ACE/ace/Time_Policy.h

   1 #ifndef ACE_TIME_POLICY_H
   2 #define ACE_TIME_POLICY_H
   3 // -*- C++ -*-
   4 /**
   5  *  @file Time_Policy.h
   6  *
   7  *  @author Carlos O'Ryan <coryan@atdesk.com>
   8  *  @author Martin Corino <mcorino@remedy.nl>
   9  */
  10 #include /**/ "ace/pre.h"
  11
  12 #include /**/ "ace/config-all.h"
  13
  14 #include /**/ "ace/Time_Value_T.h"
  15
  16 #if !defined (ACE_LACKS_PRAGMA_ONCE)
  17 # pragma once
  18 #endif /* ACE_LACKS_PRAGMA_ONCE */
  19
  20 ACE_BEGIN_VERSIONED_NAMESPACE_DECL
  21
  22 /**
  23  * @class ACE_System_Time_Policy
  24  *
  25  * @brief Implement the system time policy for ACE.
  26  *
  27  * The most common time policy is to simply use
  28  * ACE_OS::gettimeofday(), this class implements that policy, i.e., it
  29  * simply calls that function.
  30  */
  31 class ACE_Export ACE_System_Time_Policy
  32 {
  33 public:
  34   /// Return the current time according to this policy
  35   ACE_Time_Value_T<ACE_System_Time_Policy> operator() () const;
  36
  37   /// Noop. Just here to satisfy backwards compatibility demands.
  38   void set_gettimeofday (ACE_Time_Value (*gettimeofday)());
  39 };
  40
  41 /**
  42  * @class ACE_HR_Time_Policy
  43  *
  44  * @brief Implement a time policy based on the ACE Highres timer.
  45  */
  46 class ACE_Export ACE_HR_Time_Policy
  47 {
  48 public:
  49   /// Return the current time according to this policy
  50   ACE_Time_Value_T<ACE_HR_Time_Policy> operator() () const;
  51
  52   /// Noop. Just here to satisfy backwards compatibility demands.
  53   void set_gettimeofday (ACE_Time_Value (*gettimeofday)());
  54 };
  55
  56 /**
  57  * @class ACE_FPointer_Timer_Policy
  58  *
  59  * @brief Implement a time policy based on a function pointer.
  60  *
  61  * This time policy allows dynamic changes to the source of time by
  62  * using a function pointer.
  63  */
  64 class ACE_Export ACE_FPointer_Time_Policy
  65 {
  66 public:
  67   /**
  68    * @brief Default constructor uses ACE_OS::gettimeofday()
  69    *
  70    * ACE_T requires a default constructor that leaves the
  71    * policy in a functional state.  Therefore, a null pointer would
  72    * not be desirable, in other words, we need a non-trivial default
  73    * constructor.
  74    */
  75   ACE_FPointer_Time_Policy();
  76
  77   /**
  78    * @typedef FPtr
  79    *
  80    * Short-hand for the right type of pointer to function.
  81    */
  82   typedef ACE_Time_Value (*FPtr)();
  83
  84   /**
  85    * @brief Constructor from a pointer to function.
  86    *
  87    * Construct from a pointer to function.
  88    */
  89   ACE_FPointer_Time_Policy(FPtr f);
  90
  91   /// Return the current time according to this policy
  92   ACE_Time_Value_T<ACE_FPointer_Time_Policy> operator()() const;
  93
  94   /// Satisfy backwards compatibility demands.
  95   void set_gettimeofday (ACE_Time_Value (*gettimeofday)());
  96 private:
  97   FPtr function_;
  98 };
  99
 100 class ACE_Dynamic_Time_Policy_Base; // forward decl
 101
 102 /**
 103  * @class ACE_Delegating_Time_Policy
 104  *
 105  * @brief Implement a time policy that delegates to a dynamic
 106  *        time policy.
 107  */
 108 class ACE_Export ACE_Delegating_Time_Policy
 109 {
 110 public:
 111   ACE_Delegating_Time_Policy (ACE_Dynamic_Time_Policy_Base const * delegate = nullptr);
 112
 113   /// Return the current time according to this policy
 114   ACE_Time_Value_T<ACE_Delegating_Time_Policy> operator()() const;
 115
 116   /// Set delegate
 117   void set_delegate (ACE_Dynamic_Time_Policy_Base const * delegate);
 118
 119   ACE_Delegating_Time_Policy (const ACE_Delegating_Time_Policy&) = default;
 120   ACE_Delegating_Time_Policy (ACE_Delegating_Time_Policy&&) = default;
 121   ACE_Delegating_Time_Policy& operator = (ACE_Delegating_Time_Policy const &) = default;
 122   ACE_Delegating_Time_Policy &operator = (ACE_Delegating_Time_Policy&&)  = default;
 123
 124   /// Noop. Just here to satisfy backwards compatibility demands.
 125   void set_gettimeofday (ACE_Time_Value (*gettimeofday)());
 126 private:
 127   ACE_Dynamic_Time_Policy_Base const * delegate_;
 128 };
 129
 130 /**
 131  * @class ACE_Dynamic_Time_Policy_base
 132  *
 133  * @brief Abstract base class for dynamically loaded and/or shared
 134  *        time policies.
 135  */
 136 class ACE_Export ACE_Dynamic_Time_Policy_Base
 137 {
 138 public:
 139   virtual ~ACE_Dynamic_Time_Policy_Base ();
 140
 141   /// Return the current time according to this policy
 142   ACE_Time_Value_T<ACE_Delegating_Time_Policy> operator()() const;
 143
 144   /// Noop. Just here to satisfy backwards compatibility demands.
 145   void set_gettimeofday (ACE_Time_Value (*gettimeofday)());
 146 protected:
 147   /// Return the current time according to policy implementation.
 148   virtual ACE_Time_Value_T<ACE_Delegating_Time_Policy> gettimeofday () const = 0;
 149 };
 150
 151 /// Temporarily, for backwards compatibility reasons, this will
 152 /// be the default time policy. In time to be replaced by
 153 /// ACE_System_Time_Policy.
 154 typedef ACE_FPointer_Time_Policy ACE_Default_Time_Policy;
 155
 156 #if defined ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION_EXPORT
 157 template class ACE_Export ACE_Time_Value_T<ACE_System_Time_Policy>;
 158 template class ACE_Export ACE_Time_Value_T<ACE_HR_Time_Policy>;
 159 template class ACE_Export ACE_Time_Value_T<ACE_FPointer_Time_Policy>;
 160 template class ACE_Export ACE_Time_Value_T<ACE_Delegating_Time_Policy>;
 161 #endif /* ACE_HAS_EXPLICIT_TEMPLATE_INSTANTIATION_EXPORT */
 162
 163 ACE_END_VERSIONED_NAMESPACE_DECL
 164
 165 #if defined (__ACE_INLINE__)
 166 #include "ace/Time_Policy.inl"
 167 #endif /* __ACE_INLINE__ */
 168
 169 #include /**/ "ace/post.h"
 170 #endif /* ACE_TIME_POLICY_H */