HashMapによるキャッシュ
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実装:
hashmap:
テスト:
実装:
package creative.air.datastructure.map;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock.ReadLock;
import java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock;
import java.util.logging.Level;
import java.util.logging.Logger;
import creative.air.datastructure.map.AirHashMap.AirEntry;
/**
*
* @author Eric Han [email protected] 06/09/2012
* @since 0.0.1
* @version 0.0.1
*/
public class HashMapCache<H, L> {
enum ConcurrentStrategy {
NOTIFY, WAIT, TIMEOUT
}
enum FullStrategy {
NOTIFY, DISCARD, REPLACE
}
static final Logger logger = Logger.getLogger(HashMapCache.class.getName());
// cache full strategy
private int capacity = 12;
private FullStrategy fullStrategy = FullStrategy.NOTIFY;
// cache lock strategy
private static ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
private static WriteLock wLock = lock.writeLock();
private static ReadLock rLock = lock.readLock();
private ConcurrentStrategy concurrentStrategy = ConcurrentStrategy.TIMEOUT;
private long waitingLockTimeout = 500;
private AirHashMap<H, L> map;
public HashMapCache() {
map = new AirHashMap<H, L>();
}
public HashMapCache(int capacity) {
this.capacity = capacity;
map = new AirHashMap<H, L>();
}
public HashMapCache(int capacity, int initialCapacity, float loadFactor) {
this.capacity = capacity;
map = new AirHashMap<H, L>(initialCapacity, loadFactor);
}
public void clear() {
try {
lock(wLock);// tryLock(long timeout, TimeUnit unit)
map.clear();
} catch (Exception e) {
logger.log(Level.SEVERE, "clear error", e);
} finally {
wLock.unlock();
}
}
public void remove(H key) {
try {
lock(wLock);
map.remove(key);
} catch (Exception e) {
logger.log(Level.SEVERE, "clear error", e);
} finally {
wLock.unlock();
}
}
public L put(H key, L value) throws Exception {
lock(wLock);
if (this.capacity < map.size()) {
switch (fullStrategy) {
case NOTIFY:
throw new Exception("100 reached the cache's maximum");
case DISCARD:
return null;
case REPLACE:
// TODO it's a dangerous way
// which cannot guarantee the data already stored in cache
AirEntry<H, L> entry = map.getTable()[0];
remove(entry.getKey());
default:
throw new Exception("100 reached the cache's maximum");
}
}
try {
return map.put(key, value);
} catch (Exception e) {
logger.log(Level.SEVERE, "put error", e);
return null;
} finally {
wLock.unlock();
}
}
public L get(H key) {
try {
lock(rLock);
return map.get(key);
} catch (Exception e) {
logger.log(Level.SEVERE, "get error", e);
return null;
} finally {
rLock.unlock();
}
}
public Iterator<Map.Entry<H, L>> iterate() {
try {
lock(rLock);
return map.entrySet().iterator();
} catch (Exception e) {
logger.log(Level.SEVERE, "get error", e);
return null;
} finally {
rLock.unlock();
}
}
private void lock(Lock lock) throws Exception {
switch (concurrentStrategy) {
case NOTIFY:
throw new Exception("200 Cannot control the cache");
case WAIT:
lock.lock();
break;
case TIMEOUT:
lock.tryLock(waitingLockTimeout, TimeUnit.MICROSECONDS);
break;
}
}
public Set<Map.Entry<H, L>> entrySet() {
return map.entrySet();
}
public int getCapacity() {
return capacity;
}
public ConcurrentStrategy getConcurrentStrategy() {
return concurrentStrategy;
}
public FullStrategy getFullStrategy() {
return fullStrategy;
}
public void setCapacity(int capacity) {
this.capacity = capacity;
}
public void setConcurrentStrategy(ConcurrentStrategy concurrentStrategy) {
this.concurrentStrategy = concurrentStrategy;
}
public void setFullStrategy(FullStrategy fullStrategy) {
this.fullStrategy = fullStrategy;
}
