src/filters/BaseClasses/dsschedule.h

   1 //------------------------------------------------------------------------------
   2 // File: DSSchedule.h (replaces DirectX 8's schedule.h)
   3 //
   4 // Desc: DirectShow base classes.
   5 //
   6 // Copyright (c) 1996-2002 Microsoft Corporation.  All rights reserved.
   7 //------------------------------------------------------------------------------
   8
   9
  10 #ifndef __CAMSchedule__
  11 #define __CAMSchedule__
  12
  13 class CAMSchedule : private CBaseObject
  14 {
  15 public:
  16     virtual ~CAMSchedule();
  17     // ev is the event we should fire if the advise time needs re-evaluating
  18     CAMSchedule( HANDLE ev );
  19
  20     DWORD GetAdviseCount();
  21     REFERENCE_TIME GetNextAdviseTime();
  22
  23     // We need a method for derived classes to add advise packets, we return the cookie
  24     DWORD_PTR AddAdvisePacket( const REFERENCE_TIME & time1, const REFERENCE_TIME & time2, HANDLE h, BOOL periodic );
  25     // And a way to cancel
  26     HRESULT Unadvise(DWORD_PTR dwAdviseCookie);
  27
  28     // Tell us the time please, and we'll dispatch the expired events.  We return the time of the next event.
  29     // NB: The time returned will be "useless" if you start adding extra Advises.  But that's the problem of
  30     // whoever is using this helper class (typically a clock).
  31     REFERENCE_TIME Advise( const REFERENCE_TIME & rtTime );
  32
  33     // Get the event handle which will be set if advise time requires re-evaluation.
  34     HANDLE GetEvent() const { return m_ev; }
  35
  36 private:
  37     // We define the nodes that will be used in our singly linked list
  38     // of advise packets.  The list is ordered by time, with the
  39     // elements that will expire first at the front.
  40     class CAdvisePacket
  41     {
  42     public:
  43         CAdvisePacket()
  44         {}
  45
  46         CAdvisePacket * m_next;
  47         DWORD_PTR       m_dwAdviseCookie;
  48         REFERENCE_TIME  m_rtEventTime;      // Time at which event should be set
  49         REFERENCE_TIME  m_rtPeriod;         // Periodic time
  50         HANDLE          m_hNotify;          // Handle to event or semephore
  51         BOOL            m_bPeriodic;        // TRUE => Periodic event
  52
  53         CAdvisePacket( CAdvisePacket * next, LONGLONG time ) : m_next(next), m_rtEventTime(time)
  54         {}
  55
  56         void InsertAfter( CAdvisePacket * p )
  57         {
  58             p->m_next = m_next;
  59             m_next    = p;
  60         }
  61
  62         int IsZ() const // That is, is it the node that represents the end of the list
  63         { return m_next == 0; }
  64
  65         CAdvisePacket * RemoveNext()
  66         {
  67             CAdvisePacket *const next = m_next;
  68             CAdvisePacket *const new_next = next->m_next;
  69             m_next = new_next;
  70             return next;
  71         }
  72
  73         void DeleteNext()
  74         {
  75             delete RemoveNext();
  76         }
  77
  78         CAdvisePacket * Next() const
  79         {
  80             CAdvisePacket * result = m_next;
  81             if (result->IsZ()) result = 0;
  82             return result;
  83         }
  84
  85         DWORD_PTR Cookie() const
  86         { return m_dwAdviseCookie; }
  87     };
  88
  89     // Structure is:
  90     // head -> elmt1 -> elmt2 -> z -> null
  91     // So an empty list is:       head -> z -> null
  92     // Having head & z as links makes insertaion,
  93     // deletion and shunting much easier.
  94     CAdvisePacket   head, z;            // z is both a tail and a sentry
  95
  96     volatile DWORD_PTR  m_dwNextCookie;     // Strictly increasing
  97     volatile DWORD  m_dwAdviseCount;    // Number of elements on list
  98
  99     CCritSec        m_Serialize;
 100
 101     // AddAdvisePacket: adds the packet, returns the cookie (0 if failed)
 102     DWORD_PTR AddAdvisePacket( CAdvisePacket * pPacket );
 103     // Event that we should set if the packed added above will be the next to fire.
 104     const HANDLE m_ev;
 105
 106     // A Shunt is where we have changed the first element in the
 107     // list and want it re-evaluating (i.e. repositioned) in
 108     // the list.
 109     void ShuntHead();
 110
 111     // Rather than delete advise packets, we cache them for future use
 112     CAdvisePacket * m_pAdviseCache;
 113     DWORD           m_dwCacheCount;
 114     enum { dwCacheMax = 5 };             // Don't bother caching more than five
 115
 116     void Delete( CAdvisePacket * pLink );// This "Delete" will cache the Link
 117
 118 // Attributes and methods for debugging
 119 public:
 120 #ifdef DEBUG
 121     void DumpLinkedList();
 122 #else
 123     void DumpLinkedList() {}
 124 #endif
 125
 126 };
 127
 128 #endif // __CAMSchedule__