dep/ACE_wrappers/ace/Notification_Queue.h

   1 #ifndef ACE_NOTIFICATION_QUEUE_H
   2 #define ACE_NOTIFICATION_QUEUE_H
   3
   4 #include /**/ "ace/pre.h"
   5
   6 /**
   7  *  @file Notification_Queue.h
   8  *
   9  *  $Id: Notification_Queue.h 80826 2008-03-04 14:51:23Z wotte $
  10  *
  11  *  @author Carlos O'Ryan <coryan@atdesk.com>
  12  */
  13 #include "ace/Copy_Disabled.h"
  14 #include "ace/Event_Handler.h"
  15 #include "ace/Intrusive_List.h"
  16 #include "ace/Intrusive_List_Node.h"
  17 #include "ace/Unbounded_Queue.h"
  18
  19 ACE_BEGIN_VERSIONED_NAMESPACE_DECL
  20
  21 /**
  22  * @class ACE_Notification_Queue_Node
  23  *
  24  * @brief Helper class
  25  */
  26 class ACE_Export ACE_Notification_Queue_Node
  27   : public ACE_Intrusive_List_Node<ACE_Notification_Queue_Node>
  28 {
  29 public:
  30   /**
  31    * @brief Constructor
  32    */
  33   ACE_Notification_Queue_Node();
  34
  35   /**
  36    * @brief Modifier change the contained buffer
  37    */
  38   void set(ACE_Notification_Buffer const & rhs);
  39
  40   /**
  41    * @brief Accessor, fetch the contained buffer
  42    */
  43   ACE_Notification_Buffer const & get() const;
  44
  45   /**
  46    * @brief Checks if the event handler matches the purge condition
  47    */
  48   bool matches_for_purging(ACE_Event_Handler * eh) const;
  49
  50   /**
  51    * @brief Return true if clearing the mask would leave no
  52    * notifications to deliver.
  53    */
  54   bool mask_disables_all_notifications(ACE_Reactor_Mask mask);
  55
  56   /**
  57    * @brief Clear the notifications specified by @c mask
  58    */
  59   void clear_mask(ACE_Reactor_Mask mask);
  60
  61 private:
  62   ACE_Notification_Buffer contents_;
  63 };
  64
  65 /**
  66  * @class ACE_Notification_Queue
  67  *
  68  * @brief Implements a user-space queue to send Reactor notifications.
  69  *
  70  * The ACE_Reactor uses a pipe to send wake up the thread running the
  71  * event loop from other threads.  This pipe can be limited in size
  72  * under some operating systems.  For some applications, this limit
  73  * presents a problem.  A user-space notification queue is used to
  74  * overcome those limitations.  The queue tries to use as few
  75  * resources on the pipe as possible, while keeping all the data in
  76  * user space.
  77  *
  78  * This code was refactored from Select_Reactor_Base.
  79  */
  80 class ACE_Export ACE_Notification_Queue : private ACE_Copy_Disabled
  81 {
  82 public:
  83   ACE_Notification_Queue();
  84   ~ACE_Notification_Queue();
  85
  86   /**
  87    * @brief Pre-allocate resources in the queue
  88    */
  89   int open();
  90
  91   /**
  92    * @brief Release all resources in the queue
  93    */
  94   void reset();
  95
  96   /**
  97    * @brief Remove all elements in the queue matching @c eh and @c mask
  98    *
  99    * I suggest reading the documentation in ACE_Reactor to find a more
 100    * detailed description.  This is just a helper function.
 101    */
 102   int purge_pending_notifications(ACE_Event_Handler * eh,
 103                                   ACE_Reactor_Mask mask);
 104
 105   /**
 106    * @brief Add a new notification to the queue
 107    *
 108    * @return -1 on failure, 1 if a new message should be sent through
 109    * the pipe and 0 otherwise.
 110    */
 111   int push_new_notification(ACE_Notification_Buffer const & buffer);
 112
 113   /**
 114    * @brief Extract the next notification from the queue
 115    *
 116    * @return -1 on failure, 1 if a message was popped, 0 otherwise
 117    */
 118   int pop_next_notification(
 119       ACE_Notification_Buffer & current,
 120       bool & more_messages_queued,
 121       ACE_Notification_Buffer & next);
 122
 123 private:
 124   /**
 125    * @brief Allocate more memory for the queue
 126    */
 127   int allocate_more_buffers();
 128
 129 private:
 130   /// Keeps track of allocated arrays of type
 131   /// ACE_Notification_Buffer.  The idea is to amortize allocation
 132   /// costs by allocating multiple ACE_Notification_Buffer objects at
 133   /// a time.
 134   ACE_Unbounded_Queue <ACE_Notification_Queue_Node*> alloc_queue_;
 135
 136   typedef ACE_Intrusive_List<ACE_Notification_Queue_Node> Buffer_List;
 137
 138   /// Keeps track of all pending notifications.
 139   Buffer_List notify_queue_;
 140
 141   /// Keeps track of all free buffers.
 142   Buffer_List free_queue_;
 143
 144   /// Synchronization for handling of queues.
 145   ACE_SYNCH_MUTEX notify_queue_lock_;
 146 };
 147
 148 ACE_END_VERSIONED_NAMESPACE_DECL
 149
 150 #if defined (__ACE_INLINE__)
 151 #include "ace/Notification_Queue.inl"
 152 #endif /* __ACE_INLINE__ */
 153
 154 #include /**/ "ace/post.h"
 155
 156 #endif /* ACE_NOTIFICATION_QUEUE_H */