public long getWaitingLockTimeout() {
return waitingLockTimeout;
}
public void setWaitingLockTimeout(long waitingLockTimeout) {
this.waitingLockTimeout = waitingLockTimeout;
}
}
hashmap:
package creative.air.datastructure.map;
/**
*
* @author
* Eric Han [email protected]
* 16/09/2012
* @since 0.0.1
* @version 0.0.1
*/
import java.io.IOException;
import java.io.Serializable;
import java.util.AbstractCollection;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
public class AirHashMap<K, V> extends AbstractMap<K, V> implements Map<K, V>, Cloneable, Serializable {
private static final long serialVersionUID = 3476735979928755996L;
static final int DEFAULT_INITIAL_CAPACITY = 16;//
static final int MAXIMUM_CAPACITY = 1 << 30;
static final float DEFAULT_LOAD_FACTOR = 0.75f;//
transient AirEntry<K, V>[] table;// hash
transient int size;
int threshold;//
final float loadFactor;
transient int modCount;//
public AirHashMap(int initialCapacity, 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 AirEntry[capacity];
init();
}
public AirHashMap(int initialCapacity) {
this(initialCapacity, DEFAULT_LOAD_FACTOR);
}
public AirHashMap() {
this.loadFactor = DEFAULT_LOAD_FACTOR;
threshold = (int) (DEFAULT_INITIAL_CAPACITY * DEFAULT_LOAD_FACTOR);
table = new AirEntry[DEFAULT_INITIAL_CAPACITY];
init();
}
public AirHashMap(Map<? extends K, ? extends V> m) {
this(Math.max((int) (m.size() / DEFAULT_LOAD_FACTOR) + 1, DEFAULT_INITIAL_CAPACITY), DEFAULT_LOAD_FACTOR);
putAllForCreate(m);
}
void init() {
}
static int hash(int h) {
// This function ensures that hashCodes that differ only by
// constant multiples at each bit position have a bounded
// number of collisions (approximately 8 at default load factor).
h ^= (h >>> 20) ^ (h >>> 12);
return h ^ (h >>> 7) ^ (h >>> 4);
}
static int indexFor(int h, int length) {
return h & (length - 1);
}
public int size() {
return size;
}
public boolean isEmpty() {
return size == 0;
}
public V get(Object key) {
if (key == null)
return getForNullKey();
int hash = hash(key.hashCode());
for (AirEntry<K, V> e = table[indexFor(hash, table.length)]; e != null; e = e.next) {
Object k;
if (e.hash == hash && ((k = e.key) == key || key.equals(k)))
return e.value;
}
return null;
}
private V getForNullKey() {
for (AirEntry<K, V> e = table[0]; e != null; e = e.next) {
if (e.key == null)
return e.value;
}
return null;
}
public boolean containsKey(Object key) {
return getEntry(key) != null;
}
final AirEntry<K, V> getEntry(Object key) {
int hash = (key == null) ? 0 : hash(key.hashCode());
for (AirEntry<K, V> e = table[indexFor(hash, table.length)]; e != null; e = e.next) {
Object k;
if (e.hash == hash && ((k = e.key) == key || (key != null && key.equals(k))))
return e;
}
return null;
}
public V put(K key, V value) {
if (key == null)
return putForNullKey(value);
int hash = hash(key.hashCode());
int i = indexFor(hash, table.length);
for (AirEntry<K, V> e = table[i]; e != null; e = e.next) {
Object k;
if (e.hash == hash && ((k = e.key) == key || key.equals(k))) {
V oldValue = e.value;
e.value = value;
e.recordAccess(this);
return oldValue;
}
}
modCount++;
addEntry(hash, key, value, i);
return null;
}
private V putForNullKey(V value) {
for (AirEntry<K, V> e = table[0]; e != null; e = e.next) {
if (e.key == null) {
V oldValue = e.value;
e.value = value;
e.recordAccess(this);
return oldValue;
}
}
modCount++;
addEntry(0, null, value, 0);
return null;
}
private void putForCreate(K key, V value) {
int hash = (key == null) ? 0 : hash(key.hashCode());
int i = indexFor(hash, 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.
