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/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
package org.mozilla.javascript;
import java.io.Serializable;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.ConcurrentHashMap;
/**
* Cache of generated classes and data structures to access Java runtime from JavaScript.
*
* @author Igor Bukanov
* @since Rhino 1.5 Release 5
*/
public class ClassCache implements Serializable {
private static final long serialVersionUID = -8866246036237312215L;
private static final Object AKEY = "ClassCache";
private volatile boolean cachingIsEnabled = true;
private transient Map classTable;
private transient Map> classAdapterCache;
private transient Map, Object> interfaceAdapterCache;
private int generatedClassSerial;
private Scriptable associatedScope;
/**
* CacheKey is a combination of class and securityContext. This is required when classes are
* loaded from different security contexts
*/
static class CacheKey {
final Class cls;
final Object sec;
/** Constructor. */
public CacheKey(Class cls, Object securityContext) {
this.cls = cls;
this.sec = securityContext;
}
@Override
public int hashCode() {
int result = cls.hashCode();
if (sec != null) {
result = sec.hashCode() * 31;
}
return result;
}
@Override
public boolean equals(Object obj) {
return (obj instanceof CacheKey)
&& Objects.equals(this.cls, ((CacheKey) obj).cls)
&& Objects.equals(this.sec, ((CacheKey) obj).sec);
}
}
/**
* Search for ClassCache object in the given scope. The method first calls {@link
* ScriptableObject#getTopLevelScope(Scriptable scope)} to get the top most scope and then tries
* to locate associated ClassCache object in the prototype chain of the top scope.
*
* @param scope scope to search for ClassCache object.
* @return previously associated ClassCache object or a new instance of ClassCache if no
* ClassCache object was found.
* @see #associate(ScriptableObject topScope)
*/
public static ClassCache get(Scriptable scope) {
ClassCache cache = (ClassCache) ScriptableObject.getTopScopeValue(scope, AKEY);
if (cache == null) {
throw new RuntimeException("Can't find top level scope for " + "ClassCache.get");
}
return cache;
}
/**
* Associate ClassCache object with the given top-level scope. The ClassCache object can only be
* associated with the given scope once.
*
* @param topScope scope to associate this ClassCache object with.
* @return true if no previous ClassCache objects were embedded into the scope and this
* ClassCache were successfully associated or false otherwise.
* @see #get(Scriptable scope)
*/
public boolean associate(ScriptableObject topScope) {
if (topScope.getParentScope() != null) {
// Can only associate cache with top level scope
throw new IllegalArgumentException();
}
if (this == topScope.associateValue(AKEY, this)) {
associatedScope = topScope;
return true;
}
return false;
}
/** Empty caches of generated Java classes and Java reflection information. */
public synchronized void clearCaches() {
classTable = null;
classAdapterCache = null;
interfaceAdapterCache = null;
}
/** Check if generated Java classes and Java reflection information is cached. */
public final boolean isCachingEnabled() {
return cachingIsEnabled;
}
/**
* Set whether to cache some values.
*
* By default, the engine will cache the results of Class.getMethods() and
* similar calls. This can speed execution dramatically, but increases the memory footprint.
* Also, with caching enabled, references may be held to objects past the lifetime of any real
* usage.
*
*
If caching is enabled and this method is called with a false argument, the
* caches will be emptied.
*
*
Caching is enabled by default.
*
* @param enabled if true, caching is enabled
* @see #clearCaches()
*/
public synchronized void setCachingEnabled(boolean enabled) {
if (enabled == cachingIsEnabled) return;
if (!enabled) clearCaches();
cachingIsEnabled = enabled;
}
/** @return a map from classes to associated JavaMembers objects */
Map getClassCacheMap() {
if (classTable == null) {
// Use 1 as concurrency level here and for other concurrent hash maps
// as we don't expect high levels of sustained concurrent writes.
classTable = new ConcurrentHashMap(16, 0.75f, 1);
}
return classTable;
}
Map> getInterfaceAdapterCacheMap() {
if (classAdapterCache == null) {
classAdapterCache =
new ConcurrentHashMap>(16, 0.75f, 1);
}
return classAdapterCache;
}
/**
* @deprecated The method always returns false.
* @see #setInvokerOptimizationEnabled(boolean enabled)
*/
@Deprecated
public boolean isInvokerOptimizationEnabled() {
return false;
}
/**
* @deprecated The method does nothing. Invoker optimization is no longer used by Rhino. On
* modern JDK like 1.4 or 1.5 the disadvantages of the optimization like increased memory
* usage or longer initialization time overweight small speed increase that can be gained
* using generated proxy class to replace reflection.
*/
@Deprecated
public synchronized void setInvokerOptimizationEnabled(boolean enabled) {}
/**
* Internal engine method to return serial number for generated classes to ensure name
* uniqueness.
*/
public final synchronized int newClassSerialNumber() {
return ++generatedClassSerial;
}
Object getInterfaceAdapter(Class cl) {
return interfaceAdapterCache == null ? null : interfaceAdapterCache.get(cl);
}
synchronized void cacheInterfaceAdapter(Class cl, Object iadapter) {
if (cachingIsEnabled) {
if (interfaceAdapterCache == null) {
interfaceAdapterCache = new ConcurrentHashMap, Object>(16, 0.75f, 1);
}
interfaceAdapterCache.put(cl, iadapter);
}
}
Scriptable getAssociatedScope() {
return associatedScope;
}
}