source: vbox/trunk/src/libs/xpcom18a4/python/src/PyGWeakReference.cpp

/* ***** 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 the Python XPCOM language bindings.
 *
 * The Initial Developer of the Original Code is
 * ActiveState Tool Corp.
 * Portions created by the Initial Developer are Copyright (C) 2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Mark Hammond <MarkH@ActiveState.com> (original author)
 *
 * 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
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 * ***** END LICENSE BLOCK ***** */

// PyGWeakReference - implements weak references for gateways.
//
// This code is part of the XPCOM extensions for Python.
//
// Written November 2000 by Mark Hammond.
//
// Based heavily on the Python COM support, which is
// (c) Mark Hammond and Greg Stein.
//
// (c) 2000, ActiveState corp.

#include "PyXPCOM_std.h"

#include <iprt/asm.h>

PyXPCOM_GatewayWeakReference::PyXPCOM_GatewayWeakReference( PyG_Base *base )
{
        m_pBase = base;

#ifdef NS_BUILD_REFCNT_LOGGING
        // bloat view uses 40 chars - stick "(WR)" at the end of this position.
        strncpy(refcntLogRepr, m_pBase->refcntLogRepr, sizeof(refcntLogRepr));
        refcntLogRepr[sizeof(refcntLogRepr)-1] = '\0';
        char *dest = refcntLogRepr + ((strlen(refcntLogRepr) > 36) ? 36 : strlen(refcntLogRepr));
        strcpy(dest, "(WR)");
#endif // NS_BUILD_REFCNT_LOGGING
}

PyXPCOM_GatewayWeakReference::~PyXPCOM_GatewayWeakReference()
{
        // Simply zap my reference to the gateway!
        // No need to zap my gateway's reference to me, as
        // it already holds a reference, so if we are destructing,
        // then it can't possibly hold one.
        m_pBase = NULL;
}

nsrefcnt
PyXPCOM_GatewayWeakReference::AddRef(void)
{
        nsrefcnt cnt = (nsrefcnt) ASMAtomicIncS32((volatile int32_t *)&mRefCnt);
#ifdef NS_BUILD_REFCNT_LOGGING
        NS_LOG_ADDREF(this, cnt, refcntLogRepr, sizeof(*this));
#endif
        return cnt;
}

nsrefcnt
PyXPCOM_GatewayWeakReference::Release(void)
{
        nsrefcnt cnt = (nsrefcnt) ASMAtomicDecS32((volatile int32_t *)&mRefCnt);
#ifdef NS_BUILD_REFCNT_LOGGING
        NS_LOG_RELEASE(this, cnt, refcntLogRepr);
#endif
        if ( cnt == 0 )
                delete this;
        return cnt;
}

NS_IMPL_THREADSAFE_QUERY_INTERFACE1(PyXPCOM_GatewayWeakReference, nsIWeakReference)

NS_IMETHODIMP
PyXPCOM_GatewayWeakReference::QueryReferent(REFNSIID iid, void * *ret)
{
        { 
        // Temp scope for lock.  We can't hold the lock during
        // a QI, as this may itself need the lock.
        // Make sure our object isn't dieing right now on another thread.
        CEnterLeaveXPCOMFramework _celf;
        if (m_pBase == NULL)
                return NS_ERROR_NULL_POINTER;
        m_pBase->AddRef(); // Can't die while we have a ref.
        } // end of lock scope - lock unlocked.
        nsresult nr = m_pBase->QueryInterface(iid, ret);
        m_pBase->Release();
        return nr;
}