*/
for (AirEntry<K, V> e = table[i]; e != null; e = e.next) {
Object k;
if (e.hash == hash && ((k = e.key) == key || (key != null && key.equals(k)))) {
e.value = value;
return;
}
}
createEntry(hash, key, value, i);
}
private void putAllForCreate(Map<? extends K, ? extends V> m) {
for (Map.Entry<? extends K, ? extends V> e : m.entrySet())
putForCreate(e.getKey(), e.getValue());
}
void resize(int newCapacity) {
AirEntry[] oldTable = table;
int oldCapacity = oldTable.length;
if (oldCapacity == MAXIMUM_CAPACITY) {
threshold = Integer.MAX_VALUE;
return;
}
AirEntry[] newTable = new AirEntry[newCapacity];
transfer(newTable);
table = newTable;
threshold = (int) (newCapacity * loadFactor);
}
void transfer(AirEntry[] newTable) {
AirEntry[] src = table;
int newCapacity = newTable.length;
for (int j = 0; j < src.length; j++) {
AirEntry<K, V> e = src[j];
if (e != null) {
src[j] = null;
do {
AirEntry<K, V> next = e.next;
int i = indexFor(e.hash, newCapacity);
e.next = newTable[i];
newTable[i] = e;
e = next;
} while (e != null);
}
}
}
public void putAll(Map<? extends K, ? extends V> m) {
int numKeysToBeAdded = m.size();
if (numKeysToBeAdded == 0)
return;
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 (Map.Entry<? extends K, ? extends V> e : m.entrySet())
put(e.getKey(), e.getValue());
}
public V remove(Object key) {
AirEntry<K, V> e = removeEntryForKey(key);
return (e == null ? null : e.value);
}
final AirEntry<K, V> removeEntryForKey(Object key) {
int hash = (key == null) ? 0 : hash(key.hashCode());
int i = indexFor(hash, table.length);
AirEntry<K, V> prev = table[i];
AirEntry<K, V> e = prev;
while (e != null) {
AirEntry<K, V> next = e.next;
Object k;
if (e.hash == hash && ((k = e.key) == key || (key != null && key.equals(k)))) {
modCount++;
size--;
if (prev == e)
table[i] = next;
else
prev.next = next;
e.recordRemoval(this);
return e;
}
prev = e;
e = next;
}
return e;
}
final AirEntry<K, V> removeMapping(Object o) {
if (!(o instanceof Map.Entry))
return null;
Map.Entry<K, V> entry = (Map.Entry<K, V>) o;
Object key = entry.getKey();
int hash = (key == null) ? 0 : hash(key.hashCode());
int i = indexFor(hash, table.length);
AirEntry<K, V> prev = table[i];
AirEntry<K, V> e = prev;
while (e != null) {
AirEntry<K, V> next = e.next;
if (e.hash == hash && e.equals(entry)) {
modCount++;
size--;
if (prev == e)
table[i] = next;
else
prev.next = next;
e.recordRemoval(this);
return e;
}
prev = e;
e = next;
}
return e;
}
public void clear() {
modCount++;
AirEntry[] tab = table;
for (int i = 0; i < tab.length; i++)
tab[i] = null;
size = 0;
}
public boolean containsValue(Object value) {
if (value == null)
return containsNullValue();
AirEntry[] tab = table;
for (int i = 0; i < tab.length; i++)
for (AirEntry e = tab[i]; e != null; e = e.next)
if (value.equals(e.value))
return true;
return false;
}
private boolean containsNullValue() {
AirEntry[] tab = table;
for (int i = 0; i < tab.length; i++)
for (AirEntry e = tab[i]; e != null; e = e.next)
if (e.value == null)
return true;
return false;
}
public Object clone() {
AirHashMap<K, V> result = null;
try {
result = (AirHashMap<K, V>) super.clone();
} catch (CloneNotSupportedException e) {
// assert false;
}
result.table = new AirEntry[table.length];
result.entrySet = null;
result.modCount = 0;
result.size = 0;
result.init();
result.putAllForCreate(this);
return result;
}
void addEntry(int hash, K key, V value, int bucketIndex) {
AirEntry<K, V> e = table[bucketIndex];
table[bucketIndex] = new AirEntry<K, V>(hash, key, value, e);
if (size++ >= threshold)
resize(2 * table.length);
}
void createEntry(int hash, K key, V value, int bucketIndex) {
AirEntry<K, V> e = table[bucketIndex];
table[bucketIndex] = new AirEntry<K, V>(hash, key, value, e);
size++;
}
private final class ValueIterator extends HashIterator<V> {
public V next() {
return nextEntry().value;
}
}
private final class KeyIterator extends HashIterator<K> {
public K next() {
return nextEntry().getKey();
}
}
private final class EntryIterator extends HashIterator<Map.Entry<K, V>> {
public Map.Entry<K, V> next() {
return nextEntry();
}
}
// Subclass overrides these to alter behavior of views' iterator() method
Iterator<K> newKeyIterator() {
return new KeyIterator();
}
