/* -*- 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.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.io.Serializable;
/**
* 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<Class<?>,JavaMembers> classTable;
private transient Map<JavaAdapter.JavaAdapterSignature,Class<?>> classAdapterCache;
private transient Map<Class<?>,Object> interfaceAdapterCache;
private int generatedClassSerial;
private Scriptable associatedScope;
/**
* 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.
* <p>
* By default, the engine will cache the results of
* <tt>Class.getMethods()</tt> 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.
* <p>
* If caching is enabled and this method is called with a
* <code>false</code> argument, the caches will be emptied.
* <p>
* 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<Class<?>,JavaMembers> 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<Class<?>,JavaMembers>(16, 0.75f, 1);
}
return classTable;
}
Map<JavaAdapter.JavaAdapterSignature,Class<?>> getInterfaceAdapterCacheMap()
{
if (classAdapterCache == null) {
classAdapterCache = new ConcurrentHashMap<JavaAdapter.JavaAdapterSignature,Class<?>>(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<Class<?>,Object>(16, 0.75f, 1);
}
interfaceAdapterCache.put(cl, iadapter);
}
}
Scriptable getAssociatedScope() {
return associatedScope;
}
}