/**
* Returns the value to which the specified key is mapped in this hashtable.
*
* @param key a key in the hashtable.
* @return the value to which the key is mapped in this hashtable; <code>null</code> if the key is
* not mapped to any value in this hashtable.
* @see java.util.LRUCache#put(java.lang.Object, java.lang.Object)
* @since JDK1.0
*/
public Object get(Object key) {
LRUCacheEntry tab[] = table;
int hash = key.hashCode();
int index = (hash & 0x7FFFFFFF) % tab.length;
for (LRUCacheEntry e = tab[index]; e != null; e = e.next) {
if ((e.hash == hash) && e.key.equals(key)) {
if (expirationTime > 0) e.expirationTime = System.currentTimeMillis() + expirationTime;
// LoggingService.getDefaultLogger().logDebug(this, "===>"+table.length);
return e.value;
}
}
return null;
}
/**
* Removes the key (and its corresponding value) from this hashtable. This method does nothing if
* the key is not in the hashtable.
*
* @param key the key that needs to be removed.
* @return the value to which the key had been mapped in this hashtable, or <code>null</code> if
* the key did not have a mapping.
* @since JDK1.0
*/
public Object remove(Object key) {
LRUCacheEntry tab[] = table;
int hash = key.hashCode();
int index = (hash & 0x7FFFFFFF) % tab.length;
for (LRUCacheEntry e = tab[index], prev = null; e != null; prev = e, e = e.next) {
if ((e.hash == hash) && e.key.equals(key)) {
if (prev != null) {
prev.next = e.next;
} else {
tab[index] = e.next;
}
count--;
return e.value;
}
}
return null;
}
protected Object clone() {
LRUCacheEntry entry = new LRUCacheEntry();
entry.hash = hash;
entry.key = key;
entry.value = value;
entry.expirationTime = expirationTime;
entry.next = (next != null) ? (LRUCacheEntry) next.clone() : null;
return entry;
}
/**
* Rehashes the contents of the hashtable into a hashtable with a larger capacity. This method is
* called automatically when the number of keys in the hashtable exceeds this hashtable's capacity
* and load factor.
*
* @since JDK1.0
*/
protected void rehash() {
int oldCapacity = table.length;
LRUCacheEntry oldTable[] = table;
int newCapacity = oldCapacity * 2 + 1;
LRUCacheEntry newTable[] = new LRUCacheEntry[newCapacity];
threshold = (int) (newCapacity * loadFactor);
table = newTable;
// LoggingService.getDefaultLogger().logDebug(this, "rehash old=" + oldCapacity + ", new=" +
// newCapacity + ", thresh=" + threshold + ", count=" + count);
for (int i = oldCapacity; i-- > 0; ) {
for (LRUCacheEntry old = oldTable[i]; old != null; ) {
LRUCacheEntry e = old;
old = old.next;
int index = (e.hash & 0x7FFFFFFF) % newCapacity;
e.next = newTable[index];
newTable[index] = e;
}
}
}
/**
* Maps the specified <code>key</code> to the specified <code>value</code> in this hashtable.
* Neither the key nor the value can be <code>null</code>.
*
* <p>The value can be retrieved by calling the <code>get</code> method with a key that is equal
* to the original key.
*
* @param key the hashtable key.
* @param value the value.
* @return the previous value of the specified key in this hashtable, or <code>null</code> if it
* did not have one.
* @exception NullPointerException if the key or value is <code>null</code>.
* @see java.lang.Object#equals(java.lang.Object)
* @see java.util.LRUCache#get(java.lang.Object)
* @since JDK1.0
*/
public Object put(Object key, Object value) {
// Make sure the value is not null
if (value == null) {
throw new NullPointerException();
}
// Makes sure the key is not already in the hashtable.
LRUCacheEntry tab[] = table;
int hash = key.hashCode();
int index = (hash & 0x7FFFFFFF) % tab.length;
// LoggingService.getDefaultLogger().logDebug(this, "=====================>Index: "+index );
for (LRUCacheEntry e = tab[index]; e != null; e = e.next) {
if ((e.hash == hash) && e.key.equals(key)) {
Object old = e.value;
e.value = value;
return old;
}
}
if (count >= threshold) {
// Rehash the table if the threshold is exceeded
rehash();
return put(key, value);
}
// Creates the new entry.
LRUCacheEntry e = new LRUCacheEntry();
e.hash = hash;
e.key = key;
e.value = value;
e.expirationTime = (expirationTime > 0) ? (System.currentTimeMillis() + expirationTime) : -1;
e.next = tab[index];
tab[index] = e;
count++;
if (cacheMonitorThread == null || !cacheMonitorThread.isAlive()) {
cacheMonitorThread = new CacheMonitor(); // new Thread(new CacheMonitor() );
cacheMonitorThread.setDaemon(true);
cacheMonitorThread.setPriority(Thread.NORM_PRIORITY - 1);
cacheMonitorThread.start();
}
return null;
}