gecko-dev/xpcom/ds/nsObserverService.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* ***** 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 mozilla.org code.
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Pierre Phaneuf <pp@ludusdesign.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of 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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#include "prlog.h"
#include "prlock.h"
#include "nsIFactory.h"
#include "nsIServiceManager.h"
#include "nsIComponentManager.h"
#include "nsIObserverService.h"
#include "nsIObserver.h"
#include "nsISimpleEnumerator.h"
#include "nsObserverService.h"
#include "nsObserverList.h"
#include "nsHashtable.h"
#include "nsIWeakReference.h"

#define NOTIFY_GLOBAL_OBSERVERS

#if defined(PR_LOGGING)
// Log module for nsObserverService logging...
//
// To enable logging (see prlog.h for full details):
//
//    set NSPR_LOG_MODULES=ObserverService:5
//    set NSPR_LOG_FILE=nspr.log
//
// this enables PR_LOG_DEBUG level information and places all output in
// the file nspr.log
PRLogModuleInfo* observerServiceLog = nsnull;
#endif /* PR_LOGGING */

////////////////////////////////////////////////////////////////////////////////
// nsObserverService Implementation


NS_IMPL_THREADSAFE_ISUPPORTS1(nsObserverService, nsIObserverService)

nsObserverService::nsObserverService()
    : mObserverTopicTable(nsnull)
{
}

nsObserverService::~nsObserverService(void)
{
    if(mObserverTopicTable)
        delete mObserverTopicTable;
}

NS_METHOD
nsObserverService::Create(nsISupports* outer, const nsIID& aIID, void* *aInstancePtr)
{
#if defined(PR_LOGGING)
    if (!observerServiceLog)
        observerServiceLog = PR_NewLogModule("ObserverService");
#endif

    nsresult rv;
    nsObserverService* os = new nsObserverService();
    if (os == nsnull)
        return NS_ERROR_OUT_OF_MEMORY;
    NS_ADDREF(os);
    rv = os->QueryInterface(aIID, aInstancePtr);
    NS_RELEASE(os);
    return rv;
}

static PRBool PR_CALLBACK 
ReleaseObserverList(nsHashKey *aKey, void *aData, void* closure)
{
    nsObserverList* observerList = NS_STATIC_CAST(nsObserverList*, aData);
    delete(observerList);
    return PR_TRUE;
}

nsresult nsObserverService::GetObserverList(const char* aTopic, nsObserverList** anObserverList)
{
    if (anObserverList == nsnull)
        return NS_ERROR_NULL_POINTER;
    
    if(mObserverTopicTable == nsnull) 
    {
        mObserverTopicTable = new nsObjectHashtable(nsnull, 
                                                    nsnull,   // should never be cloned
                                                    ReleaseObserverList, 
                                                    nsnull,
                                                    256, 
                                                    PR_TRUE);
        if (mObserverTopicTable == nsnull)
            return NS_ERROR_OUT_OF_MEMORY;
    }
    

    nsCStringKey key(aTopic);

    nsObserverList *topicObservers;
    topicObservers = (nsObserverList *) mObserverTopicTable->Get(&key);

    if (topicObservers) 
    {
        *anObserverList = topicObservers;    
        return NS_OK;
    }

    nsresult rv = NS_OK;
    topicObservers = new nsObserverList(rv);
    if (!topicObservers)
        return NS_ERROR_OUT_OF_MEMORY;

    if (NS_FAILED(rv)) {
        delete topicObservers;
        return rv;
    }
    
    *anObserverList = topicObservers;
    mObserverTopicTable->Put(&key, topicObservers);
    
    return NS_OK;
}

NS_IMETHODIMP nsObserverService::AddObserver(nsIObserver* anObserver, const char* aTopic, PRBool ownsWeak)
{
    nsObserverList* anObserverList;
    nsresult rv;

    if (anObserver == nsnull || aTopic == nsnull)
        return NS_ERROR_NULL_POINTER;

    rv = GetObserverList(aTopic, &anObserverList);
    if (NS_FAILED(rv)) return rv;

    return anObserverList->AddObserver(anObserver, ownsWeak);
}

NS_IMETHODIMP nsObserverService::RemoveObserver(nsIObserver* anObserver, const char* aTopic)
{
    nsObserverList* anObserverList;
    nsresult rv;

    if (anObserver == nsnull || aTopic == nsnull)
        return NS_ERROR_NULL_POINTER;

    rv = GetObserverList(aTopic, &anObserverList);
    if (NS_FAILED(rv)) return rv;

    return anObserverList->RemoveObserver(anObserver);
}

NS_IMETHODIMP nsObserverService::EnumerateObservers(const char* aTopic, nsISimpleEnumerator** anEnumerator)
{
    nsObserverList* anObserverList;
    nsresult rv;

    if (anEnumerator == nsnull || aTopic == nsnull)
        return NS_ERROR_NULL_POINTER;

    rv = GetObserverList(aTopic, &anObserverList);
    if (NS_FAILED(rv)) return rv;

    return anObserverList->GetObserverList(anEnumerator);
}

// Enumerate observers of aTopic and call Observe on each.
NS_IMETHODIMP nsObserverService::NotifyObservers(nsISupports *aSubject,
                                                 const char *aTopic,
                                                 const PRUnichar *someData) {
    nsresult rv = NS_OK;
#ifdef NOTIFY_GLOBAL_OBSERVERS
    nsCOMPtr<nsISimpleEnumerator> globalObservers;
#endif
    nsCOMPtr<nsISimpleEnumerator> observers;
    nsCOMPtr<nsISupports> observerRef;

#ifdef NOTIFY_GLOBAL_OBSERVERS
    EnumerateObservers("*", getter_AddRefs(globalObservers));
#endif
    rv = EnumerateObservers(aTopic, getter_AddRefs(observers));
#ifdef NOTIFY_GLOBAL_OBSERVERS
    /* If there are no global observers and we failed to get normal observers
     * then we return the error indicating failure to get normal observers.
     */
    if (!globalObservers && NS_FAILED(rv))
        return rv;
#endif

    do
    {
        PRBool more = PR_FALSE;
        /* If observers is non null then null it out unless it really
         * has more elements (i.e. that call doesn't fail).
         */
        if (observers && NS_FAILED(observers->HasMoreElements(&more)) || !more)
        {
#ifdef NOTIFY_GLOBAL_OBSERVERS
            if (observers = globalObservers) 
                globalObservers = nsnull;
#else
            observers = nsnull;
#endif
        }
        else
        {
            observers->GetNext(getter_AddRefs(observerRef));
            nsCOMPtr<nsIObserver> observer = do_QueryInterface(observerRef);
            if (observer) 
                observer->Observe(aSubject, aTopic, someData);
        }
    } while (observers);
    return NS_OK;
}
////////////////////////////////////////////////////////////////////////////////