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      1 /*
      2  * Copyright (C) 2006 Apple Computer, 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 COMPUTER, INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #ifndef Timer_h
     27 #define Timer_h
     28 
     29 #include "platform/PlatformExport.h"
     30 #include "wtf/Noncopyable.h"
     31 #include "wtf/Threading.h"
     32 #include "wtf/Vector.h"
     33 
     34 namespace WebCore {
     35 
     36 // Time intervals are all in seconds.
     37 
     38 class TimerHeapElement;
     39 
     40 class PLATFORM_EXPORT TimerBase {
     41     WTF_MAKE_NONCOPYABLE(TimerBase); WTF_MAKE_FAST_ALLOCATED;
     42 public:
     43     TimerBase();
     44     virtual ~TimerBase();
     45 
     46     void start(double nextFireInterval, double repeatInterval);
     47 
     48     void startRepeating(double repeatInterval) { start(repeatInterval, repeatInterval); }
     49     void startOneShot(double interval) { start(interval, 0); }
     50 
     51     void stop();
     52     bool isActive() const;
     53 
     54     double nextFireInterval() const;
     55     double nextUnalignedFireInterval() const;
     56     double repeatInterval() const { return m_repeatInterval; }
     57 
     58     void augmentRepeatInterval(double delta) {
     59         setNextFireTime(m_nextFireTime + delta);
     60         m_repeatInterval += delta;
     61     }
     62 
     63     void didChangeAlignmentInterval();
     64 
     65     static void fireTimersInNestedEventLoop();
     66 
     67 private:
     68     virtual void fired() = 0;
     69 
     70     virtual double alignedFireTime(double fireTime) const { return fireTime; }
     71 
     72     void checkConsistency() const;
     73     void checkHeapIndex() const;
     74 
     75     void setNextFireTime(double);
     76 
     77     bool inHeap() const { return m_heapIndex != -1; }
     78 
     79     bool hasValidHeapPosition() const;
     80     void updateHeapIfNeeded(double oldTime);
     81 
     82     void heapDecreaseKey();
     83     void heapDelete();
     84     void heapDeleteMin();
     85     void heapIncreaseKey();
     86     void heapInsert();
     87     void heapPop();
     88     void heapPopMin();
     89 
     90     Vector<TimerBase*>& timerHeap() const { ASSERT(m_cachedThreadGlobalTimerHeap); return *m_cachedThreadGlobalTimerHeap; }
     91 
     92     double m_nextFireTime; // 0 if inactive
     93     double m_unalignedNextFireTime; // m_nextFireTime not considering alignment interval
     94     double m_repeatInterval; // 0 if not repeating
     95     int m_heapIndex; // -1 if not in heap
     96     unsigned m_heapInsertionOrder; // Used to keep order among equal-fire-time timers
     97     Vector<TimerBase*>* m_cachedThreadGlobalTimerHeap;
     98 
     99 #ifndef NDEBUG
    100     ThreadIdentifier m_thread;
    101 #endif
    102 
    103     friend class ThreadTimers;
    104     friend class TimerHeapLessThanFunction;
    105     friend class TimerHeapReference;
    106 };
    107 
    108 template <typename TimerFiredClass>
    109 class Timer : public TimerBase {
    110 public:
    111     typedef void (TimerFiredClass::*TimerFiredFunction)(Timer*);
    112 
    113     Timer(TimerFiredClass* o, TimerFiredFunction f)
    114         : m_object(o), m_function(f) { }
    115 
    116 private:
    117     virtual void fired() { (m_object->*m_function)(this); }
    118 
    119     TimerFiredClass* m_object;
    120     TimerFiredFunction m_function;
    121 };
    122 
    123 inline bool TimerBase::isActive() const
    124 {
    125     ASSERT(m_thread == currentThread());
    126     return m_nextFireTime;
    127 }
    128 
    129 template <typename TimerFiredClass>
    130 class DeferrableOneShotTimer : private TimerBase {
    131 public:
    132     typedef void (TimerFiredClass::*TimerFiredFunction)(DeferrableOneShotTimer*);
    133 
    134     DeferrableOneShotTimer(TimerFiredClass* o, TimerFiredFunction f, double delay)
    135         : m_object(o)
    136         , m_function(f)
    137         , m_delay(delay)
    138         , m_shouldRestartWhenTimerFires(false)
    139     {
    140     }
    141 
    142     void restart()
    143     {
    144         // Setting this boolean is much more efficient than calling startOneShot
    145         // again, which might result in rescheduling the system timer which
    146         // can be quite expensive.
    147 
    148         if (isActive()) {
    149             m_shouldRestartWhenTimerFires = true;
    150             return;
    151         }
    152         startOneShot(m_delay);
    153     }
    154 
    155     using TimerBase::stop;
    156     using TimerBase::isActive;
    157 
    158 private:
    159     virtual void fired()
    160     {
    161         if (m_shouldRestartWhenTimerFires) {
    162             m_shouldRestartWhenTimerFires = false;
    163             startOneShot(m_delay);
    164             return;
    165         }
    166 
    167         (m_object->*m_function)(this);
    168     }
    169 
    170     TimerFiredClass* m_object;
    171     TimerFiredFunction m_function;
    172 
    173     double m_delay;
    174     bool m_shouldRestartWhenTimerFires;
    175 };
    176 
    177 }
    178 
    179 #endif
    180