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The AspectJ weaver introduces advices to java classes
package org.aspectj.apache.bcel.util;
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2001 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" and
* "Apache BCEL" must not be used to endorse or promote products
* derived from this software without prior written permission. For
* written permission, please contact [email protected].
*
* 5. Products derived from this software may not be called "Apache",
* "Apache BCEL", nor may "Apache" appear in their name, without
* prior written permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* > localCache = new WeakHashMap>();
private static SoftHashMap /* */sharedCache = new SoftHashMap(Collections.synchronizedMap(new HashMap()));
// For fast translation of the classname *intentionally not static*
private SoftHashMap /* */nameMap = new SoftHashMap(new HashMap(), false);
public static boolean useSharedCache = System.getProperty("org.aspectj.apache.bcel.useSharedCache", "true").equalsIgnoreCase("true");
private static int cacheHitsShared = 0;
private static int missSharedEvicted = 0; // Misses in shared cache access due to reference GC
private long timeManipulatingURLs = 0L;
private long timeSpentLoading = 0L;
private int classesLoadedCount = 0;
private int misses = 0;
private int cacheHitsLocal = 0;
private int missLocalEvicted = 0; // Misses in local cache access due to reference GC
public ClassLoaderRepository(java.lang.ClassLoader loader) {
this.loaderRef = new DefaultClassLoaderReference((loader != null) ? loader : getBootClassLoader());
}
public ClassLoaderRepository(ClassLoaderReference loaderRef) {
this.loaderRef = loaderRef;
}
private static synchronized java.lang.ClassLoader getBootClassLoader() {
if (bootClassLoader == null) {
bootClassLoader = new URLClassLoader(new URL[0]);
}
return bootClassLoader;
}
// Can track back to its key
public static class SoftHashMap extends AbstractMap {
private Map map;
boolean recordMiss = true; // only interested in recording miss stats sometimes
private ReferenceQueue rq = new ReferenceQueue();
public SoftHashMap(Map map) {
this.map = map;
}
public SoftHashMap() {
this(new HashMap());
}
public SoftHashMap(Map map, boolean b) {
this(map);
this.recordMiss = b;
}
class SpecialValue extends SoftReference {
private final Object key;
SpecialValue(Object k, Object v) {
super(v, rq);
this.key = k;
}
}
private void processQueue() {
SpecialValue sv = null;
while ((sv = (SpecialValue) rq.poll()) != null) {
map.remove(sv.key);
}
}
@Override
public Object get(Object key) {
SpecialValue value = map.get(key);
if (value == null)
return null;
if (value.get() == null) {
// it got GC'd
map.remove(value.key);
if (recordMiss)
missSharedEvicted++;
return null;
} else {
return value.get();
}
}
@Override
public Object put(Object k, Object v) {
processQueue();
return map.put(k, new SpecialValue(k, v));
}
@Override
public Set entrySet() {
return map.entrySet();
}
@Override
public void clear() {
processQueue();
map.clear();
}
@Override
public int size() {
processQueue();
return map.size();
}
@Override
public Object remove(Object k) {
processQueue();
SpecialValue value = map.remove(k);
if (value == null)
return null;
if (value.get() != null) {
return value.get();
}
return null;
}
}
/**
* Store a new JavaClass into this repository as a soft reference and return the reference
*/
private void storeClassAsReference(URL url, JavaClass clazz) {
if (useSharedCache) {
clazz.setRepository(null); // can't risk setting repository, we'll get in a pickle!
sharedCache.put(url, clazz);
} else {
clazz.setRepository(this);
localCache.put(url, new SoftReference(clazz));
}
}
/**
* Store a new JavaClass into this Repository.
*/
public void storeClass(JavaClass clazz) {
storeClassAsReference(toURL(clazz.getClassName()), clazz);
}
/**
* Remove class from repository
*/
public void removeClass(JavaClass clazz) {
if (useSharedCache)
sharedCache.remove(toURL(clazz.getClassName()));
else
localCache.remove(toURL(clazz.getClassName()));
}
/**
* Find an already defined JavaClass in the local cache.
