/*******************************************************************************
* Copyright (c) 2009 IBM Corporation and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* IBM Corporation - initial API and implementation
* Zend Technologies
*******************************************************************************/
package org.eclipse.php.internal.ui.corext.util;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.dltk.core.IType;
import org.eclipse.dltk.core.ITypeHierarchy;
import org.eclipse.dltk.core.ITypeHierarchyChangedListener;
import org.eclipse.dltk.core.ModelException;
import org.eclipse.dltk.internal.core.util.MethodOverrideTester;
/**
* TODO : should be in the DLTK ui
*
* @author roy
*
*/
public class SuperTypeHierarchyCache {
private static class HierarchyCacheEntry implements
ITypeHierarchyChangedListener {
private ITypeHierarchy fTypeHierarchy;
private long fLastAccess;
public HierarchyCacheEntry(ITypeHierarchy hierarchy) {
fTypeHierarchy = hierarchy;
fTypeHierarchy.addTypeHierarchyChangedListener(this);
markAsAccessed();
}
public void typeHierarchyChanged(ITypeHierarchy typeHierarchy) {
removeHierarchyEntryFromCache(this);
}
public ITypeHierarchy getTypeHierarchy() {
return fTypeHierarchy;
}
public void markAsAccessed() {
fLastAccess = System.currentTimeMillis();
}
public long getLastAccess() {
return fLastAccess;
}
public void dispose() {
fTypeHierarchy.removeTypeHierarchyChangedListener(this);
fTypeHierarchy = null;
}
/*
* (non-Javadoc)
*
* @see java.lang.Object#toString()
*/
public String toString() {
return "Super hierarchy of: " + fTypeHierarchy.getType().getElementName(); //$NON-NLS-1$
}
}
private static final int CACHE_SIZE = 8;
private static ArrayList fgHierarchyCache = new ArrayList(CACHE_SIZE);
private static Map fgMethodOverrideTesterCache = new LRUMap(CACHE_SIZE);
private static int fgCacheHits = 0;
private static int fgCacheMisses = 0;
/**
* Get a hierarchy for the given type
*/
public static ITypeHierarchy getTypeHierarchy(IType type)
throws ModelException {
return getTypeHierarchy(type, null);
}
public static MethodOverrideTester getMethodOverrideTester(IType type)
throws ModelException {
MethodOverrideTester test = null;
synchronized (fgMethodOverrideTesterCache) {
test = (MethodOverrideTester) fgMethodOverrideTesterCache.get(type);
}
if (test == null) {
ITypeHierarchy hierarchy = getTypeHierarchy(type); // don't nest the
// locks
synchronized (fgMethodOverrideTesterCache) {
test = (MethodOverrideTester) fgMethodOverrideTesterCache
.get(type); // test again after waiting a long time for
// 'getTypeHierarchy'
if (test == null) {
test = new MethodOverrideTester(type, hierarchy);
fgMethodOverrideTesterCache.put(type, test);
}
}
}
return test;
}
private static void removeMethodOverrideTester(ITypeHierarchy hierarchy) {
synchronized (fgMethodOverrideTesterCache) {
for (Iterator iter = fgMethodOverrideTesterCache.values()
.iterator(); iter.hasNext();) {
MethodOverrideTester curr = (MethodOverrideTester) iter.next();
if (curr != null && curr.getTypeHierarchy() != null
&& curr.getTypeHierarchy().equals(hierarchy)) {
iter.remove();
}
}
}
}
/**
* Get a hierarchy for the given type
*/
public static ITypeHierarchy getTypeHierarchy(IType type,
IProgressMonitor progressMonitor) throws ModelException {
if (type == null) {
return null;
}
ITypeHierarchy hierarchy = findTypeHierarchyInCache(type);
if (hierarchy == null) {
fgCacheMisses++;
hierarchy = type.newSupertypeHierarchy(progressMonitor);
addTypeHierarchyToCache(hierarchy);
} else {
fgCacheHits++;
}
return hierarchy;
}
private static void addTypeHierarchyToCache(ITypeHierarchy hierarchy) {
synchronized (fgHierarchyCache) {
int nEntries = fgHierarchyCache.size();
if (nEntries >= CACHE_SIZE) {
// find obsolete entries or remove entry that was least recently
// accessed
HierarchyCacheEntry oldest = null;
ArrayList obsoleteHierarchies = new ArrayList(CACHE_SIZE);
for (int i = 0; i < nEntries; i++) {
HierarchyCacheEntry entry = (HierarchyCacheEntry) fgHierarchyCache
.get(i);
ITypeHierarchy curr = entry.getTypeHierarchy();
if (!curr.exists() || hierarchy.contains(curr.getType())) {
obsoleteHierarchies.add(entry);
} else {
if (oldest == null
|| entry.getLastAccess() < oldest
.getLastAccess()) {
oldest = entry;
}
}
}
if (!obsoleteHierarchies.isEmpty()) {
for (int i = 0; i < obsoleteHierarchies.size(); i++) {
removeHierarchyEntryFromCache((HierarchyCacheEntry) obsoleteHierarchies
.get(i));
}
} else if (oldest != null) {
removeHierarchyEntryFromCache(oldest);
}
}
HierarchyCacheEntry newEntry = new HierarchyCacheEntry(hierarchy);
fgHierarchyCache.add(newEntry);
}
}
/**
* Check if the given type is in the hierarchy
*
* @param type
* @return Return <code>true</code> if a hierarchy for the given type is
* cached.
*/
public static boolean hasInCache(IType type) {
return findTypeHierarchyInCache(type) != null;
}
private static ITypeHierarchy findTypeHierarchyInCache(IType type) {
if (type != null) {
synchronized (fgHierarchyCache) {
for (int i = fgHierarchyCache.size() - 1; i >= 0; i--) {
HierarchyCacheEntry curr = (HierarchyCacheEntry) fgHierarchyCache
.get(i);
ITypeHierarchy hierarchy = curr.getTypeHierarchy();
if (!hierarchy.exists()) {
removeHierarchyEntryFromCache(curr);
} else {
if (hierarchy.contains(type)) {
curr.markAsAccessed();
return hierarchy;
}
}
}
}
}
return null;
}
private static void removeHierarchyEntryFromCache(HierarchyCacheEntry entry) {
synchronized (fgHierarchyCache) {
removeMethodOverrideTester(entry.getTypeHierarchy());
entry.dispose();
fgHierarchyCache.remove(entry);
}
}
/**
* Gets the number of times the hierarchy could be taken from the hierarchy.
*
* @return Returns a int
*/
public static int getCacheHits() {
return fgCacheHits;
}
/**
* Gets the number of times the hierarchy was build. Used for testing.
*
* @return Returns a int
*/
public static int getCacheMisses() {
return fgCacheMisses;
}
/**
*
*/
public static class LRUMap extends LinkedHashMap {
private static final long serialVersionUID = 1L;
private final int fMaxSize;
public LRUMap(int maxSize) {
super(maxSize, 0.75f, true);
fMaxSize = maxSize;
}
protected boolean removeEldestEntry(java.util.Map.Entry eldest) {
return size() > fMaxSize;
}
}
}