Iterator<V> newValueIterator() {
return new ValueIterator();
}
Iterator<Map.Entry<K, V>> newEntryIterator() {
return new EntryIterator();
}
private transient Set<Map.Entry<K, V>> entrySet = null;
// public Set<K> keySet() {
// Set<K> ks = keySet;
// return (ks != null ? ks : (keySet = new KeySet()));
// }
private final class KeySet extends AbstractSet<K> {
public Iterator<K> iterator() {
return newKeyIterator();
}
public int size() {
return size;
}
public boolean contains(Object o) {
return containsKey(o);
}
public boolean remove(Object o) {
return AirHashMap.this.removeEntryForKey(o) != null;
}
public void clear() {
AirHashMap.this.clear();
}
}
// public Collection<V> values() {
// Collection<V> vs = values;
// return (vs != null ? vs : (values = new Values()));
// }
private final class Values extends AbstractCollection<V> {
public Iterator<V> iterator() {
return newValueIterator();
}
public int size() {
return size;
}
public boolean contains(Object o) {
return containsValue(o);
}
public void clear() {
AirHashMap.this.clear();
}
}
public Set<Map.Entry<K, V>> entrySet() {
return entrySet0();
}
private Set<Map.Entry<K, V>> entrySet0() {
Set<Map.Entry<K, V>> es = entrySet;
return es != null ? es : (entrySet = new EntrySet());
}
private final class EntrySet extends AbstractSet<Map.Entry<K, V>> {
public Iterator<Map.Entry<K, V>> iterator() {
return newEntryIterator();
}
public boolean contains(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry<K, V> e = (Map.Entry<K, V>) o;
AirEntry<K, V> candidate = getEntry(e.getKey());
return candidate != null && candidate.equals(e);
}
public boolean remove(Object o) {
return removeMapping(o) != null;
}
public int size() {
return size;
}
public void clear() {
AirHashMap.this.clear();
}
}
private void writeObject(java.io.ObjectOutputStream s) throws IOException {
Iterator<Map.Entry<K, V>> i = (size > 0) ? entrySet0().iterator() : null;
// Write out the threshold, loadfactor, and any hidden stuff
s.defaultWriteObject();
// Write out number of buckets
s.writeInt(table.length);
// Write out size (number of Mappings)
s.writeInt(size);
// Write out keys and values (alternating)
if (i != null) {
while (i.hasNext()) {
Map.Entry<K, V> e = i.next();
s.writeObject(e.getKey());
s.writeObject(e.getValue());
}
}
}
private void readObject(java.io.ObjectInputStream s) throws IOException, ClassNotFoundException {
// Read in the threshold, loadfactor, and any hidden stuff
s.defaultReadObject();
// Read in number of buckets and allocate the bucket array;
int numBuckets = s.readInt();
table = new AirEntry[numBuckets];
init(); // Give subclass a chance to do its thing.
// Read in size (number of Mappings)
int size = s.readInt();
// Read the keys and values, and put the mappings in the AirHashMap
for (int i = 0; i < size; i++) {
K key = (K) s.readObject();
V value = (V) s.readObject();
putForCreate(key, value);
}
}
// These methods are used when serializing HashSets
int capacity() {
return table.length;
}
float loadFactor() {
return loadFactor;
}
// ====Entry====
static class AirEntry<K, V> implements Map.Entry<K, V> {
final K key;
V value;
AirEntry<K, V> next;
final int hash;
/**
* Creates new entry.
*/
AirEntry(int h, K k, V v, AirEntry<K, V> n) {
value = v;
next = n;
key = k;
hash = h;
}
public final K getKey() {
return key;
}
public final V getValue() {
return value;
}
public final V setValue(V newValue) {
V oldValue = value;
value = newValue;
return oldValue;
}
public final boolean equals(Object o) {
if (!(o instanceof Map.Entry))
return false;
Map.Entry e = (Map.Entry) o;
Object k1 = getKey();
Object k2 = e.getKey();
if (k1 == k2 || (k1 != null && k1.equals(k2))) {
Object v1 = getValue();
Object v2 = e.getValue();
if (v1 == v2 || (v1 != null && v1.equals(v2)))
return true;
}
return false;
}
public final int hashCode() {
return (key == null ? 0 : key.hashCode()) ^ (value == null ? 0 : value.hashCode());
}
public final String toString() {
return getKey() + "=" + getValue();
}
/**
* This method is invoked whenever the value in an entry is overwritten by an invocation of put(k,v) for a key k that's already in the AirHashMap.
*/
void recordAccess(AirHashMap<K, V> m) {
}
/**
* This method is invoked whenever the entry is removed from the table.