*/
public JavaClass findClass(String className) {
if (useSharedCache)
return findClassShared(toURL(className));
else
return findClassLocal(toURL(className));
}
private JavaClass findClassLocal(URL url) {
Object o = localCache.get(url);
if (o != null) {
o = ((Reference) o).get();
if (o != null) {
return (JavaClass) o;
} else {
missLocalEvicted++;
}
}
return null;
}
/**
* Find an already defined JavaClass in the shared cache.
*/
private JavaClass findClassShared(URL url) {
return (JavaClass) sharedCache.get(url);
}
private URL toURL(String className) {
URL url = (URL) nameMap.get(className);
if (url == null) {
String classFile = className.replace('.', '/');
url = loaderRef.getClassLoader().getResource(classFile + ".class");
nameMap.put(className, url);
}
return url;
}
/**
* Lookup a JavaClass object from the Class Name provided.
*/
public JavaClass loadClass(String className) throws ClassNotFoundException {
// translate to a URL
long time = System.currentTimeMillis();
java.net.URL url = toURL(className);
timeManipulatingURLs += (System.currentTimeMillis() - time);
if (url == null)
throw new ClassNotFoundException(className + " not found - unable to determine URL");
JavaClass clazz = null;
// Look in the appropriate cache
if (useSharedCache) {
clazz = findClassShared(url);
if (clazz != null) {
cacheHitsShared++;
return clazz;
}
} else {
clazz = findClassLocal(url);
if (clazz != null) {
cacheHitsLocal++;
return clazz;
}
}
// Didn't find it in either cache
misses++;
try {
// Load it
String classFile = className.replace('.', '/');
InputStream is = (useSharedCache ? url.openStream() : loaderRef.getClassLoader().getResourceAsStream(
classFile + ".class"));
if (is == null) {
throw new ClassNotFoundException(className + " not found using url " + url);
}
ClassParser parser = new ClassParser(is, className);
clazz = parser.parse();
// Cache it
storeClassAsReference(url, clazz);
timeSpentLoading += (System.currentTimeMillis() - time);
classesLoadedCount++;
return clazz;
} catch (IOException e) {
throw new ClassNotFoundException(e.toString());
}
}
/**
* Produce a report on cache usage.
*/
public String report() {
StringBuffer sb = new StringBuffer();
sb.append("BCEL repository report.");
if (useSharedCache)
sb.append(" (shared cache)");
else
sb.append(" (local cache)");
sb.append(" Total time spent loading: " + timeSpentLoading + "ms.");
sb.append(" Time spent manipulating URLs: " + timeManipulatingURLs + "ms.");
sb.append(" Classes loaded: " + classesLoadedCount + ".");
if (useSharedCache) {
sb.append(" Shared cache size: " + sharedCache.size());
sb.append(" Shared cache (hits/missDueToEviction): (" + cacheHitsShared + "/" + missSharedEvicted + ").");
} else {
sb.append(" Local cache size: " + localCache.size());
sb.append(" Local cache (hits/missDueToEviction): (" + cacheHitsLocal + "/" + missLocalEvicted + ").");
}
return sb.toString();
}
/**
* Returns an array of the stats, for testing, the order is fixed: 0=time spent loading (static) 1=time spent manipulating URLs
* (static) 2=classes loaded (static) 3=cache hits shared (static) 4=misses in shared due to eviction (static) 5=cache hits
* local 6=misses in local due to eviction 7=shared cache size
*/
public long[] reportStats() {
return new long[] { timeSpentLoading, timeManipulatingURLs, classesLoadedCount, cacheHitsShared, missSharedEvicted,
cacheHitsLocal, missLocalEvicted, sharedCache.size() };
}
/**
* Reset statistics and clear all caches
*/
public void reset() {
timeManipulatingURLs = 0L;
timeSpentLoading = 0L;
classesLoadedCount = 0;
cacheHitsLocal = 0;
cacheHitsShared = 0;
missSharedEvicted = 0;
missLocalEvicted = 0;
misses = 0;
clear();
}
public JavaClass loadClass(Class clazz) throws ClassNotFoundException {
return loadClass(clazz.getName());
}
/** Clear all entries from the local cache */
public void clear() {
if (useSharedCache)
sharedCache.clear();
else
localCache.clear();
}
}