1/*
2 * Copyright (C) 2013 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#ifndef PageThrottler_h
27#define PageThrottler_h
28
29#include "Timer.h"
30
31#include <wtf/HashSet.h>
32#include <wtf/RefCounted.h>
33
34namespace WebCore {
35
36class Page;
37class PageActivityAssertionToken;
38
39class PageThrottler : public RefCounted<PageThrottler> {
40public:
41    static PassRefPtr<PageThrottler> create(Page* page)
42    {
43        return adoptRef(new PageThrottler(page));
44    }
45
46    bool shouldThrottleAnimations() const { return m_throttleState != PageNotThrottledState; }
47    bool shouldThrottleTimers() const { return m_throttleState != PageNotThrottledState; }
48
49    void setThrottled(bool);
50
51    void preventThrottling();
52    void reportInterestingEvent();
53    void allowThrottling();
54    void clearPage();
55
56    ~PageThrottler();
57
58private:
59    enum PageThrottleState {
60        PageNotThrottledState,
61        PageWaitingToThrottleState,
62        PageThrottledState
63    };
64
65    friend class PageActivityAssertionToken;
66    void addActivityToken(PageActivityAssertionToken*);
67    void removeActivityToken(PageActivityAssertionToken*);
68
69    PageThrottler(Page*);
70    void startThrottleHysteresisTimer();
71    void stopThrottleHysteresisTimer();
72    void throttleHysteresisTimerFired(Timer<PageThrottler>*);
73
74    Page* m_page;
75
76    void throttlePage();
77    void unthrottlePage();
78
79    unsigned m_activeThrottleBlockers;
80    PageThrottleState m_throttleState;
81    Timer<PageThrottler> m_throttleHysteresisTimer;
82    HashSet<PageActivityAssertionToken*> m_activityTokens;
83};
84
85}
86#endif
87