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/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* 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 Java XPCOM Bindings.
*
* The Initial Developer of the Original Code is
* IBM Corporation.
* Portions created by the Initial Developer are Copyright (C) 2005
* IBM Corporation. All Rights Reserved.
*
* Contributor(s):
* Javier Pedemonte (jhpedemonte@gmail.com)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#include "jni.h"
#include "nsJavaXPTCStubWeakRef.h"
#include "nsJavaXPTCStub.h"
#include "nsJavaXPCOMBindingUtils.h"
#include "nsIInterfaceInfoManager.h"
/**
* How we handle XPCOM weak references to a Java object:
*
* If XPCOM requires or asks for a weak reference of a Java object, we first
* find (or create) an nsJavaXPTCStub for that Java object. That way, there is
* always an nsJavaXPTCStub for any nsJavaXPTCStubWeakRef. However, the
* XPTCStub may not always be 'valid'; that is, its refcount may be zero if
* is not currently referenced by any XPCOM class.
* When an XPCOM method queries the referent from the weak reference, the
* weak ref checks first whether the Java object is still valid. If so, we can
* immediately return an addref'd nsJavaXPTCStub. The XPTCStub takes care of
* finding an XPTCStub for the required IID.
*/
nsJavaXPTCStubWeakRef::nsJavaXPTCStubWeakRef(jobject aJavaObject,
nsJavaXPTCStub* aXPTCStub)
: mXPTCStub(aXPTCStub)
{
JNIEnv* env = GetJNIEnv();
jobject weakref = env->NewObject(weakReferenceClass,
weakReferenceConstructorMID, aJavaObject);
mWeakRef = env->NewGlobalRef(weakref);
}
nsJavaXPTCStubWeakRef::~nsJavaXPTCStubWeakRef()
{
JNIEnv* env = GetJNIEnv();
env->CallVoidMethod(mWeakRef, clearReferentMID);
env->DeleteGlobalRef(mWeakRef);
mXPTCStub->ReleaseWeakRef();
}
NS_IMPL_ADDREF(nsJavaXPTCStubWeakRef)
NS_IMPL_RELEASE(nsJavaXPTCStubWeakRef)
NS_IMPL_QUERY_INTERFACE1(nsJavaXPTCStubWeakRef, nsIWeakReference)
NS_IMETHODIMP
nsJavaXPTCStubWeakRef::QueryReferent(const nsIID& aIID, void** aInstancePtr)
{
LOG(("nsJavaXPTCStubWeakRef::QueryReferent()\n"));
// Is weak ref still valid?
// We create a strong local ref to make sure Java object isn't garbage
// collected during this call.
JNIEnv* env = GetJNIEnv();
jobject javaObject = env->CallObjectMethod(mWeakRef, getReferentMID);
if (env->IsSameObject(javaObject, NULL))
return NS_ERROR_NULL_POINTER;
// Java object has not been garbage collected, so return QI from XPTCStub.
return mXPTCStub->QueryInterface(aIID, aInstancePtr);
}
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