/*******************************************************************************
* Copyright (c) 1998, 2008 Oracle. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.internal.identitymaps;
import java.util.*;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentHashMap;
import org.eclipse.persistence.descriptors.ClassDescriptor;
/**
* <p><b>Purpose</b>: A FullIdentityMap holds all objects stored within it for the life of the application.
* <p><b>Responsibilities</b>:<ul>
* <li> Guarantees identity
* <li> Holds all cached objects indefinitely.
* </ul>
* @since TOPLink/Java 1.0
*/
public class FullIdentityMap extends AbstractIdentityMap {
/** Hashtable of CacheKeys stored using their key. */
protected Map<CacheKey, CacheKey> cacheKeys;
public FullIdentityMap() {}
public FullIdentityMap(int size) {
super(size);
cacheKeys = new ConcurrentHashMap(size);
}
public FullIdentityMap(int size, ClassDescriptor descriptor) {
super(size, descriptor);
cacheKeys = new ConcurrentHashMap(size);
}
/**
* INTERNAL:
* Clones itself.
*/
public Object clone() {
FullIdentityMap clone = (FullIdentityMap)super.clone();
clone.setCacheKeys(new ConcurrentHashMap(getCacheKeys().size()));
for (Iterator cacheKeysIterator = getCacheKeys().values().iterator(); cacheKeysIterator.hasNext();) {
CacheKey key = (CacheKey)((CacheKey)cacheKeysIterator.next()).clone();
clone.getCacheKeys().put(key, key);
}
return clone;
}
/**
* INTERNAL:
* Used to print all the Locks in every identity map in this session.
*/
public void collectLocks(HashMap threadList) {
Iterator cacheKeyIterator = getCacheKeys().values().iterator();
while (cacheKeyIterator.hasNext()) {
CacheKey cacheKey = (CacheKey)cacheKeyIterator.next();
if (cacheKey.isAcquired()) {
Thread activeThread = cacheKey.getMutex().getActiveThread();
Set set = (Set)threadList.get(activeThread);
if (set == null) {
set = new HashSet();
threadList.put(activeThread, set);
}
set.add(cacheKey);
}
}
}
/**
* Allow for the cache to be iterated on.
*/
public Enumeration elements() {
return new IdentityMapEnumeration(this);
}
/**
* Return the cache key matching the primary key of the searchKey.
* If no object for the key exists, return null.
*/
protected CacheKey getCacheKey(CacheKey searchKey) {
return getCacheKeys().get(searchKey);
}
/**
* Return the CacheKey (with object) matching the searchKey.
* If the CacheKey is missing then put the searchKey in the map.
* The searchKey should have already been locked.
*/
protected CacheKey getCacheKeyIfAbsentPut(CacheKey searchKey) {
// PERF: First to a get, and get is non-locking, putIfAbsent locks.
CacheKey cacheKey = getCacheKeys().get(searchKey);
if (cacheKey == null) {
searchKey.setOwningMap(this);
cacheKey = (CacheKey)((ConcurrentMap)getCacheKeys()).putIfAbsent(searchKey, searchKey);
}
return cacheKey;
}
/**
* Return the cache keys.
*/
public Map<CacheKey, CacheKey> getCacheKeys() {
return cacheKeys;
}
/**
* Return the number of CacheKeys in the IdentityMap.
* This may contain weak referenced objects that have been garbage collected.
*/
public int getSize() {
return this.cacheKeys.size();
}
/**
* Return the number of actual objects of type myClass in the IdentityMap.
* Recurse = true will include subclasses of myClass in the count.
*/
public int getSize(Class myClass, boolean recurse) {
int count = 0;
Iterator keys = getCacheKeys().values().iterator();
while (keys.hasNext()) {
CacheKey key = (CacheKey)keys.next();
Object object = key.getObject();
if (object != null) {
if (recurse && myClass.isInstance(object)) {
count++;
} else if (object.getClass().equals(myClass)) {
count++;
}
}
}
return count;
}
/**
* Allow for the cache keys to be iterated on.
* Read locks will be checked.
*/
public Enumeration keys() {
return this.keys(true);
}
/**
* Allow for the cache keys to be iterated on.
* @param checkReadLocks - true if readLocks should be checked, false otherwise.
*/
public Enumeration keys(boolean checkReadLocks) {
return new IdentityMapKeyEnumeration(this, checkReadLocks);
}
/**
* Store the object in the cache at its primary key.
* This is used by InsertObjectQuery, typically into the UnitOfWork identity map.
* Merge and reads do not use put, but acquireLock.
* Also an advanced (very) user API.
* @param primaryKey is the primary key for the object.
* @param object is the domain object to cache.
* @param writeLockValue is the current write lock value of object, if null the version is ignored.
*/
public CacheKey put(Vector primaryKey, Object object, Object writeLockValue, long readTime) {
CacheKey newCacheKey = createCacheKey(primaryKey, object, writeLockValue, readTime);
// Find the cache key in the map, reset it, or put the new one.
CacheKey cacheKey = getCacheKeyIfAbsentPut(newCacheKey);
if (cacheKey != null) {
// The cache key is locked inside resetCacheKey() to keep other threads from accessing the object.
resetCacheKey(cacheKey, object, writeLockValue, readTime);
} else {
return newCacheKey;
}
return cacheKey;
}
/**
* Removes the CacheKey from the map.
* @return the object held within the CacheKey or null if no object cached for given cacheKey.
*/
public Object remove(CacheKey cacheKey) {
if (cacheKey != null) {
// Cache key needs to be locked when removing from the map.
cacheKey.acquire();
getCacheKeys().remove(cacheKey);
// Cache key needs to be released after removing from the map.
cacheKey.release();
return cacheKey.getObject();
} else {
return null;
}
}
/**
* Reset the cache key with new data.
*/
public void resetCacheKey(CacheKey key, Object object, Object writeLockValue, long readTime) {
key.acquire();
key.setObject(object);
key.setWriteLockValue(writeLockValue);
key.setReadTime(readTime);
key.release();
}
protected void setCacheKeys(Map<CacheKey, CacheKey> cacheKeys) {
this.cacheKeys = cacheKeys;
}
}