Mozilla/mozilla/modules/progress/src/nsProgressManager.cpp

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#include "nsProgressManager.h"
#include "nsTopProgressManager.h"
#include "nsSubProgressManager.h"

static NS_DEFINE_IID(kITransferListenerIID, NS_ITRANSFERLISTENER_IID);
static NS_DEFINE_IID(kISupportsIID, NS_ISUPPORTS_IID);

////////////////////////////////////////////////////////////////////////
//
// nsProgressManager
//
//

/**
 * <p>
 * This unholiness is used to keep reference counts straight for
 * all the wild and wooly ways that a progress manager can get
 * created. It recursively creates and installs progress managers,
 * walking the grid hierarchy up to the root, if necessary. Recursion
 * terminates as soon as a context is found with a progress manager
 * already installed.
 * </p>
 *
 * <p>
 * Just for posterity, there are several ways that I can think of
 * that a progress manager might be born. We need to survive all
 * of them:
 * </p>
 *
 * <ol>
 * <li>
 * A progress manager can be created in a simple window context
 * </li>
 *
 * <li>
 * A progress manager can be created in a top-level grid context,
 * which will quickly receive an <b>AllConnectionsComplete</b>
 * as soon as it reads the HTML for the frameset.
 * </li>
 *
 * <li>
 * A progress manager can be created in a child grid context, in
 * a frameset.
 * </li>
 *
 * <li>
 * A progress manager can be created in a child grid context, in
 * response to somebody clicking a link on a page in the child
 * context
 * </li>
 * </ol>
 *
 * <p>
 * In each case, we need to make sure that we properly create
 * A top-level grid context and that everything gets refcounted
 * nicely. Could be nasty situations like, I'm loading a link
 * on a left frame, and the user gets bored and clicks a link
 * in the right frame! This should take care of that, too.
 * </p>
 */

static void
pm_RecursiveEnsure(MWContext* context)
{
    if (! context)
        return;

    if (context->progressManager)
        return;

    if (context->grid_parent) {
        pm_RecursiveEnsure(context->grid_parent);
        context->progressManager =
            new nsSubProgressManager(context);
    }
    else {   
        context->progressManager =
            new nsTopProgressManager(context);
    }
}

void
nsProgressManager::Ensure(MWContext* context)
{
    pm_RecursiveEnsure(context);

    if (context->progressManager)
        context->progressManager->AddRef();
}


void
nsProgressManager::Release(MWContext* context)
{
    if (! context)
        return;

    // Note that we DO NOT set the context's progressManager
    // slot to NULL. This is due to the obscene reference
    // counting that we do: the slot will be set to NULL by
    // the progressManager's destructor.
    if (context->progressManager)
        context->progressManager->Release();
}

nsProgressManager::nsProgressManager(MWContext* context)
    : fContext(context)
{
    NS_INIT_REFCNT();
}



nsProgressManager::~nsProgressManager(void)
{
    // HERE is where we null the context's progressManager slot. We
    // wait until the progress manager is actually destroyed, because
    // there are several ways that a reference to the progress manager
    // might be held, and unfortunately, the only public way to access
    // the progress manager is through the contexts.
    if (fContext) {
        fContext->progressManager = NULL;
        fContext = NULL;
    }
}

////////////////////////////////////////////////////////////////////////

NS_IMPL_ADDREF(nsProgressManager);
NS_IMPL_RELEASE(nsProgressManager);

nsresult
nsProgressManager::QueryInterface(const nsIID& iid, void** result)
{
    if (iid.Equals(kITransferListenerIID)) {
        (*result) = (void*) ((nsITransferListener*) this);
        AddRef();
        return NS_OK;
    }
    else if (iid.Equals(kISupportsIID)) {
        (*result) = (void*) ((nsISupports*) this);
        AddRef();
        return NS_OK;
    }
    return NS_NOINTERFACE;
}