*/
void recordRemoval(AirHashMap<K, V> m) {
}
}
// ====HashIterator====
private abstract class HashIterator<E> implements Iterator<E> {
AirEntry<K, V> next; // next entry to return
int expectedModCount; // For fast-fail
int index; // current slot
AirEntry<K, V> current; // current entry
HashIterator() {
expectedModCount = modCount;
if (size > 0) { // advance to first entry
AirEntry[] t = table;
while (index < t.length && (next = t[index++]) == null)
;
}
}
public final boolean hasNext() {
return next != null;
}
final AirEntry<K, V> nextEntry() {
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
AirEntry<K, V> e = next;
if (e == null)
throw new NoSuchElementException();
if ((next = e.next) == null) {
AirEntry[] t = table;
while (index < t.length && (next = t[index++]) == null)
;
}
current = e;
return e;
}
public void remove() {
if (current == null)
throw new IllegalStateException();
if (modCount != expectedModCount)
throw new ConcurrentModificationException();
Object k = current.key;
current = null;
AirHashMap.this.removeEntryForKey(k);
expectedModCount = modCount;
}
}
public AirEntry<K, V>[] getTable() {
return table;
}
}
テスト:
package creative.air.datastructure.map;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.logging.Level;
import java.util.logging.Logger;
import junit.framework.Assert;
import org.junit.Test;
/**
* Test HashMap
* 1 map： hash：hashcode
* 2
* 3 +
* 4 loadFactor threshold
* 5
*
* Test Cache
* @author
* Eric Han [email protected]
* 06/09/2012
* @since 0.0.1
* @version 0.0.1
*/
public class HashMapTest {
static final Logger logger = Logger.getLogger(HashMapTest.class.getName());
@Test
public void test2() throws Exception {
HashMapCache<String, Integer> cacheMap = new HashMapCache<String, Integer>();
cacheMap.clear();
cacheMap.put("" + 1, null);
cacheMap.put(null, 1);
cacheMap.put(null, null);
Assert.assertNull(cacheMap.get(null));
}
@Test
public void test5() {
int n = 0;
final int maxium = 5000;
HashMapCache<String, Integer> cacheMap = new HashMapCache<String, Integer>(maxium);
HashMapCache<String, Integer> retrievingMap = new HashMapCache<String, Integer>(maxium, maxium / 10, 0.5f);
boolean inputRight = true;
while (n < maxium) {
String s = "" + n;
try {
cacheMap.put(s, n);
retrievingMap.put(s, n++);
} catch (Exception e) {
e.printStackTrace();
inputRight = false;
break;
}
}
Assert.assertTrue(inputRight);
Object[] r1 = iterate(cacheMap, Level.INFO);
Object[] r2 = iterate(retrievingMap, Level.INFO);
logger.log(Level.INFO, "default map iterating elapse:{0}(start={1},end={2})", r1);
logger.log(Level.INFO, "customize map iterating elapse:{0}(start={1},end={2})", r2);
Assert.assertTrue((Long) r1[0] >= (Long) r2[0]);
}
/**
* @param level
*
*/
private Object[] iterate(HashMapCache<String, Integer> map, Level level) {
Iterator<Map.Entry<String, Integer>> iter = map.entrySet().iterator();
long startTime = System.currentTimeMillis();
while (iter.hasNext()) {
Map.Entry<String, Integer> entry = iter.next();
String key = entry.getKey();
Integer val = entry.getValue();
logger.log(level, "{0}:{1}", new Object[] { key, val });
}
long endTime = System.currentTimeMillis();
return new Object[] { endTime - startTime, endTime, startTime };
}
@Test
public void testPutAll(){
HashMap<String,String> map=new HashMap<String,String>();
HashMap<String,HashMap<String,String>> map2=new HashMap<String,HashMap<String,String>>();
map.put("Gateway", "Thomson");
map2.put("patner", map);
map.put("Gateway", "Technicolor");
Iterator<Map.Entry<String,HashMap<String,String>>> iter = map2.entrySet().iterator();
while (iter.hasNext()) {
Map.Entry<String,HashMap<String,String>> entry = iter.next();
String key = entry.getKey();
HashMap<String,String> val = entry.getValue();
Iterator<Map.Entry<String,String>> iter2 = val.entrySet().iterator();
while (iter.hasNext()) {
Map.Entry<String,String> entry2 = iter2.next();
String key2 = entry2.getKey();
String val2 = entry2.getValue();
Assert.assertEquals("Technicolor", val2);
logger.log(Level.INFO, "{0}:{1}", new Object[] { key2, val2 });
}
logger.log(Level.INFO, "{0}:{1}", new Object[] { key, val });
}
}
}