Source/core/loader/Prerenderer.cpp

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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#include "config.h"
#include "core/loader/Prerenderer.h"

#include "core/dom/Document.h"
#include "core/loader/FrameLoader.h"
#include "core/loader/PrerendererClient.h"
#include "core/page/Frame.h"
#include "core/platform/PrerenderHandle.h"
#include "weborigin/ReferrerPolicy.h"
#include "weborigin/SecurityPolicy.h"

#include "wtf/PassOwnPtr.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/text/WTFString.h"

namespace WebCore {

// static
PassOwnPtr<Prerenderer> Prerenderer::create(Document* document)
{
    Prerenderer* prerenderer = new Prerenderer(document);
    prerenderer->suspendIfNeeded();
    return adoptPtr(prerenderer);
}

Prerenderer::Prerenderer(Document* document)
    : ActiveDOMObject(document)
    , m_initializedClient(false)
    , m_client(0)
{
}

Prerenderer::~Prerenderer()
{
}

PassRefPtr<PrerenderHandle> Prerenderer::render(PrerenderClient* prerenderClient, const KURL& url)
{
    // Prerenders are unlike requests in most ways (for instance, they pass down fragments, and they don't return data),
    // but they do have referrers.
    const ReferrerPolicy referrerPolicy = document()->referrerPolicy();

    if (!document()->frame())
        return 0;

    const String referrer = SecurityPolicy::generateReferrerHeader(referrerPolicy, url, document()->frame()->loader()->outgoingReferrer());

    RefPtr<PrerenderHandle> prerenderHandle = PrerenderHandle::create(prerenderClient, url, referrer, referrerPolicy);

    if (client())
        client()->willAddPrerender(prerenderHandle.get());
    prerenderHandle->add();

    m_activeHandles.append(prerenderHandle);
    return prerenderHandle;
}

void Prerenderer::stop()
{
    while (!m_activeHandles.isEmpty()) {
        RefPtr<PrerenderHandle> handle = m_activeHandles[0].release();
        m_activeHandles.remove(0);
        handle->abandon();
    }
    while (!m_suspendedHandles.isEmpty()) {
        RefPtr<PrerenderHandle> handle = m_suspendedHandles[0].release();
        m_suspendedHandles.remove(0);
        handle->abandon();
    }
}

void Prerenderer::suspend(ReasonForSuspension reason)
{
    if (reason == DocumentWillBecomeInactive) {
        while (!m_activeHandles.isEmpty()) {
            RefPtr<PrerenderHandle> handle = m_activeHandles[0].release();
            m_activeHandles.remove(0);
            handle->suspend();
            m_suspendedHandles.append(handle);
        }
    }
}

void Prerenderer::resume()
{
    while (!m_suspendedHandles.isEmpty()) {
        RefPtr<PrerenderHandle> handle = m_suspendedHandles[0].release();
        m_suspendedHandles.remove(0);
        handle->resume();
        m_activeHandles.append(handle);
    }
}

Document* Prerenderer::document()
{
    ASSERT(scriptExecutionContext()->isDocument());
    return toDocument(scriptExecutionContext());
}

PrerendererClient* Prerenderer::client()
{
    if (!m_initializedClient) {
        // We can't initialize the client in our contructor, because the platform might not have
        // provided our supplement by then.
        m_initializedClient = true;
        m_client = PrerendererClient::from(document()->page());
    }
    return m_client;
}

}