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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.openjpa.util;
import java.util.AbstractCollection;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.Predicate;
import org.apache.openjpa.lib.util.LRUMap;
import org.apache.openjpa.lib.util.SizedMap;
import org.apache.openjpa.lib.util.collections.AbstractReferenceMap;
import org.apache.openjpa.lib.util.collections.FilterIterator;
import org.apache.openjpa.lib.util.collections.IteratorChain;
import org.apache.openjpa.lib.util.concurrent.ConcurrentHashMap;
import org.apache.openjpa.lib.util.concurrent.ConcurrentReferenceHashMap;
/**
* Fixed-size map that has ability to pin/unpin entries and move overflow to
* a backing soft map.
*
* @author Patrick Linskey
* @author Abe White
*/
public class CacheMap
implements Map {
/**
* The map for non-expired and non-pinned references.
*/
protected final SizedMap cacheMap;
/**
* The map for expired references.
*/
protected final SizedMap softMap;
/**
* The set of objects pinned into the cache.
*/
protected final Map pinnedMap;
// number of pinned values (not including keys not mapped to values)
private int _pinnedSize = 0;
private final ReentrantReadWriteLock rwl = new ReentrantReadWriteLock(true);
private final Lock _readLock = rwl.readLock();
private final Lock _writeLock = rwl.writeLock();
/**
* Create a non-LRU (and therefore highly concurrent) cache map with a
* size of 1000.
*/
public CacheMap() {
this(false, 1000);
}
/**
* Create a cache map with a size of 1000.
*
* @param lru if true, create a LRU cache map otherwise a non-LRU map will be created.
*/
public CacheMap(boolean lru) {
this(lru, 1000);
}
/**
* Create a cache map with the given properties.
*/
public CacheMap(boolean lru, int max) {
this(lru, max, max / 2, .75F);
}
/**
* @deprecated use {@link CacheMap#CacheMap(boolean, int, int, float, int)}
* instead.
*/
@Deprecated
public CacheMap(boolean lru, int max, int size, float load) {
this(lru, max, size, load, 16);
}
/**
* Create a cache map with the given properties.
*
* @since 1.1.0
*/
public CacheMap(boolean lru, int max, int size, float load,
int concurrencyLevel) {
if (size < 0)
size = 500;
softMap = new ConcurrentReferenceHashMap(AbstractReferenceMap.ReferenceStrength.HARD,
AbstractReferenceMap.ReferenceStrength.SOFT, size, load) {
@Override
public void overflowRemoved(Object key, Object value) {
softMapOverflowRemoved(key, value);
}
@Override
public void valueExpired(Object key) {
softMapValueExpired(key);
}
};
pinnedMap = new ConcurrentHashMap();
if (!lru) {
cacheMap = new ConcurrentHashMap(size, load) {
private static final long serialVersionUID = 1L;
@Override
public void overflowRemoved(Object key, Object value) {
cacheMapOverflowRemoved(key, value);
}
};
} else {
cacheMap = new LRUMap(size, load) {
private static final long serialVersionUID = 1L;
@Override
public void overflowRemoved(Object key, Object value) {
cacheMapOverflowRemoved(key, value);
}
};
}
if (max < 0)
max = Integer.MAX_VALUE;
cacheMap.setMaxSize(max);
}
/**
* Called from {@link SizedMap#overflowRemoved} in the cache map.
*/
protected void cacheMapOverflowRemoved(Object key, Object value) {
if (softMap.size() < softMap.getMaxSize())
put(softMap, key, value);
else
entryRemoved(key, value, true);
}
/**
* Called from {@link SizedMap#overflowRemoved} in the soft map.
*/
protected void softMapOverflowRemoved(Object key, Object value) {
entryRemoved(key, value, true);
}
/**
* Called when a value expires from the soft map.
*/
protected void softMapValueExpired(Object key) {
entryRemoved(key, null, true);
}
/**
* Put the given entry into the given map. Allows subclasses to
* take additional actions.
*/
protected Object put(Map map, Object key, Object value) {
return map.put(key, value);
}
/**
* Remove the given key from the given map. Allows subclasses to
* take additional actions.
*/
protected Object remove(Map map, Object key) {
return map.remove(key);
}
/**
* Acquire read lock.
*/
public void readLock() {
_readLock.lock();
}
/**
* Release read lock.
*/
public void readUnlock() {
_readLock.unlock();
}
/**
* Acquire write lock.
*/
public void writeLock() {
_writeLock.lock();
}
/**
* Release write lock.
