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/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
*
* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (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.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Rhino code, released
* May 6, 1999.
*
* The Initial Developer of the Original Code is
* Netscape Communications Corporation.
* Portions created by the Initial Developer are Copyright (C) 1997-1999
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* Igor Bukanov, [email protected]
*
* Alternatively, the contents of this file may be used under the terms of
* the GNU General Public License Version 2 or later (the "GPL"), in which
* case the provisions of the GPL are applicable instead of those above. If
* you wish to allow use of your version of this file only under the terms of
* the GPL and not to allow others to use your version of this file under the
* MPL, indicate your decision by deleting the provisions above and replacing
* them with the notice and other provisions required by the GPL. If you do
* not delete the provisions above, a recipient may use your version of this
* file under either the MPL or the GPL.
*
* ***** END LICENSE BLOCK ***** */
package org.mozilla.javascript;
import java.util.Hashtable;
/**
* 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
{
private static final Object AKEY = new Object();
private volatile boolean cachingIsEnabled = true;
Hashtable classTable = new Hashtable();
Hashtable javaAdapterGeneratedClasses = new Hashtable();
ScriptableObject scope;
private Hashtable interfaceAdapterCache;
private int generatedClassSerial;
/**
* 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;
cache = (ClassCache)ScriptableObject.getTopScopeValue(scope, AKEY);
if (cache == null) {
// XXX warn somehow about wrong cache usage ?
cache = new ClassCache();
}
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 prevous 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)) {
scope = topScope;
return true;
}
return false;
}
/**
* Empty caches of generated Java classes and Java reflection information.
*/
public synchronized void clearCaches()
{
classTable = new Hashtable();
javaAdapterGeneratedClasses = new Hashtable();
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;
}
/**
* @deprecated
* The method always returns false.
* @see #setInvokerOptimizationEnabled(boolean enabled)
*/
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 disadvatages of the optimization
* like incresed memory usage or longer initialization time overweight
* small speed increase that can be gained using generated proxy class
* to replace reflection.
*/
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)
{
Object result;
Hashtable cache = interfaceAdapterCache;
if (cache == null) {
result = null;
} else {
result = cache.get(cl);
}
return result;
}
synchronized void cacheInterfaceAdapter(Class cl, Object iadapter)
{
if (cachingIsEnabled) {
if (interfaceAdapterCache == null) {
interfaceAdapterCache = new Hashtable();
}
interfaceAdapterCache.put(cl, iadapter);
}
}
}