/**
* Removes the entry from the entry queue.
*
* @param shuffle indicates whether we are just shuffling the queue (in which case, the entry
* table is not modified).
*/
protected void privateRemoveEntry(LRUCacheEntry entry, boolean shuffle) {
LRUCacheEntry previous, next;
previous = entry._fPrevious;
next = entry._fNext;
if (!shuffle) {
fEntryTable.remove(entry._fKey);
fCurrentSpace -= entry._fSpace;
privateNotifyDeletionFromCache(entry);
}
/* if this was the first entry */
if (previous == null) {
fEntryQueue = next;
} else {
previous._fNext = next;
}
/* if this was the last entry */
if (next == null) {
fEntryQueueTail = previous;
} else {
next._fPrevious = previous;
}
}
/**
* Sets the value in the cache at the given key. Returns the value.
*
* @param key Key of object to add.
* @param value Value of object to add.
* @return added value.
*/
public Object put(Object key, Object value) {
int newSpace, oldSpace, newTotal;
LRUCacheEntry entry;
/* Check whether there's an entry in the cache */
newSpace = spaceFor(value);
entry = (LRUCacheEntry) fEntryTable.get(key);
if (entry != null) {
/**
* Replace the entry in the cache if it would not overflow the cache. Otherwise flush the
* entry and re-add it so as to keep cache within budget
*/
oldSpace = entry._fSpace;
newTotal = getCurrentSpace() - oldSpace + newSpace;
if (newTotal <= getSpaceLimit()) {
updateTimestamp(entry);
entry._fValue = value;
entry._fSpace = newSpace;
this.fCurrentSpace = newTotal;
return value;
} else {
privateRemoveEntry(entry, false);
}
}
if (makeSpace(newSpace)) {
privateAdd(key, value, newSpace);
}
return value;
}
/**
* Updates the timestamp for the given entry, ensuring that the queue is kept in correct order.
* The entry must exist
*/
protected void updateTimestamp(LRUCacheEntry entry) {
entry._fTimestamp = fTimestampCounter++;
if (fEntryQueue != entry) {
this.privateRemoveEntry(entry, true);
this.privateAddEntry(entry, true);
}
return;
}
/**
* Adds the given entry from the receiver.
*
* @param shuffle Indicates whether we are just shuffling the queue (in which case, the entry
* table is not modified).
*/
protected void privateAddEntry(LRUCacheEntry entry, boolean shuffle) {
if (!shuffle) {
fEntryTable.put(entry._fKey, entry);
fCurrentSpace += entry._fSpace;
}
entry._fTimestamp = fTimestampCounter++;
entry._fNext = this.fEntryQueue;
entry._fPrevious = null;
if (fEntryQueue == null) {
/* this is the first and last entry */
fEntryQueueTail = entry;
} else {
fEntryQueue._fPrevious = entry;
}
fEntryQueue = entry;
}
