* as part of Map construction or "pseudo-construction" (cloning,
* deserialization). This version needn't worry about resizing the table.
*
* Subclass overrides this to alter the behavior of HashMap(Map),
* clone, and readObject.
*/
private void createEntry(long key, V value, int bucketIndex) {
Entry<V> e = table[bucketIndex];
table[bucketIndex] = new Entry<V>(key, value, e);
size++;
}
private abstract class HashIterator<E> implements Iterator<E> {
private Entry<V> next; // next entry to return
private int expectedModCount; // For fast-fail
private int index; // current slot
private Entry<V> current; // current entry
private V hardRef; //hard reference to current value to avoid ever returning null
HashIterator() {
expectedModCount = modCount;
if (size > 0) { // advance to first entry
next = new Entry<V>(0, null, null); //dummy
nextEntry();
}
}
@Override
public final boolean hasNext() {
return next != null;
}
public final boolean hasNextEntry() {
return next != null;
}
final Entry<V> nextEntry() {
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
Entry<V> e = next;
if (e == null) {
throw new NoSuchElementException();
}
current = next;
Entry<V>[] t = table;
Entry<V> prevE = e;
e = e.next;
do {
//TZ find next non-empty entry
while (e != null && (hardRef = e.get()) == null) {
//remove element
prevE.next = e.next;
modCount++;
size--;
expectedModCount++;
//proceed
prevE = e;
e = e.next;
}
if (e != null) {
break;
}
//proceed to next position in table?
while (e == null && index < t.length) {
while ((e = t[index++]) == null && index < t.length) { }
while (e != null && (hardRef = e.get()) == null) {
//remove element
table[index-1] = e.next;
modCount++;
size--;
expectedModCount++;
//proceed
e = e.next;
}
}
if (index == t.length) {
break;
}
} while (true);
next = e;
return current;
}
@Override
public void remove() {
if (current == null) {
throw new IllegalStateException();
}
if (modCount != expectedModCount) {
throw new ConcurrentModificationException();
}
long k = current.key;
current = null;
PrimLongMapLIWeak.this.removeEntryForKey(k);
expectedModCount = modCount;
}
}
public final class ValueIterator extends HashIterator<V> implements PLMValueIterator<V> {
@Override
public V next() {
return nextEntry().getValue();
}
@Override
public V nextValue() {
return nextEntry().getValue();
}
}
private final class KeyIterator extends HashIterator<Long> {
@Override
public Long next() {
return nextEntry().key;
}
}
private final class EntryIterator extends HashIterator<Entry<V>> {
@Override
public Entry<V> next() {
return nextEntry();
}
}
// Subclass overrides these to alter behavior of views' iterator() method
private KeyIterator newKeyIterator() {
return new KeyIterator();
}
private ValueIterator newValueIterator() {
return new ValueIterator();
}
private EntryIterator newEntryIterator() {
return new EntryIterator();
}
// Views
/**
* Each of these fields are initialized to contain an instance of the
* appropriate view the first time this view is requested. The views are
* stateless, so there's no reason to create more than one of each.
*/
private transient volatile Set<Long> keySet = null;
private transient volatile PrimLongValues values = null;
private transient Set<? extends PrimLongEntry<V>> entrySet = null;
/**
* Returns a {@link Set} view of the keys contained in this map.
* The set is backed by the map, so changes to the map are
* reflected in the set, and vice-versa. If the map is modified
* while an iteration over the set is in progress (except through
* the iterator's own <tt>remove</tt> operation), the results of
* the iteration are undefined. The set supports element removal,
* which removes the corresponding mapping from the map, via the
* <tt>Iterator.remove</tt>, <tt>Set.remove</tt>,
* <tt>removeAll</tt>, <tt>retainAll</tt>, and <tt>clear</tt>
* operations. It does not support the <tt>add</tt> or <tt>addAll</tt>
* operations.
*/
@Override
public Set<Long> keySet() {
Set<Long> ks = keySet;
return ks != null ? ks : (keySet = new KeySet());
}
private final class KeySet extends AbstractSet<Long> {
@Override
public KeyIterator iterator() {
return newKeyIterator();
}
@Override
public int size() {
return size;
}
@Override
public boolean contains(Object o) {
return containsKey((Long) o);
}
@Override
public boolean remove(Object o) {
return PrimLongMapLIWeak.this.removeEntryForKey((Long) o) != null;
}
@Override
public void clear() {
PrimLongMapLIWeak.this.clear();
}
}
/**
* Returns a {@link Collection} view of the values contained in this map.
* The collection is backed by the map, so changes to the map are
* reflected in the collection, and vice-versa. If the map is
* modified while an iteration over the collection is in progress
* (except through the iterator's own <tt>remove</tt> operation),
* the results of the iteration are undefined. The collection
* supports element removal, which removes the corresponding
* mapping from the map, via the <tt>Iterator.remove</tt>,
* <tt>Collection.remove</tt>, <tt>removeAll</tt>,
* <tt>retainAll</tt> and <tt>clear</tt> operations. It does not
* support the <tt>add</tt> or <tt>addAll</tt> operations.
*/
@Override
public PrimLongValues values() {
PrimLongValues vs = values;
return vs != null ? vs : (values = new PrimLongValues());
}
public final class PrimLongValues extends AbstractCollection<V> {
@Override
public ValueIterator iterator() {
return newValueIterator();
}
@Override
public int size() {
return size;
}
@SuppressWarnings("unchecked")
@Override
public boolean contains(Object o) {
return containsValue((V) o);
}
}
/**
* Returns a {@link Set} view of the mappings contained in this map.
* The set is backed by the map, so changes to the map are
* reflected in the set, and vice-versa. If the map is modified
* while an iteration over the set is in progress (except through
* the iterator's own <tt>remove</tt> operation, or through the
* <tt>setValue</tt> operation on a map entry returned by the
* iterator) the results of the iteration are undefined. The set
* supports element removal, which removes the corresponding
* mapping from the map, via the <tt>Iterator.remove</tt>,
* <tt>Set.remove</tt>, <tt>removeAll</tt>, <tt>retainAll</tt> and
* <tt>clear</tt> operations. It does not support the
* <tt>add</tt> or <tt>addAll</tt> operations.
*
* @return a set view of the mappings contained in this map
*/
@SuppressWarnings("unchecked")
@Override
public Set<PrimLongEntry<V>> entrySet() {
Set<PrimLongEntry<V>> es = (Set<PrimLongMap.PrimLongEntry<V>>) entrySet;
return (Set<PrimLongEntry<V>>) (es != null ? es : (entrySet = new EntrySet()));
}
private final class EntrySet extends AbstractSet<Entry<V>> {
@Override
public EntryIterator iterator() {
return newEntryIterator();
}
@SuppressWarnings("unchecked")
@Override
public boolean contains(Object o) {
if (!(o instanceof Entry)) {
return false;
}
Entry<V> e = (Entry<V>) o;
Entry<V> candidate = getEntry(e.getKey());
return candidate != null && candidate.equals(e);
}
@SuppressWarnings("unchecked")
@Override
public boolean remove(Object o) {
return removeMapping((Entry<V>) o) != null;
}
@Override
public int size() {
return size;
}
@Override
public void clear() {
PrimLongMapLIWeak.this.clear();
}
}
}