*/
public void writeUnlock() {
_writeLock.unlock();
}
/**
* Whether this cache map uses LRU eviction.
*/
public boolean isLRU() {
return cacheMap instanceof LRUMap;
}
/**
* The maximum number of hard references to maintain, or -1 for no limit.
*/
public void setCacheSize(int size) {
writeLock();
try {
cacheMap.setMaxSize((size < 0) ? Integer.MAX_VALUE : size);
} finally {
writeUnlock();
}
}
/**
* The maximum number of hard references to maintain, or -1 for no limit.
*/
public int getCacheSize() {
int max = cacheMap.getMaxSize();
return (max == Integer.MAX_VALUE) ? -1 : max;
}
/**
* The maximum number of soft references to maintain, or -1 for no limit.
*/
public void setSoftReferenceSize(int size) {
writeLock();
try {
softMap.setMaxSize((size < 0) ? Integer.MAX_VALUE : size);
} finally {
writeUnlock();
}
}
/**
* The maximum number of soft references to maintain, or -1 for no limit.
*/
public int getSoftReferenceSize() {
int max = softMap.getMaxSize();
return (max == Integer.MAX_VALUE) ? -1 : max;
}
/**
* The keys pinned into the map.
*/
public Set getPinnedKeys() {
readLock();
try {
return Collections.unmodifiableSet(pinnedMap.keySet());
} finally {
readUnlock();
}
}
/**
* Locks the given key and its value into the map. Objects pinned into
* the map are not counted towards the maximum cache size, and are never
* evicted implicitly. You may pin keys for which no value is in the map.
*
* @return true if the givne key's value was pinned; false if no value
* for the given key is cached
*/
public boolean pin(Object key) {
writeLock();
try {
// if we don't have a pinned map we need to create one; else if the
// pinned map already contains the key, nothing to do
if (pinnedMap.containsKey(key))
return pinnedMap.get(key) != null;
// check other maps for key
Object val = remove(cacheMap, key);
if (val == null)
val = remove(softMap, key);
// pin key
put(pinnedMap, key, val);
if (val != null) {
_pinnedSize++;
return true;
}
return false;
} finally {
writeUnlock();
}
}
/**
* Undo a pinning.
*/
public boolean unpin(Object key) {
writeLock();
try {
Object val = remove(pinnedMap, key);
if (val != null) {
// put back into unpinned cache
put(key, val);
_pinnedSize--;
return true;
}
return false;
} finally {
writeUnlock();
}
}
/**
* Invoked when a key-value pair is evicted from this data
* structure. This is invoked with expired set to
* true when an object is dropped because of space
* requirements or through garbage collection of soft references.
* It is invoked with expired set to false
* when an object is explicitly removed via the {@link #remove} or
* {@link #clear} methods. This may be invoked more than once for a
* given entry.
*
* @param value may be null if the value was a soft reference that has
* been GCd
* @since 0.2.5.0
*/
protected void entryRemoved(Object key, Object value, boolean expired) {
}
/**
* Invoked when an entry is added to the cache. This may be invoked
* more than once for an entry.
*/
protected void entryAdded(Object key, Object value) {
}
@Override
public Object get(Object key) {
boolean putcache = false;
Object val = null;
readLock();
try {
val = softMap.get(key);
if (val == null) {
val = cacheMap.get(key);
if (val == null) {
val = pinnedMap.get(key);
}
} else {
putcache = true;
}
return val;
} finally {
readUnlock();
//cannot obtain a write lock while holding a read lock
//doing it this way prevents a deadlock
if (putcache)
put(key, val);
}
}
@Override
public Object put(Object key, Object value) {
writeLock();
try {
// if the key is pinned, just interact directly with the pinned map
Object val;
if (pinnedMap.containsKey(key)) {
val = put(pinnedMap, key, value);
if (val == null) {
_pinnedSize++;
entryAdded(key, value);
} else {
entryRemoved(key, val, false);
entryAdded(key, value);
}
return val;
}
// if no hard refs, don't put anything
if (cacheMap.getMaxSize() == 0)
return null;
// otherwise, put the value into the map and clear it from the
// soft map
val = put(cacheMap, key, value);
if (val == null) {
val = remove(softMap, key);
if (val == null)
entryAdded(key, value);
else {
entryRemoved(key, val, false);
entryAdded(key, value);
}
} else {
entryRemoved(key, val, false);
entryAdded(key, value);
}
return val;
} finally {
writeUnlock();
}
}
@Override
public void putAll(Map map) {
putAll(map, true);
}
public void putAll(Map map, boolean replaceExisting) {
Map.Entry entry;
for (Object o : map.entrySet()) {
entry = (Entry) o;
if (replaceExisting || !containsKey(entry.getKey())) {
put(entry.getKey(), entry.getValue());
}
}
}
/**
* If key is pinned into the cache, the pin is
* cleared and the object is removed.
