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/*
* Copyright (c) 1999-2004 Sourceforge JACOB Project.
* All rights reserved. Originator: Dan Adler (http://danadler.com).
* Get more information about JACOB at http://sourceforge.net/projects/jacob-project
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package com.jacob.com;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.WeakHashMap;
/**
* The Running Object Table (ROT) maps each thread to a collection of all the
* JacobObjects that were created in that thread. It always operates on the
* current thread so all the methods are static and they implicitly get the
* current thread.
*
* The clearObjects method is used to release all the COM objects created by
* Jacob in the current thread prior to uninitializing COM for that thread.
*
* Prior to 1.9, manual garbage collection was the only option in Jacob, but
* from 1.9 onward, setting the com.jacob.autogc system property allows the
* objects referenced by the ROT to be automatically GCed. Automatic GC may be
* preferable in systems with heavy event callbacks.
*
* Is [ 1116101 ] jacob-msg 0284 relevant???
*/
public abstract class ROT {
/**
* Manual garbage collection was the only option pre 1.9 Can staticly cache
* the results because only one value and we don't let it change during a
* run
*/
protected static final boolean USE_AUTOMATIC_GARBAGE_COLLECTION = "true"
.equalsIgnoreCase(System.getProperty("com.jacob.autogc"));
/**
* If the code is ran from an applet that is called from javascript the Java
* Plugin does not give full permissions to the code and thus System
* properties cannot be accessed. They can be accessed at class
* initialization time.
*
* The default behavior is to include all classes in the ROT, setting a
* boolean here to indicate this prevents a call to System.getProperty as
* part of the general call flow.
*/
protected static final Boolean INCLUDE_ALL_CLASSES_IN_ROT = Boolean
.valueOf(System.getProperty("com.jacob.includeAllClassesInROT",
"true"));
/**
* Suffix added to class name to make up property name that determines if
* this object should be stored in the ROT. This 1.13 "feature" makes it
* possible to cause VariantViaEvent objects to not be added to the ROT in
* event callbacks.
*
* We don't have a static for the actual property because there is a
* different property for each class that may make use of this feature.
*/
protected static String PUT_IN_ROT_SUFFIX = ".PutInROT";
/**
* ThreadLocal with the com objects created in that thread
*/
private static ThreadLocal> rot = new ThreadLocal>();
/**
* adds a new thread storage area to rot
*
* @return Map corresponding to the thread that this call was made in
*/
protected synchronized static Map addThread() {
Map tab = rot.get();
if (tab == null) {
if (JacobObject.isDebugEnabled()) {
JacobObject.debug("ROT: Automatic GC flag == "
+ USE_AUTOMATIC_GARBAGE_COLLECTION);
}
if (!USE_AUTOMATIC_GARBAGE_COLLECTION) {
tab = new HashMap();
} else {
tab = new WeakHashMap();
}
rot.set(tab);
}
return tab;
}
/**
* Returns the pool for this thread if it exists. can create a new one if
* you wish by passing in TRUE
*
* @param createIfDoesNotExist
* @return Map the collection that holds the objects created in the current
* thread
*/
protected synchronized static Map getThreadObjects(
boolean createIfDoesNotExist) {
Map tab = rot.get();
if (tab == null && createIfDoesNotExist) {
tab = addThread();
}
return tab;
}
/**
* Iterates across all of the entries in the Hashmap in the rot that
* corresponds to this thread. This calls safeRelease() on each entry and
* then clears the map when done and removes it from the rot. All traces of
* this thread's objects will disappear. This is called by COMThread in the
* tear down and provides a synchronous way of releasing memory
*/
protected static void clearObjects() {
Map tab = getThreadObjects(false);
if (tab != null) {
if (JacobObject.isDebugEnabled()) {
JacobObject.debug("ROT: " + tab.keySet().size()
+ " objects to clear in this thread's ROT ");
}
// walk the values
Iterator it = tab.keySet().iterator();
while (it.hasNext()) {
JacobObject o = it.next();
if (o != null
// can't use this cause creates a Variant if calling SafeAray
// and we get an exception modifying the collection while
// iterating
// && o.toString() != null
) {
if (JacobObject.isDebugEnabled()) {
if (o instanceof SafeArray) {
// SafeArray create more objects when calling
// toString()
// which causes a concurrent modification exception
// in HashMap
JacobObject.debug("ROT: removing "
+ o.getClass().getName());
} else {
// Variant toString() is probably always bad in here
JacobObject.debug("ROT: removing " + o.hashCode()
+ "->" + o.getClass().getName());
}
}
o.safeRelease();
}
}
// empty the collection
tab.clear();
// remove the collection from rot
ROT.removeThread();
if (JacobObject.isDebugEnabled()) {
JacobObject.debug("ROT: thread table cleared and removed");
}
} else {
if (JacobObject.isDebugEnabled()) {
JacobObject.debug("ROT: nothing to clear!");
}
}
}
/**
* Removes the map from the rot that is associated with the current thread.
*/
private synchronized static void removeThread() {
rot.remove();
}
/**
* @deprecated the java model leave the responsibility of clearing up
* objects to the Garbage Collector. Our programming model
* should not require that the user specifically remove object
* from the thread.
* This will remove an object from the ROT
* This does not need to be synchronized because only the rot
* modification related methods need to synchronized. Each
* individual map is only modified in a single thread.
* @param o
*/
@Deprecated
protected static void removeObject(JacobObject o) {
Map tab = ROT.getThreadObjects(false);
if (tab != null) {
tab.remove(o);
}
o.safeRelease();
}
/**
* Adds an object to the HashMap for the current thread.
*
* This method does not need to be threaded because the only concurrent
* modification risk is on the hash map that contains all of the thread
* related hash maps. The individual thread related maps are only used on a
* per thread basis so there isn't a locking issue.
*
* In addition, this method cannot be threaded because it calls
* ComThread.InitMTA. The ComThread object has some methods that call ROT so
* we could end up deadlocked. This method should be safe without the
* synchronization because the ROT works on per thread basis and the methods
* that add threads and remove thread related entries are all synchronized
*
*
* @param o
*/
protected static void addObject(JacobObject o) {
String shouldIncludeClassInROT = "true";
// only call System.getProperty if we are not including all classes in
// the ROT. This lets us run with standard Jacob behavior in Applets
// without the security exception raised by System.getProperty in the
// flow
if (!ROT.INCLUDE_ALL_CLASSES_IN_ROT) {
shouldIncludeClassInROT = System.getProperty(o.getClass().getName()
+ PUT_IN_ROT_SUFFIX, "true");
}
if (shouldIncludeClassInROT.equalsIgnoreCase("false")) {
if (JacobObject.isDebugEnabled()) {
JacobObject.debug("JacobObject: New instance of "
+ o.getClass().getName() + " not added to ROT");
}
} else {
// first see if we have a table for this thread
Map tab = getThreadObjects(false);
if (tab == null) {
// this thread has not been initialized as a COM thread
// so make it part of MTA for backwards compatibility
ComThread.InitMTA(false);
// don't really need the "true" because the InitMTA will have
// called back to the ROT to create a table for this thread
tab = getThreadObjects(true);
}
if (JacobObject.isDebugEnabled()) {
JacobObject.debug("ROT: adding " + o + "->"
+ o.getClass().getName()
+ " table size prior to addition:" + tab.size());
}
// add the object to the table that is specific to this thread
if (tab != null) {
tab.put(o, null);
}
}
}
/**
* ROT can't be a subclass of JacobObject because of the way ROT pools are
* managed so we force a DLL load here by referencing JacobObject
*/
static {
LibraryLoader.loadJacobLibrary();
}
}