*/
@Override
public Object remove(Object key) {
writeLock();
try {
// if the key is pinned, just interact directly with the
// pinned map
Object val;
if (pinnedMap.containsKey(key)) {
// re-put with null value; we still want key pinned
val = put(pinnedMap, key, null);
if (val != null) {
_pinnedSize--;
entryRemoved(key, val, false);
}
return val;
}
val = remove(cacheMap, key);
if (val == null)
val = softMap.remove(key);
if (val != null)
entryRemoved(key, val, false);
return val;
} finally {
writeUnlock();
}
}
/**
* Removes pinned objects as well as unpinned ones.
*/
@Override
public void clear() {
writeLock();
try {
notifyEntryRemovals(pinnedMap.entrySet());
pinnedMap.clear();
_pinnedSize = 0;
notifyEntryRemovals(cacheMap.entrySet());
cacheMap.clear();
notifyEntryRemovals(softMap.entrySet());
softMap.clear();
} finally {
writeUnlock();
}
}
private void notifyEntryRemovals(Set set) {
Map.Entry entry;
for (Object o : set) {
entry = (Entry) o;
if (entry.getValue() != null)
entryRemoved(entry.getKey(), entry.getValue(), false);
}
}
@Override
public int size() {
readLock();
try {
return _pinnedSize + cacheMap.size() + softMap.size();
} finally {
readUnlock();
}
}
@Override
public boolean isEmpty() {
return size() == 0;
}
@Override
public boolean containsKey(Object key) {
readLock();
try {
return cacheMap.containsKey(key) || pinnedMap.get(key) != null || softMap.containsKey(key);
} finally {
readUnlock();
}
}
@Override
public boolean containsValue(Object val) {
readLock();
try {
return cacheMap.containsValue(val) || pinnedMap.containsValue(val) || softMap.containsValue(val);
} finally {
readUnlock();
}
}
@Override
public Set keySet() {
return new KeySet();
}
@Override
public Collection values() {
return new ValueCollection();
}
@Override
public Set entrySet() {
return new EntrySet();
}
@Override
public String toString() {
readLock();
try {
return "CacheMap:" + cacheMap.toString() + "::" + softMap.toString();
} finally {
readUnlock();
}
}
/**
* View of the entry set.
*/
private class EntrySet
extends AbstractSet {
@Override
public int size() {
return CacheMap.this.size();
}
@Override
public boolean add(Object o) {
Map.Entry entry = (Map.Entry) o;
put(entry.getKey(), entry.getValue());
return true;
}
@Override
public Iterator iterator() {
return new EntryIterator(EntryIterator.ENTRY);
}
}
/**
* View of the key set.
*/
private class KeySet
extends AbstractSet {
@Override
public int size() {
return CacheMap.this.size();
}
@Override
public Iterator iterator() {
return new EntryIterator(EntryIterator.KEY);
}
}
/**
* View of the value collection.
*/
private class ValueCollection
extends AbstractCollection {
@Override
public int size() {
return CacheMap.this.size();
}
@Override
public Iterator iterator() {
return new EntryIterator(EntryIterator.VALUE);
}
}
/**
* Iterator over all entries.
*/
private class EntryIterator
implements Iterator, Predicate {
public static final int ENTRY = 0;
public static final int KEY = 1;
public static final int VALUE = 2;
private final IteratorChain _itr = new IteratorChain();
private final int _type;
public EntryIterator(int type) {
_type = type;
_itr.addIterator(new FilterIterator(getView(pinnedMap), this));
_itr.addIterator(getView(cacheMap));
_itr.addIterator(getView(softMap));
}
/**
* Return an iterator over the appropriate view of the given map.
*/
private Iterator getView(Map m) {
if (m == null)
return null;
switch (_type) {
case KEY:
return m.keySet().iterator();
case VALUE:
return m.values().iterator();
default:
return m.entrySet().iterator();
}
}
@Override
public boolean hasNext() {
return _itr.hasNext();
}
@Override
public Object next() {
return _itr.next();
}
@Override
public void remove() {
_itr.remove();
}
@Override
public boolean test(Object obj) {
switch (_type) {
case ENTRY:
return ((Map.Entry) obj).getValue() != null;
case VALUE:
return obj != null;
default:
return true;
}
}
}
}
